AudioCircle

Industry Circles => GR Research => Topic started by: aceinc on 4 Feb 2017, 04:58 am

Title: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 04:58 am
In obsessing about my next DIY project, I like the idea of an OB/dipole system. Being a penurious fellow, I don't want to spend a penny more than I must. Being an IT person I am used to "mashups."

Phase 1, buy a pair of GR-Research OB 12" woofers kits, build the W frames. Double side wall which should make the cabinet 14.5" wide.

Phase 2, buy a pair of Magnepan MMG speakers.

Phase 3, strip the base off the MMGs and build sturdy, yet attractive, mounting assembly for either the entire MMG, or just the panel/xover assembly (stripping the sides off).

Another option would be to build either the H or W cabinet and lay it sideways, and mount the MMG on top.

The impertinent question, how would this sound in comparison to the same Woofer (sub if you prefer) assembly with the NX-Otica?

It would save $300.

I am looking for insight here so all comments are welcome (even derisive laughter), What do y'all think?
Title: Re: Impertinent half serious question...
Post by: ebag4 on 4 Feb 2017, 05:04 am
I can't help with the comparisons but the first thing that sprang to mind is that the amplification requirements for those speakers are completely different.  What type of amplification are you using?

Best,
Ed
Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 05:13 am
Emotiva XPA-1s Gen 1, but the Woofers would be driven by the servo amps.
Title: Re: Impertinent half serious question...
Post by: mlundy57 on 4 Feb 2017, 06:20 am
I haven't heard the MMG's but Joemamma had a pair that Danny redid the crossovers for. Joemamma then got a pair of Wedgies which he has paired with dual 12" OB subs. He kept the Wedgies and sold the Maggies.

As I said, I haven't heard the MMGs but I do have the Wedgies and the NX-Otica MTMs, both paired with dual 12" OB subs. The Wedgies and Oticas are both exceptional speakers. There are differences but I haven't decided which one I like better. They are both that good.

That's a roundabout way explaining why I would say go for the Oticas. You won't be disappointed.

Mike
Title: Re: Impertinent half serious question...
Post by: bdp24 on 4 Feb 2017, 03:38 pm
In obsessing about my next DIY project, I like the idea of an OB/dipole system. Being a penurious fellow, I don't want to spend a penny more than I must. Being an IT person I am used to "mashups."

Phase 1, buy a pair of GR-Research OB 12" woofers kits, build the W frames. Double side wall which should make the cabinet 14.5" wide.

Phase 2, buy a pair of Magnepan MMG speakers.

Phase 3, strip the base off the MMGs and build sturdy, yet attractive, mounting assembly for either the entire MMG, or just the panel/xover assembly (stripping the sides off)

Another option would be to build either the H or W cabinet and lay it sideways, and mount the MMG on top.

The impertinent question, how would this sound in comparison to the same Woofer (sub if you prefer) assembly with the NX-Otica?

It would save $300.

I am looking for insight here so all comments are welcome (even derisive laughter), What do y'all think?

I haven't heard the NX-Otica, so can't comment on it vs. the MMG. It you decide on the MMG, however, your idea of laying a pair of OB subs on their sides and using them as stands is an interesting one (I do the same with my QUAD ESL's). The MMG benefits from being raised off the floor anyway (doing so raises the image height---the MMG is rather short for a planar speaker), and the 15" width of the double-wall W-frame (13-1/2" stock, plus 1-1/2" for two more layers of 3/4" MDF) is perfect. Danny recommends against putting speakers on top of subs (because of the sub enclosure vibrations being transferred into the speakers), but what does he know ;-)? You can isolate the speakers from the sub frames with the remarkable Townshend Audio Seismic Pods, a very sophisticated design. Not cheap, but very effective. A more economical alternative is a set of roller bearings under each speaker.

By the way, love your use of the words impertinent and penurious. A good vocabulary is a rare thing these days, what with the state of education in the good ol' U.S.A. Ya'll finished High School, didn't ya?!
Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 04:44 pm
No comment on my education. It would surprise too many folks.

As I ruminated some more I believe that making a stand for the MMGs the depth of the woofer enclosure having a base that the woofer amp could mount on might be a good choice. This would allow the MMG to stand perpendicular to the floor (upright), with the amp providing counter balance. It would change the sound of the MMG (slightly I think) as it would increase the distance the front wave would need to go to meet the rear wave.

Here is a rough drawing of the concept.


(http://www.audiocircle.com/image.php?id=157371)
Title: Re: Impertinent half serious question...
Post by: nickd on 4 Feb 2017, 04:48 pm
I owned mmg's a few years back and enjoyed the transparency. Danny's designs are WAY more dynamic in the bass, mid bass and lower mids. You will end up selling the Maggie's if rock and dynamics are in your musical wheelhouse.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 4 Feb 2017, 05:48 pm
No comment on my education. It would surprise too many folks.

As I ruminated some more I believe that making a stand for the MMGs the depth of the woofer enclosure having a base that the woofer amp could mount on might be a good choice. This would allow the MMG to stand perpendicular to the floor (upright), with the amp providing counter balance. It would change the sound of the MMG (slightly I think) as it would increase the distance the front wave would need to go to meet the rear wave.

Here is a rough drawing of the concept



(http://www.audiocircle.com/image.php?id=157371)

The front wave and rear wave meet and cancel on either side of the MMG panel. Raising it will in no way change that, but the sound will be changed for other reasons, one being the panel will no longer be loaded by the floor.
Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 06:01 pm
Raising it doesn't, but adding the sides as I drew them would. The lower part of the stand would, as I understand it, create a resonant chamber whose frequency would be determined by its dimensions as well. If the resonant chamber was deleterious to the SQ, Large-ish holes could be cut into the side to alleviate that.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 4 Feb 2017, 06:09 pm
Raising it doesn't, but adding the sides as I drew them would. The lower part of the stand would, as I understand it, create a resonant chamber whose frequency would be determined by its dimensions as well. If the resonant chamber was deleterious to the SQ, Large-ish holes could be cut into the side to alleviate that.

I don't see any mention or drawing of added sides. Is it on another thread?
Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 06:14 pm
nickd, I listen to various styles of music, including rock. These speakers would also be used for HT. The speakers I currently have, (Either KEF 105.4, or B&W 802 Matrix, right now I am using the the B&Ws) sound pretty good, but they don't have my fingerprint on them.

My center channel which I designed and built myself and could certainly use Danny's xover treatment (if he wouldn't laugh at it) has my fingerprint on it as do my Subs which include a Rythmik Audio DS1500 and my rear channel speakers.

Having never heard Maggies, I would rely on people that have, such as yourself, to describe in a way that makes sense to me what you mean by more dynamic. Towards that end, could you give me some examples of songs/music that sound better, and what you noticed?

Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 06:25 pm
Here is another (enhanced) picture.

(http://www.audiocircle.com/image.php?id=157380)
Title: Re: Impertinent half serious question...
Post by: Keithh on 4 Feb 2017, 07:44 pm
I currently have both the Wedgies and MMGs and have owned the B&W Matrix 802, which I sold a while ago. Both the MMGs and 802s are good speakers, but
the Wedgies and NX-Oticas are in a completely different class. I don't know if you have heard an OB system, but everyone that has listened to the Wedgies has thought it was by far the
best speaker they had ever heard. It is hard for me to listen to conventional speakers like the 802s after hearing an OB speaker.
The MMGs compete with $1K speakers but for only $300 more you can get the NX-Oticas which compete with the best speakers made that often cost as much as new cars.

Having heard both the Wedgies and MMGs, for me it would be quick and easy decision which to choose.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 4 Feb 2017, 09:09 pm
Here is another (enhanced) picture.

(http://www.audiocircle.com/image.php?id=157380)

Ah, I see. I believe the sides would need to come all the way to the top of the MMG's to prevent front-to-back cancellation. And I think any holes drilled in those sides would allow cancellation as well, though I may be mistaken. Best ask Danny. But if the speakers and subs are for HT use, I wouldn't consider the MMG the best choice.
Title: Re: Impertinent half serious question...
Post by: mlundy57 on 4 Feb 2017, 09:42 pm
A caution learned the hard way and after multiple phone calls to Brian at Rythmik: For the LFE (Sub Out, .1/.2) channel for HT you will need a sub(s) designed for HT use (sealed or ported). OB subs are designed for normal frequencies down to 20Hz. Do not connect an OB sub to the LFE/Sub Out connection on an AVR or Pre/Pro (or set "Subwoofer" to "none"). The high intensity infasonic (below 20Hz) frequencies (sound effects) found in the LFE track of movies (especially action movies) will cause the OB drivers to bottom out.



Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 09:50 pm
Regarding using the speakers for HT, I think of this concept as a single full range speaker, which is why I keep referring to the 12" subsystem as the woofer section.

I can and would leave the existing subs in my system for HT use. These speakers would be treated as "full range" speakers by the sound processor, and would NOT have the Sub out from the processor plugged into these, I'm hoping to get 108 DB at 1 meter from each speaker 20hz-20khz, total 111 DB for the two combined. Should be able to get 102 DB at the listening position, if I am so inclined, which should be adequate for most HT. At least for me.
Title: Re: Impertinent half serious question...
Post by: aceinc on 4 Feb 2017, 09:56 pm
My thought on the woofer section of this speaker would be a narrow range say below 100 hz. I know that the subsystem is rated above that, but I have a concern about doppler distortion. Were I to ask these little buggers to go real low, and into the low midrange I could envision problems. Without having seen it, I can imagine there is a lot of excursion as the woofers try to push the air about at low frequencies.
Title: Re: Impertinent half serious question...
Post by: mlundy57 on 4 Feb 2017, 10:09 pm
Yep, that's exactly the way to think of them, as two part full range speakers with the midrange/tweeter passive and the bass active.

With the NX-Otica MTM's I cross to the bass section @ 100Hz (the Wedgies cross @ 200Hz).
Title: Re: Impertinent half serious question...
Post by: Shakeydeal on 5 Feb 2017, 12:21 pm
I agree with some of the comments about the MMG. A friend of mine had a pair for a while, and I have owned 1.6s and 3.5rs. While the transparency and openness are addictive, maggies do have their drawbacks. An OB design with Danny's subs will give you the best of both worlds. I have Super Vs and they are as open and transparent as maggies but move way more air in the mid bass and pressurize the room like a planar cannot do.

I'm sure this will be a nice enhancement to the MMGs, but it won't fully replicate what an OB design will do.

Shakey
Title: Re: Impertinent half serious question...
Post by: THROWBACK on 5 Feb 2017, 01:30 pm
Sort of depends on the room. A friend of mine has an MMG-based system (supplemented by a single DIY woofer) in a very small room and it sounds wonderful. The Super V's are terrific, but would they sound as good in my friend's room? I dunno.
Title: Re: Impertinent half serious question...
Post by: aceinc on 5 Feb 2017, 03:56 pm
For those folks that have had, or been up close & personal with the MMGs, does my Idea for a stand in the crude drawings above seem feasible?

Some of the Magnepan speakers had/have wood rails that go up the side, that could be removed and replaced with this sort of stand.

My thought would be to screw it from the side. Worst case scenario would be to have an inset with velcro stapled to the inset and the MMG.
Title: Re: Impertinent half serious question...
Post by: nrenter on 5 Feb 2017, 10:06 pm
I think Danny worked on a design that augmented the MMGs (or was it the 1.7s...or 1.6 back in the day).
Title: Re: Impertinent half serious question...
Post by: aceinc on 6 Feb 2017, 04:54 am
This is an off topic ramble, but since I started the thread, I guess it's OK.

Yesterday I took the time to recalibrate my subs, move the B&W 802 Matrixes (Matrices?) in so the front baffle is 3 feet in from the front wall. I then reran the Dirac LE that came with my Emotiva XMC-1.

Then I sat down and listened/watched a concert video, "JEFF BECK ~ Live at Ronnie Scott's" that I have on Blu-ray. I didn't listen at quite live performance levels, but the lights on my XPA-1s were dancing half way through most of it. My wife came home during the first encore, and sat and listened to it. Her main comment (she is not an R&B fan), was she felt like she was in the audience, a high compliment indeed.

I must admit that I really do like a well recorded multi-channel performance. I know for some that is heresy. Speaking of heresy, here is one of my musical journey experiences;

I had a rabid two channel analog evangelist try to convert me once. I went to his shop looking to listen to a pair of "Eminent Technology LFT-8B speakers." I literally called him up and made an appointment just to listen to those specific speakers that he was/is a dealer for. I arrive at the proscribed time and he leads me into his listening room, he has laid on the floor some massive tube mono blocks, and a pair of unassuming small tower speakers, he proudly identified all of the equipment with Mfr. & Model. He had a turntable with what looked like a 8" high translucent platter as the music source. If I had to guess probably $20-$30,000 worth of equipment, maybe more (he may have been using multi-thousand dollar interconnects and wires for all I know). He has me sit in the sweet spot, and proceeds to tell me "You are about to have an auditory epiphany."

It didn't happen, I mean the sound was good and all, but I felt like it wasn't better than the KEF 105.4s attached to the Emotiva rig I had at home. When I uttered this blasphemy, things went down hill in a hurry. He was incensed, he started talking about how digital media slices and dices the music, and that the bits and pieces they take out is what makes the music. Not to mention solid state amps kill whatever is left of the music. All the while I am listening to the slightest of pops and hisses from his vaunted analog system.What seemed to really set him off was when I told him I enjoyed listening to some multi channel music. It was like I had kicked his dog. He almost started sputtering as he explained that when you go to a concert all the music comes from the stage. I did mention, "That yes the music came from the stage but you're listening room doesn't have the acoustics of the hall it was recorded in, so you are losing the ambiance of the venue." I think he walked out of the room at that point to have a drink, not wanting to deal with a Philistine.

I guess I need to learn to shut up sometimes. He had the LFT-8Bs against the back wall with a layer of dust on them, which I never got to hear.  I would still like to hear them.

Since then, I have stayed away from high end stereo stores mostly. I buy or make things, try them and if they are good they stay, otherwise they go.

How does this apply to my thread? Rather tangentially, if at all. Since then I have had the chance to listen to some Martin Logans, and they sounded good, but without anything to directly compare it to, I wasn't blown away. I really want to get a listen to a full dipole system and even thought about going out to Linkwitz's cottage to stay for a few days. However building this system seems like it would cost about the same, and when I am done I would know if they sound good in my room.

At this point I am fairly certain I will build the "W" frame subs and buy a pair of MMGs. With their 60 day home trial, plus they seem to hold their value so I could "upgrade" later to the NX-Otica.

BTW, I am aware that this story says as much about me, the protagonist, as it does about the stereo shop owner. It may be true that I am tone deaf Philistine.
Title: Re: Impertinent half serious question...
Post by: mlundy57 on 6 Feb 2017, 05:17 am
Check out AIX records. They record in multi-channel 24/196 PCM. All discs also include 2 channel mixes. When you buy a disc you can also get the hi-Rez digital download for no additional charge.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 6 Feb 2017, 09:32 am
Good story Ace. High end dealers tend to be really opinionated, thinking their way is the only way. I've seen them be insulting, condescending, and downright rude. Surround sound is an absolute no-no with them, even though the original subjective reviewer (and founder of Stereophile) J. Gordon Holt was enthusiastic about the format. The only thing to do is walk away, and look for a better dealer or other enthusiasts who live in your area.

The dealer may have not played you the ET LFT-8b's because they have a smaller dealer margin than other brands. If you can find a used pair, they are a great value at around $1500. They also work particularly well with the OB/Dipole Sub, as do the MMG's. Either speaker with a pair of the subs will punch way above their weight class!
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 6 Feb 2017, 02:20 pm
There is a way to make the servo subs work under the MMG's. And the MMG's can be significantly upgraded as well. Here is a thread on the upgrade: http://www.audiocircle.com/index.php?topic=141550.msg1517919#msg1517919  It stock form they were rather dull. And they do need a lot of power.

Comparing these to the NX-Otica is not much of a comparison as some have already mentioned. They really are in a different class across the board.
Title: Re: Impertinent half serious question...
Post by: aceinc on 6 Feb 2017, 11:59 pm
I called Magnepan today about the MMG. An interesting conversation. The fellow I talked with seemed to indicate he was an engineer, I don't remember his name but is it possible I was speaking with a principal of Magnepan? At any rate the conversation was basically to upsell me to a .7, as the MMG was too slow for an OB woofer system. Then he said "You should also get a line array tweeter in addition to the .7."  When I added up the numbers he said, "You really should scrap the OB woofer system and just buy the 1.7s."

During the conversation I asked whether there was any more definitive specifications to be had regarding their speakers. I would like to see what I get if I chose the .7 instead of MMG. I was told "People aren't interested in specifications and the technical aspects of the speaker, they just go to a dealer, listen, fall in love and buy it." He followed it with "It is an emotional decision." I laughingly indicated  "You just said I was not in the set of 'people.'" He did not disagree.

He said "I am here all alone", and asked if "I could call back later?" I asked "Do you have any forums, are other methods where I could get more info about your products?" He said "No, we prefer people call." I don't think he got the irony of the juxtaposition of his last two statements.

I guess I have a bad attitude.

So maybe MMGs aren't for me.
Title: Re: Impertinent half serious question...
Post by: Jonathon Janusz on 7 Feb 2017, 01:32 am
Ace, it isn't just you.  I've learned the hard way that Magnepan just has a very particular way in which they market and sell their products, that could be considered (my words) a little behind the times, but it has (and continues to) work well for them and their business, so I can't really argue with success.  Some folks just prefer to do business over the phone or face to face, no matter how odd that may sound depending on situational context.  Not that I am promoting (or condemning) their products, but try not to judge the product by the sales pitch.  Magnepan makes a darn good speaker at a very reasonable price that does some things very well and that also happens to have a lot of upside potential for folks who like to tinker, tweak, mod, and upgrade - very much the kind of speaker that fits well in Danny's wheelhouse.

All that said, if you are looking for more technical information online about Magnepans, head over to the planar circle here on AC; there are a lot of people with literally decades worth of experience dissecting them to figure out what makes them tick in their stock form, and many are happy to share this information with folks looking to learn more about them.

Now, all of the above said, if you are looking for a DIY project and considering OB designs, if I had to choose between anything below a 3.7 maggie and Danny's n-xotica kit, having heard the super-7 and knowing how I loves me my lower midrange, if I had the room for OB speakers in my living space I would be ordering one of Danny's kits and the OB servo subs to go with them.  In my experience, entry level maggies give you a lot of speaker for the money; Danny's designs deliver a stupid amount of speaker for the money.

Best of luck in your search for your next project!
Title: Re: Impertinent half serious question...
Post by: Shakeydeal on 7 Feb 2017, 11:54 am
Ace,

Here is a very good forum for discussion of all things planar. Back when I was in the maggie camp, I spent a lot of time there. Should be helpful for you.

Shakey

http://www.audioasylum.com/forums/MUG/bbs.html (http://www.audioasylum.com/forums/MUG/bbs.html)
Title: Re: Impertinent half serious question...
Post by: aceinc on 7 Feb 2017, 04:38 pm
Ace, it isn't just you.  I've learned the hard way that Magnepan just has a very particular way in which they market and sell their products, that could be considered (my words) a little behind the times, but it has (and continues to) work well for them and their business, so I can't really argue with success.  Some folks just prefer to do business over the phone or face to face, no matter how odd that may sound depending on situational context.  Not that I am promoting (or condemning) their products, but try not to judge the product by the sales pitch.  Magnepan makes a darn good speaker at a very reasonable price that does some things very well and that also happens to have a lot of upside potential for folks who like to tinker, tweak, mod, and upgrade - very much the kind of speaker that fits well in Danny's wheelhouse.

All that said, if you are looking for more technical information online about Magnepans, head over to the planar circle here on AC; there are a lot of people with literally decades worth of experience dissecting them to figure out what makes them tick in their stock form, and many are happy to share this information with folks looking to learn more about them.

Now, all of the above said, if you are looking for a DIY project and considering OB designs, if I had to choose between anything below a 3.7 maggie and Danny's n-xotica kit, having heard the super-7 and knowing how I loves me my lower midrange, if I had the room for OB speakers in my living space I would be ordering one of Danny's kits and the OB servo subs to go with them.  In my experience, entry level maggies give you a lot of speaker for the money; Danny's designs deliver a stupid amount of speaker for the money.

Best of luck in your search for your next project!

I like the fact that I can pick up the phone and talk to someone. I don't like that they are using the MMG as a loss-leader/bait & switch product. I will review the site mentioned.
Title: Re: Impertinent half serious question...
Post by: Beardy on 7 Feb 2017, 07:18 pm
context: not an educated listener...
I can sympathize but I would note that MMGs are really quite good for the money.  That said my daughter and I built a set of LS classic kits from Danny and I have been very impressed, so perhaps more accurately (and for me, my opinion; normal disclaimers etc...), the MMGs are good compared to most other offerings at that price.  I don't think they are intentionally `bait and switch' but they maybe loss leaders to get people to see what they are missing.  For that reason alone I am grateful...

I went through a similar process and got MMGs on their trial program and it opened my eyes to what I was missing and immediately wanted more.  I thought along the same lines as your proposal but then bought a set of used 1.6QRs and built a pair of Phoenix dipole subwoofers each two 12 inch peerless drivers and driven by an emotiva amp.  They run off a single OPPO sub-output so unfortunately are not L&R.

The sound is good to my ears (disclaimer...), but I have an issue with the lack of imaging and localization; single vocalists sound like they have the mouth of a whale.

In the process of playing around with the kit from Danny I bought a miniwatt and HifimeDIY sabre DAC and ended up with a nice budget system/learning experience for my daughter.  Unfortunately I also gained a yearning to go to a more efficient set of speakers and a tube amp.  Again I thought about rebuilding a set of magnepans and biamping with a tube amp to capture the highs and a more cost effective amp for the bulk of the power, but I can't get away from the other issues of these planars.  Maybe its just me, but the current plan is a MP301 and a set of MTMs (when Danny gets the price up) and then later swap out the W subs for some servos (from Danny).

PS. glad to hear its not just me....
:o)
Beardy
Title: Re: Impertinent half serious question...
Post by: josh358 on 8 Feb 2017, 04:43 am
I like the fact that I can pick up the phone and talk to someone. I don't like that they are using the MMG as a loss-leader/bait & switch product. I will review the site mentioned.
Knowing the people at Magnepan as I do I can tell you that they aren't doing bait and switch. They have much too much integrity for that. They're perfectly open about the fact that the purpose of the MMG is to introduce people to the Magnepan sound knowing that some of them will move up to a larger model. And the basic reason behind that as I understand it is that with the shrinkage of the high end dealer network, fewer people have the opportunity to hear their speakers -- and it's the sound that sells them. But there's no bait and switch. The MMG's are one of audio's best bargains and I know Wendell (their director of sales, who you probably spoke to) well enough to know that he'll only suggest what he thinks is right for the customer, even if that means telling the customer to get a *smaller* model. As it happens, and having used MMG's as well as larger Maggies in a home theater system, I also agree with him that the 1.7's would be a better match for what you want to do (as I said in my post on the Asylum).

By the way, running wings up to the top of the MMG's as in your other post isn't necessary and won't work. You'll be putting an organ pipe on your midrange! And changing the tonal balance by increasing effective baffle width as well, they take dipole cancellation into account when they tune the drivers. If you put the speakers on top of the OB woofers all you'll need is the W-frame baffle. You don't want to cut holes in the side of it either. As I said on the Asylum, it seems to me that you'd be better off keeping the woofers separate so you can position them for optimum bass and also to reduce vibration in the panels and the possibility that the woofer baffle's resonance will color the midrange.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 8 Feb 2017, 08:09 pm
All real good points Josh, especially about the wings. My Eminent Technology LFT-4's came with wings from the factory, but the speaker was voiced with them in place, unlike the MMG. I think the op still doesn't understand that front-to-back cancellation can NOT be achieved by running wings only halfway up the sides of the MMG. But your point is even more important, Josh---it should not be done! F-t-b cancellation will then become frequency related, changing not just the SPL output capability of the speaker, but it's frequency response as well.

Now, Danny's MMG mod doesn't just haphazardly change the speakers fr, it corrects it's non-linearity, improving the speakers response. THAT'S the right approach to take imo.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 8 Feb 2017, 08:54 pm
I was getting some dipping in the response down low with the MMG's in my listening room. It was centered around 140Hz or so. So I tried some make shift wings to see if it would correct the dipped area, but it did not. It really had no positive effect. I think the response dip that I was getting had to be caused by a floor or room related reflection.
Title: Re: Impertinent half serious question...
Post by: josh358 on 8 Feb 2017, 11:27 pm
I tried a single wing once, oriented laterally to extend the baffle. It just ended up sounding muddy. Some people put wings just near the bottom where the lowest frequency resonant sections are and where they don't interfere with the mids as much.

I've seen those dips in other MMG midbass measurements and I think you're right that they're caused by cancellation from the wall reflection of the backwave. If they were 4' out from the wall the total path length from speaker to wall and back again would correspond to one cycle at 140 Hz. And since it's a total null there's no easy way to fix it. I'm thinking that a bass trap would work, or maybe using a DWM for fill?
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 9 Feb 2017, 02:50 am
I tried a single wing once, oriented laterally to extend the baffle. It just ended up sounding muddy. Some people put wings just near the bottom where the lowest frequency resonant sections are and where they don't interfere with the mids as much.

I've seen those dips in other MMG midbass measurements and I think you're right that they're caused by cancellation from the wall reflection of the backwave. If they were 4' out from the wall the total path length from speaker to wall and back again would correspond to one cycle at 140 Hz. And since it's a total null there's no easy way to fix it. I'm thinking that a bass trap would work, or maybe using a DWM for fill?

It was about six feet or more out into the room for the measurements. I didn't see it with any of our other open baffle designs. So it kind of puzzled me. And our room here at GR Research has a pretty well treated front wall.

I tried the wing extending back (90 degrees to the front baffle) and on the mid side. It just didn't change it too much.
Title: Re: Impertinent half serious question...
Post by: josh358 on 9 Feb 2017, 03:07 pm
That's interesting. The curves in Dick Olsher's review also show a dip above 100 Hz, though not at precisely the same frequency.

Near field (1 meter):

(http://www.audiocircle.com/image.php?id=157623)

Far field:

(http://www.audiocircle.com/image.php?id=157624)

So maybe it is intrinsic to the speaker after all? You'd really need some outdoor measurements to be sure. But it seems to me it could have something to do with the acoustic equalization. The resonant sections in the left and right speakers are asymmetrical because there isn't enough diaphragm area to do complete acoustical dipole equalization in one speaker. So it may be that the left and the right speakers have dips in different and complementary locations?
Title: Re: Impertinent half serious question...
Post by: aceinc on 9 Feb 2017, 05:17 pm
Here is one person's subjective analysis when playing with wings.

http://www.integracoustics.com/MUG/MUG/tweaks/wings/mike.html

This is based on a 1.6, wonder if it holds true on an MMG?

I definitely agree (I assume that I am OP) that I lack knowledge, but that is what I am here for.
Title: Re: Impertinent half serious question...
Post by: Shakeydeal on 9 Feb 2017, 05:46 pm
I found that upgrading the xover on the 1.6 went a long way towards improving bass response and definition. I'm sure on a smaller scale, the same would hold true for the MMG. It was hard to listen to a stock 1.6 after living with the upgraded pair for a while.

Shakey
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 9 Feb 2017, 05:53 pm
I found that upgrading the xover on the 1.6 went a long way towards improving bass response and definition. I'm sure on a smaller scale, the same would hold true for the MMG. It was hard to listen to a stock 1.6 after living with the upgraded pair for a while.

Shakey

I felt the same way after upgrading the MMG.
Title: Re: Impertinent half serious question...
Post by: josh358 on 9 Feb 2017, 08:07 pm
Here is one person's subjective analysis when playing with wings.

http://www.integracoustics.com/MUG/MUG/tweaks/wings/mike.html

This is based on a 1.6, wonder if it holds true on an MMG?

I definitely agree (I assume that I am OP) that I lack knowledge, but that is what I am here for.
I'm sure it's true of the MMG as well, in fact, I read that very post a few years ago and it's one of the reasons I said what I did. I think his principles are good ones -- keep the wing low, use it on only one side to minimize the organ pipe resonance, and keep it away from the tweeter side.

You'll also sometimes see a single wing running the full length of the speaker, as on the woofer side of the Martin Logan CLX:

https://www.martinlogan.com/clxart/gallery.php

Note the way they've tapered it to reduce resonances.

In terms of frequency response, you have to watch out for the response issues that BDP mentioned. The larger the effective baffle size, the lower the frequency at which the bass response starts to roll off at 6 dB/octave. So when you add a wing, you're lowering that point. The diaphragm of a planar is tuned to compensate for the 6 dB/octave rolloff of the baffle. So when you extend baffle width, you start to get too much bass. So I think you have to experiment a bit.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 9 Feb 2017, 08:09 pm
Here is one person's subjective analysis when playing with wings.

http://www.integracoustics.com/MUG/MUG/tweaks/wings/mike.html

This is based on a 1.6, wonder if it holds true on an MMG?

I definitely agree (I assume that I am OP) that I lack knowledge, but that is what I am here for.

No offense intended! We are all here to pick each others brains, especially Danny's!
Title: Re: Impertinent half serious question...
Post by: aceinc on 9 Feb 2017, 10:40 pm
Takes more than that to offend me.

My dad used to tell me that I was too ignorant to be offended.
Title: Re: Impertinent half serious question...
Post by: aceinc on 9 Feb 2017, 10:43 pm
Danny, what is the lead time on shipping the 12" OB sub kits? Two of them.

I was thinking about making some sawdust this weekend. If I order the kits on Monday would I have them by Friday of next week?
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 10 Feb 2017, 12:00 am
Danny, what is the lead time on shipping the 12" OB sub kits? Two of them.

I was thinking about making some sawdust this weekend. If I order the kits on Monday would I have them by Friday of next week?

I ship the day you order unless you order late in the day.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 10 Feb 2017, 12:28 am
Takes more than that to offend me.

My dad used to tell me that I was too ignorant to be offended.

Ha, good one! Are you going to make W-frames, or H?
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 03:43 am
"W" frames, bought the MDF at HD tonight. Had them rip the MDF into strips one 13", two 13.5" and two 15-1/8" wide.

I have a sliding compound miter saw, that I should be able to do the other cuts with. Since I can't easily dado anything I will probably screw and glue the inner cabinet and finish nail and glue the outer cabinet.

The 15-1/8" pieces are for the outer cabinet to give me a 13/16" overhang on the front & the back for a grill cloth frame. Hopefully that additional distance won't cause any issues with SQ.

On another note;

Someone locally has a large (16'x6') CNC router for $4,700, I am very tempted, but I can't really justify it. If anyone in my area wants to get in the business part time, I have the space and the cash, but not the time to do the work. Well, there would be a learning curve for me as well.
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 03:56 am
On a mostly unrelated topic, what is the consensus opinion of an L-Pad vs a fixed resistor SQ wise?

Since I have a tenuous grasp (at best) on what I am doing when designing a crossover network, I tend to use L-Pads in the circuit to balance things out. This also has to do with my lack of test equipment.

Is this OK?

Is this reasonable for testing and then measure the resistance and replace with a fixed value resistor?

If everything is more or less equal, I would leave the L-Pad in there for playing when I get the speaker into the room.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 10 Feb 2017, 04:16 am
On a mostly unrelated topic, what is the consensus opinion of an L-Pad vs a fixed resistor SQ wise?

Since I have a tenuous grasp (at best) on what I am doing when designing a crossover network, I tend to use L-Pads in the circuit to balance things out. This also has to do with my lack of test equipment.

Is this OK?

Is this reasonable for testing and then measure the resistance and replace with a fixed value resistor?

If everything is more or less equal, I would leave the L-Pad in there for playing when I get the speaker into the room.

There are different reasons for both, and nothing wrong with having a properly implemented L-pad in a circuit.

I don't recommend designing the crossover based on electrical parameters or resistance levels. They really have to be designed based on acoustic output.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 10 Feb 2017, 06:23 am
On a mostly unrelated topic, what is the consensus opinion of an L-Pad vs a fixed resistor SQ wise?

Since I have a tenuous grasp (at best) on what I am doing when designing a crossover network, I tend to use L-Pads in the circuit to balance things out. This also has to do with my lack of test equipment.

Is this OK?

Is this reasonable for testing and then measure the resistance and replace with a fixed value resistor?

If everything is more or less equal, I would leave the L-Pad in there for playing when I get the speaker into the room.



Ace, if you want to go with Magnepans, there is a pair of MG 1.6 with Sound Anchor stands on Audiogon right now, asking price $1000. They are located in Texas.
Title: Re: Impertinent half serious question...
Post by: Keithh on 10 Feb 2017, 08:25 am
Quote
bought the MDF at HD tonight

I know it is too late for aceinc, but don't buy MDF from HD unless you know what you are looking at.
In this forum MDF is always treated as a singular product. It is not! What one person finds on a shelf marked as MDF can
be something completely different than what is in another store. Where I work we presently have 9 brands of MDF available and there are
many more out there. Six are totally unsuitable for speaker building but they all will show up on some store shelf marked as MDF.
Stick to brands from the Pacific NW and Canada(SierraPine or Plum Creek for example). Chain stores will usually have junk
from China, Chile or Argentina. It will cost more but buy from small hardwoods dealers that cater to woodworkers and
actually know what they are selling. If you don't know what the brand is you can usually go by weight. Good brands of MDF are quite heavy compared
to a sheet of plywood. If it is the same weight or lighter than plywood, stay away from it.
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 01:43 pm
I did not compare the MDF weight, but it seemed pretty heavy, if I had to guess as heavy or heavier than plywood.

I suppose the 1.6's would work with the OB's sideways as a base. One concern I have with older Magnepans is delamination and deterioration. I once naively purchased a pair of smallish (don't remember the model) Maggies for $150, and the seller told me one didn't work. He said Magnepan would provide parts to repair it. When I got them home and took the failing one apart, the membrane was dark brown literally flaked apart as I touched it. When I called Magnepan the cost to replace the panel was close to or more than the MMGs. I ended up giving them to a buddy who bought a turntable from me. I have no idea what he did with them.

Since my crossover designs are fairly simple first order affairs, I use the L-Pads to adjust the levels of the various drivers to balance the volume of the tweeter/midrange vs the woofer which is usually lower.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 10 Feb 2017, 01:51 pm
Since my crossover designs are fairly simple first order affairs, I use the L-Pads to adjust the levels of the various drivers to balance the volume of the tweeter/midrange vs the woofer which is usually lower.

We have a testing and measuring service. You just cover the shipping cost both ways and we'll run a complete set of measurements, evaluation, and recommendations, for free.

If it is a big heavy speaker though then you might have to show up with it and help set up and take down.
Title: Re: Impertinent half serious question...
Post by: Shakeydeal on 10 Feb 2017, 02:07 pm
We have a testing and measuring service. You just cover the shipping cost both ways and we'll run a complete set of measurements, evaluation, and recommendations, for free.

If it is a big heavy speaker though then you might have to show up with it and help set up and take down.

Now that's what I call "customer service"............

Shakey
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 02:12 pm
Danny, if I were closer, I might be there weekly.
Title: Re: Impertinent half serious question...
Post by: josh358 on 10 Feb 2017, 05:10 pm
I did not compare the MDF weight, but it seemed pretty heavy, if I had to guess as heavy or heavier than plywood.

I suppose the 1.6's would work with the OB's sideways as a base. One concern I have with older Magnepans is delamination and deterioration. I once naively purchased a pair of smallish (don't remember the model) Maggies for $150, and the seller told me one didn't work. He said Magnepan would provide parts to repair it. When I got them home and took the failing one apart, the membrane was dark brown literally flaked apart as I touched it. When I called Magnepan the cost to replace the panel was close to or more than the MMGs. I ended up giving them to a buddy who bought a turntable from me. I have no idea what he did with them.

Since my crossover designs are fairly simple first order affairs, I use the L-Pads to adjust the levels of the various drivers to balance the volume of the tweeter/midrange vs the woofer which is usually lower.
Magnepan changed their adhesive in IIRC 2005 after an R&D effort to find a more stable adhesive. The ones made before then are moisture sensitive or in the very early years sensitive to ultraviolet, but the ones made since then don't delaminate. So what I'd do is get the serial numbers of the Maggies in question, then call Magnepan's service department. They'll tell you when they were made and if they use the newer adhesive.

You can repair delaminated Maggies yourself, by the way -- Magnepan sells you the wire and glue for a nominal price (they can't ship the glue in the winter, though, since it freezes). It's a weekend project -- you remove the fabric socks, take off the old wire, foil, and adhesive with acetone, put new wire and foil on with 3M spray cement, then lightly brush the adhesive over it. But of course if you have to do that, you should pay less for the speakers.

By the way, I heard from Wendell Diller, Magnepan's director of sales -- he's the guy you spoke to. He remembered your call and saw your post on the Asylum. Wendell said he thought that the .7's would work well in your application. The problem with the MMG's from his perspective is that the midrange drivers aren't fast enough. Remember that the MMG is a budget speaker -- Wendell referred to it as a Volkswagen. It offers incredible bang for the buck, but it's entry level and it isn't suited for every application. So rather than couple an entry-level speaker to a pair of OB subs I think you should either go for the .7's, which are maybe $300 above your budget, or buy used 1.6's. The .7's would be great because they use the latest technology and they're really compact -- with the GR woofers you don't need all of the bass diaphragm area of the 1.6.

If it were me, I'd go with the .7's, they've gotten rave reviews.
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 06:28 pm
I am sure this one had UV damage.

I wonder why Magnepan never went the "printed circuit board" approach, where a layer of material was deposited on the membrane. I had a pair of Carver AL III+ that used that technology for the mid/tweeter and it seemed to work pretty well.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 10 Feb 2017, 07:39 pm
I am sure this one had UV damage.

I wonder why Magnepan never went the "printed circuit board" approach, where a layer of material was deposited on the membrane. I had a pair of Carver AL III+ that used that technology for the mid/tweeter and it seemed to work pretty well.

Eminent Technology does as well in their LFT line of magnetic-planar loudspeakers. Bass, midrange, and tweeter drivers, all with etched vapor-deposited conductors, not high-mass wires like Magnepan.
Title: Re: Impertinent half serious question...
Post by: aceinc on 10 Feb 2017, 08:36 pm
Spoke with Bruce at Eminent Technologies, unfortunately they won't sell their panels separately for DIY use.
Title: Re: Impertinent half serious question...
Post by: josh358 on 10 Feb 2017, 11:05 pm
I wonder why Magnepan never went the "printed circuit board" approach, where a layer of material was deposited on the membrane. I had a pair of Carver AL III+ that used that technology for the mid/tweeter and it seemed to work pretty well.
They did build a facility for that purpose up on the second level of the factory -- I didn't get an interior shot but you can see part of the outside wall on the left in this shot of the factory floor, with a red fire extinguisher on it:

(http://www.audiocircle.com/image.php?id=157668)

The reason they chosen not to do it that way is that they found that it was too difficult to make production changes. It's a good technology for small drivers like the Eminent Tech or the BG Neo 8 which require a lot of traces and/or can run hot enough heat to melt adhesive, but for larger drivers, it's more practical to use adhesive and wire by hand and most manufacturers of large planars seem to use that approach.

I wonder if the new large ink jet printed circuit technology will change that?
Title: Re: Impertinent half serious question...
Post by: bdp24 on 11 Feb 2017, 12:41 am
Spoke with Bruce at Eminent Technologies, unfortunately they won't sell their panels separately for DIY use.

Of course not, but the LFT-8b has separate connections for the planar panel and the cone box woofer. An LFT owner is free to not use the woofer, substituting the OB/Dipole Sub, or any other bass reproducer he/she chooses. The LFT-8b retails for $2499, the MG 1.7i for $2100. They are both fine loudspeakers, direct competition for each other. Both benefit from aftermarket stands, the LFT-8 by Sound Anchor at around $300, the MG 1.7i by Mye at around twice that. With those stands, the LFT-8b and the MG 1.7i are about the same price, and both benefit from a sub, particularly the OB/Dipole, for obvious reasons.
Title: Re: Impertinent half serious question...
Post by: aceinc on 11 Feb 2017, 08:31 pm
I am thinking that for fun I am going to use a flock of divers that I have laying about in an open baffle arrangement. I have a bunch of 5", 3" and 5/8" drivers. I will stuff them into a baffle, since the tweeters are silk dome, I will probably put some facing the front and some facing the rear. Wire them all up so their resistance (since I can't easily measure impedance) are similar and hook them to a premade crossover that I have and see how bad it sounds.

I am using REW so I can see visually how bad it sounds as well.

I previously used these drivers for a center channel build that I am still using and it sounds good. See the picture below.

(http://www.audiocircle.com/image.php?id=157710)
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 12 Feb 2017, 01:30 am
Do yourself a favor and just use one forward facing tweeter. Using multiples like that will just cause comb filtering and some pretty significant peaks and dips.
Title: Re: Impertinent half serious question...
Post by: aceinc on 12 Feb 2017, 01:43 am
In the center channel, it hasn't been a problem, that I can hear, or that anyone has complained about. I have not tried to measure comb filtering, so it may be there but unnoticed.

While I can't do fancy testing I can do a freq plot using REW of just that speaker from the listening position. This has a simple cap only crossover and a couple of L-Pads. So it should look pretty funky.

I believe I have sixteen of each driver, so I was thinking about going crazy with eight of each driver in each speaker.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 12 Feb 2017, 03:40 am
In the center channel, it hasn't been a problem, that I can hear, or that anyone has complained about. I have not tried to measure comb filtering, so it may be there but unnoticed.

While I can't do fancy testing I can do a freq plot using REW of just that speaker from the listening position. This has a simple cap only crossover and a couple of L-Pads. So it should look pretty funky.

I believe I have sixteen of each driver, so I was thinking about going crazy with eight of each driver in each speaker.

It is a lot worse than you think. Check out this thread and then scroll to the bottom of the first page where I show the measured effects.

http://www.audiocircle.com/index.php?topic=124751.0
Title: Re: Impertinent half serious question...
Post by: aceinc on 12 Feb 2017, 04:29 am
Danny, I read what you referenced. In your test, the tweeters were 6.5" (center to center?) apart. Have you done further testing where the centers were closer together?

My understanding (flawed as it may be) is that there is a correlation between the frequencies generated and the distance between the center of the drivers. The higher the frequency, the closer they needed to be together. When proper distance was maintained, combing was avoided, and multiple drivers would create a single wave front.

<speaking out my nose>
If the obliqueness of the angle were problematic because of time delay, why doesn't a large radiator like a Neo 8 or some of the larger 15 & 30 inch ribbon tweeters, sound bad off angle? Wouldn't the sound from one end of the driver reach the ear at a different time than the other end of the driver?
</speaking out my nose>

Again if I were closer I would run the center channel over for your free check up, and you could test it with your equipment. I am a rather empirical kind of guy, and I think you may be as well.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 12 Feb 2017, 03:13 pm
Danny, I read what you referenced. In your test, the tweeters were 6.5" (center to center?) apart. Have you done further testing where the centers were closer together?

Yes. the effect is less dramatic when the acoustic centers are closer.

Quote
My understanding (flawed as it may be) is that there is a correlation between the frequencies generated and the distance between the center of the drivers.


That is correct.

Quote
The higher the frequency, the closer they needed to be together. When proper distance was maintained, combing was avoided, and multiple drivers would create a single wave front.

Yes, for two drivers.

But when you have a line of four of them then you also have cancellation between driver 1 and 3, 2 and 4, and 1 and 4.

Quote
<speaking out my nose>
If the obliqueness of the angle were problematic because of time delay, why doesn't a large radiator like a Neo 8 or some of the larger 15 & 30 inch ribbon tweeters, sound bad off angle?


Vertically, yes. Anytime you have a line of drivers, or one long driver, you have limited upper frequency range limits above and below the line.

Quote
Wouldn't the sound from one end of the driver reach the ear at a different time than the other end of the driver?
</speaking out my nose>

Yes.

But with a continues line of planar drivers (close together), or a single long line, when some drivers are creating comb filtering that drops out the response. Other drivers that you are still on axis with fills in the holes. So what you get is a frequency response up top that is +/-2db or so. And changing heights a little changes the placement of the +/-2db peaks and dips.

Quote
Again if I were closer I would run the center channel over for your free check up, and you could test it with your equipment. I am a rather empirical kind of guy, and I think you may be as well.

That would be good.

And running a short line is the same as a tweeter of the same height. So with four tweeters stacked you have a narrow range about the height of the tweeter middle tweeters when you have a reasonable response. Above or below that the upper ranges will really drop off. This creates an uneven room response and takes away imaging and spacial ques that are found in those top octaves.

Generally go with a single point source tweeter for more even coverage, or create a line long enough that keeps you in the near field. 
Title: Re: Impertinent half serious question...
Post by: aceinc on 12 Feb 2017, 06:00 pm
I found this;

http://www.audioroundtable.com/misc/nflawp.pdf

I am trying to wrap my brain around all of it, specifically, the near field to far field frequency to line height portion to listening distance, but the center to center distance of my tweeters should keep lobing above 10 khz.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 12 Feb 2017, 06:06 pm
I found this;

http://www.audioroundtable.com/misc/nflawp.pdf

I am trying to wrap my brain around all of it, specifically, the near field to far field frequency to line height portion to listening distance, but the center to center distance of my tweeters should keep lobing above 10 khz.

Careful, some of that data is not correct. What you see on page 15 doesn't really work that way.
Title: Re: Impertinent half serious question...
Post by: aceinc on 14 Feb 2017, 08:43 pm
Danny, is there somewhere I can go to find better data about line arrays?
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 14 Feb 2017, 08:48 pm
Danny, is there somewhere I can go to find better data about line arrays?

Maybe one day I'll write a book.

I might even release more line array kits one of these days.

I just need more time in the day.

Honestly though, I don't know of any good place to send you.

But if you have a desire to build a custom line source of some kind then I'll be glad to help you with it. Finding the right divers is not easy though. I really couldn't find any suitable and had to resort to designing some for that application. So it really starts with driver design.
Title: Re: Impertinent half serious question...
Post by: aceinc on 15 Feb 2017, 06:22 pm
Danny, I was thinking of using some 8" AMT mid/tweeters for an array. Based on James Griffin's paper, If I crossed it over at 2khz, I would need a 4' tweeter array. The maximum woofer size should be 4" with a 2Khz crossover as well. I am thinking 72"-80" woofer array.

This would lead to 6-AMTs and 18-20 woofers.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 15 Feb 2017, 06:59 pm
Danny, I was thinking of using some 8" AMT mid/tweeters for an array. Based on James Griffin's paper, If I crossed it over at 2khz, I would need a 4' tweeter array. The maximum woofer size should be 4" with a 2Khz crossover as well. I am thinking 72"-80" woofer array.

This would lead to 6-AMTs and 18-20 woofers.


The length of the array needs to be taller than 4' to be effective.

The woofer size is not relevant.

And the crossover point is never predetermined. It will have to be based on the acoustic output of the drivers.

Here is the real key. You need to match your impedance's and sensitivity of the drivers.

You won't really gain SPL levels with series/parallel groups of tweeters, but you will with the woofers. So you need high sensitivity tweeters and very low sensitivity woofers.

To match a line of Neo 8 tweeters I had to design a 6.5" woofer with 83 to 84db sensitivity.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 15 Feb 2017, 07:00 pm
I do know of a guy that is about to down size and very reluctantly is going to have to let go of a pair of LS-6's.
Title: Re: Impertinent half serious question...
Post by: aceinc on 15 Feb 2017, 08:14 pm
Danny, while that sounds tempting, as do the OB7s for sale in Providence, I am really interested in building something myself.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 15 Feb 2017, 08:37 pm
Danny, while that sounds tempting, as do the OB7s for sale in Providence, I am really interested in building something myself.

DIY line source done right is not easy. I couldn't do it without the tools that I have for measuring, and testing. Textbook crossover or slopes do not apply to line sources. Filters have to correct for coupling that takes place within the pass band of each group of drivers.

Post your ideas though, or driver considerations and I'll try to help you with them if you really want to give it a shot.
Title: Re: Impertinent half serious question...
Post by: aceinc on 15 Feb 2017, 09:29 pm
Danny, I'm in it for the fun. I might be getting some of the drivers from dodgy sources (quality wise) and if I send you a couple of samples, could/would you test them for me?

For a 4" low cost driver I was looking at this;

https://www.madisoundspeakerstore.com/approx-4-woofers/hi-vi-m4n-4-wide-range-woofer-copper-color-cone/

The freq/spl graph on Madisound is much nicer than the one on Parts Express, however.

http://b2b.parts-express.com/pedocs/more-info/297-434-hi-vi-m4n--40709.pdf

The tweeters I am looking at say their frequency response is 200-20,000 hz. I think that unlikely so I felt a 2Khz would be a safe xover. Also I remember somewhere that having a single driver covering 100-1,800hz is a good practice. If I do cross at 2khz, what do you recommend is the largest woofer size I use?

Did I mention I was going to try to go OB on this as well?
Title: Re: Impertinent half serious question...
Post by: aceinc on 15 Feb 2017, 09:39 pm
Danny, Is this your friend?

http://www.ebay.com/itm/AV123-LS-6-SPEAKERS-/322208442758

He is in Miami, which is very close to where I am.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 15 Feb 2017, 10:00 pm
Danny, I'm in it for the fun. I might be getting some of the drivers from dodgy sources (quality wise) and if I send you a couple of samples, could/would you test them for me?

For a 4" low cost driver I was looking at this;

https://www.madisoundspeakerstore.com/approx-4-woofers/hi-vi-m4n-4-wide-range-woofer-copper-color-cone/

The freq/spl graph on Madisound is much nicer than the one on Parts Express, however.

http://b2b.parts-express.com/pedocs/more-info/297-434-hi-vi-m4n--40709.pdf

The quality level is not great. However, that driver has a good low sensitivity and a really high Qts. So you could use them in an open baffle. But a boxed design would cause the box volume to get huge.

And you can only use them up to about 1kHz. After that the response gets rough and there will be some ringing.

Quote
The tweeters I am looking at say their frequency response is 200-20,000 hz. I think that unlikely so I felt a 2Khz would be a safe xover.


You never know until you look at the frequency response. It is often best to work with the natural roll off of the drivers.

Quote
Also I remember somewhere that having a single driver covering 100-1,800hz is a good practice. If I do cross at 2khz, what do you recommend is the largest woofer size I use?

Actually 300Hz to 500Hz is the heart of the mid-range that you want to avoid. So one octave above that is fine.

Quote
Did I mention I was going to try to go OB on this as well?

Then consider the Neo 8's for tweeters. I also have a modification for them that really helps. They can cross down to 850Hz to 1000Hz depending on how many you use. They are the same front to back (so open baffle is good). They handle a lot of power and they sound great.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 15 Feb 2017, 10:01 pm
Danny, Is this your friend?

http://www.ebay.com/itm/AV123-LS-6-SPEAKERS-/322208442758

He is in Miami, which is very close to where I am.

No, but that is a great price. I used to sell just the parts as a kit for that speaker for $1,995. And those are great sounding speakers. For anyone watching, that is a great deal.
Title: Re: Impertinent half serious question...
Post by: bdp24 on 15 Feb 2017, 10:53 pm
There are a pair of LS6 on Audiogon right now, asking price $1700, located in Napa California.
Title: Re: Impertinent half serious question...
Post by: aceinc on 15 Feb 2017, 11:10 pm
Napa is a bit of a hike, from sunny SoFla.
Title: Re: Impertinent half serious question...
Post by: danvprod on 15 Feb 2017, 11:33 pm
Those ones on eBay are really nice looking.
Title: Re: Impertinent half serious question...
Post by: S Clark on 16 Feb 2017, 12:00 am
There are a pair of LS6 on Audiogon right now, asking price $1700, located in Napa California.
What?  I'm sorry but that's just crazy.  I've been to enough RMAF's and been in enough high end living rooms to know that those are not common speakers, yet they are priced like a set of high end book shelf speakers???
I agree they aren't the easiest to place, and need space, but holy cow!!!  Seventeen hundred bucks?  Where else can you find speakers that were at the top of all speakers displayed at a major show about 10 years back.  I just shake my head.
Title: Re: Impertinent half serious question...
Post by: aceinc on 16 Feb 2017, 01:33 am
The ones on Audiogon, and E-bay are the same ones;

https://www.audiogon.com/listings/full-range-av123-ls-6-speakers-lowest-price-ever-2017-02-02-speakers-33193-miami-fl--2

If anyone wants them, I can pick them up and store them in my living room, until you can come get them.  :green:
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 16 Feb 2017, 01:52 am
Man, that is a crazy great deal for someone.
Title: Re: Impertinent half serious question...
Post by: aceinc on 16 Feb 2017, 03:12 am
So if I were to use the 16 of the 4" HiVi drivers and something similar to 8 of the Neo 8s, what would the baffle shape look like?

Would there be a wing like the Nx-otica? If there was a "wing", could it be 90 degrees?

It looks like the drivers would fit on a 9" to 9-1/2" baffle.

The idea would be to mate it to the OB subs I am building. So I don't think it needs to handle any frequencies below 100hz, which I think makes a difference in the baffle/wing design.

Paul
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 16 Feb 2017, 04:43 am
You'll have to shape the baffle and side wing to be like the one I designed for Mockingbird Audio.

http://mockingbirddistribution.com/mockingbird-audio-lsx-speaker-system/
Title: Re: Impertinent half serious question...
Post by: aceinc on 16 Feb 2017, 07:16 pm
Impressive looking speakers. Impressive price. Hopefully I can achieve a large fraction of the performance at a small fraction of the price.

I assume the depth of the side wing is based on the low frequency that you are trying to get to. If I was looking for a 120hz cross to the sub, how big should the wing be?
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 17 Feb 2017, 02:57 pm
I assume the depth of the side wing is based on the low frequency that you are trying to get to. If I was looking for a 120hz cross to the sub, how big should the wing be?

The lower you can cross them to the subs the easier it is to blend.

The LSX line sources crossed in the 80Hz range. And it seems like that wing was about 16" deep.
Title: Re: Impertinent half serious question...
Post by: aceinc on 17 Feb 2017, 05:40 pm
Will the 4" HiVi drivers I am looking at cross at 80hz?

Since my woodworking skills are questionable at best and since the baffle would be fairly narrow, would dimensional lumber (1" x 10" hardwood) be satisfactory? This way I do not need to try and veneer it.

An alternative might be;

https://b2b.parts-express.com/dayton-audio-pa130-8-5-full-range-pa-driver--295-010
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 18 Feb 2017, 12:03 am
Will the 4" HiVi drivers I am looking at cross at 80hz?

Since my woodworking skills are questionable at best and since the baffle would be fairly narrow, would dimensional lumber (1" x 10" hardwood) be satisfactory? This way I do not need to try and veneer it.

You can use hardwood for the baffle, but I'd also couple it to at least a thin layer of MDF.

Quote
An alternative might be;

https://b2b.parts-express.com/dayton-audio-pa130-8-5-full-range-pa-driver--295-010

The sensitivity is getting up there real quick with that one and you'd have a tough time matching the sensitivity levels to the tweeters.
Title: Re: Impertinent half serious question...
Post by: aceinc on 18 Feb 2017, 12:36 am
The sensitivity is getting up there real quick with that one and you'd have a tough time matching the sensitivity levels to the tweeters.

I was thinking;
<talking out my nose>
if I could reduce the SPL on the frequencies between 150hz and 600hz, things might be OK.
</talking out my nose>

Of course I have no idea how to build that kind of circuit, or if it could be accomplished mechanically.
Title: Re: Impertinent half serious question...
Post by: aceinc on 18 Feb 2017, 04:17 am
Danny, you have mentioned and inferred that ribbon tweeters in an array behave differently than do cone woofers in the sense that the woofer's efficiency will increase the more drivers that are added and the ribbon tweeters don't.

Can you elaborate, or point me to where I can get a better understanding of this phenomenon?

I always thought you get ~3db extra SPL per watt (in their frequency range) for every driver you threw on the fire. Is this different behavior because;

My curiosity is so that I can better screen drivers without coming to you and saying, "How about this one?" 187 times.

For open baffles, I understand high QTS is good. The fellow that designed the Carver Amazings indicated the ratio between QTS and QMS linearity (whatever that means) is important. I know you say low efficiency is good, but if the old 3db per driver boost rule of thumb works for the woofers and the woofer is 80 db per watt, 16 woofers would make the efficiency 128db per watt, which is unlikely, but would require a very efficient tweeter if they didn't get any boost in multiples.

So as always, I am confused.
Title: Re: Impertinent half serious question...
Post by: aceinc on 18 Feb 2017, 02:49 pm
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 20 Feb 2017, 03:40 pm
Danny, you have mentioned and inferred that ribbon tweeters in an array behave differently than do cone woofers in the sense that the woofer's efficiency will increase the more drivers that are added and the ribbon tweeters don't.

Can you elaborate, or point me to where I can get a better understanding of this phenomenon?

I always thought you get ~3db extra SPL per watt (in their frequency range) for every driver you threw on the fire. Is this different behavior because;
  • It is a line array?
  • The driver is a planar?
  • Of the frequency range?

My curiosity is so that I can better screen drivers without coming to you and saying, "How about this one?" 187 times.

For open baffles, I understand high QTS is good. The fellow that designed the Carver Amazings indicated the ratio between QTS and QMS linearity (whatever that means) is important. I know you say low efficiency is good, but if the old 3db per driver boost rule of thumb works for the woofers and the woofer is 80 db per watt, 16 woofers would make the efficiency 128db per watt, which is unlikely, but would require a very efficient tweeter if they didn't get any boost in multiples.

So as always, I am confused.

Anytime a driver is playing a frequency range when the width (or height) of the driver is greater than the length of the wavelength that it is playing then it is in what we call its beaming range. In other words it will play it straight forward only and not spread out in all directions. 

Check out the picture on page 15 of Jim's paper that you referenced earlier. Note the lines that he drew out from the tweeters. This is what happens at 20kHz. Each tweeter plays that range straight ahead. The short wavelengths do not spread out and couple with the other tweeters. As you move up or down then you are out of the range of all but one tweeter. So at 20kHz you never exceed the SPL capability of one tweeter.

Now this is only true for the top octave. Actually only the very top of the top octave. As wavelengths increase the output begins to spread out. It is just like looking at the off axis response of any driver. As the wavelengths increase and spread out then they start to couple. Some waves arrive delayed in time compared to others and cause out of phase cancellations. But the few that you are in front of are not delayed too much in time and they couple.

By the time you reach 1kHz most of the output is in phase and coupling. So you get a huge increase in output. You get a response line that starts at 20kHz that is no greater than one tweeter. But will increase 20db or so going to 1kHz. So the filter has to correct for the response with in that range of those drivers and not just create a crossover point.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 20 Feb 2017, 03:42 pm
      I re-read the article by Griffin, especially the end section.

      Two things gleaned/interpreted.

      • By changing the total impedance of the overall woofer array, one can ameliorate the increase in efficiency.
      • It is beneficial to decrease the sensitivity of the drivers at the outer ends of the array in relation to the center of the array. This can also be accomplished by changing the impedance of the sets of drivers from the center out.

    All that I need now is a spreadsheet or program that I can plug in the driver size, their frequency ranges and efficiency ratings, add the distance to the listening position, an voila I could get an optimal wiring diagram. Anybody know of the existence of such a program, script or spreadsheet?


Power tapering the impedance on short lines like this doesn't really work out real well.

But you can vary the series/parallel grouping of the woofers to reduce or increase output. The key is that you need the impedance of the woofer and tweeter line to closely match and you need the sensitivity levels to closely match.
Title: Re: Impertinent half serious question...
Post by: aceinc on 20 Feb 2017, 05:48 pm
Danny, the arrays I am thinking of are 64" on the tweeter, and 72" - 80" on the woofer. Does this qualify as a short line?

If the impedance does not closely match between the woofer array and the tweeter array, can't this be compensated for in the crossover?

In a standard MT environment, if one driver is 4 ohms and the other is 8 ohms and I want to crossover at say 2khz, can't I just adjust the capacitor and inductor values to compensate?
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 21 Feb 2017, 02:12 am
Danny, the arrays I am thinking of are 64" on the tweeter, and 72" - 80" on the woofer. Does this qualify as a short line?

That's a pretty good sized line. I still wouldn't taper them though.

Quote
If the impedance does not closely match between the woofer array and the tweeter array, can't this be compensated for in the crossover?

Not really. If the tweeter level is higher and the impedance is lower then you can add a resistor to bring down the sensitivity and increase the impedance. That's really rare with a line source though.

Quote
In a standard MT environment, if one driver is 4 ohms and the other is 8 ohms and I want to crossover at say 2khz, can't I just adjust the capacitor and inductor values to compensate?

Yes, the crossover values can be adjusted, but you still have an impedance mismatch. Think of how solid state amps react to different loads verses a tube amp.
Title: Re: Impertinent half serious question...
Post by: aceinc on 21 Feb 2017, 02:44 am
Is this description I found a reasonable explanation?

Impedance is a function of frequency. Don't confuse "Impedance" with "Resistance." Both impedance and resistance are measured in "Ohms" but impedance can and will change as the frequency changes. Audio frequencies are typically in the range from 20 Hertz to 20,000 Hertz (20Hz - 20KHz).

Pure simple resistance doesn't concern itself with frequency, because it is measured at no frequency (zero Hertz).

A typical 8ohm woofer might have an impedance that varies from slightly below 8ohms at 1 Hertz to maybe 60ohms or more at it's resonant frequency peak and then back down to somewhere near 8ohms again. After that a woofer's impedance continues to rise gradually as the frequency extends towards and beyond 20,000 Hertz.

If you use an 8ohm woofer and an 8ohm tweeter WITHOUT a crossover, your impedance would be 4ohms! But who would use a woofer and a tweeter together without a crossover? A crossover is a frequency dividing network. As long as you are using a crossover with an 8ohm woofer and an 8ohm tweeter then your impedance will remain at or near 8ohms straight across, not 4ohms.

If you use a 4ohm woofer and an 8ohm tweeter without a crossover, your impedance would be 2.66ohms. But with a crossover, your impedance would be 4ohms in the range of frequencies covered by the woofer and 8ohms in the range of frequencies covered by the tweeter. If you use a 4ohm woofer with an 8ohm midrange and a 6ohm tweeter all with a crossover, then your impedance would be 4ohms in the range of frequencies covered by the woofer and 8ohms in the range of frequencies covered by the midrange and 6ohms in the range of frequencies covered by the tweeter.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 21 Feb 2017, 02:30 pm
That's true except that the crossover can also change impedance. In some cases the components in shunt will lower the impedance, and inline resistors or L-pads can be used to raise it.
Title: Re: Impertinent half serious question...
Post by: aceinc on 21 Feb 2017, 08:50 pm
Danny, a related question.

Given two 4 ohm woofers rated at 89 DB @ 2.83v efficiency are hooked up in series yielding a nominal 8 ohm load and an 8 ohm tweeter rated at 89 DB @2.83v efficiency, using a standard first order crossover, what would the relative efficiency between the woofer and tweeter section be?

Would the woofer section and tweeter both produce 89 DB? (at 2.83v)
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 21 Feb 2017, 09:22 pm
Danny, a related question.

Given two 4 ohm woofers rated at 89 DB @ 2.83v efficiency are hooked up in series yielding a nominal 8 ohm load and an 8 ohm tweeter rated at 89 DB @2.83v efficiency, using a standard first order crossover, what would the relative efficiency between the woofer and tweeter section be?

Would the woofer section and tweeter both produce 89 DB? (at 2.83v)

Yes, they would technically hit 89db. But that doesn't take into account baffle step loss.

And if you find a woofer that will cross to a tweeter using only a first order crossover then let me know. I have yet to find one. Even our woofers (that are really smooth) still like a second order slope best.
Title: Re: Impertinent half serious question...
Post by: aceinc on 21 Feb 2017, 09:37 pm
Danny, that was a hypothetical question to make sure I understood basic information, namely that two woofers in series will double the impedance and not increase the efficiency.

I believe the reverse would be true that two woofers in parallel will halve the impedance and increase the efficiency by 3 DB.

I assume a second order crossover will not change the efficiency either, unless additional tweaks are added.
Title: Re: Impertinent half serious question...
Post by: Danny Richie on 22 Feb 2017, 07:10 pm
Danny, that was a hypothetical question to make sure I understood basic information, namely that two woofers in series will double the impedance and not increase the efficiency.

I believe the reverse would be true that two woofers in parallel will halve the impedance and increase the efficiency by 3 DB.

I assume a second order crossover will not change the efficiency either, unless additional tweaks are added.

Yes, that is correct. But halving the impedance might also increase the current from the amplifier and give you additional output.

The order of the crossover will not change the efficiency.