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About DavidR

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  • Birthday 06/21/1951

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  1. I think they are Cello Amati's, no?
  2. Well, its one of 2 shunt circuits on the UMR. The 8uF and the 40uF+6ohm resistor+coil. They are both filter circuits. They would control frequency and slope/roll off.
  3. I'm currently working on one pair of 9s. Still doing cabinet work and haven't gotten to the caps yet. However, I did my AR90s and the results are below. For some reason it will not format correctly so hope you can follow. Even though many of the caps were within spec the speakers were VERY dull. I thought my tweeters were suffering from dried ferro-fluid - Nope, they were fine. Old caps can act like resistors. My point is to change them when they are old no matter what they read. Caps tested with an Agilent U1733
  4. @Giorgio AR Now those are some impressive towers
  5. Yes, it is a Sansui 838. It still runs great. I have an NOS Acutex 412STR for the current cartridge.
  6. For 4 ohm operation: Woofer 4Pi, Mid 0dB, T 0dB 8 ohm: Woofer - 2Pi, Mid -3db, T -3db 16 ohm: Woofer Pi, Mid -6dB, T -6dB
  7. I do not believe AR ever used ribbed cones on the woofers. It could have been re-coned. The only way to tell if it's an AR driver is to remove it and look at the back for proper ID. I believe those tweeters can be rebuilt by one or two members here at CSP. I'm sure someone with more knowledge on the older AR speakers will pitch in.
  8. Depends on what amp he has as to whether he can do that. Many amps, especially tube amps, either have external taps for the different impedances or are internally wired like my tube amp. Would it work? Probably. Would it sound its best? No. If I understand him correctly he was wanting to know what position the switches should be in for 4, 8 and 16 ohm. All to the left for 4 ohm, all in the middle for 8, etc. This does not mean the 3 switches all need to be in the same position. i.e. one can be all the way left, another in the middle and the 3rd to the right; or any variable that gives the
  9. Here's a pdf of an AR90 xover that someone did. Who ever made it did a great job. It makes the wiring much easier to understand. ar90 xoverschematic.pdf
  10. The tweeter, UMR and LMR in the AR90 are wired out of phase. The AR9 is wired in phase for those drivers. The AR90 does not have the tank circuit (2500uF cap) that the AR9 has on the woofers. The 30uF on the LMR is a shunt cap. The 80uF is the series cap. Both look to be wired the same other than the phase. At least on the schematics I have. Not sure if this is the difference you are seeing.
  11. I've read that the highest is 16 ohm but was on a site that lists all AR speakers and their specs. The AR Manual would be more accurate.
  12. Its a photo from the internet just to show the labelling. 4 ohm would be with all switches to the left. Sorry.
  13. That is my understanding this crossover. It was a major step forward for room control.
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