AudioCircle

Audio/Video Gear and Systems => The Vintage Circle => Topic started by: Wayner on 7 Jan 2012, 09:45 pm

Title: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 7 Jan 2012, 09:45 pm
I have been looking for a nice pair for several years now. I used to own a pair of AR-2ax and AR-5 speakers and eventually, they went away in one trade or another (audiophile disease).

So today, that very rare opportunity came to be. The AR-4x was the least expensive in the AR line, consisting of an 8" woofer and a 2.50" paper tweeter. It's smallish size (19 X 10 X 9) put it really in the "bookshelf" category and, I believe it was literally designed to be put on a bookshelf (horizontally). It should work well in my studio.

The years of manufacture were about 1965 to about 1973. It was highly praised by both Stereo Review and High Fidelity as the "best of 20" in a speaker stand-off. Many reviewers said that it sounded almost as good as the then flagship model, the AR-3.

Why is this AR the one to collect? It was the only speaker made with a cloth surround on the woofer! No foam rot to deal with. While this speaker will not crank to high heavens, it will produce very accurate musical reproductions, perhaps a rival to some of today's speakers.

I also believe that Henry Kloss worked on these (as my Advent Model 3) and I'm sure this acoustic suspension will be fun.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: rpf on 7 Jan 2012, 09:50 pm
I also owned a pair of AR5s; my first audiophile speaker. I loved the ARs and lusted after the pair of 3As a friend's father owned.

A friend has a pair of small ARs in his father's house, which he's cleaning out. Haven't gotten close enough to see which ones they are but I am going to borrow and play with them.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: WGH on 7 Jan 2012, 09:51 pm
Cool find, are you going to replace the caps since they are at least 39 years old and bring them up to spec?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: ecramer on 7 Jan 2012, 10:01 pm
nice find lets see some pictures
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 7 Jan 2012, 10:09 pm
Unless I hear signs of cap failure, no. I have the original caps in my 2 sets of Dynaco A25xl and my Advent Model 3s. I just don't really worry about stuff like that. If it ain't broke, don't fix it.

In the case of vintage Marantz stuff, if you want the value of it to go to almost zero, then replace all the original caps.

Mike Zuccaro of Audiocraftsman: (http://audiocraftsman.com/ (http://audiocraftsman.com/)) gets really pissed off when people do that. He's told me several times that for the most part, it's a waste of time. Mike has done work for me with my vintage Marantz stuff. His qualifications are staggering.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 7 Jan 2012, 11:36 pm
AR-4x was the speaker that planted the "hi-fi" bug for me. Still remember the first time hearing "Abraxas" on it. Turntable was the Dual with the "girder" style tonearm, Shure M91E cart and a Nikko 15WPC (IIRC) integrated. Older next door neighbor's setup. Been an audiophool ever since.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 7 Jan 2012, 11:51 pm
nice find lets see some pictures

They are in transit. Photos will come, as well as long listening sessions. Y'all are welcome.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: WGH on 8 Jan 2012, 12:22 am
Unless I hear signs of cap failure, no. I have the original caps in my 2 sets of Dynaco A25xl and my Advent Model 3s. I just don't really worry about stuff like that. If it ain't broke, don't fix it.

In the case of vintage Marantz stuff, if you want the value of it to go to almost zero, then replace all the original caps.

Mike Zuccaro of Audiocraftsman: (http://audiocraftsman.com/ (http://audiocraftsman.com/)) gets really pissed off when people do that. He's told me several times that for the most part, it's a waste of time. Mike has done work for me with my vintage Marantz stuff. His qualifications are staggering.

Wayner

That is good to know, now I can leave the caps in my JBL L100's alone. I just had caps on my mind because I had to rebuild my computer last week because the the capacitors on a 7 year old ASUS motherboard failed.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 8 Jan 2012, 01:16 pm
Capacitors have a fairly wide tolerance range to begin with, so I am not so concerned about the aging values changing a little. However, Wayne does bring up a good point, and that is to at least be aware that they could change in value too much. The point of that would be that the cross-over frequencies would change (lowering) and then the tweeter would try to produce sounds that are to low for it to handle. The result may be cone break-up, or at higher volumes, cone damage.

I think these ARs are from the later part of their manufacturing dates, as the cabinets are made from MDF rather then plywood as their earlier models. So, if that puts them some where around 1972 for manufacture, they are then 40 years old.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 15 Jan 2012, 11:57 pm
I have received the AR-4Xs on Saturday. While they are, in appearance, mint, there are some issues. These issues have plunged me into a rebuild. Problem number one was (as expected) a troublesome L-pad. Problem 2 was discovered when I had the box open and tested the capacitor. Way out of rating.

I hope to post some photos tomorrow, but I'm getting a crown. No, not of a kingdom, rather on a troublesome tooth.

I have repaired the L pads. I must say they are robustly built, being made with a ceramic coil section. The pads are held together by a wire bale, and after removing this, the entire innards can be gotten at. The usual culprit was the contact swipe, being very corroded. Some Deoxit-5 and some steel wool have made them shinny again.

Tomorrow, I will order 2 20mfd capacitors to replace the old ones. This speaker is rolled off at 1000 cycles. The cross-over is a simple 6db slope, with a 20mfd cap in series with the tweeter (L-pad is in between cap and tweeter as well, and a 1.2mh coil in parallel series with the woofer terminals.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 16 Jan 2012, 06:32 am
My first really nice system was a pair of AR4Xs, a Dynaco SCA-35 and a PE turntable with Shure M91ED. 1973, I think.

It was really sweet and the speakers tolerated being close to the wall, that is, they seemed genuinely to function as "bookshelf" speakers.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 07:39 am
I have received the AR-4Xs on Saturday. While they are, in appearance, mint, there are some issues. These issues have plunged me into a rebuild. Problem number one was (as expected) a troublesome L-pad. Problem 2 was discovered when I had the box open and tested the capacitor. Way out of rating.

I hope to post some photos tomorrow, but I'm getting a crown. No, not of a kingdom, rather on a troublesome tooth.

I have repaired the L pads. I must say they are robustly built, being made with a ceramic coil section. The pads are held together by a wire bale, and after removing this, the entire innards can be gotten at. The usual culprit was the contact swipe, being very corroded. Some Deoxit-5 and some steel wool have made them shinny again.

Tomorrow, I will order 2 20mfd capacitors to replace the old ones. This speaker is rolled off at 1000 cycles. The cross-over is a simple 6db slope, with a 20mfd cap in series with the tweeter (L-pad is in between cap and tweeter as well, and a 1.2mh coil in parallel with the woofer terminals.

Wayner

Are they actual L-pads? Or are they potentiometers? They often look the same and the only way you'll know for sure if they are marked, otherwise you have to use an ohmmeter.

A coil in parallel with the woofer? Doesn't seem right. A parallel crossover has the inductor in series with the woofer.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 12:58 pm
They are L-pads. L-pads are used to reduce tweeter volume, without screwing up the values of the cross-over network. It is a 15 ohm, 25 watt version. L-pads are designed for low impedance networks.

w
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 06:53 pm
They are L-pads. L-pads are used to reduce tweeter volume, without screwing up the values of the cross-over network. It is a 15 ohm, 25 watt version. L-pads are designed for low impedance networks.

w

A 15 ohm L-pad? I've never ever seen or heard of a 15 ohm L-pad. Not that it couldn't exist, but it would be a rather uncommon value. Are you sure it isn't a 15 ohm pot or rheostat? What impedance is the tweeter anyway? Now if the tweeter is 16 ohms, I'll believe in a 15 ohm L-pad, otherwise it really doesn't make sense. 16 ohms loudspeakers go way back, probably even predating stereo.

Would you happen have an original manufacturers schematic or wiring diagram for your pair of loudspeakers?

You might not care to test your L-pad, but the correct way to test it would be to disconnect it from the circuit and in place of the tweeter use a 15 ohm resistor instead. Then measure at the input tab and the common tab while rotating the L-pad knob, the impedance or in this case resistance should maintain itself at or near 15 ohms regardless of where you rotate the knob.

(http://www.audiocircle.com/image.php?id=56424)

Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 07:08 pm
They are L-pads. L-pads are used to reduce tweeter volume, without screwing up the values of the cross-over network. It is a 15 ohm, 25 watt version. L-pads are designed for low impedance networks.

w

I dug around a bit at "The Classic Speaker Pages" website. The AR-4x is listed as 8 ohms.
So why would they be using a 15 ohm L-pad on what I suspect is an 8 ohm tweeter?
Doesn't make sense, doesn't make sense.
One uses an 8 ohm L-pad with an 8 ohm tweeter.

I'd really like to see an original schematic.

If as you said previously, the inductor is in parallel with the woofer, then the impedance at that point would drop to almost nothing, maybe a few tenths of an ohm. Your typical crossover inductor has low resistance and if you paralleled a woofer with that low of resistance, you'd end up shorting the amplifier output.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 07:25 pm
I have the original wiring diagram. They are 15 ohm and they are repaired. I've restored probably 15-20 pairs of speakers in my life and I've just about seen it all, tho every make has another surprise.

If you will read my earlier post, I edited it. Of course the inductor is in series, as my brain sometimes is.

I have done lots of research on this, including other audio sites. There is plenty-o-dis-information out there.

For one, they say the cross-over is at 1200hz, but it's really even lower then that, at 1000 hz. Why AR chose a odd ball 15 ohm L-pad is beyond me, and I respect you questioning my info. I question my own info, at least until I get inside the speakers and get a good read on the cross-over.

This is the first AR I have had apart, but simple as it is, there is no way to return it to it's original condition. The capacitor is made by Industrial Cond.(uctor?) Corp out of Chicago and is a real odd duck in construction.

 (http://www.audiocircle.com/image.php?id=56425)

 (http://www.audiocircle.com/image.php?id=56426)

The schematic does match the actual.

Wayner

Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 07:33 pm
I also just found a date on the tweeter. 1970. So these babies are 42 fricken years old.........

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 07:40 pm
I have the original wiring diagram. They are 15 ohm and they are repaired. I've restored probably 15-20 pairs of speakers in my life and I've just about seen it all, tho every make has another surprise.

If you will read my earlier post, I edited it. Of course the inductor is in series, as my brain sometimes is.

I have done lots of research on this, including other audio sites. There is plenty-o-dis-information out there.

For one, they say the cross-over is at 1200hz, but it's really even lower then that, at 1000 hz. Why AR chose a odd ball 15 ohm L-pad is beyond me, and I respect you questioning my info. I question my own info, at least until I get inside the speakers and get a good read on the cross-over.

This is the first AR I have had apart, but simple as it is, there is no way to return it to it's original condition. The capacitor is made by Industrial Cond.(uctor?) Corp out of Chicago and is a real odd duck in construction.

 The schematic does match the actual.

Wayner

I can only see two terminals in the photo. Where is the yellow wire connected? It's hard to see in the picture.

Why not just use a new high grade capacitor? It would sound better than an antique capacitor.

Are you trying to restore them to original condition? Or are you maybe interested in improving them for long term listening enjoyment?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 08:15 pm
There are 3 terminals on the L-pad, it's under the wire bale. Yellow wire goes to it.

I have to change the caps, because they measure at 30mfd on one an 35.X on another. That would put the X-over down around 500hz........no good.

After talking to my fearless leader (Frank Van Alstine), he is going to send me some 10mfd, 100 volt capacitors, and I will put 2 in parallel to get the 20mfd value as the original.

I find it interesting (and I did not know this) that some types of caps will increase in value as they age (as apparently these did), and the result was a lower X-over point. I was suspect of this after some listening when I first got them. That and the L-pad conditions, are the steering mechanism to overhaul these.

AE, yes, I want to at least restore them to as new performance condition. I do not want to change any drivers or deviate from the original design. Basically, I want to make them like new again.

Wayner

Later added: Frank spoke about adhering to the capacitor voltage as being very important to maintaining the original cross-over point. I know that there are lots of folks out there peddling caps, but their voltages are like, 250, 400 or even higher. No good.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 08:28 pm
There are 3 terminals on the L-pad, it's under the wire bale. Yellow wire goes to it.

I have to change the caps, because they measure at 30mfd on one an 35.X on another. That would put the X-over down around 500hz........no good.

After talking to my fearless leader (Frank Van Alstine), he is going to send me some 10mfd, 100 volt capacitors, and I will put 2 in parallel to get the 20mfd value as the original.

I find it interesting (and I did not know this) that some types of caps will increase in value as they age (as apparently these did), and the result was a lower X-over point. I was suspect of this after some listening when I first got them. That and the L-pad conditions, are the steering mechanism to overhaul these.

AE, yes, I want to at least restore them to as new performance condition. I do not want to change any drivers or deviate from the original design. Basically, I want to make them like new again.

Wayner

I still think those aren't L-pads, but then again maybe I'm wrong. Anyway, if you do the math then 20uF at 15 ohms is 795Hz! Basically you'd be high passing the tweeter at 800Hz and you'd still have some music power for at least two octaves below 800Hz.

Why not just wire them up properly with a modern 8 ohm L-pad and some high quality film capacitors? 20uf at 8 ohms would be ~1000Hz!
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 08:42 pm
Alan, these speakers got rave reviews! Some claimed that only AR-3a bettered them and that was because of the bass output.

That is what I'm all about. It's not taking vintage gear and making it sound like stuff today, it's restoring it to it's original performance. That is what made it great in the first place, and I'd like to know why. The only way I know how to do that is to restore it to it's original intended condition, or at least as close as I can.

If I want ultra performance, I can listen to my Martin Logan speakers or my other new ones. I'll let the other guys try to improve on the old stuff, but odds are, they'll make them worse. Vintage stuff was created by some of the greatest audio minds on earth, like Henry Kloss, Saul Marantz, Edgar Villchur, David Hafler and even Frank Van Alstine is in the mix. I'm trying to restore history, not create my own. I in no way could ever match up to these guys, not for one second.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: eclein on 16 Jan 2012, 08:51 pm
Wayner go for it buddy!!!!! I'm right with you, I've heard alot of the modern day speakers and they are excellent but the vintage stuff, rebuilt, spiffed up is Toe Tapping get into it listening!!!!
 Wayner did you post pics...I haven't seen the whole thread so I'll look now but post some if you can! Thanks!! :thumb: :thumb:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 08:55 pm
Ed, the first day I got them (Saturday) I listened to them and Sunday I decided to start taking them apart. I can snap a photo or two of the drivers if you wish.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 09:07 pm
Alan, these speakers got rave reviews! Some claimed that only AR-3a bettered them and that was because of the bass output.

That is what I'm all about. It's not taking vintage gear and making it sound like stuff today, it's restoring it to it's original performance. That is what made it great in the first place, and I'd like to know why. The only way I know how to do that is to restore it to it's original intended condition, or at least as close as I can.

If I want ultra performance, I can listen to my Martin Logan speakers or my other new ones. I'll let the other guys try to improve on the old stuff, but odds are, they made them worse. Vintage stuff was created by some of the greatest audio minds on earth, like Henry Kloss, Saul Marantz, Edgar Villchur, David Hafler and even Frank Van Alstine are in the mix. I'm try to restore history, not create my own. I in no way could ever match up to these guys, not for one second.

Wayner

Well, they are yours to do with whatever you please.

But let me make this (anal) analogy, I see no reason why if someone picked up an old 70s muscle car and restored it that they couldn't hop it up even more. New wheels and tires certainly perform better than the tires of the 70s, disc brakes wouldn't hurt either, some new cams and headers and a high flow exhaust, electronic double spark ignition, and a whole bunch of other things too. It would still be a 70s muscle car, but with a hundred plus more horses under the hood.

That bit about preserving the original capacitor voltage doesn't fit into the formula, equations. You either misunderstood what he had to say about it, otherwise it's a bogus statement. A 20uf 250v cap will work just the same as a 20uf 400v cap. A 100 watt amplifier is only 28.3 volts!
I'll always choose a higher voltage cap over a marginal, borderline voltage cap. Voltages are only likely to be a problem when using electrolytics, which I just won't use in passive crossovers.

The math for capacitive reactance doesn't require a voltage value.

(http://www.audiocircle.com/image.php?id=56436)
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 09:45 pm
Did you get up on the wrong side of the bed today? It's my project, not yours. I thought some people would enjoy seeing the insides of an AR speaker.

I guess I can just stop posting.
For all the others, this thread has just died. I will no longer post any results of the project with no discuss any conclusions or results.[/]
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 16 Jan 2012, 10:14 pm
Did you get up on the wrong side of the bed today? It's my project, not yours. I thought some people would enjoy seeing the insides of an AR speaker.

I guess I can just stop posting.

For all the others, this thread has just died. I will no longer post any results of the project with no discuss any conclusions or results.
no offense, wayner, but me-thinks it might be you who woke up on the wrong side of the bed.  or, mebbe you are still asleep?   :o

best,

doug s.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 16 Jan 2012, 10:22 pm
Did you get up on the wrong side of the bed today? It's my project, not yours. I thought some people would enjoy seeing the insides of an AR speaker.

I guess I can just stop posting.

For all the others, this thread has just died. I will no longer post any results of the project with no discuss any conclusions or results.

Please keep posting, don't stop on account of me. I am thoroughly enjoying this thread. More pictures!
I really apologize if I upset you, not my intention.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 16 Jan 2012, 11:12 pm
Once again a "volunteer" you seem to stir the pot and more then one occasion. I suspect that your "stripes" need to be stripped.

 8)
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 16 Jan 2012, 11:50 pm
Once again a "volunteer" you seem to stir the pot and more then one occasion. I suspect that your "stripes" need to be stripped.

 8)
i yust call 'em as i see 'em.  i wasn't the one w/the rude incendiary post...  someone on your thread simply making helpful suggestions - which you can take or leave at your pleasure - and you rip him a new one and act like a child and say you're gonna take your ball and go home so no one can play.

i need to "have my stripes stripped"?  lol - kinda like the pot calling the kettle black. 

whatever... :roll:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: neobop on 17 Jan 2012, 02:05 am
i yust call 'em as i see 'em.  i wasn't the one w/the rude incendiary post...  someone on your thread simply making helpful suggestions - which you can take or leave at your pleasure - and you rip him a new one and act like a child and say you're gonna take your ball and go home so no one can play.

i need to "have my stripes stripped"?  lol - kinda like the pot calling the kettle black. 

whatever... :roll:

Was that post necessary? Please let it go. I know all too well how Wayner feels, whether those feelings are justified (in your mind) or not.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: neobop on 17 Jan 2012, 02:30 am
Hey Wayner,
When I was a kid I bought a bran new pr of 4Xs. They replaced another pr of speakers in my family's stereo. That consisted of a Garrard Type A, Dyna 70 and PAS-2. That was a cool stereo and we were real audiophiles - no stacking records on the Garrard.  :thumb:  The speakers were on their sides in bookshelves and had a nice sound. The acoustic suspension design lent itself to judicious use of the bass control for tonal balance.

I never took the speakers apart or had them repaired and I find your thread fascinating. Please don't let these posts distract you. BTW, I was wondering if Frank mentioned why voltage rating is important in crossover caps. The voltage rating is usually way over anything they will see and I thought it didn't matter. Keep going buddy. I'm holding my breath until further installments.
neo
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 17 Jan 2012, 05:28 am
Was that post necessary? Please let it go. I know all too well how Wayner feels, whether those feelings are justified (in your mind) or not.
?!?  you're kidding, right?  i, too, want wayner to keep posting about these - that's why i was watching the thread.  i was simply a wee bit disappointed to see him get so bent outta shape.  i agree w/wayner that he can keep 'em stock if he wishes.  but, saying he was done posting simply cuz someone has suggestions to try something different?   :scratch:  i, like you, and like ae, hope wayner settles down and keeps the info coming...

ymmv,

doug s.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 17 Jan 2012, 01:00 pm
As I understand the cap voltage problem, it is very important to select a cap that is close (but not under) the operating range the cap will be used in, for them to operate properly. Not only did Frank make this statement, but others like Mike Zuccaro have said this too. The problem wont show up in a formula, but there will be a shift in the desired cut-off frequencies, because the cap will not function (as a formula says it should), in an incorrect voltage application. I had ordered some 20mfd 250 volt caps, but Frank recommended I not use them, instead, he had some 10mfd, 100 volt that would be more appropriate for the cross-over application, using 2 in parallel to get the 20mfd rating the cross-over requires.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Quiet Earth on 17 Jan 2012, 02:51 pm
Hi Wayner,

Can you tell us how much (and what kind of) batting/insulation was inside the box? There is no batting at all in the picture you posted. Also, it looks like the sides are ply and the back is mdf. Maybe you can describe this too when you have the time.

It's not taking vintage gear and making it sound like stuff today, it's restoring it to it's original performance. That is what made it great in the first place, and I'd like to know why. The only way I know how to do that is to restore it to it's original intended condition, or at least as close as I can.

I agree.  :thumb:

Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 17 Jan 2012, 04:24 pm
The batting is the usual yellow type insulation, like it's in clumps. The entire speaker was filled with it. Where the woofer was located, there was a "cheese cloth"  type of material, that was used to keep the chunks of insulation from getting into the woofer's spider assembly. The L-pad (or what ever anyone wants to call it) may have had some failure due to that fact that insulation may have gotten inside of it. The construction is open and I saw evidence of material inside of the control. When I re-assemble, I'm going to cover the control with some cheese cloth to keep the stuff out of there.

All drivers were secured with internal steel T-nuts, rather then just wood screws holding them in. The back plate that has the level control and cross-over mounted to is 1/4" wood backing material. The existing cap is about the size of a pack of cigarettes but only about 3/8" think. It's held in place with a bracket that is rivet to the wood backplate. The coil for the woofer is mounted to this bracket with a stud and a Pal-nut type of fastener. I've decided that the old cap is going to stay in there, and I will find a new home for the new caps.

The cabinet is 3/4" MDF walnut veneer, with the veneer also on the inside. These are how my modified Dynaco A25XLs are made. I was told by the cabinet maker that this type of mdf with the veneer on booth sides is more stable to moisture attack, expansion and contraction. To that note, the seams on the cabinet are tight.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 17 Jan 2012, 06:35 pm
Tweeter:

 (http://www.audiocircle.com/image.php?id=56491)

 (http://www.audiocircle.com/image.php?id=56492)

 (http://www.audiocircle.com/image.php?id=56493)

Woofer:

 (http://www.audiocircle.com/image.php?id=56494)

 (http://www.audiocircle.com/image.php?id=56495)

Cabinet:

 (http://www.audiocircle.com/image.php?id=56496)

 (http://www.audiocircle.com/image.php?id=56497)

'ner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 18 Jan 2012, 09:17 pm
As I understand the cap voltage problem, it is very important to select a cap that is close (but not under) the operating range the cap will be used in, for them to operate properly. Not only did Frank make this statement, but others like Mike Zuccaro have said this too. The problem wont show up in a formula, but there will be a shift in the desired cut-off frequencies, because the cap will not function (as a formula says it should), in an incorrect voltage application. I had ordered some 20mfd 250 volt caps, but Frank recommended I not use them, instead, he had some 10mfd, 100 volt that would be more appropriate for the cross-over application, using 2 in parallel to get the 20mfd rating the cross-over requires.

Wayner

Sorry to interject again, but I just posted and received a reply from Frank Van Alstine.

http://www.audiocircle.com/index.php?topic=102606.msg1040686#msg1040686

By the way, that enclosure, cabinet work looks really nice. Did you re-stain or wax, polish the veneer?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 18 Jan 2012, 10:04 pm
Cabinets and drivers were original and in excellent condition, but I did lightly sand and re oil the cabinets, as I always do with my restoration projects. The only reason I sanded, is because the top has a couple of light white paint spots, and sanding took them out. Unfortunately, when you do sand on these earlier veneer cabinets, you will also discover that the manufacturer used a stain in the oil. I always used Watco medium walnut oil for refinishing. The oil may have to be applied a couple of times, left on over night and buffed out by hand the next day. It's lots of work, but brings out the wood grain quiet well. That is why they call it "hand rubbed finish".

I have also had to do minor repair work to the tweeter as the glue on the outside of the surround has let loose from the years of use. That has been re-bonded and also siliconed.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Mitsuman on 18 Jan 2012, 10:10 pm
Cabinets and drivers were original and in excellent condition, but I did lightly sand and re oil the cabinets, as I always do with my restoration projects. The only reason I sanded, is because the top has a couple of light white paint spots, and sanding took them out. Unfortunately, when you do sand on these earlier veneer cabinets, you will also discover that the manufacturer used a stain in the oil. I always used Watco medium walnut oil for refinishing. The oil may have to be applied a couple of times, left on over night and buffed out by hand the next day. It's lots of work, but brings out the wood grain quiet well. That is why they call it "hand rubbed finish".

I have also had to do minor repair work to the tweeter as the glue on the outside of the surround has let loose from the years of use. That has been re-bonded and also siliconed.

Wayner

Wayner, I didn't realize they didn't use cast baskets in the early AR's. I just assumed they would be.  :scratch: Very nice work by the way, I recently re-did some Mitsubishi 3-way monitors and I enjoyed the end result alot. :beer:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 18 Jan 2012, 10:35 pm
Cast baskets are a more recent "boutique" phenomenon, in reality more to satisfy market expectations than for much real advantage, especially for bass drivers, I think. Witness Fostex drivers.

These were probably made by CTS of Paducah Kentucky, as were 90% of all drivers in the USA. With CTS, a manufacturer could specify almost any design parameter, even with relatively low-number production runs.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Mitsuman on 18 Jan 2012, 10:40 pm
Cast baskets are a more recent "boutique" phenomenon, in reality more to satisfy market expectations than for much real advantage, especially for bass drivers, I think. Witness Fostex drivers.

These were probably made by CTS of Paducah Kentucky, as were 90% of all drivers in the USA. With CTS, a manufacturer could specify almost any design parameter, even with relatively low-number production runs.

Uh, well all of my vintage Mitsu speakers from 1974-1979 all have cast baskets so I don't think it is a recent "boutique" phenomenon.  :D
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 18 Jan 2012, 10:46 pm
Uh, well all of my vintage Mitsu speakers from 1974-1979 all have cast baskets so I don't think it is a recent "boutique" phenomenon.  :D

Yeah, I've seen some pretty old stuff that had cast frames. Can't remember the names, but bigger professional types of drivers used in studio or on stage. Cast frames for ruggedness.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 18 Jan 2012, 10:50 pm
I still maintain it was market driven, and boutique. Cast looks so much cooler than stamped that it became associated with quality, and was thus presumed to sound better. I can see the advantage of not having a large reflective area behind the cone, but a lot of drivers did pretty well with that handicap.

..and 1974 is "more" recent than the AR-4X design, if not actually "recent".  :D
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 18 Jan 2012, 10:56 pm
I still maintain it was market driven, and boutique. Cast looks so much cooler than stamped that it became associated with quality, and was thus presumed to sound better. I can see the advantage of not having a large reflective area behind the cone, but a lot of drivers did pretty well with that handicap.

..and 1974 is "more" recent than the AR-4X design, if not actually "recent".  :D

Well, just like one can conduct a "knuckle" test on an enclosure, one can also "flick" a stamped or cast woofer frame and easily hear the difference. Stamped frames kind of have a tinging, clinking sound to them. Whenever I use woofer with a stamped basket, I'll finger flick it and if it rings, I'll apply some of that peel and stick damping sheet material to the basket.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Mitsuman on 18 Jan 2012, 10:58 pm
I still maintain it was market driven, and boutique. Cast looks so much cooler than stamped that it became associated with quality, and was thus presumed to sound better. I can see the advantage of not having a large reflective area behind the cone, but a lot of drivers did pretty well with that handicap.

..and 1974 is "more" recent than the AR-4X design, if not actually "recent".  :D

All I know is that Diatone (Mitsubishi here) has used cast woofer baskets since prior to any of their speakers I own. I really think "boutique" and market driven were not as big of an influence in Japan during the 60's and 70's like we think of those terms now.

Sorry for the OT Wayner, I applaud your restoration efforts. :beer:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 18 Jan 2012, 11:10 pm
Yeah, I've seen some pretty old stuff that had cast frames. Can't remember the names, but bigger professional types of drivers used in studio or on stage. Cast frames for ruggedness.

That would be JBL or Altec Lansing.....

W
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 18 Jan 2012, 11:23 pm
Cast baskets or better yet, die-cast baskets or the use of them is probably determined by expect quantities to produce, as the tooling for one size could be quiet high, like $50,000 or more. So you would need lots of units to amortize the cost of the driver. I'm pretty sure when the AR-4x was designed (1965 +/-) cost was a huge consideration, as it was the lowest priced speaker in the AR line, selling for $51 dollars in unfinished pine, $57 dollars for oiled walnut. How do I know this? I have a 1969 catalog from Allied Radio (from Chicago), and these are listed in the there.

The thing that always impressed me with AR is that they could make some damn fine speakers and not use way expensive drivers. The frames for the rest of the series, I'm betting is made out of stamped steel baskets as well. They are not pretty, but they are functional. At one time, AR had a huge, huge share of the American speaker market, I thought I read once, something like 80%, at least in certain regions. These boys were makin' some sawdust!

Too bad they chose the awful sponge surround for the rest of their line-up. I'd love to have a pair of AR-3a's, but I'm not interested in the reconing costs, let alone the rest of the rehab.

So far I have over 20 hours in these, and I'm not done, tho close to it. I have also spent about $50 dollars on supplies for the project.

I would not recommend refurbishing to a newbie. There are lots of little things that have to be done right, to keep the whole thing from becoming land fill material. One slip, and you could easily destroy a driver that is scarce to find.

And it continues................
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 20 Jan 2012, 11:14 am
I thought some caps were coming, but apparently not, so I cannibalized another old project and found some 12mdf caps. I had some 8mfd, so that makes 20. In they went. I also covered up all the cross-over circuits before repacking the wadding, to keep the wadding out of the level control.

 (http://www.audiocircle.com/image.php?id=56618)

 (http://www.audiocircle.com/image.php?id=56619)

I had just got them in place when the bride came home. She poured herself a nice glass of wine and came down to the studio for a listen. I had the FM going, and I thought to myself that it was kind of boring, no stereo, kind of like mono.

I use 3/4" wide masking tape to mark and align speaker positions on the shelf. They are there permanently. The ARs went in the middle position, normally where the Advent Model 3s went. Well, I got up and moved each speaker outward, the width of the tape, or 3/4" over with both speakers, so now that's an inch and a half, and the wife said, we just went into stereo mode! Sure enough, the entire stage changed, and changed drastically. We had found the sweet spot.

I don't claim to fully understand what goes on here, finding the sweet spot, but it's happened with all of the speakers. One thing for sure is what I call a "pressure ridge" created by the woofers. I believe that when speakers are too close together, the air pressure created by the woofers, blocks high frequencies. Moving the speakers father apart, always seems to fix this problem.

This is another reason why I don't understand why some people put their speakers along the short wall. To me, this is so wrong in so many ways, the above reason being number one, but the short wall location also invites second and 3rd reflections, turning the listening experience into a blur.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 20 Jan 2012, 01:25 pm
Well, just like one can conduct a "knuckle" test on an enclosure, one can also "flick" a stamped or cast woofer frame and easily hear the difference. Stamped frames kind of have a tinging, clinking sound to them. Whenever I use woofer with a stamped basket, I'll finger flick it and if it rings, I'll apply some of that peel and stick damping sheet material to the basket.
Plast-i-clay on the stamped speaker baskets, as recommended by Frank Van Alstine, works probably just as well or better for a fraction of the cost. Bet it would dramatically improve the little ARs.

I'm getting a major nostalgia buzz off these btw, wayner.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 20 Jan 2012, 01:32 pm
Follow up thought, I wish acoustic suspension would make a comeback, but somewhere along the line, a port became a "must-have" selling point to John Q. Public, rather than a design approach that has advantages and drawbacks, like every design approach does. Only brand I am aware of still using this technique is NHT.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 20 Jan 2012, 03:41 pm
Plast-i-clay on the stamped speaker baskets, as recommended by Frank Van Alstine, works probably just as well or better for a fraction of the cost. Bet it would dramatically improve the little ARs.

I'm getting a major nostalgia buzz off these btw, wayner.


I have and have used non-hardening modeling clay also. I prefer the peel and stick variety simply because it is neater and looks cleaner. I buy generic sheets from Parts Express, not very expensive at all.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 20 Jan 2012, 03:47 pm
Follow up thought, I wish acoustic suspension would make a comeback, but somewhere along the line, a port became a "must-have" selling point to John Q. Public, rather than a design approach that has advantages and drawbacks, like every design approach does. Only brand I am aware of still using this technique is NHT.


The problem with "acoustic suspension" is the distortion, especially when using a small woofer. If you try and squeeze too much bass out of it at some point the distortion becomes gross distortion.

I'm not absolutely sure about their efficiency, but I'm thinking that woofers designed for acoustic suspension aren't all that efficient either, they have long throw, overhung voice coils, never a lot of turns in the gap.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 20 Jan 2012, 04:37 pm
I think the main problem with acoustic suspension speakers is a misunderstanding of the nature of the beast. They are not made to play at concert levels. If you want that, go buy some JBLs or Cerwin Vegas. They are made to produce incredible, life-like bass and an incredible sound stage at lower volume levels, with a much smaller cabinet, than is required for a ported speaker. This was Edgar Villchur's goal from the beginning.

Last night I played a couple of LPs into these speakers: Dead Can Dance-Spiritchaser and Andreas Vollenweider-White Winds. The imaging was superb and when the musical content for bass was appropriate, they actually startled me a couple of times, especially on side 3 of DCD. I have the tweeter level at about 3/4 open. Both drivers blend very well. I thought the tweeter might be a little "cheezy", but it is infact, impressive.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 20 Jan 2012, 06:07 pm
hi wayner,

congrats on a great yob w/your speakers!   :thumb:

a few questions/comments about soundstaging.  i think most folks place their speakers on the short wall because in the vast majority of cases, you will get better soundstaging - that's why so many folks do it.  if the room is too narrow, you may have sidewall reflection issues, but this can be addressed w/absorbtion at first reflection points - placing the speakers on the long wall of a wery narrow room means your back will be up against the rear wall, which is even worse, in most cases, than having speakers close to side walls.

also, when you audition your speakers, are they as shown in the pics?  that close to the rear wall?  other speakers adjacent?  unless speakers are specifically designed to be tight to the rear wall, they will always soundstage better out into the room.  and, it's been shown that having other inactive speakers nearby will negatively impact soundstaging and tone, as the inactive speakers will wibrate and add their own sound, due to excitation by the driven speakers.

ymmv,

doug s.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 20 Jan 2012, 07:51 pm
FWIW, my experience has led me to always try speakers on the long wall first, as that usually sounds best to me. I cringe whenever I see speakers close to side walls in a narrow room: I have never heard a pleasant sound yet under those circumstances - it seems as though breathing room to the sides of speakers may be more important than breathing room behind.
More off topic, I am surprised that so few speakers are specifically designed to work with wall reinforcement. Seems to me that would open up possibilities for typical home use. This also may be why the AR-4X works in that placement - sealed boxes have predictable smooth shallow roll-offs in the bass, rather than the precipitous plunge following the resonant hump of the typical reflex. The roll-off of the sealed box is more like the inverse of the wall reinforcement. Roy Allison used this to good effect in some of his designs.

As to the other speakers reacting, this can be helped a lot with shorting links across the terminals of the unused speakers. This damps the woofers' resonances.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 20 Jan 2012, 08:24 pm
As to the other speakers reacting, this can be helped a lot with shorting links across the terminals of the unused speakers. This damps the woofers' resonances.


Totally awesome suggestion, one that really works. :thumb: Wonder why I didn't think of it.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 20 Jan 2012, 08:49 pm
FWIW, my experience has led me to always try speakers on the long wall first, as that usually sounds best to me. I cringe whenever I see speakers close to side walls in a narrow room: I have never heard a pleasant sound yet under those circumstances - it seems as though breathing room to the sides of speakers may be more important than breathing room behind.
More off topic, I am surprised that so few speakers are specifically designed to work with wall reinforcement. Seems to me that would open up possibilities for typical home use. This also may be why the AR-4X works in that placement - sealed boxes have predictable smooth shallow roll-offs in the bass, rather than the precipitous plunge following the resonant hump of the typical reflex. The roll-off of the sealed box is more like the inverse of the wall reinforcement. Roy Allison used this to good effect in some of his designs.

As to the other speakers reacting, this can be helped a lot with shorting links across the terminals of the unused speakers. This damps the woofers' resonances.
yust to be clear - i am not talking about breathing room behind the speakers so much as breathing room behind the listening position.  while i agree that having speakers close to side walls is not good, ime it is preferable to having the listening position directly against the back wall.  the reflection off a wall directly behind the listening position is harder to ameliorate, imo, than reflections off side walls.  of course, experimentation is best.

and, i agree - it is surprising more speakers are not designed to work with rear-wall reinforcement.  some, tho, are specifically designed w/this in mind...

and i second the suggestion of shorting unused speaker's drivers - it seems this would help reduce unwanted output from them.

as always, ymmv...

doug s.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 20 Jan 2012, 09:30 pm
Thanks for your input. The Studio is a very small room in the lowest level of the house. At one time it was my personal recording studio. Now it serves as the vinyl room. As you may have noticed, all of my speakers in the studio are of the "bookshelf" variety. They love being on the shelf, but each one is in a very specific position, and toe-in angle(s) as they demanded it of me, to produce the huge, 3D soundstage that they do. The studio is in fact, a giant live in set of headphones, as my bride and I listen to everything in near-field. While the speakers are in slightly less then desirable positions, the near-field experience more then makes up for the situation.

Frank has been here and I think was very impressed with the sound this room produces. The lesson is that almost any room can be tamed, if you are diligent on your methodologies.

Each speaker set has it's own amplifier. One set of speakers can be set to two different amplifiers. There are 2 separate preamplifiers that can run any combination of amps. There is also a 3rd, all tube preamp, that is occasionally brought in. Each preamp has it's own phono board, and I also have an all tube AVA phono preamp, that has only one brother.

We also sport 3 FM tuners, 4 turntables and a reel-to-reel and CD recorder. Three separate dedicated branch circuits feed the rooms power and we also have LED and Incandescent dimmed lighting.

The room comfortably seats 2. In my glider, I can swivel around and have access to about 1000 albums, that are my favorite. In the next room is the other equpment room with another 3000 LPs and 4 more turntables, and some more amps, preamps, receivers and my workbench, where I build the Longhorn phono cartridges.

If there is any interaction with other non used speakers, it's not much, nor is it a problem, as the music in this room is not "blasted",nor is it necessary. We can (and do) play things rather loud at times, but for the most part, this is a very mellow and personal listening room.

The AR-4x speakers fit very well into the scheme of things.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Quiet Earth on 20 Jan 2012, 09:56 pm

I am surprised that so few speakers are specifically designed to work with wall reinforcement. Seems to me that would open up possibilities for typical home use.

Pretty sad state of affairs that something meant to be enjoyed in the home is not designed for home use anymore. If you are going to cringe about anything in this hobby, that should be it.

I personally like the side walls, but I don't use modern (trendy) speakers anymore.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: doug s. on 20 Jan 2012, 09:57 pm
sounds like a wery cool set-up, wayner.  and yes, i agree - w/nearfield listening, many otherwise "normal" acoustical issues go away...

doug s.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: eclein on 20 Jan 2012, 11:47 pm
Wayner---looks great and I'm sure it sounds great too......I have seen you refer to that Andreas V. album a few times but never was nearby my rig when I read about it....its finally playing right now...This could be the next stuff I wear out....LOL...very cool!!!! :thumb:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 21 Jan 2012, 02:35 am

The problem with "acoustic suspension" is the distortion, especially when using a small woofer. If you try and squeeze too much bass out of it at some point the distortion becomes gross distortion.

I'm not absolutely sure about their efficiency, but I'm thinking that woofers designed for acoustic suspension aren't all that efficient either, they have long throw, overhung voice coils, never a lot of turns in the gap.
?
Low distortion bass was always one of the hallmarks of good acoustic suspension designs, such as the AR line, the Advents, and the Allisons, just to name a few. Any speaker will distort badly if it is driven to its xmax. Yes, acoustic suspension woofers are theoretically less efficient; the design was impractical in the era of ten watt amplifiers. Watts were cheaper by the fifties.


Here is an excerpt from an interview with Edgar Villchur, co-inventor of the acoustic suspension design:

David Lander: You've said you turned your attention to loudspeakers because, back in the early 1950s, they were the weak link in the hi-fi component chain.

Edgar Villchur: In those days you could buy an amplifier for home use with 0.5% distortion or less, even at the frequency extremes and at full rated power. Loudspeakers showed distortion levels in the low bass of 20 to 100 times that amount. The problem was the mechanical suspension that held the cone in place. When the cone moved a large distance, the suspension would stretch. It wouldn't allow the cone to travel the full distance in response to low-frequency waveform peaks. I thought, Well, what we need is a linear restoring force, one that doesn't bind, one that allows the cone to move a large distance and brings it back elastically. That's when the light went on. This linear spring had been there all the time. The cushion of air in the cabinet was exactly the kind of spring I wanted.

Lander: So you decided to reduce the springiness of the mechanical structure and replace it with air.

Villchur: By reducing the stiffness of the mechanical cone suspensions and then reducing the size of the air cushion—which is to say, reducing the size of the cabinet. The latter is something you have to do; it won't work otherwise. You end up with a linear restoring force, radically reduced low-frequency distortion, and—as an extra dividend, not a primary dividend—a small cabinet.

Full interview at http://www.stereophile.com/interviews/105villchur

Here is a page from the Allison brochure of late 70s- early 80s vintage, for the Model Three, showing distortion levels for inputs of 2.8 watts (90 db reverberant spl), 14 watts, and 70 watts. Allison pointed out in their brochure that they had never seen this type of data published for inputs of over 20 watts, and neither have I.

(http://www.audiocircle.com/image.php?id=56669)


Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 21 Jan 2012, 07:12 am
?

So, do you think Acoustic Suspension typically has less distortion than Bass Reflex?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 21 Jan 2012, 01:51 pm
Yes. Both harmonic and phase distortion. I've owned both.
I have furnished some data to support my contention, based on a middle of the line (but well engineered) acoustic suspension speaker. Let's see some distortion plots for 70W input into your favorite phase inversion (the technically correct term for bass reflex) box. We'll see if they match the 30+yo Allison.

There have been both good and crappy acoustic suspension designs, and good and crappy vented designs. I don't know what your blanket statement was based on.

Driver and enclosure engineering have improved over the years but the laws of physics haven't.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 21 Jan 2012, 06:24 pm
Yes. Both harmonic and phase distortion. I've owned both.
I have furnished some data to support my contention, based on a middle of the line (but well engineered) acoustic suspension speaker. Let's see some distortion plots for 70W input into your favorite phase inversion (the technically correct term for bass reflex) box. We'll see if they match the 30+yo Allison.

There have been both good and crappy acoustic suspension designs, and good and crappy vented designs. I don't know what your blanket statement was based on.

Driver and enclosure engineering have improved over the years but the laws of physics haven't.

My statements are based on the obvious market trend that seems to like ever smaller and smaller loudspeakers. That is the reason there are so many bass reflex designs. Squeezing bass from as small of an enclosure as possible. Like this little teeny tiny set of desktop computer speakers that are plugged into my computer. I don't use them for music appreciation, I just have them there so I can hear whatever it is they have to say, but the darn little things are actually ported!

So, how would a 6.5 inch acoustic suspension design stack up against a 6.5 inch bass reflex design? The epitome of a two way is most often a 6.5 mid-woofer with a 1 inch tweeter in a bass reflex enclosure. I also wonder how the two would compare in the efficiency department. There must be a reason why acoustic suspension has slipped into near oblivion.

Doesn't really matter what the phase is, as long as the port output doesn't cancel the woofers output. Never really a problem with a properly designed 4th order alignment.

The more correct term which really makes sense, is Helmholtz Resonator.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 21 Jan 2012, 06:38 pm
I think acoustic suspension cabinets, as a general rule, are smaller, then ported enclosures. May not be a steadfast rule, but from my observations, it seems to be the trend, at least in the past.

My Advent Model 3's will hold their own in a shoot out (with a volume limit) with anything within it's comparative size. It has a 6 1/2" acoustic suspension woofer, and the box measures about 10 x 6.5 x 16. Surprising bass for such a small cabinet.

As another general rule, acoustic suspension speakers are less efficient then ported speakers. Just guessing, the AR-4x is probably somewhere about the 86-87 db/m/w category. It simply needs a little more nudge to get it to the same levels as, say my Dynaco A25XLs (slot loaded, 91db/m/w).

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 22 Jan 2012, 02:50 pm
My statements are based on the obvious market trend that seems to like ever smaller and smaller loudspeakers. That is the reason there are so many bass reflex designs. Squeezing bass from as small of an enclosure as possible. Like this little teeny tiny set of desktop computer speakers that are plugged into my computer. I don't use them for music appreciation, I just have them there so I can hear whatever it is they have to say, but the darn little things are actually ported!

So, how would a 6.5 inch acoustic suspension design stack up against a 6.5 inch bass reflex design? The epitome of a two way is most often a 6.5 mid-woofer with a 1 inch tweeter in a bass reflex enclosure. I also wonder how the two would compare in the efficiency department. There must be a reason why acoustic suspension has slipped into near oblivion.

Doesn't really matter what the phase is, as long as the port output doesn't cancel the woofers output. Never really a problem with a properly designed 4th order alignment.

The more correct term which really makes sense, is Helmholtz Resonator.

That seems different from the original argument, which as I understood it was that acoustic suspension fell out of favor due to high distortion levels. I wonder if Wayner is hearing high distortion from his AR's. I certainly didn't from the pair I listened to at length. It is a small 'bookshelf' model with an 8" woofer, so I wouldn't expect it to rattle windows in a big room, but a pair of Allison Ones (for example) would.

I too have seen ported computer speakers. While some are certainly legit, I have observed some with ports that are about an inch and a half deep. I haven't done the calculations to determine the resonant frequency of a one and a half inch deep port, but I have a dollar that says it's well above the bass range. It's there because people expect to see a port these days. In other words, it's there for marketing reasons, not for any acoustic reason. I am just saying that that marketing reasons have something, maybe not everything, to do with the disfavor acoustic suspension has fallen into.

Many of the speaker makers in acoustic suspension's heyday- AR, KLH, Advent and Allison come to mind- made their own drivers. Only a small handful do today and most of those are "deep end" ($$$$) boutique brands.  So most speaker companies today outsource their drivers and are basically designing the enclosure and crossover around available drivers. And when driver manufacturers gear their product line towards what sells- a driver suitable for acoustic suspension has very different characteristics than one suited for a ported box- a snowball effect ensues: fewer sealed designs>fewer suitable drivers offered>even fewer sealed designs. The speaker driver manufacturer has a mortgage to pay too.


I believe the port tube is a Helmholtz resonator and 'phase inversion'  refers to the enclosure as a whole, but I don't want to get bogged down in terminology. I just wanted to challenge the assertion that acoustic suspension=high distortion.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 22 Jan 2012, 07:30 pm


Many of the speaker makers in acoustic suspension's heyday- AR, KLH, Advent and Allison come to mind- made their own drivers. Only a small handful do today and most of those are "deep end" ($$$$) boutique brands.


My understanding is the opposite - in "the day" most speakers used drivers made by CTS (Chicago Telephone Systems) of Paducah Kentucky. This included AR and even Altec Lansing, apparently. CTS would build precisely to supplied parameters, whether defined by physical dimensions - top plate thickness, etc. - or performance criteria.
This is lifted from another site:

 Bob Gault worked for CTS which was indeed in Paducah. He split off in '66 to start Eminence. According to the Eminence website:

In 1966, Bob Gault founded what was to become the world's largest loudspeaker manufacturing company after working as an engineer for Magnavox and CTS (Chicago Telephone Supply). Ironically, Gault started Eminence hoping to maintain three 18" speakers per day, based on a commitment from Ampeg's Everett Hull. Under the leadership of Gault and most recently his son, Rob, the company's capacity has grown to over 10,000 speakers per day, employing nearly 200 people.

As I understand "the old days", as CTS started to decline a lot of the customers came over to Eminence and Bob stuck with a lot of the same vendors, hence the similarities like the Wendy's magnets. I worked there after Bob retired but he came in a couple of times a week between rounds of golf (he was a serious golfer even with both hips replaced) to check on things. He was a great guy (passed in '02) and his son is too.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 22 Jan 2012, 09:12 pm
That seems different from the original argument, which as I understood it was that acoustic suspension fell out of favor due to high distortion levels. I wonder if Wayner is hearing high distortion from his AR's. I certainly didn't from the pair I listened to at length. It is a small 'bookshelf' model with an 8" woofer, so I wouldn't expect it to rattle windows in a big room, but a pair of Allison Ones (for example) would.

I too have seen ported computer speakers. While some are certainly legit, I have observed some with ports that are about an inch and a half deep. I haven't done the calculations to determine the resonant frequency of a one and a half inch deep port, but I have a dollar that says it's well above the bass range. It's there because people expect to see a port these days. In other words, it's there for marketing reasons, not for any acoustic reason. I am just saying that that marketing reasons have something, maybe not everything, to do with the disfavor acoustic suspension has fallen into.

Many of the speaker makers in acoustic suspension's heyday- AR, KLH, Advent and Allison come to mind- made their own drivers. Only a small handful do today and most of those are "deep end" ($$$$) boutique brands.  So most speaker companies today outsource their drivers and are basically designing the enclosure and crossover around available drivers. And when driver manufacturers gear their product line towards what sells- a driver suitable for acoustic suspension has very different characteristics than one suited for a ported box- a snowball effect ensues: fewer sealed designs>fewer suitable drivers offered>even fewer sealed designs. The speaker driver manufacturer has a mortgage to pay too.


I believe the port tube is a Helmholtz resonator and 'phase inversion'  refers to the enclosure as a whole, but I don't want to get bogged down in terminology. I just wanted to challenge the assertion that acoustic suspension=high distortion.


The only real way to know at what frequency a bass reflex port is tuned, would be to run an impedance curve or close mic the port output. The port is not independent of the woofer and the enclosure, so physically measuring the port all by itself is kind of meaningless.

But I do agree with you as far as having an appearance. I've seen plastic boom box radio, enclosures with fake ports that didn't go anywhere, they were obviously there for the looks.

Try giving an acoustic suspension design some baffle step correction and see what happens to the distortion.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 22 Jan 2012, 09:42 pm

Full interview at http://www.stereophile.com/interviews/105villchur

Thanks for the link, dB - a good read. He, along with Henry Kloss, are two of my heroes in American Audio.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 22 Jan 2012, 11:35 pm
Back atcha, Russell; thanks for the history. (I am listening to my Tivoli One radio, designed by Kloss, right now.) I remember mfr literature from Allison and Advent claiming they made their own drive units. Advent woofer cones were supposed to contain ground up newspapers and felt. Allison had those unique midranges and tweeters.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 22 Jan 2012, 11:39 pm
Thanks for the link, dB - a good read. He, along with Henry Kloss, are two of my heroes in American Audio.


I think everyone already knows this, but just in case.
http://www.nytimes.com/2011/10/18/business/edgar-m-villchur-hi-fi-innovator-dies-at-94.html (http://www.nytimes.com/2011/10/18/business/edgar-m-villchur-hi-fi-innovator-dies-at-94.html)
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 23 Jan 2012, 05:00 am
Try giving an acoustic suspension design some baffle step correction and see what happens to the distortion.
Let's see some data.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 23 Jan 2012, 05:39 am
Let's see some data.


I don't have to drive a car into a telephone pole just so I can see whether or not it will smash in the bumper, grill and hood.

Do you even know why or what BSC is?

So, you take an already somewhat low efficiency woofer and then you depress, attenuate the upper bass and midrange by 3-6dB. That already inefficient woofer now has to move even farther than before bass wise, to achieve the same midrange SPL as previously. Resulting in even more distortion. Simple concept applicable to all systems employing passive BSC.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 23 Jan 2012, 02:12 pm
That's what I thought.

Yes, I do, but I don't choose to interact with someone who apparently is just looking for an argument. You have yet to put up one piece of evidence supporting your blanket statement that acoustic suspension has inherently higher distortion than bass reflex. Every response from you has seemed to be oriented around demonstrating your mastery of acronyms is better than mine. My contention (which is only that acoustic suspension does not in and of itself equate to high distortion) is based on years of extensively owning and/or listening to Allisons, ARs, Advents, and many others, as well as ported speakers of many stripes, as well as the longstanding, well-known reputation of this design for delivering low distortion bass. I have yet to determine what your position is based on despite attempting several times to find out. Your snide tone shows you are not interested in having a real discussion. Buh-bye. On 'ignore' you go; suggest you follow suit as we are apparently destined only to annoy one another.

BTW the upper bass depression  you talk about was specifically addressed by Allison in their designs 35 years ago (I thought frequency response anomalies are not the same thing as distortion, but WTF do I know, apparently not much) :

(http://www.audiocircle.com/image.php?id=56841)

Say Wayner, how are those AR-4x's working out?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Quiet Earth on 23 Jan 2012, 02:47 pm
Bass Reflex vs. Acoustic Suspension,,,, CD vs. Vinyl,,,  .... when will we outgrow these silly arguments?

 :deadhorse: :deadhorse: :deadhorse: :deadhorse: :deadhorse:


 :oops:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 23 Jan 2012, 02:51 pm
Bass Reflex vs. Acoustic Suspension,,,, CD vs. Vinyl,,,  .... when will we outgrow these silly arguments?
 :oops:
Your point is well taken, Quiet Earth. I was actually trying to have a discussion, not an argument, but it didn't quite work out. Think I'll just put on some tunes instead next time, or choose a more neutral topic, such as POLITICS...  :roll:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Quiet Earth on 23 Jan 2012, 03:34 pm
No biggie, we all get caught up in it. I am just as guilty (as charged  :D).

I can imagine that we have all heard great examples of many different speaker building techniques, so it is probably not so much of a question of which method is superior but more of a question of "how did you get that to sound so good?".

I am fascinated with the old stuff and how they got so much out of so little.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 23 Jan 2012, 04:22 pm
The ARs are fun! Spent much of Saturday afternoon listening to many good quality LPs and at my usual volume levels, they were very enjoyable. Solid bass, creamy mid-range and very detailed high end. Hard to believe that inconspicuous little driver can make nice.

I haven't put them on the Ultravalve yet, but I'll give it a week or so more so I am comfortably "learned" on how these speakers reproduce. I'm just glad to have been lucky enough to find a pair that was in this good of condition to do a restoration that would be worth while.

I just wanted to have one nice pair of ARs in the collection.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: dB Cooper on 23 Jan 2012, 04:30 pm
As I mentioned early on, the AR-4x was in the first real "hi-fi" system I ever heard and gave me my first case of "audio goosebumps." An impressive little speaker. Almost bought AR6's for my own first system but settled on original Dyna A25 instead. Probably a good thing- I believe the AR6 used foam surrounds (which would be long gone now) while my ex-brother-in-law still has my old Dynas and they still work.

I would expect droolworthy sound from these playing off the Ultravalve.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 23 Jan 2012, 05:31 pm
I certainly didn't need another pair of speakers, call me an "audio historian", or whatever else you want to (good or bad). When you grow up with this stuff, like dbcooper and others, there is an attachment, that can't be explained. I almost get teary eyed when I think about the old days.

When I was a teen, I decided to build a Dynaco PAT-4 and Stereo 120 amp, spending every night after skool soldering and assembling. I also had enough to spend on a pair of AR-2ax's.

When I had finished the Dynacos, the ARs had arrived (by train), I remember the day like it was yesterday. We went to the Willmar train depot and picked them up. When we got them home, I quickly hooked them up. Now remember, the Dynacos were freshly assembled, but not tested. Well, I turned the system on, and a big puff of smoke came out of the amp. Silence fell into the room. I was mortally wounded.

So, after I gathered my cool, I decided I must have surely wired something wrong in the amp, the preamp worked, at least with headphones. So off it went to Jensen's stereo shop, in Burnsville. Little did I know that  there would be a connection with a certain individual, nor did I know that we would meet again in different circumstances.

Well, the amp came back. I hooked it all up again, and still one speaker did not play. I switch the speakers around, and then suddenly I realized that the same speaker on the same channel that got smoked, also got fried. I was once again mortified.

So, after a call to AR, the speaker got loaded back into the car, back to Willmar and back on the train. 2 and 1/2 fricken, agonizing months goes buy, and a note comes from the Willmar depot that they had a large package for me.

Finally, and end to the shaky beginning.

I remember listening to some music that night in my bedroom. I had Crosby, Stills, Nash and Young's Deja Vu playing. My dad, actually came into the room and sat on my bed next to me and listened to a couple of songs. He said "pretty nice" and left the room. That was the only time that ever happened.

There is the AR story.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: martyo on 23 Jan 2012, 05:38 pm
Great story, thanks for sharing it with us. 8)
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Quiet Earth on 23 Jan 2012, 06:32 pm
Good times Wayner, good times!  :thumb:

Wayner's Audio Museum
Open Tuesday thru Saturday 10am - 6pm
Closed on Christmas Day
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Delta Wave on 23 Jan 2012, 06:44 pm
Excellent!  :thumb:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 23 Jan 2012, 09:34 pm
BTW the upper bass depression you talk about was specifically addressed by Allison in their designs 35 years ago (I thought frequency response anomalies are not the same thing as distortion, but WTF do I know, apparently not much)

Yes, I'm fairly familiar with the Allison placement techniques, methodology. I may have an article or two tucked away somewhere. I still have his/the original "Best Place" software on floppy diskette. If I remember correctly it was designed to run on Windows 3.11, not that I'll ever be using DOS/Windows 3.11 again. I think the last time I actually used the software was with Windows 98.

Zaph has a massive collection of distortion measurements. If you see any Acoustic Suspension woofers at his website, let me know and I can compare distortion specs. I'm not equipped to measure distortion, I have no need to invest in that sort of equipment.
I suppose one could dig up some old magazine reviews.

BSC=Baffle Step Correction. It is discussed here at AudioCircle. Has nothing to do with distortion per se, but as you drive any woofer harder and harder the distortion rises regardless of the type of woofer be it Acoustic Suspension or Bass Reflex. A bass reflex woofer has the distinct advantage of having to move less, only because the port is a major bass contributor too. Of course ports do have their limitations.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Mitsuman on 23 Jan 2012, 09:53 pm
I certainly didn't need another pair of speakers, call me an "audio historian", or whatever else you want to (good or bad). When you grow up with this stuff, like dbcooper and others, there is an attachment, that can't be explained. I almost get teary eyed when I think about the old days.

When I was a teen, I decided to build a Dynaco PAT-4 and Stereo 120 amp, spending every night after skool soldering and assembling. I also had enough to spend on a pair of AR-2ax's.

When I had finished the Dynacos, the ARs had arrived (by train), I remember the day like it was yesterday. We went to the Willmar train depot and picked them up. When we got them home, I quickly hooked them up. Now remember, the Dynacos were freshly assembled, but not tested. Well, I turned the system on, and a big puff of smoke came out of the amp. Silence fell into the room. I was mortally wounded.

So, after I gathered my cool, I decided I must have surely wired something wrong in the amp, the preamp worked, at least with headphones. So off it went to Jensen's stereo shop, in Burnsville. Little did I know that  there would be a connection with a certain individual, nor did I know that we would meet again in different circumstances.

Well, the amp came back. I hooked it all up again, and still one speaker did not play. I switch the speakers around, and then suddenly I realized that the same speaker on the same channel that got smoked, also got fried. I was once again mortified.

So, after a call to AR, the speaker got loaded back into the car, back to Willmar and back on the train. 2 and 1/2 fricken, agonizing months goes buy, and a note comes from the Willmar depot that they had a large package for me.

Finally, and end to the shaky beginning.

I remember listening to some music that night in my bedroom. I had Crosby, Stills, Nash and Young's Deja Vu playing. My dad, actually came into the room and sat on my bed next to me and listened to a couple of songs. He said "pretty nice" and left the room. That was the only time that ever happened.

There is the AR story.

Wayner

Wayner, I'm probably mis-speaking here but I share your passion for vintage gear and my impression is that nostalgia is probably lost on the newer generation. I see it in posts I read here, and in the obsession today with instant gratification and the idea that everything is disposable. I just wonder if 30 years from now, there will be a rabid group here that is restoring gear being produced today.  :scratch:

Great post and here's to you. :beer:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 23 Jan 2012, 10:21 pm
Mitsuman, I don't know what future generations will do. Perhaps, someday when I'm gone, someone will simply throw my ARs into the dumpster, along with my records and turntables. How do you you go about restoring an Ipod?

I don't know about you guys, but audio (and music) is my whole life. Perhaps that means I'm a really shallow person, getting lost on the audiophool highway.

I do occasionally remember the reason I have equipment. It's to listen to the music. While humans are busy being crappy to each other, they can some how paint a different picture with music. It's one of the few nice things we can do to (or for) each other, bridging religion, race, or political points of view.

Even if we occasionally argue in these silly blogs, we all have a common thread, and that thread is the musica.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: WGH on 24 Jan 2012, 12:53 am
I just wonder if 30 years from now, there will be a rabid group here that is restoring gear being produced today.

But of course there will be. I'll still be here extolling the virtues of my "ancient" Salk HT2-TL's. My JBL L100's are 40 years old and still sound great, wonder what the young whippersnappers will think as I blast rock and roll through 70 year old speakers? (At 93 I'll be half deaf of course and will have to blast the music just to hear it.)

Wayne 
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Delta Wave on 24 Jan 2012, 11:52 am
Mitsuman, I don't know what future generations will do. Perhaps, someday when I'm gone, someone will simply throw my ARs into the dumpster, along with my records and turntables. How do you you go about restoring an Ipod?

I don't know about you guys, but audio (and music) is my whole life. Perhaps that means I'm a really shallow person, getting lost on the audiophool highway.

I do occasionally remember the reason I have equipment. It's to listen to the music. While humans are busy being crappy to each other, they can some how paint a different picture with music. It's one of the few nice things we can do to (or for) each other, bridging religion, race, or political points of view.

Even if we occasionally argue in these silly blogs, we all have a common thread, and that thread is the musica.

Wayner

 :thumb:
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: rcag_ils on 10 Feb 2012, 01:27 am
Wayne, what year did your AR story happen?
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Russell Dawkins on 10 Feb 2012, 01:45 am
In my estimation, the AR-2ax was the prototype of the modern 3 way speaker.

I would have bought a pair if I could have afforded them at the time, but the AR-4xs which I bought instead started my father on his hi-fi trip - which culminated in a pair of Clements RT7s.

I'll never forget coming home one night soon after, shortly after he bought a pair of Koss Pro4As, to find him marveling (via headphones) at Jimi Hendrix's "Gypsy Eyes", surrounded by a veritable fog of a certain kind of smoke and grinning ear to ear. This would be 1972 and he was 60.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 10 Feb 2012, 03:13 am
I'll never forget coming home one night soon after, shortly after he bought a pair of Koss Pro4As, to find him marveling (via headphones) at Jimi Hendrix's "Gypsy Eyes", surrounded by a veritable fog of a certain kind of smoke and grinning ear to ear. This would be 1972 and he was 60.

Wonderful story.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 10 Feb 2012, 01:01 pm
Wayne, what year did your AR story happen?

I think it was 1971 or 1972.....
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: rcag_ils on 10 Feb 2012, 04:36 pm
I am wondering what Burnsville and the Jensen Stereo Shop was like back then, I don't suppose you took any picture. I have a Dyna FM-5 built by the Jensen Stereo Shop, it might have been from that era.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 10 Feb 2012, 05:14 pm
It was the nearest repair center for Dynaco at the time, so that is where it ended up.

Wayner
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: avahifi on 11 Feb 2012, 12:55 am
Jensens Stereo Shop way back then was not all that much different that Audio by Van Alstine today.  Today however, we have many years more experience and a lot more skilled and motivated electrical engineering talent, and with the same kind of small group of dedicated audio purists producing the highest quality equipment we can do. Its still fun!

Wayner is a big part of our clan here now, doing all the metal design work and more, including the Longhorn phono cartridges.  What he designs always fits perfectly. That is a far cry from the Dyna metal parts of old, which required the use of two crowbars and a metal file to fit the pieces together, assuming that the sheet metal screws did not strip out.

By the way, my first stereo system consisted of a Dual 1009 turntable, Grado cartridge, Dyna FM-3 tuner, Dyna PAS-3 preamp (I waited on this until they lost the brown plastic knobs and painted brass faceplate), two Dyna MK IV amplifiers (mono versions of the ST-70) and a pair of KLH 6 loudspeakers.  It was pretty darn good for those days.  It replaced my mono system; Heathkit 7 watt tube integrated amp, Garrard Model T turntable, Grado cartridge, and a Electro-voice 8" dual cone speaker in their Baronet folded horn cabinet (all built myself when I was in 7th grade.

Those were the days!

Regards,

Frank Van Alstine
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: rcag_ils on 11 Feb 2012, 02:55 am
Thanks for the history Frank. I was in junior high school in Roseville taking electronic. Learned how to read the resistor color band, cap and coil, how to use soldering iron, flux and all. I built a fish caller that didn't work, a handshake shocker, basically a step up transformer, and a police siren, that was kind of cool. There's where I took my first soldering class.

I didn't get into hifi until a little later.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Wayner on 11 Feb 2012, 01:01 pm
Bad Boys Rape Our Young Girls But Violet Gives Willingly...........
(black, brown, red, orange, yellow, green, blue, violet, gray and white) as I recall....

The resistor color code, put to (perhaps poor taste) poetry. I certainly didn't come up with it, this is what they taught us in school....

 :D
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: Æ on 11 Feb 2012, 06:26 pm
Bad Boys Rape Our Young Girls But Violet Gives Willingly...........
(black, brown, red, orange, yellow, green, blue, violet, gray and white) as I recall....

The resistor color code, put to (perhaps poor taste) poetry. I certainly didn't come up with it, this is what they taught us in school....

 :D

It's just another helpful mnemonic for remembering something. But I found an even better way. :lol:

(http://www.audiocircle.com/image.php?id=57814)

Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: wvabbit on 28 Feb 2012, 01:08 am
I still think those aren't L-pads, but then again maybe I'm wrong. Anyway, if you do the math then 20uF at 15 ohms is 795Hz! Basically you'd be high passing the tweeter at 800Hz and you'd still have some music power for at least two octaves below 800Hz.

Why not just wire them up properly with a modern 8 ohm L-pad and some high quality film capacitors? 20uf at 8 ohms would be ~1000Hz!
You are correct, they are rehostats sometimes called potentiometers not L pads.
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: wvabbit on 28 Feb 2012, 01:59 am
The ARs are fun! Spent much of Saturday afternoon listening to many good quality LPs and at my usual volume levels, they were very enjoyable. Solid bass, creamy mid-range and very detailed high end. Hard to believe that inconspicuous little driver can make nice.

I haven't put them on the Ultravalve yet, but I'll give it a week or so more so I am comfortably "learned" on how these speakers reproduce. I'm just glad to have been lucky enough to find a pair that was in this good of condition to do a restoration that would be worth while.

I just wanted to have one nice pair of ARs in the collection.

Wayner
Wayner, this is a great post.  I have spent many nights and weekends working on  my Ar's.  My first pair were AR6's. I had them when I was 16, I'm now 40 years older.  My goal is to collect the first generation.  I have 2's- 2a's-2AXs,-3A's-4x's-6's-7's-10PI's.  I'm looking for garage sale 5's and 8's. I have had LST-2's (should never have sold them)  and an adoptive pair of AR1's with 755s ( I vist them every now and then).  Once it bites you, it never lets go!

[Edited for Quoting error - ServerAdmin]
Title: Re: Picked up a pair of AR-4X speakers today.......
Post by: michaelhigh on 11 Apr 2012, 01:58 am
I have been looking for a nice pair for several years now. I used to own a pair of AR-2ax and AR-5 speakers and eventually, they went away in one trade or another (audiophile disease).

So today, that very rare opportunity came to be. The AR-4x was the least expensive in the AR line, consisting of an 8" woofer and a 2.50" paper tweeter. It's smallish size (19 X 10 X 9) put it really in the "bookshelf" category and, I believe it was literally designed to be put on a bookshelf (horizontally). It should work well in my studio.

The years of manufacture were about 1965 to about 1973. It was highly praised by both Stereo Review and High Fidelity as the "best of 20" in a speaker stand-off. Many reviewers said that it sounded almost as good as the then flagship model, the AR-3.

Why is this AR the one to collect? It was the only speaker made with a cloth surround on the woofer! No foam rot to deal with. While this speaker will not crank to high heavens, it will produce very accurate musical reproductions, perhaps a rival to some of today's speakers.

I also believe that Henry Kloss worked on these (as my Advent Model 3) and I'm sure this acoustic suspension will be fun.

Wayner
I LOVE mine! I usually listen to Klipsch Forte I's with a Sansui 8080DB or a Pioneer SX-838, but more and more I find myself testing CD rips and miscellaneous tasks with a pair of AR4X's and a Harman Kardon 430 Twin. Nice, warm presentation and a beauty to look at makes these oldies viable for me. I'm glad to see that yours are so satisfying and beautiful as well. :green: