Pio1980
AK Member
The quality of answers is frequently based on how the question is framed. They may have done the search under the terms of their development, rather than a general search for any sealed box baffle.
AR-3A speakers, Why were they so good regarding the deep Bass
- Thread starter markbark12
- Start date
This was Electrovoice vs. AR where basically, I assume, they did not want to pay AR royalties when building/selling
air suspension speakers. I don't know if they just started selling them without paying and got sued by AR, or what
happened but this was the court case and it is a good logical result IMO.
Thank you. It makes sense of the whole thing. I agree too. I would say AR overstepped, asking for royalties. AR certainly refined the concept and produced some great sounding speakers.
I think Ed Vilchur believed he hadn't just refined a concept, and instead, he believed he had radically reinterpreted it to produce an unexpectedly beneficial result. Hence his patent claim.
At this point, with computer programs and so on, and especially to someone so well versed in acoustics as Pete, the idea of going to a lower resonant frequency and then raising it with a tiny box doesn't seem so crazy and unprecedented as it did back in the 50s. The patent court in the court may have decided that the idea was inherent in Olsen's patent, but Vilchur's design landed like a bombshell in the playground of the speaker designers (to repurpose a description of Karl Barth's Church Dogmatics) because no one else had thought to use the ideas in Olsen's patent in that way. Which suggests Vilchur had come up with a genuine new idea, even if it wasn't legally and theoretically new.
At this point, with computer programs and so on, and especially to someone so well versed in acoustics as Pete, the idea of going to a lower resonant frequency and then raising it with a tiny box doesn't seem so crazy and unprecedented as it did back in the 50s. The patent court in the court may have decided that the idea was inherent in Olsen's patent, but Vilchur's design landed like a bombshell in the playground of the speaker designers (to repurpose a description of Karl Barth's Church Dogmatics) because no one else had thought to use the ideas in Olsen's patent in that way. Which suggests Vilchur had come up with a genuine new idea, even if it wasn't legally and theoretically new.
Last edited:
Pio1980
AK Member
There were later similar approaches with newer better drivers from several manufacturers.ARs - Cool!!
Too bad you just couldn't purchase a new pair of the old style today.I'd get a pair.
I don't believe that anyone has stated it in this way but here's the bottom line analysis:
If you look at the model for a closed box speaker, which they had at that time, it is a simple (once you
combine things) second order resonant system. It is a mass, spring, damper system where the mass is
the cone (plus voice coil etc) plus air load. The spring is the total suspension compliance (Cms) in parallel
with the air spring (Cas), and the total damping (Qts) is the losses in the suspension (Qms) combined with
the electro-acoustical damping (Qes "braking") of the motor.
Now, lets look at the two extremes for getting a desired closed box resonant frequency (Fc) first came
infinite baffle. In this system the woofer designer chooses a cone mass and suspension compliance to
get the desired Fs that is already at or near Fc. Consider what happens to the box, it must be huge so
as to not add significant air spring pressure which would raise Fc and was named infinite baffle for this reason.
The genius of Olson's patent was to recognize that because the two compliances are in parallel it is
possible to raise the compliance of the suspension, and then drastically lower the box compliance by
making it much smaller to obtain the same total compliance.
A side benefit is that if the suspension compliance is somewhat non-linear having the air spring compliance
dominate, makes a combined compliance that is more linear. It should be noted that AR always used the
wording that the air spring was MORE linear because air is in fact not perfectly linear.
What in fact probably had a larger impact on making the AR woofer more linear (as pointed out by my project
advisor) was the overhung voice coil which was not common at that time. And, I don't think this was mentioned
by AR probably because they wanted to keep it company private.
Also, consider this, once you choose to design an air suspension speaker the closed box resonance is determined
to a major extent by only the box volume, and for a given size cone the cone mass. Pick the box size and desired
Fc and the moving mass can be computed as long as the woofer compliance is MUCH larger than that of the air
suspension it does not come into the equation. In fact the value is not critical, if it is 10X that is good, 100X is
even better but probably will not keep the voice coil centered - there are practical considerations.
Consider that as the suspension compliance goes up the box size goes down to maintain a constant Fc and all
else not changing. Infinite suspension compliance (not physically realizable) is the value for the absolute smallest
box. As you decrease the suspension compliance you pay a penalty in that a larger box is required, of course
there is a point of diminishing returns as you increase the suspension compliance.
I'm hoping to write this up with figures and diagrams to present at a Frankenfest within the next few years. This
is more of a how it works than here's all the math and equations.
If you look at the model for a closed box speaker, which they had at that time, it is a simple (once you
combine things) second order resonant system. It is a mass, spring, damper system where the mass is
the cone (plus voice coil etc) plus air load. The spring is the total suspension compliance (Cms) in parallel
with the air spring (Cas), and the total damping (Qts) is the losses in the suspension (Qms) combined with
the electro-acoustical damping (Qes "braking") of the motor.
Now, lets look at the two extremes for getting a desired closed box resonant frequency (Fc) first came
infinite baffle. In this system the woofer designer chooses a cone mass and suspension compliance to
get the desired Fs that is already at or near Fc. Consider what happens to the box, it must be huge so
as to not add significant air spring pressure which would raise Fc and was named infinite baffle for this reason.
The genius of Olson's patent was to recognize that because the two compliances are in parallel it is
possible to raise the compliance of the suspension, and then drastically lower the box compliance by
making it much smaller to obtain the same total compliance.
A side benefit is that if the suspension compliance is somewhat non-linear having the air spring compliance
dominate, makes a combined compliance that is more linear. It should be noted that AR always used the
wording that the air spring was MORE linear because air is in fact not perfectly linear.
What in fact probably had a larger impact on making the AR woofer more linear (as pointed out by my project
advisor) was the overhung voice coil which was not common at that time. And, I don't think this was mentioned
by AR probably because they wanted to keep it company private.
Also, consider this, once you choose to design an air suspension speaker the closed box resonance is determined
to a major extent by only the box volume, and for a given size cone the cone mass. Pick the box size and desired
Fc and the moving mass can be computed as long as the woofer compliance is MUCH larger than that of the air
suspension it does not come into the equation. In fact the value is not critical, if it is 10X that is good, 100X is
even better but probably will not keep the voice coil centered - there are practical considerations.
Consider that as the suspension compliance goes up the box size goes down to maintain a constant Fc and all
else not changing. Infinite suspension compliance (not physically realizable) is the value for the absolute smallest
box. As you decrease the suspension compliance you pay a penalty in that a larger box is required, of course
there is a point of diminishing returns as you increase the suspension compliance.
I'm hoping to write this up with figures and diagrams to present at a Frankenfest within the next few years. This
is more of a how it works than here's all the math and equations.
Last edited:
@bluesky Are you saying that you'd buy a new AR-3a if it was available today?ARs - Cool!!
Too bad you just couldn't purchase a new pair of the old style today.
I've been very slowly working on an "AR-3a" inspired design and might show/complete it within the next few years.
Yes about the AR 303, somewhere I read that Ken got some AR-3a samples to measure, one pair I think from
Tom Tyson. Maybe Tom wrote it up at CSP. Here's the Stereophile review:
www.stereophile.com
Julian Hirsh review in Stereo Review pg 39 in the .pdf:
From Ken Kantor:
Tom Tyson posted this at CSP:
Although I had nothing whatsoever to do with the design of either speaker, I admire them both. I furnished a pair of mint-condition AR-3a's for Julian Hirsch to use in his June, 1995 *Stereo Review* audition of the AR-303. I did receive quite a bit of correspondence from Mr. Hirsch regarding testing both speakers, and for the benefit of the readers here, his comments from a fax on March 25, 1995, were as follows:
"The averaged room response of the two were remarkable similar, although the AR-303 had a markedly superior top end, above about 6,000 Hz. As a result, I set the two controls of the AR-3a to their maximum positions, which I believe was their usual preferred setting from the start if you wanted to sound as good as or better than your competition. The AR-3a was 2 dB more sensitive than the AR-303."
(Tom Tyson Note: putting both level controls at the maximum position will probably result in too much midrange. The usual preferred setting for best response has been to put the midrange slightly above the "dot," and the high-frequency control at or near maximum).
"On-axis MLS response measurements showed that the AR-303 was a clear winner on overall response and flatness. Its bass distortion was also lower than that of the AR-3a (and my old AR-1). In listening comparisons between the 303 and the 3a, the closest match occurred with the 3a controls set to the 'dots,' giving the two a very similar overall sound character. This was consistent with what I heard using a variety of program material. My conclusion was that the AR-303 has the best and deepest bass of any current speaker in its size range, and that a subwoofer is really not needed to improve it. I did couple it with my HSU subwoofers, and except for bringing out some 20-25 Hz. organ pedals a bit more prominently, it did nothing for the overall bass performance. Actually, this was the first speaker I have come across in recent years for which that could be said."
So it would seem that Ken Kantor and his staff (notably Bill Bush) succeeded in achieving their goals of keeping the family resemblence, yet improving an already-excellent design!
--Tom Tyson
Tom Tyson. Maybe Tom wrote it up at CSP. Here's the Stereophile review:
Acoustic Research AR 303 loudspeaker | Stereophile.com
It's a common audiophile failing to remember the past as being much better than it actually was. (Though, of course, some things were better.) I remember the first time I heard a pair of Acoustic Research LST loudspeakers, in 1974 or thereabouts. Compared with the Wharfedales I used in my own...
Julian Hirsh review in Stereo Review pg 39 in the .pdf:
From Ken Kantor:
Tom Tyson posted this at CSP:
Although I had nothing whatsoever to do with the design of either speaker, I admire them both. I furnished a pair of mint-condition AR-3a's for Julian Hirsch to use in his June, 1995 *Stereo Review* audition of the AR-303. I did receive quite a bit of correspondence from Mr. Hirsch regarding testing both speakers, and for the benefit of the readers here, his comments from a fax on March 25, 1995, were as follows:
"The averaged room response of the two were remarkable similar, although the AR-303 had a markedly superior top end, above about 6,000 Hz. As a result, I set the two controls of the AR-3a to their maximum positions, which I believe was their usual preferred setting from the start if you wanted to sound as good as or better than your competition. The AR-3a was 2 dB more sensitive than the AR-303."
(Tom Tyson Note: putting both level controls at the maximum position will probably result in too much midrange. The usual preferred setting for best response has been to put the midrange slightly above the "dot," and the high-frequency control at or near maximum).
"On-axis MLS response measurements showed that the AR-303 was a clear winner on overall response and flatness. Its bass distortion was also lower than that of the AR-3a (and my old AR-1). In listening comparisons between the 303 and the 3a, the closest match occurred with the 3a controls set to the 'dots,' giving the two a very similar overall sound character. This was consistent with what I heard using a variety of program material. My conclusion was that the AR-303 has the best and deepest bass of any current speaker in its size range, and that a subwoofer is really not needed to improve it. I did couple it with my HSU subwoofers, and except for bringing out some 20-25 Hz. organ pedals a bit more prominently, it did nothing for the overall bass performance. Actually, this was the first speaker I have come across in recent years for which that could be said."
So it would seem that Ken Kantor and his staff (notably Bill Bush) succeeded in achieving their goals of keeping the family resemblence, yet improving an already-excellent design!
--Tom Tyson
Last edited:
Olson article reprint, note Figures 3 and 4:
Reprint paper by Harry F Olson
I recently acquired a very nice pair of AR-3a's, a 1 owner set "untouched" since they left the factory in the 70'ies. Tom Tyson has been so kind to help me establish their production year and site and these babies were assembled at Amersfoort, Holland in the 1972-73 time-frames. The previous owne...
community.classicspeakerpages.net