I've owned this amplifier for thirty years now, and I've always used the bias led's to set the bias. I decided to buy a bias meter to check the level they used because I always got very short tube life and I was getting tired of the cost of replacing them. Well, when I checked the led's against the bias meter with brand new tubes, it was 55ma. Maybe I'm wrong, but isn't that a little excessive?
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What output tubes are they? If they are 6550/KT88 types, then 55mA per tube is reasonable. EL34 or 6L6 and you have too much dissipation at 55mA per tube.
Yeah that seems excessive for a class AB1 pp EL34 amp rated at 50 watts/ch. Dial it back to 40mv and see how it sounds.
jeff
I have Mullard 6CA7/EL34s running on 50mA and a 420V supply, with no problems ever.
Many such tube designs for home audio have similar operating points.
Many such tube designs for home audio have similar operating points.
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Real Mullard Xf2's? Just trying to be conservative, as modern EL34's won't last as long as Mullards. Also couldn't find a schem. for the MV50, so don't know what the B+ is etc.
jeff
jeff
They were manufactured in 1975, a matched quad. I bought them new, and they still work like new.
I think the CJ MV-50 has a somewhat higher power supply voltage, but their documentation is poor.
It does have an ultralinear output stage. He could measure the voltage, if he has a suitable meter.
I think the CJ MV-50 has a somewhat higher power supply voltage, but their documentation is poor.
It does have an ultralinear output stage. He could measure the voltage, if he has a suitable meter.
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