Biasing Cayin TA-30


I am installing new EL34's in my TA-30, and although familiar with electonics, have never biased an amp before.
Note: This unit does not have Paul's mod for external biasing.

1.Do I need to have speakers hooked up while biasing?
2.I ground the black meter lead. Black speaker terminal OK?
3.Red lead to bias resister between resistor and tube socket?
4.I see ref to biasing to mA, the Cayin calls for .35 volts. Just a different procedure?
Thanks in advance
John
jdcrox
See if this helps.

http://www.audioasylum.com/cgi/m.pl?forum=tubes&n=129030
The problem with that link (I have looked at it before) is that the diagram link is broken, and it doesnt answer the rest of my questions.
John
John,

I also have a TA-30, sans external bias mod. Answers based on how I do it:

1.Do I need to have speakers hooked up while biasing?

No. Normally I bias at the kitchen table, so the only thing plugged into the amp is a power cord. Volume is turned all the way down.

2.I ground the black meter lead. Black speaker terminal OK?

I have always read "across the resistor" to mean I should attach leads on either side of the resistor. Voltage drop is either positive or negative depending on where I attach them, but which it is is irrelevant--the absolute value of the reading is the same.

3.Red lead to bias resister between resistor and tube socket?

See number 2.

4.I see ref to biasing to mA, the Cayin calls for .35 volts. Just a different procedure?

.35V = 350 mV

I have absolutely no formal training in electronics, so it could be that I've misunderstood and misused info I've gotten from the web. However, my amp works fine & sounds great, so what I've been doing doesn't seem to have hurt it anyway. Good luck, & if my hedging has scared you off at all, hopefully someone with more knowledge--or at least someone less careful than I am about pretending to be authoritative--will confirm my method.

Brent
go to http://www.angelfire.com/biz/bizzyb/TA30ADJUSTMENTS.html
Thanks Brent, that was exactly what I needed!
Cyanzky, problem is that mine doesnt have the external adjustment mod.
Paul is a great guy at bizzybee, but understandably he is reluctant to give out instructions on biasing inside the unit, given the lethal high voltages involved, and of course potential lawsuits. I dont blame him for this one bit.
John
Glad to help, John. Did you replace the tubes out of necessity, or just to try something different? Also, I'd be glad to hear a report of their sound, if they're of different make from the stock tubes.

Brent