Bias Dynavox/audio institute vr-70e

you must measure the voltage across the 10 Ohm resistors and set to 350 mV for 35 mA with the corresponding bias pot.

Think you measure the difference between the cathodes, this must be near zero, so you see your amp needs new biasing.

Reinhard

Exactly what I needed to know! Danke

Hello,
I biased the amplifier yesterday with these values. Before I rebiased, the values were quite different from each other: left channel ca. 560 and 420mv / right channel ca. 390 and 440mv . Result: better soundstaging, two channels more balanced (the music comes right from the middle). Maybe other Dynavox owners could benefit from a rebias , mine is two months old, first month with the standard chinese valves, later with Svetlana =C= matched quartett. Happy listening!

hi,

have you changed the ecf82? if not do it and you are smiling like pacman.

kai

Hi Kai,

I have used a pair of new EI ecf82. The amp sounded indeed a lot better , but one channel was (considerably) louder, and some 20 seconds after I powered it up, I heard (every time) a loud crack in a speaker, and saw the light in the corresponding ecf82 light up . Now the standard tubes are in again, but I'll measure the EI's (BTB-elektronik didn't want to match the tubes ) with a tube tester soon. I also ordered a matched pair of GE nos ecf82.

What struck me when I opened the amp, was the junk potmeter (maybe worth 1euro?). I'll replace it with a diy stepped attenuator...if the comments of the 'audiophile community' are any good, this should be a big step forward (I'm curious) !

Well...enjoy!