Jump to content

AR-10pi Bass Compensation, Voicing, Design Details


Pete B

Recommended Posts

I was aware that the 10pi used an auto transformer in the crossover but had not seen a crossover schematic. Here's a link to the bass compensation patent ("Woofer equalizer") and it even includes component values, which is common since details of a working "best" implementation is suggested for patents:

http://patft.uspto.gov/netacgi/nph-Parser?...yne+AND+speaker

The patent number is 4,021,614 which can be entered at the main patent page in case the above link doesn't work:

http://patft.uspto.gov/netahtml/srchnum.htm

Does anyone have:

Published frequency response curves?

Crossover schematics at least with AR inductor numbers and DCR?

Correct driver numbers and any other details?

I'll offer some comments on the voicing if we can find this data.

Link to comment
Share on other sites

>Does anyone have:

>

>Published frequency response curves?

>

>Crossover schematics at least with AR inductor numbers and

>DCR?

>

>Correct driver numbers and any other details?

>

>I'll offer some comments on the voicing if we can find this

>data.

Pete,

Out of curiosity, what sort of comments would you be offering the forum regarding the "voicing" of the AR-10Pi? Would you be giving us your view on the subjective sound quality (i.e., the pros and cons) of the AR-10Pi based on quantitative frequency-response data, driver numbers and crossover values?

Thanks,

--Tom Tyson

Link to comment
Share on other sites

Hi Tom,

If I got curious enough after looking at the crossover I might whip up a quick CALSOD model which might shed some light on what the final elecro-acoustic crossover types are. I already have a clue about the voicing having looked at the AR-3a and LST curves assuming there is a "family" sound. I mainly wanted to address Bret's harshness observation and could offer a very simple line level circuit to test the theory behind my thoughts.

Pete B

>>Does anyone have:

>>

>>Published frequency response curves?

>>

>>Crossover schematics at least with AR inductor numbers and

>>DCR?

>>

>>Correct driver numbers and any other details?

>>

>>I'll offer some comments on the voicing if we can find this

>>data.

>

>Pete,

>

>Out of curiosity, what sort of comments would you be offering

>the forum regarding the "voicing" of the AR-10Pi? Would you

>be giving us your view on the subjective sound quality (i.e.,

>the pros and cons) of the AR-10Pi based on quantitative

>frequency-response data, driver numbers and crossover values?

>

>

>Thanks,

>

>--Tom Tyson

>

Link to comment
Share on other sites

It should be remembered that at the time of the appearance of the AR ten pi on the market, low cost consumer friendly graphic and parametric equalizers didn't exist. The ten pi was a recognition of the difficulties of integrating a loudspeaker into the acoustics of the typical listening room in both residential and professional installations. So was the unique tone controls invented for the AR amplifier. It wasn't that long afterwards that the situation changed radically. It is surprising and IMO most unfortunate that audiophiles have rejected what has to be one of the most powerful tools available for improving the performance of home sound reproduction systems. By contrast, no professional sound system I have seen lacks for one. Altec Lansing called its early third octave equalizer "Acousta Voice." I've been told that most recording studios have the accuracy of their equalization checked frequently.

The arrival of the digital compact disc has heralded a different era in consumer audio, an era which for the first time allows studio master tape quality to be brought into the consumer's home at very low cost. The pervasiveness of the cd has exposed many of the worst shortcomings of modern loudspeaker design. Rather than focusing on them and demanding effective engineering solutions, audiophiles have regressed to the most primitive concepts the consumer audio industry ever offered. Thus we see a resurgance to the regressive concepts of vacuum tube amplifiers and preamplifiers including low powered class A amplifiers, elimination of all tone controls both on preamplifiers and level controls on loudpeakers, vinyl phonograph records played with moving coil cartridges, horn type loudspeakers including single driver full range types, and when these systems prove unsatisfactory, the use of exotic wires to try to correct them. It's a very strange world we live in.

Link to comment
Share on other sites

Guest treblehit

Somehow with the URL change I got locked-out. I haven't been ignoring you.

The driver compliment is:

Woofer: 200003

Midrange: 200010-1

Tweeter: 200011

There is a system assembly TIF in the forum library showing this and other details, but no schematic.

Thanks for the patent link.

Bret

Link to comment
Share on other sites

Guest Brian_D

Gonna have to agree with you there.

Even speakers with very flat responses can benefit in some way from a high-quality EQ in the circuit. (Usualy as a result of placement)

Lets face it; not every speaker can be placed to put you in the "sweet spot" and not every bit of source material (or source unit for that matter) will be satisfactory to your ears.

I couldn't live without my AudioSource EQ. It's an oldy but a goody and I use it any time I set up a system.

I, too, feel its a shame that many "audiophiles" will balk at their presence in a system. It's true that they're often used for band-aids for larger problems, but they can do good as well!

-Brian

Link to comment
Share on other sites

Here's some discussion concerning related patents by McIntosh where the problem of low frequency distortion caused by autotransformer saturation is mentioned.

http://www.roger-russell.com/ml1cpg.htm#related

Interesting discussion of low distortion drivers and another patent:

http://www.roger-russell.com/xr250.htm

Link to comment
Share on other sites

I love the observation that the transformer goes into saturation at 20Hz on the 10pi.

Much of that is interesting. I hadn't seen that speaker, or a photo of it, in a very long time.

Bret

Link to comment
Share on other sites

The selection of the maximum flux density in the transformer core before saturation at a particular frequency for determining the autotransformer core design must have been determined by the maximum necessary loudspeaker output likely to ever be encountered by the overwhelming majority of users in the overwhelming majority of applications. The core and transformer could have been made arbitrarily larger and heavier at correspondingly greater cost. The choice was an engineering decision, not an accident. The availability of program material which could have saturated the core at tolerable volume in real world conditions in a home environment was undoubtedly taken into consideration. Although there were some high powered amplifiers available at the time, the vinyl phonograph record and analog magnetic tape as well as the kinds of acoustical and electronic musical instruments to be reproduced made a larger transformer unnecessary. This radically changed with the invention and marketing of the digital compact disc in the early 1980s not to mention much more powerful electonic basses capable of producing very low frequencies. Acoustic Research's answer was the AR9 which not only doubled the woofers but used air core inductors which obviously won't saturate. Equalization of the bass output was done at the speaker level by precision adjustment the level of the other drivers downward from flat and by that time, low level equalization at the preamplifier stage became inexpensive and reliable.

Link to comment
Share on other sites

>The core and transformer could have been made arbitrarily larger and heavier at correspondingly greater cost. <

Well, I'd love to have an arbitrarily larger pair, not because of saturation, but to be certain that the ones I have are in-spec.

It makes no sense to me, none at all, that my 10pi cabinets would be much brighter than my friends, driver-swaps and all unless something somewhere has "gone bad." The chokes, sorry, inductors don't look or feel or smell melted, switches work as they should. . . gotta be the transformer.

Bret

Link to comment
Share on other sites

All of the hot shot engineers that I know shake their heads when discussing the auto transformer in the LST and 10pi. A major advantage of solid state amps is eliminating the output transformer.

Saturation is not sudden, distortion rises with increasing level and decreasing frequency.

Do you find the low frequency contour useful?

The next obvious question is have you considered moving to, what would be the correct crossover, AR3a Limited or AR11 without the transformer?

You might be surprised at the improvement.

Pete B.

>>The core and transformer could have been made arbitrarily

>larger and heavier at correspondingly greater cost. <

>

>Well, I'd love to have an arbitrarily larger pair, not because

>of saturation, but to be certain that the ones I have are

>in-spec.

>

>It makes no sense to me, none at all, that my 10pi cabinets

>would be much brighter than my friends, driver-swaps and all

>unless something somewhere has "gone bad." The chokes, sorry,

>inductors don't look or feel or smell melted, switches work as

>they should. . . gotta be the transformer.

>

>Bret

Link to comment
Share on other sites

As I see it, the AR 10 pi is an idea whose time has passed. Active equalization at the preamplifier level is far preferable to passive equalization at the loudspeaker level. If I owned a 10 pi, I'd also get rid of the autransformer and replace it with the LF section of the AR3a...or just bi-amplifiy it.

Link to comment
Share on other sites

Hi Pete,

Given the direction of this thread I decided to answer your question here rather than in the unwieldy woofer thread.

The mid '90's '3a drivers in my AR-3a "Limited" clone have the following serial numbers:

-tweeter is #1200084AB with a #8134H under it...It is certainly different sounding than the original '3a type tweeter and I suspect much more like the AR-11/10pi. Like the later tweeters there was foam on the faceplate.

-mid is #12100010-1A with #332TNH under it.

-woofer is the (re-worked) Tonegen 1210003-2A with #132TNB under it.

Another forum member informed me that the Tonegen "Limited" '3a drivers were based on the AR-11 era which is why I have high hopes for Bret's ultimate victory. Also, the '11 and '10pi have essentially the same cabinet volume as the '3a.

Both the mid and (especially) the tweeter are more sensitive than their old '3a counterparts with the tweeter having more low frequency output than the original '3a tweeter. The woofer we've already discussed to death.

I'm going to try the combo with a '3a crossover now that the woofer has been improved. My philosophy has always been "if it ain't broke, lets see what I can do to screw it up again" :-).

Bret, one speaker of a pair of '3a's (1974 vintage) I acquired a couple of months ago had an original "#9" coil which is supposed to be 2.85mh that was out of spec by over .40mh (it measured 2.43mh). You may want to check those things out if you already haven't. I doubt its the problem but it would be one possibility eliminated.

Roy

Link to comment
Share on other sites

>As I see it, the AR 10 pi is an idea whose time has passed.<

Of course you're right. I think that can be said for every "classic" speaker we discuss, can't it?

I'd never do what you suggest for the same reason I wouldn't install McPherson struts on a Rolls Royce Silver Cloud.

Bret

Link to comment
Share on other sites

>You may want to check those things out if you already haven't.<

I haven't. I don't have a meter, but worse, I don't have a parts-list. All I could do would be to check them against another pair then if there were differences wonder which is right, or if there were updates to the design.

Looks like maybe I'll have to trade one meter for another.

Bret

Link to comment
Share on other sites

>This is one limitation you can overcome if and when you want to. <

But this is the last speaker used in live vs recorded demonstrations, wasn't it? How bad can it be?

Do you consider this speaker to be more "sow's ear" than "silk purse?"

BTW - I'm not being stuffy or arrogant or have any other attitude. I'll tell you frankly that I didn't know what a "micro-dynamic" really was until a couple of weeks ago since I'd never heard with / without, with / without, before. I'm still on the road to "gettin' there."

BTW again - I think I've decided to hate tubes.

Bret

Link to comment
Share on other sites

I really don't know, I only heard this speaker a few times and then only briefly. As I said, IMO the design took into account the limitations of recordings at the time they were manufactured. Newer technology, namely the CD has made it possible to reproduce lower louder bass notes. Can the 10 pi meet the challenge? Why did AR feel that it would be advantageous to add a second woofer and double the size of the cabinet and extend the low end response of its best system when it introduced AR9? It had never done that before. Frankly, not owning them and it not being my problem, I don't care one way or the other. I'm just saying that if it is a problem, there are options short of chucking the speaker.

Link to comment
Share on other sites

Hi Roy,

Thanks for the details about your limiteds, it will probably be useful in the future. Just wondering if you've had a chance to hear the limited and 11 side by side?

The value of that choke sounds too far off for normal production tolerances, I wonder if it got mislabeled or if they just had a bad day on the coil winder? Things are bound to slip by. Do you think turns could be shorted due to overheating perhaps? I think it's unlikely unless it an amp failed and put out full rail DC voltage which can quickly cause overheating.

Pete B.

>Hi Pete,

>Given the direction of this thread I decided to answer your

>question here rather than in the unwieldy woofer thread.

>

>The mid '90's '3a drivers in my AR-3a "Limited" clone have the

>following serial numbers:

>-tweeter is #1200084AB with a #8134H under it...It is

>certainly different sounding than the original '3a type

>tweeter and I suspect much more like the AR-11/10pi. Like the

>later tweeters there was foam on the faceplate.

>-mid is #12100010-1A with #332TNH under it.

>-woofer is the (re-worked) Tonegen 1210003-2A with #132TNB

>under it.

>

>Another forum member informed me that the Tonegen "Limited"

>'3a drivers were based on the AR-11 era which is why I have

>high hopes for Bret's ultimate victory. Also, the '11 and

>'10pi have essentially the same cabinet volume as the '3a.

>

>Both the mid and (especially) the tweeter are more sensitive

>than their old '3a counterparts with the tweeter having more

>low frequency output than the original '3a tweeter. The woofer

>we've already discussed to death.

>

>I'm going to try the combo with a '3a crossover now that the

>woofer has been improved. My philosophy has always been "if it

>ain't broke, lets see what I can do to screw it up again"

>:-).

>

>Bret, one speaker of a pair of '3a's (1974 vintage) I acquired

>a couple of months ago had an original "#9" coil which is

>supposed to be 2.85mh that was out of spec by over .40mh (it

>measured 2.43mh). You may want to check those things out if

>you already haven't. I doubt its the problem but it would be

>one possibility eliminated.

>

>Roy

Link to comment
Share on other sites

Hi Bret,

I believe that AR wanted to offer new features, patented makes them all the better for marketing. Sometimes there are no disadvantages to new innovations, other times some disadvantages come along with them. I don't think that the advantages are significant enough to warrant an autotransformer, we can see that it was later dropped. There is one additional feature that's not mentioned often which is that the cap and autotransformer form a high pass filter and will attenuate very low frequency material that would waste driver excursion. This would help in a live vs. recorded demo, however I believe that an upsized transformer was used in that demo. It was not exactly the 10pi that people purchase that was used. It is much more cost effective to implement such a high pass filter at line level and it's often not needed.

I don't know what people view as the best in this line of ARs but I'd want vertically aligned drivers and a crossover without an autotransformer.

I wouldn't suggest modifying your 10pi speakers in any destructive way, just to try an experiment to see if you might prefer the 11s or the limiteds. Perhaps a test crossover could be outboarded, but it is a lot of work.

Pete B.

>>This is one limitation you can overcome if and when you want

>to. <

>

>But this is the last speaker used in live vs recorded

>demonstrations, wasn't it? How bad can it be?

>

>Do you consider this speaker to be more "sow's ear" than "silk

>purse?"

>

>BTW - I'm not being stuffy or arrogant or have any other

>attitude. I'll tell you frankly that I didn't know what a

>"micro-dynamic" really was until a couple of weeks ago since

>I'd never heard with / without, with / without, before. I'm

>still on the road to "gettin' there."

>

>BTW again - I think I've decided to hate tubes.

>

>Bret

Link to comment
Share on other sites

>Perhaps a test crossover could be outboarded, but it is a lot of work.<

Hi Pete,

I appreciate the comments both you and Sean have made about the inadvisability of including an auto-transformer in any crossover, and do not doubt your observations and conclusions for an instant. It is heartening to know that here, at The Classic Speaker Pages, there are people who put their expertise, time, and energy into helping others achieve the best possible result.

The majority of the fun in this for me is attempting to restore these speakers to their former glory, which as you know can also be a great frustration. I accept that new driver configurations, narrow baffles, better drivers, better cabinets, and all the rest of it can produce a better speaker than either the AR-9 or the 10pi or the LST or 3a and company (in the right hands). The desirability of improving the character of a “classic” design was at the root of my asking you about using a dome in our musing over a new speaker in the tradition of the classic AR-9.

Certainly, if the auto-transformer is going to saturate, the 10pi's measured performance could be improved by turning it into an 11, then adding external equalization. We could improve it again by turning that into an AR-91. We could improve it again by turning it into a 303. We could improve it again by turning it into a . . . whatever they are now, some MTM configuration. We could tri-amp it, completely ridding ourselves of the problems a passive crossover causes. Then if we changed to better drivers it'd spec-out like modern speaker! I have no question that such a speaker would out-perform the classic 10pi, and in an A/B test would win hands-down in every category except, “Does it sound like a 10pi?”

There are qualities of the sound produced by the 10pi, the 3a, the LST, the 9, (insert your favorite classic here) and the 2ax that were lost in the course of improving them. That isn't to say that an AR-14 didn't measure better, image better, and “hang together” better than an AR-2ax, because it did. The 2ax had a signature that the 14 did not share.

Whether that’s a good or bad thing is determined by emotion, not so much intellect. The facts are not in question. Rather it presents itself to us as a philosophical riddle. Whether a halogen lamp is a “better” source of light than five candles is simultaneously demonstrably true and yet highly debatable.

It is my belief that most of the speakers we talk about here achieved the standard of classics because the compounding of their specific faults and foibles gave them a unique sound which resulted in a certain charm. This might reasonably be subjectively compared to the distinctions of performers.

If we agree that Louis Armstrong has a style and manner which we revel in hearing; then it follows we would not look for ways to measurably improve his voice such that he sang as well as Andrea Bocelli. Doing so would be to dismiss that which made Armstrong, Armstrong.

Link to comment
Share on other sites

>The majority of the fun in this for me is attempting to

>restore these speakers to their former glory, which as you

>know can also be a great frustration. I accept that new

>driver configurations, narrow baffles, better drivers, better

>cabinets, and all the rest of it can produce a better speaker

>than either the AR-9 or the 10pi or the LST or 3a and company

>(in the right hands). The desirability of improving the

>character of a “classic” design was at the root of my asking

>you about using a dome in our musing over a new speaker in the

>tradition of the classic AR-9.

First let me say that all I'm trying to do is address your issues with the sound of your 10-pi's as simply as possible. However, your taking my point beyond what I proposed. You've come to the conclusion that the "problem" is the autotransformer, I believe more testing is required but we can go on that hunch. Let me point out that it's possible that there was a revision to the autotransformer at some point in production and that your 10-pi's with the reconditioned woofers might be up to spec. Would you then be happy with your properly restored 10-pi's or would you still want the "better" autotransformer? Yet, you still seem to want better sound or sound equal to your friend's 10-pi's. The AR-11 crossover or actual AR-11s might be the best way to achieve your goals, that's the point I'm trying to make. Building the crossover is probably too much work and I'm not offended by a no thanks answer. You might want to A/B them with 11s if you ever get the chance.

With regard to philosophy, I don't see it as philosophy but rather simple, boring speaker repair/restoration. I happen to know a bit about auto restoration and part of being a collector is knowing when it's worth it, economically and/or time wise. Certainly one of a kind or limited production items are usually worth restoring, but often worn out high volume commercial production items are not worth restoring in any perfectionistic way. The purist view held by a few on this forum, that every AR ever built must be restored their way is a polarized view not often held by professional collectors.

Vertically aligned drivers is something important to me, if it's not to you that's fine.

As far as the analogy to singers, I don't see it because I don't have an emotional attachment to AR speakers. People are different, that's life.

Pete B.

>Certainly, if the auto-transformer is going to saturate, the

>10pi's measured performance could be improved by turning it

>into an 11, then adding external equalization. We could

>improve it again by turning that into an AR-91. We could

>improve it again by turning it into a 303. We could improve

>it again by turning it into a . . . whatever they are now,

>some MTM configuration. We could tri-amp it, completely

>ridding ourselves of the problems a passive crossover causes.

> Then if we changed to better drivers it'd spec-out like

>modern speaker! I have no question that such a speaker would

>out-perform the classic 10pi, and in an A/B test would win

>hands-down in every category except, “Does it sound like a

>10pi?”

>

>There are qualities of the sound produced by the 10pi, the 3a,

>the LST, the 9, (insert your favorite classic here) and the

>2ax that were lost in the course of improving them. That

>isn't to say that an AR-14 didn't measure better, image

>better, and “hang together” better than an AR-2ax, because it

>did. The 2ax had a signature that the 14 did not share.

>

>Whether that’s a good or bad thing is determined by emotion,

>not so much intellect. The facts are not in question. Rather

>it presents itself to us as a philosophical riddle. Whether

>a halogen lamp is a “better” source of light than five candles

>is simultaneously demonstrably true and yet highly debatable.

>

>It is my belief that most of the speakers we talk about here

>achieved the standard of classics because the compounding of

>their specific faults and foibles gave them a unique sound

>which resulted in a certain charm. This might reasonably be

>subjectively compared to the distinctions of performers.

>

>If we agree that Louis Armstrong has a style and manner which

>we revel in hearing; then it follows we would not look for

>ways to measurably improve his voice such that he sang as well

>as Andrea Bocelli. Doing so would be to dismiss that which

>made Armstrong, Armstrong.

Link to comment
Share on other sites

>First let me say that all I'm trying to do is address your issues with the sound of your 10-pi's as simply as possible.<

Yes, Pete. I know. I've said so. I've thanked you for the effort and I've acknowledged that you DID solve the problem. I have also acknowledged that my pig-headed refusal to use a good remedy for a known *possible* problem (possible only because I don’t know that I’ve ever saturated the transformer), is somewhat irrational.

> However, your taking my point beyond what I proposed. <

No sir, I didn't and I’m not. I was illustrating *my* point of view / perspective on the situation; NOT correcting yours. It was an entirely new thought which only began at your premise that I would find improving the speaker beyond its original design to be desirable. That is, afterall, what a reasonable inventor and engineer would conclude.

>You've come to the conclusion that the "problem" is the autotransformer<

No. . . not really. What I was saying was that if I had a new one, I would know it was in-spec. We are running-out of things to blame differences on. There’s been more discovered, I just haven’t posted it yet thinking everyone’s tired of the subject. At least for a while.

>Yet, you still seem to want better sound or sound equal to your friend's 10-pi's.<

This is one heck-of-a Pandora’s box, Pete. What I want is for all four of our 10pi’s to sound so close to one-another that they are indistinguishable from each other. Also, I would like all four of them to sound as good as they can - as 10pi speakers.

>The AR-11 crossover or actual AR-11s might be the best way to achieve your goals, that's the point I'm trying to make.<

You made that point very eloquently, rationally, and I agree with you that this would be the best way to a quick and effective work-around for any problems associated with the crossover of a 10pi; possibly resulting in higher performance than the speaker originally had. I have said so multiple times. My deciding not to pursue it does not mean I do not understand it or appreciate the implications.

Your recent discoveries about the motor differences in the woofers does throw a wrench in those works, however.

>Building the crossover is probably too much work and I'm not offended by a no thanks answer.<

No trouble at all. If I choose not to build an 11 crossover for my 10pi’s it has nothing to do with how much work it would be. I did give you a “no-thanks” answer (long-windedly, I confess) for the reasons I did cite. Explaining was an attempt at being amiable rather than just saying, “Not going to happen, Pete.”

>You might want to A/B them with 11s if you ever get the chance.<

That would be fun. I haven’t done that since the mid/late 70s. But I HAVE done it. Whatever the problems the 10pi has that the 11 doesn’t, the 10pi sounds different than the 11 and I *like* the difference. That isn’t to say I don’t like the 11. I almost didn’t want to sell the last set of 11s the dealer I worked-for had, but I sold them and put them in the customers' car and they drove away (the customers, not the speakers). . . the 10pi’s had been sold-out shortly before I went to work there. . . boy, did I ever make the JBL rep mad that day. . . landed me a job, though.

>With regard to philosophy, I don't see it as philosophy but rather simple, boring speaker repair/restoration.<

Evidently I’ve been misunderstood. I didn’t mean anything about the restoration/repair was philosophical. In fact, with your help I’ve been trying to make it scientific.

>The purist view held by a few on this forum, that every AR ever built must be restored their way is a polarized view not often held by professional collectors.<

Oh, I think that depends entirely on the thing being collected, doesn’t it? What happens to the value of antique furnishings if they have been refinished, or if sterling was cleaned of its patina? And then there is always the destruction of a toy’s collectors’ value if it has been repainted or restored in any way. The cars I’ve seen go for $100k+ at international auctions on TV are more “show car” (in the “Batmobile” sense) than restoration work.

But I’m glad you brought-up the car analogy for the “collector’s” aspect. Rhetorical question: What is the point in restoring a 193x Jaguar Mk V when a 1985 Honda Prelude with 350,000 miles on it and a fouled spark plug, running on improperly inflated tires, could blow the Jaguar into the weeds both in the straights and on the corners even with the a/c running - all the while getting better gas mileage and giving the driver a better ride? I think the answer approximates, “Because it’s there.”

>As far as the analogy to singers, I don't see it because I don't have an emotional attachment to AR speakers<

I’m surprised to hear that the simile didn’t work for you. That’s too bad because the comparison of the peculiarities of a speaker’s “voice” to a human’s “voice” is about the best I can do.

If you have already answered this question elsewhere, forgive me. Have you ever owned a pair of the “classic” AR speakers? If so, what did you like, or not-like about them? If you haven’t owned any, let me suggest you pick-up a pair of 3a’s or 11s, make sure they are working right, and spend a few hundred hours in front of them.

I’m not saying you’d agree that they are worthy of worship, but I think you’d understand how others might think so. I'm guessing you might consider them "gems" even if flawed gems. No fair starting with an LST or a 9. . . well, okay, but then prepare to be smitten. We really don’t like these “New England” speakers because we are irrational back-woods folk who know no better, have heard nothing else, and have no choices. Well . . . for the most part, anyway. ;-)

>People are different, that's life.<

Yes, we are. I agree. I’m glad there’s more than vanilla, or even chocolate and vanilla.

And may I add:

“About tastes there is no disputing.”

Bret

Link to comment
Share on other sites

>>First let me say that all I'm trying to do is address your

>issues with the sound of your 10-pi's as simply as possible.<

>

>Yes, Pete. I know. I've said so. I've thanked you for the

>effort and I've acknowledged that you DID solve the problem.

>I have also acknowledged that my pig-headed refusal to use a

>good remedy for a known *possible* problem (possible only

>because I don’t know that I’ve ever saturated the

>transformer), is somewhat irrational.

Bret, I followed that your bass problem was solved with the older woofers that you used and I think they were a good choice since you prefer the restore to original approach, that's fine. But, I didn't see anything about the harshness being fixed, did I miss it? My view is that there are many reasonable ways to solve these problems and each person should choose the approach that fits their needs and is reasonable. I think you follow this but there are other purist collectors here that seem to want to tell others what to do.

>> However, your taking my point beyond what I proposed. <

>

>No sir, I didn't and I’m not. I was illustrating *my* point

>of view / perspective on the situation; NOT correcting yours.

>It was an entirely new thought which only began at your

>premise that I would find improving the speaker beyond its

>original design to be desirable. That is, afterall, what a

>reasonable inventor and engineer would conclude.

I do think that the speaker would sound better with more improvements but I understand the collectors view also. Some want better sound, others want to restore both are valid choices.

>>You've come to the conclusion that the "problem" is the

>autotransformer<

>

>No. . . not really. What I was saying was that if I had a new

>one, I would know it was in-spec. We are running-out of

>things to blame differences on. There’s been more discovered,

>I just haven’t posted it yet thinking everyone’s tired of the

>subject. At least for a while.

I for one would like to get back to technical discussion and wrap up the first step in your restoration based on your new discoveries.

>>Yet, you still seem to want better sound or sound equal to

>your friend's 10-pi's.<

>

>This is one heck-of-a Pandora’s box, Pete. What I want is for

>all four of our 10pi’s to sound so close to one-another that

>they are indistinguishable from each other. Also, I would like

>all four of them to sound as good as they can - as 10pi

>speakers.

This is fine, it seemed that you were emphasizing better sound, restoration is fine also.

>>The AR-11 crossover or actual AR-11s might be the best way to

>achieve your goals, that's the point I'm trying to make.<

>

>You made that point very eloquently, rationally, and I agree

>with you that this would be the best way to a quick and

>effective work-around for any problems associated with the

>crossover of a 10pi; possibly resulting in higher performance

>than the speaker originally had. I have said so multiple

>times. My deciding not to pursue it does not mean I do not

>understand it or appreciate the implications.

I think we both understand each other now, it would have helped to know a few messages back that you already had experience with 11s.

>Your recent discoveries about the motor differences in the

>woofers does throw a wrench in those works, however.

Are you suggesting that you and perhaps your friend's 10pi's might have the lower flux density woofers which are *not* the correct ones? I do not put a lot of trust in marketing literature, it's possible that some 10pi's were built with the other woofer, changes are made during production. Thinking back, your friend's woofers were the lower Bl product woofers and if we go by the spec then your friends were modified 10pi's not original.

>>Building the crossover is probably too much work and I'm not

>offended by a no thanks answer.<

>

>No trouble at all. If I choose not to build an 11 crossover

>for my 10pi’s it has nothing to do with how much work it would

>be. I did give you a “no-thanks” answer (long-windedly, I

>confess) for the reasons I did cite. Explaining was an

>attempt at being amiable rather than just saying, “Not going

>to happen, Pete.”

Yes, I understand your position better and while I brought up what professional collectors do I only bring it up for those who try to tell others what to do as if they know more about collecting, this was not toward you. We don't all have to act as professional collectors, it's perfectly reasonable to restore because we like them, but others should not try to tell us what to do unless it's clear that one is making a major error.

>>You might want to A/B them with 11s if you ever get the

>chance.<

>

>That would be fun. I haven’t done that since the mid/late

>70s. But I HAVE done it. Whatever the problems the 10pi has

>that the 11 doesn’t, the 10pi sounds different than the 11 and

>I *like* the difference. That isn’t to say I don’t like the

>11. I almost didn’t want to sell the last set of 11s the

>dealer I worked-for had, but I sold them and put them in the

>customers' car and they drove away (the customers, not the

>speakers). . . the 10pi’s had been sold-out shortly before I

>went to work there. . . boy, did I ever make the JBL rep mad

>that day. . . landed me a job, though.

Would have been good to know that you've already made the comparison.

>

>>With regard to philosophy, I don't see it as philosophy but

>rather simple, boring speaker repair/restoration.<

>

>Evidently I’ve been misunderstood. I didn’t mean anything

>about the restoration/repair was philosophical. In fact, with

>your help I’ve been trying to make it scientific.

>

>>The purist view held by a few on this forum, that every AR

>ever built must be restored their way is a polarized view not

>often held by professional collectors.<

>

>Oh, I think that depends entirely on the thing being

>collected, doesn’t it? What happens to the value of antique

>furnishings if they have been refinished, or if sterling was

>cleaned of its patina? And then there is always the

>destruction of a toy’s collectors’ value if it has been

>repainted or restored in any way. The cars I’ve seen go for

>$100k+ at international auctions on TV are more “show car” (in

>the “Batmobile” sense) than restoration work.

My point is that most speakers, especially high volume products that we're discussing, are not antiques that are so rare that altering them in any way destroys their value. Believe me I know about the perspective you offer, I've photographed antique museum pieces where I was not allowed to use a flash due to preservation concerns. But again these speakers are not antiques.

>But I’m glad you brought-up the car analogy for the

>“collector’s” aspect. Rhetorical question: What is the point

>in restoring a 193x Jaguar Mk V when a 1985 Honda Prelude with

>350,000 miles on it and a fouled spark plug, running on

>improperly inflated tires, could blow the Jaguar into the

>weeds both in the straights and on the corners even with the

>a/c running - all the while getting better gas mileage and

>giving the driver a better ride? I think the answer

>approximates, “Because it’s there.”

What I agree with here is that we don't all have to act as professional collectors, however, on the other hand, others here should not pressure the perfectionistic restoration of every piece, there should be a bit more faith that each person is capable of accessing their own situation. Yes, some may choose to restore "just because" they like them probably because they bring back memories, nothing wrong with that. This is probably getting worn out and I could go on at length so I'll try to be brief. I made the analogy of AR's to Chevy's perhaps the 9 is like a Corvette, and the "top of the line" models like Cadillac's. But I would not draw the analogy to a Rolls Royce, or Jag which I realize you do not outwardly state but suggest through example. There *are* Chevy's that are highly collectable, the rare L88 Corvette, 1960s Z28 Camaro, especially the 302 model - how about that dual quad option. These go for over 100K. But the vast majority of worn out Chevy's around are not worth perfectionistic restoration.

>>As far as the analogy to singers, I don't see it because I

>don't have an emotional attachment to AR speakers<

>

>I’m surprised to hear that the simile didn’t work for you.

>That’s too bad because the comparison of the peculiarities of

>a speaker’s “voice” to a human’s “voice” is about the best I

>can do.

Perhaps I should put it that I understand the restoration position without any need for the analogy. Humans are imperfect, and we usually don't give them a tune up, speakers and cars do get and need tune ups from time to time. I do view speaker design as art from a technical perspective, however the more significant art is the music and I prefer speakers that sonically "get out of the way" of the music. This makes it more difficult IMO to dismiss or live with the flaws in speakers.

>If you have already answered this question elsewhere, forgive

>me. Have you ever owned a pair of the “classic” AR speakers?

> If so, what did you like, or not-like about them? If you

>haven’t owned any, let me suggest you pick-up a pair of 3a’s

>or 11s, make sure they are working right, and spend a few

>hundred hours in front of them.

I stated in another thread that I never bought a pair of AR speakers, I meant new in their day. You probably noticed that my first post was about a pair of AR-2ax's that I bought used for the boxes. I'm very particular about speakers and I've always found the vintage ARs to have driver integration problems, phasyness in the crossover region. Interesting that most of the published curves from AR show individual driver responses, I think in part because they don't sum very well. Now, before I get attacked let me offer that the High Fidelity test report of the AR2ax shows about a 7 dB dip at 6 kHz, yes that's a driver integration problem and it *is* audible. The curve also shows that it lacks baffle step compensation and is plus or minus 5 dB, that's a lot as I'm sure you know, from 40 to 20 kHz. They don't disappear, they have good bass for a small box, I'll give them that. The power response argument is an excuse to cover the poor driver integration, it's possible to have both, good power response and good driver integration or on axis response. We've learned a lot about crossover design over the years. AR speakers have been a topic of technical discussion among many friends of mine for over 30 years, that's why I'm interested. I'd be willing to live with ARs for a while if a pair cross my path. I've started simulating the AR-11 and will probably come up with a revised crossover at some point.

>I’m not saying you’d agree that they are worthy of worship,

>but I think you’d understand how others might think so. I'm

>guessing you might consider them "gems" even if flawed gems.

>No fair starting with an LST or a 9. . . well, okay, but then

>prepare to be smitten. We really don’t like these “New

>England” speakers because we are irrational back-woods folk

>who know no better, have heard nothing else, and have no

>choices. Well . . . for the most part, anyway. ;-)

I've mostly designed and built my own speakers and I'm very particular about selecting commercial speakers. My main system has a pair of 1259s on each side, so perhaps I *should* start with 9s. We're thinking along the same lines, I've offered a few people here to bring their speakers, to compare with one of my favorite commercial designs. I have a high current A/B switchbox with line level matching ability. Hmm, I'm from the area myself and the only thing I'm finding irrational are people who say AR love them or leave, or try to force a decision or viewpoint without knowing the details. I hope you don't read anymore into my position.

I'd prefer to get back to the technical issues if your still interested.

Pete B.

Link to comment
Share on other sites

This seems to me to be one of the sillier arguements I've read here in awhile. What to do with 10 pis or anything else depends only on what your goal is. If you want to restore them as closely as possible to the way they were when they were new, warts and all, then clearly the autotransformers stays and if any other crossover elements such as capacitors need replacing, they have to be replaced in kind whether you believe more modern types like polypros sound better or not. OTOH, if you are not completely satisfied with the original sound and want to try to "improve" on it, there are many avenues of experimentation possible. Insofar as the autotransformer being a limiting factor in any practical situation is concerned, it should first be kept in mind that the statement that the AR 10pi autotransformer core saturated was offered to justify a competitors model the McIntosh ML1C having a different scheme without any specifics as to the actual limitations of the 10 pi in use, or proof of that claim. (I also own a pair of these speakers which need restoration and IMO it is hardly a paradyme to be copied and was never a real success on the market. I use them as end tables in my living room because of their unique grills which is a whole story all by itself.) AR was meticulous in testing and evaluating its designs and it should not be assumed out of hand that the autotransformer would saturate under conditions likely to be encountered in a home environment. That should be the subject of testing perhaps comparing 10 pis not to each other but to its closest relative (11s?). The engineering safety margin of the transformers may be far more than necessary. So far all we've got is speculation. I'll assume the original R&D and factory test data is no longer available.

As for AR speakers of that era being "phasey" which I consider is the equivalent of saying they had substantial frquency response irregularities in their crossover regions, I think that is a very plausible explanation of why they were not universally accepted on the market. I know that despite the very impressive live versus recorded demos I was priveleged to attend, they never sounded quite accurate to me reproducing commercially made recordings. AR used to print a graph on the back of their speakers showing ruler flat response. Was that graph made by splicing the response of the individual drivers together???? Matching the output of a 12" acoustic suspension woofer responding down to 35 hz is tough when the next driver is a small dome, the differences being so stark. Even today, fine 2" domes have difficulty extending response below 700 hz. IMO, the 8" driver used in AR9 was a wonderful idea which solved the problem handily. It should also be remembered that the original AR1 used an 8" Altec or Western Electric tweeter, didn't it? AR was hardly alone in this problem. JBL made some of the finest drivers in the world and assembled them into one awful sounding loudspeaker system after another.

To this day, I cannot understand how a loudspeaker system with a single forward firing tweeter can achieve both flat on axis response and flat total power radiated response. With off axis energy clearly falling away faster as frequencies get higher for virtually all tweeters, it seems to me that if on axis repsonse is flat, total power radiated will have a high end falloff. LST seemed to me like a step towards solving this problem. Perhaps someone could offer an explanation. It was Peter Snell whom I first heard comment that it wasn't the power response that the speaker radiated which mattered but the response which reaches the listener's ear. Clearly integration of the speaker into the listening room's acoustics was of concern to him too. I think this is a problem which most speaker designers to this day have failed to address.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...