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Tubed DAC problems,opinions please.

Hi to all.
Recently I purchased a used AUDIO RESEARCH DAC-3 Tubed DAC with four 6922's output stage. When I hooked it up to my system I heard pops coming from the speakers and first blamed my ARC line stage LS3B and thought that volume control was dusty or something. I actually started a thread on AMPS-PREAMPS about it.
I was about ready to take my line stage in for check-up but the last minute I decided to re-check my whole set-up one more time.
Today after carefull ispection I realised that the DAC-3 is creating the pops and very low volume level (I mean low,to the point that at 11:00 pm position of volume control on the LS3B LINE STAGE the sound is barely noticeable).
Note that the DAC-3 is feeding my LS3B LINE STAGE which is driving a CONRAD JOHNSON MV55.
There is no doubt that something is wrong with DAC-3 .
The previous owner claims that it left his house in good working condition,but the FEDEX must of dropped it.
Do you think the problem got to do with the 6922,s tubes or must be something more serious.
I mean could the tubes produce above problems and by replacing with new ones everything gets fixed, the previous owner was using telefunken NOS and just put the stock 6922's in prior to shipping. But he says he checked two times and everything worked ,before shipping it to me.
I am confused,and not an expert ,please let me know your thoughts
Best regards
George
128x128yioryos

Showing 1 response by garyk

garyk
30 posts
 
I recently had the same problem with my Kora Hermes II dac. At first I thought it was a problem with my integrated amp, so I swapped in another amp and it was still there.

In discussing the problem with my local tech, he suggested the dac's output voltage may be overdriving the integrated's preamp section. He mentioned that a lot of tube dacs dump a high (7+) voltage unfiltered signal to the pre that (typically) is expecting only the industry standard 2 volts.

I don't know what the DAC-3's output voltage is but I'd ask the ARC tech support if this might be an issue.
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