2. amps-preamps
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help with audio resesrch d76

Hi I just picked up a couple arc amps a d76 and a 90b both in mint condition. What one is the better of the 2 and what do they sell for. I'm getting rid of one or the other. Gary
tubesmore
hifigeek1
770 posts
 
The original D-90 had 6550 outputs.
hifigeek1
770 posts
 
...also the D90 did not have a servo in it. The D90B does.
apfdirtdoctor
36 posts
 
Thanks HifiGeek!! I have never looked at the schematic for the original D90. Clearly shows matched GE6550s. I was fooled by the http://www.arcdb.ws/D90/D90.html website. Has a picture of D90 with GE6l6s in it. must be D90Revised...oh those ARC guys. When I talked to Mr. Johnson he said there was a heated debate between himself and his "engineers" between the 6550 and 6l6, but I did not realize they produced a 6550 version. Mr. Johnson seemed pleased he produced an amp using 6l6s. Also, I have an amp stamped on the back with D90-B and it does not have the servo in it. Leonard at ARC finally told me that it was at a dealer and was sent back for the B update and they took a little short cut... ;) Thanks again for the audio trivia. Larry
hifigeek1
770 posts
 
Larry, hopefully it doesn't have the white relay in it either. That can become problematic.
apfdirtdoctor
36 posts
 
Hifigeek1 I need your help. What was the purpose of the "Servo" circuit? in the ARC 90B? Also, is the white/gray relay located down in between the large grey tall power supply caps? where the 6550 power supply tube was located in the 90? I do not have one in mine. The reason I am asking is that all of a sudden my 90B(ish) upon start up, the output tubes glow orange after about 30 seconds and then the fuse blows. Techs look at my 90B and say it does not match the ARC schematic for 90B?? Again ARC said it started out as a 90?? or 90Revised. Very confused. Thanks Larry
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