AR-3a High-Frequency Spectral Balance

[tysontom]

Since you were there, do you recall if the tweeters were the later ferrofluid black cloth, or the earlier lighter colored ones?

I have a suspicion, but I'd like you to confirm it for me.

Bret

Bret,

The tweeters were black Ferrofluid version. I own the speakers (there were three sets) that were used in the demonstrations, and I use them everyday in my office system.

--Tom Tyson

[Diamonds&Rust]

Bret,

The tweeters were black Ferrofluid version. I own the speakers (there were three sets) that were used in the demonstrations, and I use them everyday in my office system.

--Tom Tyson

Now THAT, Tom, definitely qualifies as "cool."

Thanks for that answer. And thanks for the crossover pictures. I'm *very* surprised by the crossover photo. Those have to be of "later" manufacture since they are using the Callins NPEs instead of the Sprague Compulytics and I don't see the extra connections to the fuse holders.

I don't know if I told you, but the pair my friend owns were so early, there is a piece of tape on one of the transformers with a "manufacturer's sample number" note hand written on it, and *one* of his had (no longer does) a Chicago "Royalitic" capacitor in it - oh, and the switches are hard wired instead of being on a PC board. <all of that indicates to me that he got one of the first several pairs ever made>

Between you two I think you've got the model pretty-well covered.

Do you have all three pair that were used in the L vs R demos? That would be remarkable.

Bret

[tysontom]

No, there probably was not another speaker of that time period that could reproduce a jazz quartet with spectral accuracy at lifelike SPLs, even if the requisite recording and amplification equipment existed. (Remember, the recording and amplification equipment was barely—just barely—up to the task in 1976.) Other speakers of the early ‘60’s time period were too uneven in their response and did not have the deep bass extension with the same lack of distortion as the AR-3 to have performed as well in an L v R test.

The AR-3 had exceptional bass-midrange response in terms of accuracy, smooth, even response, lack of distortion, transient behavior, etc. The high frequencies were certainly as good as the bass and MR in terms of the quality and accuracy of reproduction. In fact, AR even said that within its frequency range, the new HF dome radiator achieved the highest degree of accuracy of any of the three radiators.

However, the 1 3/8” tweeter simply did not have the output necessary to achieve lifelike SPLs in small (essentially nearfield) acoustic spaces. So what worked for a string quartet in a concert hall would not have worked for a jazz group in a small club setting. The 3a would have been better, but still would not have done as well as the 10Pi/11.

It would have been interesting to have heard an AR-9 under those same L v R conditions. I remember Victor Campos (the Head of AR’s Engineering, who managed the 10Pi/Grover demo exercise) telling me that they tried the LST, and it didn’t do as well as the 10Pi—too much overlap and interference from the multiple mid-high drivers. The single MR and HF units of the 10Pi—coupled with their exceptionally wide dispersion and amazing power-handling—proved to be the key to replicating “reality.”

Steve F.

It is important to realize that when the Fine Arts Quartet and Gustavo Lopez Live-versus-recorded concerts were being performed, a preamplifier had to be used between the Ampex tape recorder and the power amplifiers prior to input into the AR-3s for playback. At nearly every venue (there were in excess of 75 concerts performed in five or six major cities across the country), the preamp tone controls had to be “fine adjusted” to bring the output in line with the acoustics in the concert hall, and this required boost much of the time. There were instances in which the treble control had to be reduced, but usually there was the requirement of some treble boost.

The live-vs.-recorded concert was “live” music, and therefore the AR-3s had to mimic the exact output from violins, cellos and guitars (or Nickelodeons) at exactly the same level as the instruments in that same space. Both the live musicians and the AR-3s would have sounded “duller” well back in the music halls where these sessions were being performed, and the effect is the initial reverberation for both the AR-3s and the instruments. With recorded sound in the home, the attempt is to “take you to the concert hall,” not "bring the musicians into your listening room,” and thus the overall sound balance of most large venues is one of rolled-off highs when you consider the effects of diffraction, absorption and reflection in any large space. The reverberation at home with recorded music is actually a form of “double” reverberation, since the reflected sound from the original music is blended with the reflection of the listening room itself (remember that the live musicians in the live-vs.-recorded music were recorded outdoors in basically anechoic space to avoid “double reverberation” in the playback). Nevertheless, the brain does a superb job of psycho-acoustically “sorting out” these reflections in most cases except those where a room has little or no absorption from furniture, carpets and so forth. These overly live rooms often make the sound very diffuse and muddy, easily rectified with the proper room treatment.

Ironically, most current speakers today with flat on-axis power suffer significant off-axis power losses (when compared to the AR-3 and AR-3a), and thus the acoustic-power into any listening room will be that of gradually diminishing high-frequency output as you get further and further into the reverberant space. Some so-called “flat” speakers actually sound quite dull well back into the room, thus the manufacturers suggest that you sit in a “sweet” spot in the near field, positioned in a focused array between the speakers. The really nice thing about the older ARs was the exceptional dispersion and excellent acoustic-power response, thus giving the illusion of spaciousness and three-dimension -- greatly lacking in some current-model speakers. One might say that speakers should image such and such a way, and that one intends to sit in the “sweet spot” anyway, and that flat on-axis energy is the only important thing. This is fine if no other listeners are planning to listen to music in the same place; besides, if imaging is the most important thing, why not invest in a good set of headphones and get the ultimate “imaging” capability!

Would the AR-3 work as well in a jazz ensemble? I think probably not due to the required SPL level required in the near-field listening experience. I am not sure that even an AR-10Pi would be up to the task since jazz trumpets, saxophones, in addition to cymbals and snare sounds, would likely overpower the linear output capability of the dome tweeters. I'm not sure that even the AR-9 could sustain the high SPL levels necessary in the middle frequencies. It would likely take stacked AR-10Pis or AR-3s/AR-3as to replicate the sound of a jazz group.

--Tom Tyson

[tysontom]

Now THAT, Tom, definitely qualifies as "cool."

Thanks for that answer. And thanks for the crossover pictures. I'm *very* surprised by the crossover photo. Those have to be of "later" manufacture since they are using the Callins NPEs instead of the Sprague Compulytics and I don't see the extra connections to the fuse holders.

I don't know if I told you, but the pair my friend owns were so early, there is a piece of tape on one of the transformers with a "manufacturer's sample number" note hand written on it, and *one* of his had (no longer does) a Chicago "Royalitic" capacitor in it - oh, and the switches are hard wired instead of being on a PC board. <all of that indicates to me that he got one of the first several pairs ever made>

Between you two I think you've got the model pretty-well covered.

Do you have all three pair that were used in the L vs R demos? That would be remarkable.

Bret

Bret,

This pair of AR-10s was built in 1976 with the old-style brass logo plates but the first iteration of the Ferrofluid soft-dome tweeter. The most interesting thing about the crossover picture is the use of heavy-duty components in the critical areas. The auto-transformer is *double* the size of the standard unit, and the wiring-size in some areas as well as the rating of some capacitors, was increased to accomodate the 800-watt peaks. Note, too, the addition of the additional "2 x 4" internal braces. You have to look closely. I think the resonance probably went up a few cycles due to the extra space required for those components and additions, but all of that was necessary for durability. The AR-10s really did a remarkable job of standing up to long-term, high-power abuse!

I only have one pair, but I think the other two were "back ups" in the event of damage to this pair. The pair I have are in use several hours each day, but they are under no stress: I have a Velodyne HSG18 to handle the deep bass, and the room is small enough that big power is not the norm. The Velodyne was not necessary, and it does not add that much to the output of the AR-10's woofers. However, it does take the stress off of the low-end of the 10s and it makes a difference with the really deep-bass electronic sub-sonic stuff. It's also good to know that if you need to add additional cracks to the plaster, the big Velodyne is certainly the device to do it.

--Tom Tyson

[kkantor]

Tom,

I was with you right up to the point where you said,

"...besides, if imaging is the most important thing, why not invest in a good set of headphones and get the ultimate “imaging” capability!"

I have various decent headphones, but I have never heard one with, "imaging" capabilities. The basic acoustics and psycho-acoustics of current headphone technology does not permit localization, only lateralization, IMO.

Also, why create a dichotomy between axial response and power response? Wouldn't the more "accurate" speaker, attempt to balance both factors? (Eg- would a concert hall sound good if a foam barrier was placed between you and the orchestra? Of course not, even if the power response at your ears was substantially unaltered.)

-k

www.kenkantor.com

www.ztamplifiers.com

It is important to realize that when the Fine Arts Quartet and Gustavo Lopez Live-versus-recorded concerts were being performed, a preamplifier had to be used between the Ampex tape recorder and the power amplifiers prior to input into the AR-3s for playback. At nearly every venue (there were in excess of 75 concerts performed in five or six major cities across the country), the preamp tone controls had to be “fine adjusted” to bring the output in line with the acoustics in the concert hall, and this required boost much of the time. There were instances in which the treble control had to be reduced, but usually there was the requirement of some treble boost.

The live-vs.-recorded concert was “live” music, and therefore the AR-3s had to mimic the exact output from violins, cellos and guitars (or Nickelodeons) at exactly the same level as the instruments in that same space. Both the live musicians and the AR-3s would have sounded “duller” well back in the music halls where these sessions were being performed, and the effect is the initial reverberation for both the AR-3s and the instruments. With recorded sound in the home, the attempt is to “take you to the concert hall,” not "bring the musicians into your listening room,” and thus the overall sound balance of most large venues is one of rolled-off highs when you consider the effects of diffraction, absorption and reflection in any large space. The reverberation at home with recorded music is actually a form of “double” reverberation, since the reflected sound from the original music is blended with the reflection of the listening room itself (remember that the live musicians in the live-vs.-recorded music were recorded outdoors in basically anechoic space to avoid “double reverberation” in the playback). Nevertheless, the brain does a superb job of psycho-acoustically “sorting out” these reflections in most cases except those where a room has little or no absorption from furniture, carpets and so forth. These overly live rooms often make the sound very diffuse and muddy, easily rectified with the proper room treatment.

Ironically, most current speakers today with flat on-axis power suffer significant off-axis power losses (when compared to the AR-3 and AR-3a), and thus the acoustic-power into any listening room will be that of gradually diminishing high-frequency output as you get further and further into the reverberant space. Some so-called “flat” speakers actually sound quite dull well back into the room, thus the manufacturers suggest that you sit in a “sweet” spot in the near field, positioned in a focused array between the speakers. The really nice thing about the older ARs was the exceptional dispersion and excellent acoustic-power response, thus giving the illusion of spaciousness and three-dimension -- greatly lacking in some current-model speakers. One might say that speakers should image such and such a way, and that one intends to sit in the “sweet spot” anyway, and that flat on-axis energy is the only important thing. This is fine if no other listeners are planning to listen to music in the same place; besides, if imaging is the most important thing, why not invest in a good set of headphones and get the ultimate “imaging” capability!

Would the AR-3 work as well in a jazz ensemble? I think probably not due to the required SPL level required in the near-field listening experience. I am not sure that even an AR-10Pi would be up to the task since jazz trumpets, saxophones, in addition to cymbals and snare sounds, would likely overpower the linear output capability of the dome tweeters. I'm not sure that even the AR-9 could sustain the high SPL levels necessary in the middle frequencies. It would likely take stacked AR-10Pis or AR-3s/AR-3as to replicate the sound of a jazz group.

--Tom Tyson

[tysontom]

Tom,

I was with you right up to the point where you said,

"...besides, if imaging is the most important thing, why not invest in a good set of headphones and get the ultimate “imaging” capability!"

I have various decent headphones, but I have never heard one with, "imaging" capabilities. The basic acoustics and psycho-acoustics of current headphone technology does not permit localization, only lateralization, IMO.

Also, why create a dichotomy between axial response and power response? Wouldn't the more "accurate" speaker, attempt to balance both factors? (Eg- would a concert hall sound good if a foam barrier was placed between you and the orchestra? Of course not, even if the power response at your ears was substantially unaltered.)

-k

www.kenkantor.com

www.ztamplifiers.com

Ken,

Well, I *did* get a little carried away. Headphones with “imaging…” well I guess not. What is the exact meaning of “imaging,” anyway?

What I was trying to convey was the relentless search by some audiophiles for the echo-free listening environment, with a focused sound from speakers without interaction with room reflections. Therefore, the tendency in audiophile speaker design over the years seems to have evolved into directional, flat on-axis speakers, especially in the midrange, with some meager off-axis performance from the generic (but high-quality) recessed-dome 1-inch dome tweeter, rear-facing tweeters or dipole designs yielding a modicum of “spaciousness” to the sound. I believe that these speakers are designed to eliminate refracted sound in a listening room. In my view, the cost for many audiophiles for this relentless pursuit has been high: very, very expensive loudspeakers conveying a sense of “focus,” “soundstage,” “left-to-right localization” and “image.” A few years ago audiophiles attempted the “Dead-End, Live-End” approach, but that trend seems to have faded in recent years probably because audiophile speakers have become more directional than ever. So my point was that if you want to get this sort of sensation, it is *much* cheaper to get a good set of headphones (e.g., the superb Etymōtic ER-4 earphones), which totally eliminate the room reflection issue albeit with the addition of a “surround-sound” effect. The realism is indisputable.

Oh yes, certainly the goal in good speaker design must be to combine flat axial response and perfect power response -- perhaps a “pulsating sphere” flat on- and off-axis. I understand that, and I should not have discounted it. The AR-LST approached this goal, as well as the Allison: One and Allison IC20 and perhaps others. Nevertheless, when I get back into the listening environment I find that the AR-3 and the AR-3a, among a myriad other similar designs, give me a satisfactory sense of spaciousness, realism and enjoyment that I never quite got with such speakers as my (somewhat boomy) B&W 801 Matrix or the KEF 107R, both *excellent* speakers in nearly every regard. I suspect that I have conditioned my hearing to “accept” a slight lack of localization from better axial response, so the problem is mostly mine. In any event, either philosophy is still a long way from the live concert-hall experience. On the other hand, reproducing the “up-front” experience of a jazz ensemble, speakers such as the B&W Nautilus 801s (I also owned briefly) are probably unsurpassed, and I am convinced could easily reproduce the full SPL output of a jazz group.

Your points were well taken!

--Tom Tyson

[Mexicomike]

Re headphones/speakers...

I just recently purchased Bruce Springsteen's latest album, "Magic." This album sounds as if it was mixed FOR headphones. Through my AR3As, the sound is muddy and so reverbed that it's very difficult to hear the various instruments and voices. On a set of Ipod ear buds (!), it sounds quite decent - clean and articulate. To me it's almost unlistenable through speakers, and this includes not only my 3As but our Thiel CS2s and our Magnaplanars. I'd hate to think that recordings are now being mastered with their primary "use" being seen as through headphones and portable devices but it might be the case...

[kkantor]

Likewise. Thanks for the clarification.

Rooms, reflections, axial vs. power response.... these are vexing questions for those recording engineers and speaker designers willing to consider them. They render simplistic approaches to "flat response" somewhat moot. In my reading, AR's approach over the years tried to balance both factors, with different technical leaders perhaps tending a bit toward one or the other, but everyone cognizant of the importance of both. For example, the US guys loved their beanpole, came up with the ADSP, etc. These were approaches driven by first arrival. AR in England had its concrete reverb room, something the US never bothered with, to my knowledge. Like any organization populated by creative thinkers, AR was not monolithic about its technical ideals. There were factions and plenty of debates. What actually made it to the product line undoubtedly "reflected" a range of input.

So much for philosophy on a Saturday evening... definitions are so much easier!

"Auditory Localization" is the ability of a listener to determine the location of a perceived sound source, according to the three axes of azimuth, elevation and distance. To this day, scientists don't fully understand the phenomenon, let alone how to reproduce it consistently in a recording. They do know, however, that headphones don't normally create "localization," (unless complex signal processing tricks are applied to the signal.) For this reason, the spatial spread one hears with headphones is instead called, "Auditory Lateralization." This refers to placing perceived sounds on an axis between and left and right ears, rather than on a spherical surface surrounding the listener. If a carefully made binaural recording is reproduced over good headphones, it is often possible to hear azimuth and elevation cues. However, even this process is unreliable, due to the strong influence of individual ear shapes, and of sub-awareness head movement, on spatial hearing. It was probably my turn to get a bit carried away to suggest that headphones can't ever provide "localization."

-k

www.kenkantor.com

www.ztamplifers.com

Ken,

Well, I *did* get a little carried away. Headphones with “imaging…” well I guess not. What is the exact meaning of “imaging,” anyway?

What I was trying to convey was the relentless search by some audiophiles for the echo-free listening environment, with a focused sound from speakers without interaction with room reflections. Therefore, the tendency in audiophile speaker design over the years seems to have evolved into directional, flat on-axis speakers, especially in the midrange, with some meager off-axis performance from the generic (but high-quality) recessed-dome 1-inch dome tweeter, rear-facing tweeters or dipole designs yielding a modicum of “spaciousness” to the sound. I believe that these speakers are designed to eliminate refracted sound in a listening room. In my view, the cost for many audiophiles for this relentless pursuit has been high: very, very expensive loudspeakers conveying a sense of “focus,” “soundstage,” “left-to-right localization” and “image.” A few years ago audiophiles attempted the “Dead-End, Live-End” approach, but that trend seems to have faded in recent years probably because audiophile speakers have become more directional than ever. So my point was that if you want to get this sort of sensation, it is *much* cheaper to get a good set of headphones (e.g., the superb Etymōtic ER-4 earphones), which totally eliminate the room reflection issue albeit with the addition of a “surround-sound” effect. The realism is indisputable.

Oh yes, certainly the goal in good speaker design must be to combine flat axial response and perfect power response -- perhaps a “pulsating sphere” flat on- and off-axis. I understand that, and I should not have discounted it. The AR-LST approached this goal, as well as the Allison: One and Allison IC20 and perhaps others. Nevertheless, when I get back into the listening environment I find that the AR-3 and the AR-3a, among a myriad other similar designs, give me a satisfactory sense of spaciousness, realism and enjoyment that I never quite got with such speakers as my (somewhat boomy) B&W 801 Matrix or the KEF 107R, both *excellent* speakers in nearly every regard. I suspect that I have conditioned my hearing to “accept” a slight lack of localization from better axial response, so the problem is mostly mine. In any event, either philosophy is still a long way from the live concert-hall experience. On the other hand, reproducing the “up-front” experience of a jazz ensemble, speakers such as the B&W Nautilus 801s (I also owned briefly) are probably unsurpassed, and I am convinced could easily reproduce the full SPL output of a jazz group.

Your points were well taken!

--Tom Tyson