Fixed Bias

  • Thread starter Thread starter hbucker
  • Start date Start date
No. They are designed to be quick and easy to re-bias.

:rock:
 
I think there may be a bit of confusion. Fixed bias (I think) means that you must bias it yourself. Cathode bias is where you just plug and play. Pretty sure I'm right, and I do believe the two amps in question are "fixed bias" amps, meaning you have to bias them when swapping power tubes.

Note: Bruce makes his amps so easy to bias......no need for tech support.
 
Peavey amps use a fixed bias which means you don't need to have the amp biased when you retube.

How does one set the bias on an Egnater without a tech or preexisting biasing knowledge?
 
You need to get a voltmeter, and you just stick the appropriate pin into the appropriate hole and turn the screw until you get the right reading.

It's easy to do- No need to take it to a tech for that. The manuals give you all the info you need.

:rock:
 
hbucker":ec3ilsfr said:
Peavey amps use a fixed bias which means you don't need to have the amp biased when you retube.

How does one set the bias on an Egnater without a tech or preexisting biasing knowledge?
Click to expand...

No, the Peavey amps are "Cathode Bias" which means plug and play.

Like Len said, just get a multi meter from Radio Shack and the manual will walk you through it. Bruce makes his amps EXTREMELY easy to bias!! Trust us on this.
 
FWIW:
A reply from the PV forum:
"Depends on the Amp and Peavey only has a few Cathode biased Amps. Until a year ago only the Classic 20 was Cathode biased but one of the newer amps I think the Single tube one is also Cathode biased. If there is a Capacitor and power resistor from the Cathode to ground it's Cathode biased but the huge majority of Peavey amps are fixed bias and some adjustable and most of them not."

A page from Eurotubes.com referencing several "fixed bias" amps:
http://eurotubes.com/euro-k.htm

I don't have a dog in this fight. ...I'm just sayin' :confused:
 
I'll point you to an authoritative source who explains it well - Randall Aiken. No disparagement mmeant to any of the posters to this thread.

http://www.aikenamps.com/TI_Aiken_int.htm

The Rebel 30 I have has very nice bias points installed. They have the preferred voltage noted on the board and tell you which bias points are for which pair of tubes. I have to drop the chasis out to get to them. I think some of the other Egnater amps have external bias points.

Remember, if you do the bias calculation for a single tube and the bias adjustment is for a pair of tubes, you need to double the amount. If they put the right setting on the circuit board, then just follow their suggestion.
 
From Randall Aiken:

There are two main types of biasing: fixed biasing and cathode biasing. Fixed biasing does not mean the bias is not adjustable, in fact, it usually means the opposite. Cathode biasing is usually fixed, and not adjustable, and fixed biasing is usually adjustable with a small trimmer potentiometer, or "trimpot". It is no wonder the subject is confusing to people!

Really, it doesn't matter much though. The thing I love about my Mod 50 and Bruce's amps in general, is that they are so easy to bias. No chassis pulling and putting your probes on whatever leg of the tube socket.........heck with that!! Put in new tubes, plug the multi meter in the designated points, turn the little trim tab until desired readings. Takes me all of about 2 minutes to bias with a power tube swap. Love it.
 
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