Picked up a pair of AR-4X speakers today.......

0 Members and 1 Guest are viewing this topic. Read 14336 times.

Wayner

  • Full Member
  • Posts: 6758
Picked up a pair of AR-4X speakers today.......
« 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

rpf

Re: Picked up a pair of AR-4X speakers today.......
« Reply #1 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.

WGH

  • Full Member
  • Posts: 2221
  • Artwork that Opens and Closes
    • WGH Woodworking
Re: Picked up a pair of AR-4X speakers today.......
« Reply #2 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?

ecramer

  • Volunteer
  • Posts: 3114
  • In time whats deserved always get served.
Re: Picked up a pair of AR-4X speakers today.......
« Reply #3 on: 7 Jan 2012, 10:01 pm »
nice find lets see some pictures

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #4 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/) 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

dB Cooper

Re: Picked up a pair of AR-4X speakers today.......
« Reply #5 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.

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #6 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

WGH

  • Full Member
  • Posts: 2221
  • Artwork that Opens and Closes
    • WGH Woodworking
Re: Picked up a pair of AR-4X speakers today.......
« Reply #7 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/) 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.

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #8 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

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #9 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
« Last Edit: 16 Jan 2012, 01:00 pm by Wayner »

Russell Dawkins

Re: Picked up a pair of AR-4X speakers today.......
« Reply #10 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.

Æ

  • Full Member
  • Posts: 859
Re: Picked up a pair of AR-4X speakers today.......
« Reply #11 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.

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #12 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

Æ

  • Full Member
  • Posts: 859
Re: Picked up a pair of AR-4X speakers today.......
« Reply #13 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.




Æ

  • Full Member
  • Posts: 859
Re: Picked up a pair of AR-4X speakers today.......
« Reply #14 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.

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #15 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.

 

 

The schematic does match the actual.

Wayner


Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #16 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

Æ

  • Full Member
  • Posts: 859
Re: Picked up a pair of AR-4X speakers today.......
« Reply #17 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?

Wayner

  • Full Member
  • Posts: 6758
Re: Picked up a pair of AR-4X speakers today.......
« Reply #18 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.

Æ

  • Full Member
  • Posts: 859
Re: Picked up a pair of AR-4X speakers today.......
« Reply #19 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!