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
128x128tubesmore
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 ;)
In certain situations a servo ic is used to eliminate coupling caps from one section of a given circuit, utilizing the ic in a feedback loop, usually at the input. Although coupling caps are a necessity in tube products, they do have their own set of coloration that add to the sound of the product. A tone control of sorts. Some designers felt that by removing them at the input of the circuit and replacing them with a servo ic there would be less coloration. What we now know is there's no free lunch. Servo ic's do have their own set of coloration with each manufacturers ic's sounding different. In some cases they can actually sound worse than a high quality coupling cap.
Hifigeek1,
I was wondering if you could answer a question I have, is the arc d-90b triod?
Thanks,
Whitestar23
If you mean the output configuration the answer is no. I believe the output circuit topology is partially cathode coupled, not triode configured.
Thanks Hifigeek,

that is exactly what I wanted to know. You have confirmed my suspicions my tech is a very good solder monkey.

I was talking having my sockets replaced in mine and he said that it was wired in triod. I asked if it was suppose to be he said according to the ARC schematic it was. I asked him to double check and he said he just confirmed it by re looking at schematic in the manual.

This made no sense to me that it could be triod with 80 watts output and that small of output transformers.
They dimensionally look the exact same to me as the Classic 60 outputs.