help with audio resesrch d76

I own both....very similar driver circuits. The reason ARC came out with the D-90 is that Mr. Johnson's favorite sounding tube was the 6l6 (personal communication) That is one of the reasons he used the 6L6 in the ARC/Dynaco ST70-C mod. He told me his ARC guys always pushed the higher power 6550. Tube brands have a larger effect on sound than the different circuits. Mr. Johnson liked the GE 6550 in the 76/a and GE 6l6 in the 90B. The JJ 6l6 and the mesa boogie STR440 sound similar to the GE 6l6. The 90B set up correctly has the power to "float" an orchestra...as HP use to say. The 76 is gorgeous sounding especially in the midrange...but the 90b has BALLS!! ;)

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 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

HiFigeek1 you have sent myself and my fellow audio buddies on a wild goose chase.....for several days...we just thought we were dumb and didn't know how to ask you...Illuminate coupling caps???? We thought you knew an audio term we did not know....WELL DID YOU MEAN ELIMINATE coupling caps...??? Larry ;)