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Found 9 results

  1. Many of you recall from my post titled "AR-9 / AR-90 Crossover Re-capping Adventure" that I had a heck of time trying to find the proper combination of the attenuation resistor switches to achieve acceptable results. People probably thought I was crazy or losing my hearing. The culprit was the 24uF Solen MKP 400V capacitor installed inline with the Upper Mid Range (UMR.) It was all over the place depending on program material. It sounded anywhere from great to shrill and exhibited the uncanny ability to drill down into a recording, extract whatever grain is there and put it front and center. This cap seems to be incompatible in this particular circuit with this driver. Stimpy suggested adding a Dayton 0.1uF F&F bypass cap as a fix. Doing so decreased the shrillness of the Solen, but also increased the grain to the point of rendering many recordings unlistenable. My goal is not simply to obtain the best sound from the best source material, but also to get acceptable results from average recordings. So this very unforgiving capacitor had to go. I decided to try one other poly cap before going to an NPE as Carl, RoyC and others had suggested. I had read that the Jantzen Cross Caps are considered comparatively smooth sounding, so I installed them in place of the Solen. Although the improvement was a step change, I still wasn't quite where I wanted to be. A 16 hour burn-in period using high volume pink noise made no difference. So I installed Mundorf E-Caps (Plain) in matched pairs purchased from Sonic Craft: http://www.soniccraft.com/index.php/mundorf-ecap-ac-c-23_318_358 Like magic, everything was now where I wanted it to be and has remained so after several days...no "it sounds different on Tuesday afternoon than it did Monday night;" no waiting for burn-in; no endless effing around with the attenuation switches. Great recordings still sound great, average material is very listenable, and I perceive no loss of detail in going from the poly cap to the Mundorf. Remarkably, the Mundorf sounds like it has more "air" and "depth." I surmise that this perception is related to how the E-Cap integrates into the entire speaker system rather how it directly compares to the poly caps. Notes: 1) I confirmed with Carl that the E-Caps with their 70VDC/50VAC rating is a suitable replacement for the stock 100VAC Callins NPE. 2) The 24uF Solens were still installed in the AR9 surround speakers and got the 16 hours of pink noise burn in. It still isn't acceptable but for some unknown reason has always sounded more tame in the AR9 than the AR90. 3) I use -4.5dB (estimated) attenuation with the E-Caps in the UMR. I've always used -3dB going back to 1980. The attenuation network is now set up so that I can go back to -3dB if desired. The AR9's are next. I may try the Cross Caps first just as an experiment before going to the E-Caps.
  2. Being big on spare parts I've been acquiring spare drivers for my AR90's. I've been successful with all drivers except the LMR p/n 200027-0. They seem to get swiped up quickly on eBay. I've parted out (3) AR94 speakers. The full range/mid drivers are the ones that came in the AR9LS p/n 2100450B. The woofers used p/n 2100370 and look more like the 200027-0 LMR. Can I assume these 8 inch drivers are all pretty much the same? Which would be the better replacement to use (should I ever need to)?
  3. Finally happened.... no 'dumpster find' but close... As I was walking to get a Sunday newspaper today I walked past a set a speakers and some other items in a pile with a "free" sign propped up against the speakers. The speakers were a pair of AR90s complete with both front and side grills and all the acoustic foam insulation still in place and like new. I called my wife to bring the truck (didn't want to leave this find alone!) and the 90s were quickly loaded and driven to my garage. Inspection the speakers: physically the boxes are great with no nicks or missing wood, tops will have to be reworked.. no real damage. The four woofer side speakers will need new surrounds, the 8" front woofers have new surrounds (sloppy job with glue smeared half way down the cone). The midranges look good with only one dome pushed in. Tweeters look new... I would rate these speakers condition 7-8 as is .. grills no major problems, both badges good condition, would need wood cleanup and re-staining on the top... a light strip and a coat of Howard's would being the boxes back to life. I would assume the caps and wires are original. Now I have to decide whether to keep and restore......restore and sell, sell as is, or part out..... ( I already have: AR9, AR91, AR93 and AR94)
  4. I decided it's time to begin my adventure into rebuilding the crossovers in my AR90's. AR Surround's thread kind of got me to it. Also I have noticed the Right speaker (UMR) was not quite as loud as the left - so its time. I pulled a woofer to take a peek. One crossover was very neat and looked easy to remove the old caps. The other was well, uumm ........ here's a picture. Looking for ideas on how to clear away the mass amount of glue. The glue is still a bit gummy but still hard. My wife and son go away during April vacation to Newport so that's going to be prime time to work on them. AR90 Caps.xlsx
  5. My amplifier's right channel went south and took out both woofers. The voice coil resistance check shows they are burned out. What are my options?
  6. I just bought one of these and the seller has another. Very nice condition and good price. eBay item number: 331907115846 Here is a rare 1978 find for the Acoustic Research speaker fan; a full size original AR-90 advertisement poster measuring 27 1/4 X 34 1/4 inches on medium stock. Never displayed, it is in near mint condition for its age. Signed within the poster's design by the recently deceased artist Frank Modell, a cartoonist who regularly drew for New Yorker magazine. Poster will be shipped rolled in a mailing tube for maximum protection. I am sure there are not many of these still around.
  7. I recently picked up a pair of AR90's from Craigslist in fairly rough condition. The price of $100 was right, but one speaker appears to have been dropped with enough force to crack the base of the cabinet. Both will eventually need refresh on the walnut finish, foam surrounds, and capacitors. The one speaker that was dropped has a woofer with a tear in the paper cone. I've attached pictures to solicit ideas on how to best restore it. While I could glue it with some high strength epoxy, I really can't tell if there is coil rubbing or spider damage leading to a driver not functioning to spec. Since these are speakers worth restoring, I would prefer to have the driver repaired correctly. The driver still functions electrically. While I've done several successful foam surrounds, I am not comfortable with cone repair. Would appreciate recommendations on how best to proceed. Thanks, Brian
  8. Ever since re-capping my AR91s with PP caps I've wanted to do my AR90s. I have a question on the tweeter crossover difference. The 91 has only a 4uF cap in series with a .2mH coil in parallel and the AR9 and 90 have a 0.105mH coil with a 4uF and 6uF caps in series. I'm wondering what the 4uF and 6uF in series does. Is the difference only because of the coil difference?
  9. Yesterday I got to replacing all the caps on the LMR, UMR, HF crossover board in my AR-90s. I did this with the crossover boards in place. I found it quite easy to get adequate access by removing both woofers and using a small flexible neck lamp to give me great illumination. I purchased the caps by mail from ERSE. They arrived promptly and all are 250V but in spite of this their sizes were suitable for replacement in the same locations occupied by the original caps. ERSE didn't have a 40 uF cap so I bought their 39 uF caps and parallelled with a couple of old GE nominal 1.2 uF caps I had already. The values in the attached screen clip include the 39+1.2 uF caps in parallel. You'll see that the original caps that measured significantly differently from their nominal values all did so on the high side. One of the black and red caps, an 8 uF one, had started leaking a white substance, otherwise all the original caps looked fine. I had planned to leave one speaker as it was and then measure for before and after comparison but decided to just get the project done and listen to music instead. I may get around to measuring the results eventually but have numerous other projects. Do they sound different? Maybe, but I'm suspicious of my being susceptible to wanting to hear an improvement ... the truth is I enjoyed them before and do now also. If anything, based on a few hours of listening, I sense a bit more stable positioning of soloists, either vocal or instrumental. Anyway, I'm pleased that the replacement was easy and that I don't have to worry about capacitor failure for the tops of these speakers. I'm driving them with a Sansui AU-D11 integrated amplifier I recently rescued (multiple issues but I really like the Sansui engineers' pushing of the envelope on this and the AU-D9 with their incorporation of output stage feed-forward and consider these two amps to be really lovely to listen to - I have one of each). Source material comes in directly from a Thorens+SME+Ortofon MC20 or via an Emotiva XDA-2 from CD, server, or MOG. Now to decide how to thin out my AR inventory - I've got two pairs of 3a, a pair of 2ax, a pair of 92, a pair of 4ax, and or course, the 90s.
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