Aadams

I have devised a way to overcome the inertia of moving this system to a much larger room, but I must wait until an amplifier is returned from being rebuilt sometime within the next 30 days. This accelerated plan is possible because, for one time only I will violate my speaker ethics and experiment using my 3as as the bass speaker sitting beneath the satellite array. Using this approach, I will only need to move the array and the very portable associated electronics to a position right beside the AR9s. This is not a test of 9s against The Stack, rather it is a test to see if The Stack can produce a good sound field from a 15-20ft listening position while I am standing, sitting and somewhat mobile. More later. Adams

Ligs Thanks for your comment. I am not a big experimenter I just fell into this by accident and from frustration with powered subs and their bias toward HT. I was lucky to stumble upon a good result. I listen to this system almost every day as entertainment and for evaluation to find flaws and have not changed it since my last post about satellite array positioning, but I will report my impressions in a few months either way. I think I am being objective when I say It does sound good. The ultimate test will be to make myself move this system to a much larger room but there is too much inertia to make that happen anytime soon. I agree, there have been huge advances in small speaker systems since AR left the field and there are a lot of good candidates for integrating into this type of system. Adams

I was not thinking of the 3a and 500hz crossovers. I was referring to 700hz, the crossover for all 3way 12” systems through the TSW series, excluding the Connoisseur and MGC. You seem to be saying the use of the 8inch LMR was all about power handling----that the 8inch did not add to the refinement of the sound. I have a 58s pair, very similar to a 91, that I have compared to the AR9 and while, once equalized, they do sound similar, there is no way the 58s sounds as good as the 9 between 200 and 1000Hz. AR said the 91 was its premiere 3way system. I have never heard one with its acoustic blanket, but I have not read anything by anyone claiming it sounded like a 9 with less bass. We see the 90 discussed as a baby 9 but never the 91 as such. My point is, the lower woofer crossover and the single 8 inch speaker for the critical mid-range between 200hz and 1200hz makes an audible difference-----or is it my imagination? Again, I am not talking about the 3a but about where AR was headed. Here is part of their pitch for the new mid-range in the Connoisseur series. “the 6.5” midrange operates between 200hz and 4kz so that phase shifts are minimized in the critical mid-range. Crossover points are consequently avoided where the ear is most sensitive and the low-bass-to-mid crossover point results in very low IM distortion.” Adams

Tysontom Thanks You were so focused on correcting the first two assumptions that you failed to correct the last assumption. After AR embarked on the bifurcated path with the verticals, evidence shows that all 12" systems below TOTL had higher crossovers. Adams

Given the freedom to employ the 12" to its greatest advantage AR consistently chose lower crossover points finally settling on 200hz in their 4way systems. The point has been made, that the AR9 side firing woofer configuration may have forced a 4way design to keep the LMR in the front. The AR9LS, LSi and 98 all had forward firing woofers but AR kept the crossover at 200hz. I am speculating here with no help from Google---------- in tall columns with large spatial separation between drivers a high crossed woofer at the bottom of the column will make some human voices and instruments seem to move up and down the column. The same should be true today. Even though an 8 or 6" speaker can carry a large band of frequencies, when they are used in multiples as woofers in tall columns with a port, the crossover must be placed low enough to prevent this illusion of relocation. The same applies to powered sub-woofers and satellites. Apparently AR felt the big 12" was in its best range when cut at 200hz, which implies that anything much higher represented compromise. Adams

It turns out, from 1979 until 1995 NO AR TOTL speaker had higher than a 300hz woofer crossover. Interesting facts about the Connoisseur Series: Note the paragraph regarding the new midrange driver. The Connoisseur 50 12” 3way with a -3b point of 30hz is incorrect though the misprint may have been intentional. The correct number is 39. Adams

Below is a list of passive, full range, loudspeakers available today with woofer area and crossover frequency. All are TOTL or near, most are bass reflex designs and all use 6 inch or smaller LMR and/or midrange drivers. I only listed speakers for which the manufacturer published performance specs. Some of the claims for low freq extension seemed dubious to me while others seemed reasonable. Adams

I think you may be on to something regarding the original AR9. For the last year I have been seeing my AR9s as an expensive 8 inch system sitting atop a finely integrated passive sub woofer. With side firing woofers, crossing even a little above 200hz would have female voices singing out the sides but why not go lower than 200hz? After all, the 8 inch could easily get to 80hz. Maybe power handling? I am not confident the speaker would perceivably sound better with a lower woofer crossover. BTW the 910 was also a 4 way but using all cones and was the last to use an 8 inch low mid before the Classic Series switched to 5.25 low mids. Adams

The AR Classic Series of the 1990s, did not include a 4 way but 3 of the 4 systems in the line up crossed over the woofer at 200hz. This was also the first and last time AR used 5.25 inch cones to span the mid-range from 200hz to 2khz.

And I repeat, I absolutely agree. For at least 4 reasons. 1-------In 1968 Roy Allison was still on a quest for concert hall realism above all else 2-------Distortion in the 12” was very low and voice was well presented 3-------AR had no small cone speaker to cover the low-mid range if they had desired to do so. 4-------The men pictured below are not concerned about deciphering the lyrics to Louie Louie. I have reviewed the entire thread and cannot find any post where I said the woofer crossover was lowered to get vocal clarity. Though I did wonder if voice may have been better in the 3 vs 3a because almost all of it originated in the woofer but, I did not say so in a post. I did say, the woofer crossover point was lowered with every succeeding generation of TOTL speakers containing dome mids. Lowering the crossover point for whatever reason eliminated, from the woofer, fundamental frequencies of the low mid-range, whence nearly all voice originates. The voice clarity and timbre issue was introduced in this thread when I referred to a difference in clarity between the 3a and the 9 not 3 to 3a. I have agreed with you the 3a vs 9 difference is probably due to a frequency imbalance caused by a couple of things and has nothing to do with simply crossing over in the middle of the voice range. You say In 1968, or even now, this problem could be addressed by mounting the 3a in the wall. I would say this was a last resort solution for men who expected to be single or needed to find a use for " The Story of Civilization". Today I would use an adequate equalizer. Regarding the above: Thank you. Though I wonder how many non-classical recordings these days are actually produced using anything other than headphones and 6” monitors for evaluation of sound. Adams

Leaving 3a measurement behind and getting back to the thread topic of why AR continued to lower the crossover of the 12" woofer. Page 18 of the Roy Allison paper on speaker and listening room integration. Note the very last paragraph of the article. Is uniform room loading another reason the woofer crossover was dropped to 200hz in the 4 way systems? The Allison 1 used 350hz in its 3 way design. Adams

Below is an excerpt from a Roy Allison technical presentation made in 1970. The full paper is in the library. And, I know this document has been referenced in other threads. http://www.classicspeakerpages.net/library/acoustic_research/special_sections/additional_ar_documents/the_sound_field_in_home_lis/ Three impressions I took away. 1------The “typical” Boston area listening rooms that were used for home measurement are NOTHING like the “typical” rooms in which you find systems today or even then. 2-----The 3a was optimized for recreating a live performance experience. 3------He concluded it is beyond the capability of a speaker to reconcile concert hall, reverberant field, sound with the listening room experience of sound captured through near field microphones. The best suggestion he had at the time was to encourage liberal use of amplifier tone controls. This was before the availability of inexpensive equalizers.

This not supposed to be a 3a thread, but this last chart reminds me of what can be found among ancient CSP writings. A prominent example: Before my time here, Zilch, a man full of speaker knowledge and who is recently deceased, found great joy in winding up the AR Iconophiles at this site by using all sorts of analysis,graphs and relentless,articulate, argument to cast the 3a as an inadequate antique. One thread shows a hemispherical measurement of 3a dispersion uniformity, using color intensity, that he produced. To paraphrase his words, it was a mess. I don't know if Zilch or anyone, outside of NASA, or Harman has the tools and talent to perform accurate objective measurements of any loudspeaker. I am skeptical of anyone with a home setup. AR was careful with their data collection and measurement, concerned that the results should be repeatable by anyone following the protocols. The point is: ----------These Murphy charts show zero resemblance to anything published by AR. ----------The Zilch chart also shows zero resemblance but is of a type not possible 50 years ago. The common result of both measurements of the 3a ----------Murphy says, “Still it sounds better than you might think” ----------Zilch, a CSP gadfly who actually had a lot of speaker cred, said, – to paraphrase- “Maybe this explains why the 3a sounds so good in certain rooms” and “The problem with the 3a is it needs the right room which most people don’t have.” Zilch felt that modern waveguides (horns) were more appropriate for most situations and liked big JBLs. On balance, however, I am in no position to say their work was any less valid than that of someone who fabricates graphs to support a subjective opinion. Adams

TysonTom Here is the new chart. Of course, I see the same issue I saw in the previous chart regarding diminished output in the critical human voice mid range. I tried to be objective and welcome your critique. I repeat myself by saying, IMO the 3a does not generally have a problem with voices, only certain voices. When a musical instrument, other than voice, drops a couple of db in a portion of its timbre range humans don’t notice but certain male and female voices are very recognizable and those timbre shifts can be detected by ear. I will concede this may only be an issue at my house but if the 3a curve was the sine qua non for speaker quality the AR9 would have the same curve. Someone with influence at AR saw an opportunity for improvement in an area important to retail purchasers. Bonus Question- I think you have intimated that absolute clarity and dispersion are mutually exclusive features. Does this mean if AR could have taken the dome mid-range down to 200hz that voices would have been more dispersed but somehow perceivably less defined? Adams

Tom Tyson Thanks. I can work with this too. I actually thought there must be blending. I don't have time tonight but I will make a new chart showing a 3db and 6db down tracing. It seems logical turning the pot down any degree from max has to proportionally diminish output of all frequencies handled by driver so the graph line should be pretty much the same slope and linearity. Should it not? It seems almost impossible that I could be totally incorrect on this. Aadams

The thread is still creeping but that is ok because it is near the end. SteveF, my eyes were damp after reading your closing remarks. Speaking of the 3a as you did, reminded me of the great warrior Achilles who, with his classic look, could do extraordinary things but was terrible at picking the right shoes. I spent this afternoon listening only to my 3as. In my experience, there is still no speaker better at presenting a large-scale string recording. My 9s have more bass and the sound chiseled but they don’t ever provide a “you are there” experience as the 3s sometimes do. Maybe that is why Roy Allison was so interested in the sound of Chicago Symphony Hall. That takes care of the 70s and 80s. Adams

Thread creep alert This thread IS NOT about how good or bad the AR12” woofer is at producing voice or mid-range frequencies, though apparently it is quite good in comparison to other similar woofers. This thread IS about how evidence shows, with each new generation of speakers, AR sought to increasingly diminish the role of the 12” woofer in the critical range between 80hz and 1000hz when used in their premier products. Some of the reasons for crossover choices are known but one thing verifiable today, beginning in 1979 the “AR Sound” that is today still seen as a measurement standard, is the sound of the 4 ways, in which the woofer was used for its best purpose and the critical mid- range was left to smaller drivers. AR3 - 1000hz AR3a - 575hz AR10Pi, 11 - 525hz AR98 - 200hz AR9, ls, lsi, - 200hz Adams

3 posts prior. LST is cited as not having this problem but the LST also had a completely different approach to achieving "spectral balance". I have never heard an 11 or a 10pi and not seen a graph for either and don't know if that same notch at 575hz is present. I also stated in the previous post that the problem could be solved with a 1/3 octave equalizer. IMO neither the world's most powerful tweeter nor a simple treble control adjustment around 5khz will restore the missing harmonics and overtones, between 600 and 1600hz, so you can clearly hear what Ellen Foley is singing, which is the origin of this thread. Good to see you back. Adams Addendum: I found this in archives: A letter from Allison to Hoffman, 1970. Items D and E give insight into the thinking of the creator about the objective of the 3a design-----------Clearly, not drum demos in club sized rooms. There are no response curves for the ADD designs to be found.

Agree . Voice is the only sound most untrained ears can blindly discern with good discrimination IMO. IMO, the tweeter issue is unrelated to the woofer output at 500hz and was just an easy target. Also, probably the the only way to make a 2ax outperform a 3a is by focusing on a specific type of human voice and ignoring all of the other superior aspects of the 3a that are happening simultaneously. Ultimately, with the emergence of high power amps and fascination with loudness, even a perfected 3a would not be competitive. Today, if I felt it were important enough, I would use a $300 31 band equalizer to eliminate the issue it but in the 1970s an Altec Acoustavoicette was around $700. And, who sells a pair of speakers one moment and in the next asks "what about that equalizer?" Adams

The modified chart below is what I see based on the clarification above and the tendency of owners to keep the 3a mid output at around the attenuator mid point. Maybe the 10Pi addressed this. I know the LST did.

Thanks. There is a thread here asking 3a owners where they set their mid and tweeter controls. I think the vast majority said tweeter max and mid at the mid point. I was the same. This tells me the relative lower sensitivity of the mid is not a problem so much as the inability to contour the specific output in the voice band which leads to equalizers or complexities that many don't want to deal with. Its also ironic that, at the time in their lives when they worry most about about tweeter roll off, most geezers can't hear above 10khz, frequently less. The topic is still AR woofers and crossovers but borders on mods and tweaks. BTW all of my 12" 3 way ARs are 12" off the floor and about 1 ft from rear walls. Regarding your statement above Does this imply that if I were to place AR58s or 11s ( for instance) back to back, in AR9 fashion, on the floor and limit their output to 200hz, I could achieve AR 9 level bass to 32hz that could also be easily managed? Assume the tweeters and mids have been cannibalized. Adams

Tysontom In retrospect, the above comment sounds perhaps terse and dismissive. It was not meant that way. That equalizer influences the sound of all my systems and it is simply not worth the effort to live with the ripple it will create for me to attempt resolving this tiny bit of difference. I am fortunate that someone with your deep knowledge of AR, and speakers in general, is around and willing to talk about this. There are many that hole up and don't bother. Apology offered. The topic is still AR woofers and crossovers. Re the 3a. I spent a lot of time listening to a wide variety vocals yesterday. Without a reference, it is difficult to find fault in how the 3a presents voice but in relation to more recent vintage speakers that have smaller drivers covering the voice range, my 3a seems to add a slight warmth or heaviness in the tenor and low alto voices. The difference is most noticeable with female voice. The arcane 20 seconds of which I spoke earlier is a low alto female voice. I am still surprised at the superior presentation by the 3a of string ensembles and live recordings. I no longer shop for new speakers but I would be surprised to hear anything new that can top an AR3a in those areas. I don’t think this is true with voice, now that I am beginning be more attentive to musical lyrics. Most people today, who listen to music, listen to music with lyrics and that is why I suspect AR changed the sound of their systems in such a telling way, beginning with the AR9. Edit: I think the difference could probably be equalized out,with a 1/3 octave equalizer, to be practically imperceptible but back then that wasn't a cost effective idea. Adams

I should give credit to a recent discussion in the AR forum for providing impetus to achieve this version of the system. Had I not looked more deeply into the capabilities of DSP regulated amps as a result of that discussion, I believe this system would still have its previous klugey, less resolving, form. So, hats off to the CSP! Adams

The point in question is not important to me and I did say it was arcane. I have absolutely zero dispute with anything you have said and have complete confidence it is accurate. Have you listened to the piece of music in question? The final 20 seconds is all this is about? Regarding mid-range fidelity: I can verify you are correct. The mid range driver can be heard to reproduce the lyrics with unquestionable clarity if your ear is very close to the driver. Same for the woofer, as I said before. And you appear to agree with me the apparent improved vocal clarity of the AR9 is because the voice range is contained almost entirely in the 8” driver. My point was merely that the AR3a ultimately is not as good at presenting vocals in my living room at 12-15ft as my AR9s and by extension any of the other 4 way ARs which are very similar. Whether the cause is diffraction or splitting the instrument in the crossover and creating difference in timing or phase, related to driver location, I do not know but somebody at AR decided the difference was sufficiently great that in 1979 all top of the line systems became 4ways for at least a decade and the 12” 3 way became second tier. The two speakers in question are on a 10 band software equalizer seen below The room is 3000cft and rectangular, moderately live. The full wall opposite the speakers in the long dimension is a bookcase full of irregular shapes. Speaker attenuators or pots are set to max output. I think you are going to say the equalizer settings put the 3a midrange at a disadvantage due to its slightly reduced output in relation to the woofer. You very well could be correct, but I am not changing anything because this is not a genuine problem. The only thing you have said that I take issue with is people are better at hearing differences in strings than voice. The only reason I caught this is because I understand spoken English. If this had been German, Italian or Stradivari or Guarneri It would have been heard as fadeout music and completely unnoticed. If you hear a familiar voice you can put a face with it. When you a hear a middle C can you, or most people, distinguish between a viola and violin? Much less which luthier did the build. Cheers Adams