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tysontom

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  1. A/D/S/ L1590

    Glitch, Thanks for your interesting comments and for the part numbers as listed. The L980 and AR-3a are very similar, of course, in layout and function. Both are low-resonance acoustic-suspension designs with dome midrange and dome tweeters (both ¾-inch) and similar crossover characteristics. A direct A-B comparison would be very interesting. I've never read a report on a comparison between these two fine speakers, but I think there were far fewer L980s out there than AR-3as or its later iterations (AR-10, AR-58, AR98Ls, etc). On the other hand, I did compare my L1290/2 and AR-3a speakers, and I can comment a bit on that comparison. It was difficult to compare them, as the optimal spot for the 3a is flush in a bookshelf, and the 1290 has to be out slightly from the front wall, toed-in a bit, to be positioned optimally. I am fond of both the 1290/2 and the AR-3a; unfortunately, the 50-year-old AR-3a dome tweeters are beginning to deteriorate, causing lower output from the domes. Perhaps a better comparison for the L980 would be an AR-10π, AR58 or AR78 with their cloth-dome tweeters. In the bass, the AR-3a has a slight advantage in low-frequency extension, but the differences are subtle and only noticeable on organ or electronic music or jazz with prominent kick drum or orchestral bass drum. The 1290 isn't deficient, but it's slightly less prominent and less "warm." Part of this difference, too, is the relative balance between the woofers and high-range drivers in the ADS vs. AR speakers. AR's midrange and treble are more reticent, on-axis, and the output is slightly downward-sloping in the higher frequencies; this is not the case with the 1290, as it is quite uniform throughout the midrange and treble. Therefore, the 1290 is more "forward" and brighter-sounding than the AR-3a; however, well back in the reverberant listening area, where the predominant sound is reflected, there are fewer differences in the balance of the sound between these two systems, mainly because the dispersion of the 3a's hard-dome tweeter is somewhat wider than that of the soft-dome ADS tweeter. Therefore, the excellent power response of the AR-3a makes up for its on-axis reticence. The AR-3a's 1½-inch dome midrange also has better dispersion than the 2-inch dome in 1290, but the clarity of the output from the ADS tweeters is just about unsurpassed. Both of these speaker systems are so good that it would be hard to find too much fault with either system. Therefore, I never found a favorite. The ADS seems to bring you a bit closer to the music and there is that outstanding midrange and treble clarity. The AR-3a is more laid-back, but it has a smooth, very natural reproduction of midrange and treble. In the bass, the AR-3a is more solid, but the differences are subtle. Perhaps a draw. —Tom Tyson
  2. A/D/S/ L1590

    Hi Glitch, Great message. Regarding the L980s, I wonder how it would compare, ultimately, with the AR-3a? There would be a fairly close resemblance in terms of bandwidth and spectral balance, except that the ADS speakers would have noticeably greater upper-midrange and treble output in comparison with the AR-3a. As for accuracy, it would be a close call, with both speakers representing a very high level of smoothness and low distortion. I am quite surprised that at least one of ADS's later designs didn't make it to Stereophile magazine's "Best Top Speakers of the Past 40 Years." You just never know how these things will go, but there were several ADS speaker that could easily have outmatched several of the magazine's top picks. Of course, Stereophile magazine (much like TAS) reviews and articles were heavily weighed on subjective evaluation and judgment, and the results were usually more emotional than objective. https://www.stereophile.com/content/40-years-istereophilei-hot-100-products-page-7 By the way, you are exactly right about the different part numbers for the ADS 1590 and 1290! For some reason I thought the tweeters were identical, but it's not the case. According to what I found in my files: L1290: tweeter 206-0117, mid 206-0211, woofer 206-0349 L1590: tweeter 206-0119, mid 206-0213, woofer 206-0350. I'm not positive that these are the Series 2 part numbers or the original series, but I think so. You may know for sure. --Tom
  3. A/D/S/ L1590

    Hi Glitch, These were very interesting comments, especially the contrast between the L1590 and L1290. Sorry I'm so late in commenting on them, over a year later! I think the different crossovers and slight differences between the 2-inch dome midrange drivers between the two speakers probably accounts somewhat for the difference in perceived transient performance. Except for the more robust L1590 woofers, I don't understand why the L1590 has greater overall power-handling capability than the L1290, especially since the 2-inch dome is driven to a lower crossover frequency in the big speaker. How this could represent greater power-handling, I don't know! The upper end should be equal across the board. Thoughts? Also, do you have any copies of your measurements on these speakers? I would love to see them if you have saved any. If you could do some impulse tests—even the old transient-response tests—it would be interesting to see if there are any differences in the two speakers' midrange performance. I would not think so, as both use the same magnet and voice-coil assemblies. Did you actually find the Ferrofluid dried up in the 1290s? Was it partially dry or what was the case? Also, as for imaging, I would think that the L1290 and L890 speakers, with their higher midrange crossover, might image slightly better than the 1590, but the latter would have somewhat greater "spaciousness" in the reverberant field. More three-dimensional in the far field. These were all great speakers! Do you also have a pair of L980s? —Tom Tyson
  4. AR-5 Technical Details

    Hi Pete, I think 1.15 is very close to the average Qtc measurement for the 10-inch (and 8-inch) series. --Tom
  5. Both controls at or near maximum. These were my AR-3as that were tested at AR by Bill Bush and KK before being sent to Julian Hirsch for the initial test of the AR-303 by Hirsch-Houck Labs. AR-303-Review_H-H_Julian-Hirsch_June1995.pdf --Tom
  6. AR-5 Frequency Response "Problem"

    Steve's message is interesting and clearly describes what happened during that testing of the AR-5 by Julian Hirsch! We will never know exactly what caused the issue with Hirsch's AR-5 test, but once he had stated and published his findings, he could not possibly back down. As Steve mentioned, to Hirsch's credit, he published the "back-and-forth" correspondence he had with Roy Allison. Once the stake was in the ground, it's hard to back off. The anomaly in the AR-5's response is almost surely caused by some interaction in the measurement that could not be traced down; as Steve commented, the AR-3a and AR-5 shown in the subsequent Hirsch overlaid response curves show very close correspondence, so this raises questions as well. Julian's test-measurement method was not done in anechoic space, yet he developed an in-room measurement technique that gave close correspondence to what he felt was heard from the speakers and quite similar to tests made by CBS Labs and Audio magazine and others. Note that this was before the days of gated measurements, so the measurement microphones would detect all sorts of artifacts from various boundaries, diffraction effect, microphone positioning differences and phase anomalies. But Hirsch was an extremely knowledgeable electrical engineer, and he knew as much about audio technology as anyone in the field, so he was able to improvise a valid test method. Through years of experimentation, he was able to average the overall output from the microphones to get a clean and representative acoustic output into his room. Julian felt that neither anechoic nor reverberant measurement space was completely realistic as to how the speaker would sound, so his measurements were done in a "live" room with calibrated microphones: one capacitor microphone on the center axis close to the speaker and three microphones suspended from the ceiling at various positions that were determined by trial and error over years of testing. The output from these four microphones were fed into a mic mixer and then to a GenRad preamp and an automatically traced GR graphic-recording system, commonly used in the day. We'll never know exactly what caused the 2kHz dip Hirsch found in the AR-5 and whether or not it affected the sales of the AR-5. Most likely it hampered sales somewhat, despite generally excellent reviews throughout the industry. —Tom
  7. AR speakers and Dynaco electronics were frequently paired, and David Hafler of Dynaco (founder) was good friends with AR founder Ed Villchur. AR usually recommended Dynaco amps for use with their speakers up until the late 1960s, at which time the AR Amplifier was introduced. AR used Dynaco Mark IIIs and Stereo 70s, as well as PAS-3x preamps, to drive most of the equipment in the AR Music Rooms. During the Live vs. Recorded concerts with the Fine Arts Quartet and so forth, Dynaco Mark III amps were used as well. The Mark III could hit undistorted peaks of 120+ watts, so it provided ample power for most uses. On the other hand, there were many McIntosh MC 60s and MC 275s, as well as Marantz 9Bs and 8s used to drive AR speakers, too. The AR-3 sounded great with the Marantz 9B amplifier at high-output levels! --Tom Tyson
  8. AR LST crossover

    Michele, Klaus and Roy, When the fuse is blown in an AR-LST, rather than have a "totally silent" speaker as you might expect, there remains a high-impedance path through the autotransformer causing a 30 dB drop in system output, but the speaker is not completely shut off. The older Buss Fusetron FNM fuses do sometimes deteriorate over time and can open partially or completely, causing this sensation. --Tom
  9. We've talked about the AR Music Rooms several times in the past. AR had two "permanent" music rooms, one in New York City on the west balcony of Grand Central Terminal and the other room was located on Brattle Street in Cambridge, Massachusetts. A third room was temporarily located at the World's Fair one year. The New York location was, by far, the most-visited of the rooms with over 100,000 visitors each year. No sales were ever allowed at any of the music rooms, but any and all questions about high-fidelity sound equipment were answered objectively, and the equipment was demonstrated for any visitor. The main AR employee in the New York Music Room was Walter Berry, but prior to that many AR executives began their careers working in these music rooms. Gerald Landau, marketing director, and Victor Campos, customer services, started their careers in those rooms. On the roof of the building was a pair of AR-3s, originally driven by two Dynaco Mark III amplfiers, to provide music throughout the huge railroad station! At times, the amplifiers were driven to near-clipping levels, but there were never any damaged AR-3s to my knowledge. The AR Music Room was a fabled venue for high-fidelity music. The New York room was opened in July, 1959 and was closed in 1974 about a year after AR moved its plant to Norwood. --Tom Tyson
  10. AR woofer crossover points in perspective

    Adams your last sentence was not necessarily an incorrect assumption (as I hurriedly stated) except to say that AR knew from the beginning that driving the 12-inch woofer too high represented a slight compromise. However, with the AR-3a, that compromise was reduced significantly, because the 12-inch woofer works well on- and off-axis up into the 500 Hz region. The cone is not terribly directional in that region, but around 1000 Hz, it is becoming more directional. Obviously, 200 Hz is better yet with the main consideration of the 8-inch LMR handling much of the lower midrange, protecting the midrange dome and increasing power-handling capability.
  11. AR woofer crossover points in perspective

    >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. [incorrect assumption]. >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. [incorrect assumption]. >Apparently AR felt the big 12" was in its best range when cut at 200hz, which implies that anything much higher represented compromise. [This, too, is an incorrect assumption]. >Adams ____________________________________________ AR did not design the tower speakers with those things in mind. It just doesn't work that way. The two 12-inch woofers needed to be placed close to the floor-wall intersection to reduce the possibility of out-of-phase cancellations. The existing 8-inch Lower-Midrange driver was an existing in-house driver, for the most part, used in numerous other AR systems, and it could easily get down well below 200 Hz. Also, AR wanted to improve the lower-midrange power-handling capability of the dome midrange and tweeter units, so the 8-inch LMR helped with that as well. The "art" in the AR9 design is the almost seamless integration between the two 12-inch woofers and this 8-inch lower-midrange unit—working together as though one single unit. There are no clues that there is any transition from the woofers to the LMR, and AR was most proud of this and considered it to be one of the great achievements in the design of the 9's crossover. Unless you are listing to your speakers about a foot away, you will never sense that "human voices and instruments seem to move up and down the column." This just doesn't happen unless you had all large cone drivers operating into the midrange and treble, and thus you might sense a wandering image with highly directional speakers that are projecting to you predominantly first-arrival sound, but these speaker systems are generally objectionable to listen to anyway. —Tom
  12. AR's honesty and the 3a's excellence

    I think it was a matter of a slight difference in the BL of the two woofers. The newer ferrite woofer definitely has a slightly larger magnet (≈11 lb. structure vs. 9.6 lbs), but the voice coil is almost identical and the moving system is nearly identical in weight. The production details of the new woofer were done mainly by Chuck McShane under Roy Allison's direction. —Tom
  13. AR's honesty and the 3a's excellence

    I think this is a great message about the AR-3a, and Steve has described the AR-3a well! Figure 8 of Roy Allison’s paper was indeed a 4π anechoic rather than “room” measurement, but Steve’s description is nevertheless completely accurate. As he states, the curve show’s Acoustic Research’s basic honesty in presenting the performance curves, and it shows AR’s proficiency in quantifying the performance of their speakers. To repeat what we’ve said before, not all speaker companies adhered to such a strict “standard,” but from the beginning this attitude of honesty prevailed at AR. The important thing about this AES paper was to show the AR-3a’s true acoustic-power response, the “integrated-output” response of the system, which was shown in later figures within Allison’s paper. It is noteworthy that the grill molding did cause some disturbances in the midrange, particularly, that could be seen in the pressure response, but those irregularities do not affect the total integrated output, so that in effect one does not hear interference differences in amplitude that are picked up by a microphone placed 1 meter in front of a loudspeaker. It has also been shown that by merely moving the microphone a few inches one way or the other changes the frequencies in which those irregularities occur, further reinforcing that fact. The hard thing to understand is that, despite the lower relative energy level of the AR-3a tweeter, the total energy put into a listening room by the AR-3a is strong all the way out to the limits of audibility. By comparison, if you had another speaker with completely flat on-axis response out to 20kHz, but poor off-axis response, its total energy into the room would be lower at these highest frequencies than the AR-3a; that is, the AR-3a would sound brighter in the reverberant listening field. A highly directional speaker in the upper midrange and treble might measure "flat" on axis, but it will invariably sound "dull" well back into a normally damped, reverberant listening environment. The drop-off in the AR-3a’s bass response below about 400 Hz—the difference between the 4π and 2π mounting configuration in the anechoic chamber—is quite dramatic, but predictable, and shows how bass response responds to different mounting positions; this bass difference shows up when mounting a speaker in a room, such as in a corner, along a wall or out into the room. In the mid-1960s, a couple years before the introduction of the AR-3a, Edgar Villchur received a letter from a new AR-3 owner who had taken his speaker to the Harvard University anechoic chamber and measured the woofer’s response. An engineer friend had prompted the test, saying that the AR woofer wasn’t flat into the deep bass and was defective and perhaps overrated. The engineer then told the owner that he could prove it by testing it in an anechoic chamber. Sure enough, the measured response did show a severe drop-off in response, and the owner was distraught. What the engineer-friend hadn’t considered was the measurement solid angle. He had measured it into a 4π angle, and the big Harvard chamber was anechoic down to fairly low frequencies. Had the speaker been measured into a 180° sold angle, the output would have been flat down to resonance. —Tom
  14. AR woofer crossover points in perspective

    Adams: Once again, AR lowered the crossover on the AR-3a from the earlier AR-1 and AR-3 levels because the new midrange could operate lower in the midrange, thus keeping the woofer out of the higher frequencies. This was always the goal. The problem has to do with off-axis response, smoothness and linearity of the large woofer cone; the lower crossover was not related to vocalist clarity or midrange intelligibility. With the AR-3, the lowest Villchur could operate the 2-inch phenolic-dome midrange was ≈1000 Hz, thus the 1 kHz crossover. The AR-3's woofer thus had to operate up to 1000 Hz, and even though the woofer is flat, on axis, from 38-1000 Hz within ±1½dB on axis, the off-axis response is compromised. With the 1½-inch AR-3a soft-dome midrange, the resonance frequency was a half-octave lower; therefore, AR could lower the midrange crossover was set to 575 Hz. The result was improved dispersion in the midrange and upper-bass frequencies. What Roy Allison is referring to is the boundary dip that is caused by a reflected, out-of-phase low-frequency wave from the woofer cone that bounces off the floor or wall and returns and partially cancels the front wave, causing a dip in the response at certain frequencies in the upper bass. By placing the woofer(s) close to the floor-wall boundary, and crossing over below that frequency, the dip can be avoided. The AR9 was also designed with this in mind, of course, with the two woofers close to the floor on each side (instead of in front up high). This has come to be called the "Allison Effect." There is still debate on the efficacy of trying to remove the dip (do recording studios compensate in recordings for a dip they may or may not get from their studio monitors?), as it may cause some "softness" in certain frequencies, but in general that dip is there and can be avoided. It is possible that you are losing some intelligibility around the frequency of the boundary dip. If you re-mount your AR-3a speakers flush with a wall or bookcase, you can avoid this problem. —Tom
  15. AR woofer crossover points in perspective

    Adams, in response to your comments above about Zilch. "Zilch" "Zilch," Evan R. Flavell, who died about seven years ago from lung cancer, was definitely one of the more knowledgeable and accomplished home-style speaker testers. He was a major JBL-style contributor to AudioKarma's Speaker Forum, and his measurements always seemed reasonably accurate for the type of testing he was doing. He certainly understood what he was doing, but his preference was near-field fr testing more than acoustic-power testing, and it appears that he preferred flat on-axis output from a speaker rather than rolled-off highs. Nevertheless, he did a lot of polar-response and off-axis testing as well. At one time, Zilch had been a conditioning coach for the swim team at UC Berkeley and developed a "swim bench," a dry-land exercise device for swim teams. He was an engineer and held several patents in the field of exercise equipment. Zilch used his engineering background to delve into the field of audio-loudspeaker design, and he developed (and marketed) a crossover network to incorporate a constant-directivity horn-tweeter, the "Econowave," as a replacement device to add the benefit of a "flat curve" to replace the old "rolled-off" high frequencies of speakers such as ARs, EPIs and Advents, etc. This system has apparently had (and perhaps still has) a good following, and the system actually sounds pretty good from my brief experience. I think Roy C of our forum has had experience with that setup with very satisfactory results, and Roy might elaborate on the Econowave design. Insofar as Zilch was marketing his Econowave horn tweeter replacement, he had an ax to grind concerning speakers like ARs, and he frequently offered rather extensive measurements made on some of the old speakers, including many ARs. His measurements were generally much more comprehensive than most of the other DIY measurements and these were not terribly different from the anechoic measurements done in AR's anechoic chamber. DIY Measurements of the AR-3a What this comes down to is that for years the AR-3a, and many other AR classic speakers, have been tested a dozen different ways from Sunday by numerous and enthusiastic DIY audio testers—most folks equipped with inexpensive digital software and non-calibrated electret microphones—in an effort to quantify that the AR-3a speaker wasn't really all that great or to explain that the speaker system might have been overrated because it didn't measure so well, even though it seemed to sound great. Of course, no two tests were the same and few resembled each other, and virtually none was governed by the old standards of measurements used in the hi-fi industry! The fact that the AR-3a received such great commercial success and stellar reviews (except for CU's comments at one point) only compounded the dilemma. One thing stands out: there is 100% disagreement by most "weekend warriors" on the measurement standards used to test the speakers. Chart speed, levels, vertical resolution, smoothing and testing conditions in general rarely resemble each other. Some amateur reviewers tested the AR-3a outdoors and some indoors; some were done at 1 meter for the entire system while other tests are tested at 2 or 3 meters. Some testers tried rta measurements while others tried full-system frequency response tests, most with the notion of proving why the speaker sounds "rolled-off" in the high frequencies, yet ironically, most testers agree that the speaker always sounded much better than it appeared to measure. It appears that most amateur testers also strongly believe that what you measure when you put a microphone in front of a speaker is what the speaker "is doing." —Tom
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