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ligs

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  1. Measurements by Carl Richard for the refoamed 12" woofer and 8" LMR used in AR9.
  2. I was using that clip as an example for you to consider , not my system unfortunately:( BTW, try the lossless audio selection on youtube. George
  3. Have you considered uploading your sound recording to youtube then linking your yourtube to this forum? Your are limited only by your microphones and not by the file size. Here is an example.
  4. I have 4 AR 91/92/58 exposed dome midranges in my parts bin. I may do something with them someday yet. I wonder what are the real differences between exposed dome midrange and fried egg type(AR3a, 5), in terms of sound quality. George
  5. "I guess I was hoping for a miracle, but it didn’t happen. The mid is still too bright by about 3db but using the equalizer allowed me to dial it in to be pleasant sounding and make it very difficult to distinguish from the AR5, with very good imaging, though not expansive like the 5 or the 3a. The 58s can be an excellent top for a subwoofer but, like the 98ls, doesn’t fit into my scheme of things so it will go back to subwoofer duty. I don’t mind adjusting gain when switching but having to remember equalizer settings from speaker to speaker is too much. " Even with 3 db adjustment in the mid, you still favor AR5 over AR58?
  6. Nowadays I am listening to 2 pairs of Infinity R152's in the normal stacked MTTM fashion(both speaker facing forward with tweeters close together in a vertical line). Listening to the beginning of this youtube piece, the delicate music box-like instrument sounds so pristine and so pure. The sensitivity of Infinity R152 is 87db. The stacked R152's connected in parallel will theoretically produce 93 db. I suspect the improved sensitivity is responsible for the cleaner perceived sound.
  7. After back and forth listening between the regular front facing MTTM vs bi-polar(front and back) MTTM using 4 stacked Infinity R152’s, here are the findings. 1. Regular MTTM has higher sensitivity, narrower sweet spot, more extended treble. 2. Bi-polar MTTM sounds more diffused and can tolerate less pristine music sources. 3. Regular MTTM is more dynamic (perhaps due to higher sensitivity) and better separation of music instruments. Thus, stacked speakers offer 2 very different sound fields and you may prefer one arrangement over the other depending on the music.
  8. "The AR98LS has been modified to achieve its highest purpose at my house. It is now a passive subwoofer, which means the internal crossover has been bypassed and the woofer directly wired to the amplifier with the active crossover set at 200hz in this case. The woofer sits very low in the 98LS cabinet which was intended to be placed on the floor and against the wall, but I turned it sideways so the baffle is perpendicular to both reflective surfaces. The bass is very smooth. No peaks or dips that I can detect by ear from the listening position." Did you notice any difference in the bass quality of the AR woofer driven through the crossover vs driven directly by the amplifier? Without the resistance(perhaps as high as 0.8 ohm) from the crossover inductor, the AR woofer may sound more controlled and more extended in the bass.
  9. I am glad you can contour the sound of speakers to your liking with simple adjustments. Here is an article talking about the effect of felt ring(or block) on the tweeter, suggesting a cleaner sound is possible with the proper use of felt. https://www.speakerdesign.net/felt/felt_ring_vs_blocks.html George
  10. "The bottom line: A hot midrange in the 4k range skews voice timbre and explains why cymbals and gated snare are so prominent on a 98ls. Still it can image very well and clarity is superb." Let us assume both AR 98LS and CR65 have the same axial response around 4K hz, AR 98LS would sound louder just because the wide dispersion characteristics of the 1.5" dome midrange. I think our ears receive directional clues from the first arrival sound but our perception of loudness is from the total acoustic energy(power response) from all directions. Many audiophiles prefer an overall frequency response for a speaker which is sloping very slightly down from bass to mid to high range. In addition, our ears are most sensitive in the midrange. Proper voicing the midrange, hence , is critical for naturalness and musical enjoyment.
  11. Now I have three different BP(Bi Polar or ambience) speakers to play with my main imaging(Infinity R152) speakers including an extra pair of R152. I have found several Infinity TSS 750 satellites with 150 Hz to beyond 20 k Hz response. I estimate Bose double cubes are similar except the highs are not as extended. https://www.soundandvision.com/content/infinity-tss-750-speaker-system-ht-labs-measures Some observations: They all sound better turning away from the main speakers instead of directly forward. Bose double cubes can produce some wield sound fields because each cube can turn totally independently from its mate. It is hard to tell apart what is preferred from what is merely different. Isn't that the dilemma when we are facing multiple of choices:)
  12. The Bose cubes could probably be made to work and I am sure you can make this work with the cubes. So far the acceptable BP speaker will likely to be: 1. Delayed by at least 20 millisecond from the front speaker(as mentioned in Stereophile about AR MGC-1). It can be easily met by pointing BP speaker away from the main speaker or perhaps behind the main speaker by about 3 inches or more in the x-axis. 2. A frequency range of perhaps 300-5000hz or wider. Yes, Bose cubes could work. But, you could just move your rear facing Infinity closer to the wall, which may be what you were saying, and experiment until you like what you hear. Are you using music or test tones to evaluate your success? Here comes the empirical part. In general moving the BP speaker closer to the wall will decrease the delay, vice versa. I have not thought about should the wall be reflective or sound absorbing, etc. So far I have not seen any acoustic measurements of the BP speaker so one would have just to try and listen😊 “Regarding Classic ARs. I have been listening to AR5s and my stack most of this afternoon. I can verify that a properly working AR5 with rebuilt tweeters sitting away from the wall can image very well. I used to accept what others have said about the less than stellar imaging capabilities of the classic dome ARs but no more. Indeed. Unless placed properly, the stereo imaging can be destroyed by placing too close to the wall. I wonder when placed away from the wall the main speaker’s edge and side/back radiations could serve as its own BP twin. These radiations will already be delayed(simply because they will take longer time to reach your ears) with respective to the main speaker. Could this phantom or pseudo BP radiations serve to improve the image quality of the direct radiating main speaker? Many European stand mount (to differentiate from bookshelf) speakers have excellent imaging quality but you need to mount them on dedicated stands at your ear level and away from corners and back wall, very different from the bookshelf position recommended for many classic speakers. “The flaw in all this IMO is when imaging came into vogue with high dynamic range recordings most classic AR tweeters had deteriorated putting them at a disadvantage. Another problem is classic ARs are almost always near or against a wall to preserve the bass performance. “ You nailed it. Unless the frequency response of the left and right speakers is closely matched(at least in the mid and high), the image will suffer. Has anyone measured the performance of vintage drivers after 30 to 60 years of service or storage? “If you pull them away from the wall you get bass roll off but the image improves dramatically. This would be where your well set up sub woofer comes in handy.” I agree totally!
  13. More information worth considering. The relative spl level of the BP(bi-polar or rear facing) speaker. One can achieve 6 lower db than the front speaker in a number of ways. My listening distance to each speaker is about 9 ft. The wall behind the speaker is 2ft away . So the sound from the BP speaker bounced to the back wall would have to travel 13 ft to arrive at my ears at about 3db lower than the front speaker. This -3 db is estimated from the db vs distance table for 3m and 4.3m. The sound bounced to the 15 ft ceiling will travel at least 30 ft to my ears at about -10db level. 2. While it may sound unrelated to our discussion but Acoustic Research MGC-1 does use a set of direct radiating module and an indirect sound module to achieve a unique sound field. According to the write up in Stereophile about AR MGC-1, the indirect sound module is electronically delayed by 20 milliseconds and covers only 300 to 5000 hz. https://www.stereophile.com/content/acoustic-research-mgc-1-loudspeaker 3. The 20 millisecond-delay for the indirect module is to make certain it would not smear the stereo image of the front speaker, which is very precise unlike most classic AR speakers. So perhaps we can use BP speakers with less extended frequency range( 300 to 5000 hz as in AR MGC-1), such as Bose cubes or double cubes after all. How about 20 millisecond-delay? I think the rear facing BP speaker in my current setup will provide about at least 67 milliseconds delay. This delay is calculated by the extra distance(9 inches) the BP speaker has to travel to my ears divided by the speed of sound of 343 meters/sec.
  14. My initial impression was there was a bloating of the midrange response when I replaced the rear facing R152’s with two Bose double cubes. I did not try with single cubes. This begs these questions? 1. Does the rear facing speaker have to be identical the front speaker so not to alter the frequency balance. 2. Efficiency match between the front and back speaker? Instead of experimenting further I decided to do some reading. Definitive Technology is probably the largest established company making Bi-polar speakers. In an inside view of their BP9080x speaker, it has a front and a rear module. There is also a top facing Dolby Atmos module. All modules seem to use the same driver units. There is also a discussion that the rear module being 6 db less efficient than the front one. So it appears the suitable rear speakers would likely to be identical to the front ones and perhaps at lower efficiency as well. Bose double cube is mostly a midrange module without extended highend and appears to be too loud as a BP speaker for Infinity R152. According to the review at “Sound and Vision” “Of course, these wouldn’t be BP’s if they weren’t bipole designs that fire in two directions. In keeping with Definitive’s long practice, the towers each have two midrange/tweeter arrays: a front-facing mid-tweet-mid assembly and a rear-firing mid-tweet array. As you might expect, thanks to all those intentional reflections from room surfaces, bipoles tend to produce a bigger, more spacious, and somewhat more diffuse sonic fingerprint than conventional direct-radiating, front-firing-only, cone ’n’ dome speakers. This can come at a certain penalty in hard-imaged soundstaging, something Definitive addresses with a further refinement in this series of the “Forward-Focused” design it introduced in the 8000 series bipolar. This results in the rear-radiating pattern being attenuated 6 decibels down from the front-firing array.” https://www.soundandvision.com/content/definitive-technology-bp9080x-speaker-system-review-inside-bp9000-series
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