Jump to content

Loudspeaker directivity by Roy Allison


Howard Ferstler

Recommended Posts

This question may be a bit OT but I'm looking for a list of speaker brands, models and rankings from the 2001 CR Aug. issue (pp 33-37) "Small Boxes, Big Sound" article/review. If anybody has them, please PM me.

Thanks!

Link to comment
Share on other sites

  • Replies 179
  • Created
  • Last Reply
Toole's useful contribution to knowledge of sound seems to be that you need four subwoofers arranged as he describes to get reasonably uniform bass response in a typical room.

Yes, thats all he ever contributed. In fact he just filled a 500 page book with the four subwoofer notion, nothing else.

Villchur's major contributions were the acoustic suspension low frequency loudspeaker system, the wide dispersion dome tweeter and midrange, ferrofluid cooling of tweeters and midrange drives to increase power handling, a practical method for isolating turntables from feedback causing vibrations generated by low frequency loudspeaker systems, and hearing aids to mitigate the damage people did to their hearing by listening to other than serious music at insanely loud levels.

The acoustic suspension patent was disallowed by prior art from Harry Olson at RCA, as I have quoted earlier in these forums. John King at Cletron was the first, and held the patent, for the use of ferrofluid in loudspeakers. (United States Patent 4017694)

Even if Villchur's contributions have all been eclipsed, and it is not at all clear that they have, he set the benchmark others had to compete against. He not only set technical benchmarks for performace but for quality, reliability, and value for money. It was a hard combination to beat. I'm not sure anyone has.

True enough.

David

Link to comment
Share on other sites

Yes, thats all he ever contributed. In fact he just filled a 500 page book with the four subwoofer notion, nothing else.

The AR patent was disavowed by prior art from Harry Olson at RCA, as I have quoted earlier in these forums. John King at Cletron was the first, and held the patent, for the use of ferrofluid in loudspeakers. (United States Patent 4017694)

True enough.

David

It scares me when you agree with me. It makes me wonder where I got it wrong.

Link to comment
Share on other sites

Well, that's the inevitable problem of trying to have a technical discussion on a site devoted to vintage anything. "Better" is in the eye (or in this case, the ear) of the beholder,and the membership tends to be skewed toward those whose view is that newer didn't represent "progress,""improvement" or "better" if it moved things away from what they liked best.

I'm with Steve here in that it is perfectly fine to admire and prefer a vintage item of any era. In my house you would find bicycles from the 70's, LPs from the 60s and 70 (lots of "serious" piano music), watches and cameras from all eras.

Certainly some of those items where built in a quality or style that either isn't done today or costs a ton of money. I think we just need to acknowledge that progress is continuous. Technology brings higher performance at lower cost to all fields. Mechanical precision gives way to electronic, or now, digital sophistication, primarily because customers like the tradeoff. If you want something made the way they used to buy a Leica or a Rolex, great stuff but at a heavy price.

The audio business certainly exhibits this continuous evolution. Any product is surpassed within a decade. However, if a speaker is able to rise above its peers, was far better than the norm of its era, then that is significant. The AR3a was a very impressive product when surrounded by other speakers of 1967. It significantly advanced the art and forced a round of "catch up'. The fact that many speakers ran circles around it by 1980 doesn't detract from its importance.

To proclaim it (or an Allison product) as somehow the "best ever" and the end of progress is, in my mind, silly.

Link to comment
Share on other sites

I'm with Steve here in that it is perfectly fine to admire and prefer a vintage item of any era. In my house you would find bicycles from the 70's, LPs from the 60s and 70 (lots of "serious" piano music), watches and cameras from all eras.

Certainly some of those items where built in a quality or style that either isn't done today or costs a ton of money. I think we just need to acknowledge that progress is continuous. Technology brings higher performance at lower cost to all fields. Mechanical precision gives way to electronic, or now, digital sophistication, primarily because customers like the tradeoff. If you want something made the way they used to buy a Leica or a Rolex, great stuff but at a heavy price.

The audio business certainly exhibits this continuous evolution. Any product is surpassed within a decade. However, if a speaker is able to rise above its peers, was far better than the norm of its era, then that is significant. The AR3a was a very impressive product when surrounded by other speakers of 1967. It significantly advanced the art and forced a round of "catch up'. The fact that many speakers ran circles around it by 1980 doesn't detract from its importance.

To proclaim it (or an Allison product) as somehow the "best ever" and the end of progress is, in my mind, silly.

"I think we just need to acknowledge that progress is continuous."

It is? I wonder. If AR3as were given the benefit of modern high powered amplifiers, corrected for FR aberations with careful equalization, and the source material were compact discs, how would they compare with today's so called high end products? How about products of comparable price when adjusted for inflation? Certainly an equalizer can compensate for the lower midrange Allison cancellation effect and for the rolled off high end of the tweeter. No that's not cheating, that's engineering. It's results that count, not how you get there, people listen to recording/playback audio systems, not speakers.

"The fact that many speakers ran circles around it by 1980 doesn't detract from its importance."

That was what Peter Breunniger's article in Stereophile Magazine was supposed to give us at least some insight into. Evidently his boss didn't agree with the idea, so much so that it cost Breunniger his job. Did Atkinson simply feel that there wouldn't be enough interest in it? Or that his current advertisers might be mad enough to pull their ads if the results showed that a 40 year old speaker ran rings around their current best offerings even though the new products cost many times the price? And AR3a didn't need no stinkin' outboard subwoofer to produce deep low distortion bass either.

Link to comment
Share on other sites

If AR3as were given the benefit of modern high powered amplifiers, corrected for FR aberations with careful equalization, and the source material were compact discs, how would they compare with today's so called high end products?

Maybe Dave's next Mods and Tweaks project should be an AR-3a crossover...

Link to comment
Share on other sites

If AR3as were given the benefit of modern high powered amplifiers, corrected for FR aberations with careful equalization, and ...

Corrected for frequency response aberations? So a good speaker can have poor frequency response and require remedial action by the owner?

Thats going to absolve us poor designers of a lot of extra work. Good to know.

David

Link to comment
Share on other sites

Corrected for frequency response aberations? So a good speaker can have poor frequency response and require remedial action by the owner?

Thats going to absolve us poor designers of a lot of extra work. Good to know.

David

Where I was taught, engineers were trained to think in terms of system performance and to put the characteristics of individual elements in that larger context. Just because a loudspeaker system needs frequency filtering to improve overall results does not invalidate its merits. What do you think a crossover network is anyway if not a series of frequency filters. And many of them are not merely bandpass filters either but use further equaliztion to shape response within each passband to improve overall response.

Link to comment
Share on other sites

Where I was taught, engineers were trained to think in terms of system performance and to put the characteristics of individual elements in that larger context. Just because a loudspeaker system needs frequency filtering to improve overall results does not invalidate its merits. What do you think a crossover network is anyway if not a series of frequency filters. And many of them are not merely bandpass filters either but use further equaliztion to shape response within each passband to improve overall response.

I have no problem with any amount of filtering or EQ. I just think that if you sell a product to a customer that doesn't sound its best without that customer providing (and adjusting) external EQ, then you haven't done your job.

"Its a great car, assuming you change the tires and anti-roll bar, rechip the engine, and add an airdam."

Otherwise we open the door for those horrid JBL systems to be superior, assuming the right EQ is added.

David

Link to comment
Share on other sites

I just think that if you sell a product to a customer that doesn't sound its best without that customer providing (and adjusting) external EQ, then you haven't done your job.

Wasn't the entire "east coast/west coast" thing just people buying speakers whose response was essentially "pre-equalized" to their preference? For any owner who has been happily listening to these speakers for decades and has no desire to "correct" their "FR aberrations," the designers already did their job.

Link to comment
Share on other sites

I have no problem with any amount of filtering or EQ. I just think that if you sell a product to a customer that doesn't sound its best without that customer providing (and adjusting) external EQ, then you haven't done your job.

"Its a great car, assuming you change the tires and anti-roll bar, rechip the engine, and add an airdam."

Otherwise we open the door for those horrid JBL systems to be superior, assuming the right EQ is added.

David

Then you would agree that anyone who designs and sells a speaker system which needs an external subwoofer sold separately to reproduce the lowest bass hasn't done their job which seems today to be most of the industry. Especially when that system is a pair of miserable 5 1/2 inch two way systems that sells for $4000 as a typical example.

Zilch, I think he just slammed your Ranger Paragons.

Link to comment
Share on other sites

How about a constant directivity horn for those ring radiators at least? :P

Beamy exponential suckers, they're just what is required by the design for precedence compensation.

[Too bad they're nasty to boot.... :P ]

Link to comment
Share on other sites

As for the mono listening comparisons as illustated in the left diagram, well, I simply do not think they are of much use to those looking to determine how well speakers integrate a soundstage into a listening room. Toole and his people were listening for speaker characteristics in isolation and not the room/speakers interface. They hate the room, or are at least manifestly suspicious of it, which is why they use drapes to cover much of the room up. The floor was also capeted, of course, which is OK by me.

Howard Ferstler

Well, read the book again. They found that mono tests were more revealing of differences, including spaciousness. Specifically the ESL63 was downgraded for a lack of spaciousness when listened to in mono. When tested in stereo, having a second speaker contributed some spaciousness and allowed the ESL63 to nearly catch up with other speakers in the test.

You keep cutting down Toole's opinions when he actually agrees with you more than several others here do. He doesn't "hate the room", he repeatedly states that the ear is very forgiving of the many reflections that the room adds. He likes the spaciousness that a live room adds.

Read the book, again (with an open mind)!

Link to comment
Share on other sites

I have reviewed a fair number of loudspeakers for published reports and I have NEVER found any (including even my own IC-20 Allison models) that were not at least helped a tad (and usually a bit more) by a bit of outboard equalization.

Howard Ferstler

As a reviewer should you judge the speaker by what the average consumer gets when they buy it and use it, or by what you, a highly skilled practitioner, can achieve when you carefully EQ it?

David

Link to comment
Share on other sites

As for Olson and the acoustic suspension woofer, well, I will paraphrase some comments from Roy Allison on that issue. "Harry Olson, brilliant as he was, really had absolutely no idea of the implications of such a system. His emphasis was on frequency response and that the response was still good when the speaker driver was in a small enclosure.

So, what Villchur was mainly after was a woofer with low distortion, as well as decent extension. Olson was not oriented towards that at all, and his approach was to simply make use of a woofer in a sealed enclosure to control resonance and determine extension. No mention of using acoustic air pressure to control and reduce distortion.

Howard Ferstler

"It will be seen that the mechanical reactance caused by the air chamber behind the cone is three times the mechanical reactance resulting from the suspension system. Therefore, in the range where the compliances are the controlling mechanical reactances the compliance caused by the air chamber is the controlling compliance. (Hence a high alpha or Acoustic Suspension system). This expedient reduces the distortion caused by a nonlinearity of the suspension system."

From the RCA patent. Comment within brackets is from me.

Of course, I don't expect contradictory facts to change your opinion in the least,

David

Link to comment
Share on other sites

OK, I must confess to being a sucker for rhetorical questions and always think that the poster of such material is being serious.

Anyway, Re: the Neil Grover LvR demos. Yep, the 3 and 3a could not have played as loud as the 10 Pi. Hey, thank you ferrofluid! "Better" for you in this particular discussion seems to primarily involve the ability to play louder. Jeeze, if that is the case the Klipschorn beats the pants off of everybody else.

However, if you subtract the max-output issue, subtract the midrange dispersion issue (between 500 and 1000 Hz), deal with the mid-bass suckout (Allison boundary effect that impacts normal listening rooms) issue, and the treble dispersion issue (the .75-inch AR dome tweeter still beats most contemporary 1-inch domes and of course the AR-3 dome), super-low bass reproduction (thank you Velodyne, Hsu, and SVS), I think we can see that really not all that much has advanced since the Villchur LvR era. Sure, some of the later designs were improvements, but if we use the LvR demos as a reference standard what are we to make of those later designs? Do you suppose they could have delivered results that were even more "realistic" sounding than the live performers?

Ferrofluid allowed the Model 11 to deliver flatter respose (not smoother, just flatter, with less of a high-range tilt downward) than the AR-3a. As best I can tell, that was about it, and also I am pretty sure the AR-3a (at least the earlier versions with the more loosely suspended woofer) could reach deeper into the low bass range than the 11.

Howard Ferstler

I regard the LST as a super AR3a. I'd find it hard to believe that four AR3a tweeters and four AR3a midrange drivers could not produce as much sound before distorting as one AR11 tweeter and one AR 11 midrange driver. The design not only has four times the sound power output of the AR3a in the midrange and tweeter sections but extends the dispersion to virtually 180 degrees horizontally. The only disappointment is that I'd think the arrangement would have been even better with the midrange and tweeters on four equiangular panels instead of the arrangement on LST but that may be quibbling. I'm sure it would have added a lot to the cost of the cabinet.

I am amazed at how well the 3/4 inch dome tweeter in my restored AR2axs work when properly equalized. I was blown away by how smooth, clear, crisp, and accurate they can be made to sound. For a single tweeter I don't think I've heard better. In a room about 12 x 15 with a drape behind them as shown in the standard JAES listening room and with the speakers placed in the corners about 2 feet off the floor and angled at 45 degrees toed in, I don't think you could ask for more uniform high frequency coverage of the entire area. Hard to believe they are direct firing. Imaging is excellent with a vocalist at the center like he's right in front of you. A bass boost is also required and results in very satisfactory bass too. Not quite AR3 and certainly not AR 9 (but then what is?) but better than KLH Model 6 (Haven't tried the goop for sealing the cloth surrounds yet.)

Is LST better than AR9? Yes and no. It has better lateral dispersion of midrange and treble, not as deep bass. AR9 may be better at some sounds just above the woofer crossover frequency where the midrange drivers don't quite reach. I'm not htat familiar with the sound of AR3a or LST, it's been a long time since I heard either. Properly equalized, AR2ax sounds far better than I ever remember it or other AR speakers of that era. Unequalized even with the tweeter level all the way up, it sill sounds muffled with a high frequency rolloff on everything I've listened to with them to my ears. Perhaps the treble peak of an Ortophon moving coil cartridge in the old days helped.

Link to comment
Share on other sites

You got me (and Allison, and I suppose Villchur) on this one. I wonder why they did not build and market such a system. Interestingly, while some companies did go on to produce acoustic suspension woofer systems (after AR gave up on defending the patent), none of them, at least for a while, managed to make driver/enclosure combinations that would match the AR line at the various price points.

Howard Ferstler

'Tis the nature of invention that it is very hard to invent something that no one else has tried before. Vilcher was enough of a visionary to see the importance of the approach and willing to make speakers very different from the market norm, with the disadvantage of markedly lower sensitivity.

Full credit for that.

David

Link to comment
Share on other sites

"It will be seen that the mechanical reactance caused by the air chamber behind the cone is three times the mechanical reactance resulting from the suspension system. Therefore, in the range where the compliances are the controlling mechanical reactances the compliance caused by the air chamber is the controlling compliance. (Hence a high alpha or Acoustic Suspension system). This expedient reduces the distortion caused by a nonlinearity of the suspension system."

From the RCA patent. Comment within brackets is from me.

Of course, I don't expect contradictory facts to change your opinion in the least,

David

It is unfortunate that Villchur would not pay a patent lawyer $200, less than the cost of a single AR3 to help him, nor for the services of a physicist who understood Newton's second law of motion and how it applied to his invention. If he had, he could have written his patent application in such a way that it would have circumvented Olsen's. The way to beat another patent is not to ignore it in your own application but to point it out and draw a clear distinction between what the prior patent claimed and your own invention. I'm confronted with that very same problem right now, getting around another patent....my own :rolleyes:

Link to comment
Share on other sites

Just how normal does that room look? Note the draped front wall and the drapes that extend down the side walls enough to approach an LEDE arrangement. Not fully that way, but just how many living rooms have we seen that are outfitted like that? Also, note the close-up listening distances with both arrangements. Do many here sit that close? Obviously, the whole thing is designed to subtract as much of the room as possible and get the listener primarily into the direct field. Well, that works, and the result is a bad situation for wide and super-wide dispersion models - models that Toole avoided dealing with to any serious extent in his book.

Howard Ferstler drapes the front wall. The side walls are not draped further than the location of the speakers themselves, and those walls are reflective. At the ~8' distance shown, the listener would be well within the imaginary Beranek reverberant field, according to Allison and Berkovitz....

Link to comment
Share on other sites

... I think we can see that really not all that much has advanced since the Villchur LvR era. Sure, some of the later designs were improvements, but if we use the LvR demos as a reference standard what are we to make of those later designs? Do you suppose they could have delivered results that were even more "realistic" sounding than the live performers?

Of course, considering what they were....

Link to comment
Share on other sites

I have no serious problem with some of Toole's findings, but I was patently offended when he left out serious performance examples and discussions of of some of the most notable speakers in history, especially east-coast models that are heavily represented right here on this Classic Speaker Pages site.

I should think a writer patently offended by omissions might find that to comprise motivation to correct the error in writing their own book.

[Oh, WAIT, been there and done that already.... :rolleyes: ]

Link to comment
Share on other sites

Archived

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


×
×
  • Create New...