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Tube amp biasing question---

hello all,

just wondering, my amp, a Jc Verdier Audiobloc II has to be manually biased to 18v Dc.

at the MINIMUM range of the bias pot, I still get approx 18.9v DC, at the top range of the Bias pot, i can get almost 26v dc.

my tubes are all tested in the good range.

my question....could it be my tubes are too strong?
would swapping in some weaker tubes (aged tubes) allow me to lower the bias point to reach 18v dc?
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2 responses Add your response
marakanetz's avatar
marakanetz
5,473 posts
 
Hey dude!
Here's your fuse problem's origin!
One or more DC electrolytics are at failure.
Get it serviced and use some substitute that while and don't kill tubes you're doing eventually. Overbiasing by .9V is way too much!
atmasphere's avatar
atmasphere
11,794 posts
 
My guess is that your tubes are not too strong. No amp manufacturer would offer an amp that could not handle strong tubes. More likely is that there is some sort of failure in the bias circuit, perhaps some resistor values in the bias network that have drifted off value.
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