• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Audio Research VS 110 bias port issues

Hi,

Did you sort this out? I am experiencing the same for my VS115. I changed my tubes and managed to adjust the bias. But during the play, the left speaker made a pop noise briefly. I then measured the bias and could not get a reading from V5. However adjusting V5 bias changes the V7 bias. So I am suspecting the bias testing ports are fried.

Curious to know if your experience at the end.

Kind regards,

Tom
 
ARC VS55

Total newb here... Reviving thread as problem is same.

I picked up a Audio Research VS55 which is similar to VS110. Sounds great, everything seems fine. Power tubes light up and get hot. So I go to check bias and am able to set bias to 55mA (New ARC recommended setting for 6650c tubes) on the right channel and one of the tubes (V5) on the left channel. V7 however only reads 0.3mVDC (0.4mVDC when hot) and adjusting the pot has no effect on the reading. Will I make things worse if I keep running it? TIA John