| Author |
Topic: Amp Biasing question |
Jon Light
From:
Saugerties, NY
|
Posted 27 Jan 2006 3:03 pm |
|
I'm in over my head here. I do simple maintanence things by following instructions, tutorials, etc. but I surely don't have much basic understanding.
Here's how my Tone King Comet is described:
quote:
Output Stage
• Consists of two seperate 20W power amplifiers running in parallel
• Each 20W power amplifier has its own pair of 6V6 tubes and its own output transformer, and drives its' own 12" speaker.
• Cathode biased operation
• Class-A mode operation up to point of overdrive; Class-AB operation in overdrive.
Electronics
My question is, do I bias a new set of tubes or do they not need biasing?[This message was edited by Jon Light on 27 January 2006 at 03:04 PM.] |
|
|
 |
Jon Light
From:
Saugerties, NY
|
Posted 27 Jan 2006 3:17 pm
|
|
| I guess a tiny bit of research is all I needed to answer my question--cathode biased amps are "self-biased", right? and new tubes don't need to be biased. |
|
|
|
Andy Zynda
From:
Wisconsin
|
Posted 27 Jan 2006 3:24 pm
|
|
Yup, cathode biased is also called 'self biased".
Plug and go.
-andy-
|
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 27 Jan 2006 3:35 pm
|
|
| Nifty. Thanks. |
|
|
|
John Daugherty
From:
Rolla, Missouri, USA
|
Posted 28 Jan 2006 10:31 am
|
|
Jon, here is a little trick I have used for tube amps with cathode resistors. Replace the cathode bypass capacitor with one of larger value.
For instance, if the cathode bypass cap is 10-50mfd, replace it with a 150mfd. It gave me a little more power and a cleaner sound.
------------------
www.phelpscountychoppers.com/steelguitar
|
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 28 Jan 2006 5:16 pm
|
|
I didn't see your post, John, until now. I'm going to get in touch with Mark Bartel to see if I can get hold of a schemo. If this were a Fender I would be bolder about mucking around inside because I'm a little familiar with the layouts. But this chassis is unlike any Fender so I'm not going to do anyting rash. I am definitely not someone who can study a chassis and read the circuit.
I would also like to look into experimenting with the voicing--it has no mid control and the mids are a bit fat for my taste. I added a mid control to my Deluxe Reverb and would like to either try that or just change the resistor to a different fixed value. However, that is assuming that the tone stack is Fender related. The rhythm channel is decribed as sounding "black face" but I don't know if that means it is derived the same way as a BF Fender.
Anyway, thanks for the suggestion.
Meanwhile, I've got a set of JJ 6V6's on their way, the reason for my initial question about biasing. |
|
|
|
