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AUDIO RESEARCH D-76A

I am new to this trade so bare with me if I ask dum questions.
I have a AUDIO RESEARCH D-76A power amp that I been using for few months now. as you probably know this amp has the most tubes than any other tube amp that I can remember. the middle of the amp are four 12AX7. I notice that one of the 12AX7 [middle top] are not lighting up nor hot. so I had all the sockets replace but still no light nor hot. I was told that its normal. how could it be? will this de-grade my sound? please enlighten me. I will appreciate any advice. thanks
torogi
hifigeek1
770 posts
 
I'm in L.A.
hifigeek1
770 posts
 
Bifwynne your amp is totally different then the D-76A. I would have to look at the D-76A to see if it's been 'messed' with before I can quote. Also the unit needs to be repaired before anything else can be done to it.
torogi OP
6 posts
 
Hi guys, I decided to open up the ARC underneath the transformer and power caps only to found out that there are two 2x 400volts 200uf robycon caps that are added.I assume that the original mallory caps are half dead. this is more problematic than I anticipated. I think I will focus on this one first. do you think it has something to do with the tubes? I took some pictures If you guys are interested I can send some.thanks
hifigeek1
770 posts
 
Let me suggest you either send it to ARC or to an authorized service facility. Since those are non-standard parts, and the fact that the unit runs at high voltage, I really do think you would be best served by getting it repaired by people who know all about the unit and ARC in particular.
tbg
5,263 posts
 
Given the age of this amplifier, I would definitely have someone thoroughly check it out. It is not just a matter of the tubes. I had two of these amps in the early 1970s! I am surprised that you have not blown a fuse.
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