Bias chart

[Tachy]

I found this table regarding Bias chart of el34s, but I don't Know what class is guitar amps and voltage...someone can help me?

 

[Mr. Brokenamp]

Hi the class is the style of circuit design. MOST guitar amps are Class AB.

 

[Tachy]

Ok but wath I can do to determinate the voltage for correct bias current?

 

[\m/FRNK\m/]

Take out your tubes, switch the amp on (with a load connected (speaker or so)), and measure the voltage between pin 3 and 8 of the tube socket.

 

[Tachy]

If I do this I can hurt my amp??

 

[kaomao]

Ok but wath I can do to determinate the voltage for correct bias current?

You have to measure the plate current, it's a risky task, you can get electrocuted if you're not very trained.
Anyway on www.framus.de you can find the dragon guide with the exact voltage, but there isn't a guide for the cobra.
Send an email to them they will tell you for sure what's the right setting.

Maurizio

 

[Tachy]

Thanks Maurizio, I'm a tech but I Know about transistors...tubes are not my apecialization...I get my diploma 10 years ago and at this time electronic is not in my head!