Biasing a Rectifier. Worth it?

[khabibissell]

I've got a Mesa Single Recto and I love it, but I was wondering if it's worth it to have it biased. I know Mesa claims that it's unnecessary on their amps, but I know from past experience that having the bias set to get optimum tone from your chosen tubes is mandatory. What do you think? Thanks!

[PallarAndersVisa]

Re: Biasing a Rectifier. Worth it?

i was also wondering this for a peavey 5150. I dont want to pay for biasing/installation if i dont have to.

[metafaza]

Re: Biasing a Rectifier. Worth it?

That's where I get most confused. Everywhere you read about tube amps they talk about re-biasing after every tube change. Then, some people (including Mesa) say it's necessary. Can some of our tube amp gurus clarify the matter once and for all?

[Chuckracer]

Re: Biasing a Rectifier. Worth it?

I'm no guru, but I have a basic understanding of the biasing situation, and in Mesa's case, they have a set bias because they want you to buy their own overpriced labeled tubes. The theory is that if the bias is set to a certain rating of tube (lets say white in Mesa lingo), then if you buy tubes from Mesa with that white rating, your bias is fine.

I have no idea why 5150 are fixed other than they built them as cheaply as possible.

There is a guy here who has modded many 5150s by installing a bias pot and dialing them in and I hear its a dramatic difference. I'd imagine the same could be done to a Mesa.

[Dreamland_Rebel]

Re: Biasing a Rectifier. Worth it?

they don't have to install a bias pot. its just a matter or replacing resistors in each tube sockets circitry. no matter what brand of tubes you buy, i reccomend getting your amp properly biased by an experienced tech. mesa's come biased cold. so there POWER tubes will last longer. even if the amp is brand new, and has mesa tubes, a pro tech will be able to set the bias to peak performace for the tubes inside. no matter what brand of tubes.

[Chuckracer]

Re: Biasing a Rectifier. Worth it?

Sorry, but a bias pot has to be installed to adjust the bias. You change resistors to change tube types on amps that don't have switching convenience (ie; most).

Otherwise, thats what I said! [img]images/icons/wink.gif[/img]

[khabibissell]

Re: Biasing a Rectifier. Worth it?

Thanks guys, I figured that. IMO The amp sounds pretty good now, but I think it's missing something. There is no way that they could have perfect bias set on all their amps, even when using tubes within a certain tolerance range.

[metafaza]

Re: Biasing a Rectifier. Worth it?

How difficult it it to bias an amp by yourself? Anyone has done that?

[buzzsaww]

Re: Biasing a Rectifier. Worth it?

adjustable bias needs a pot installed. some testing jacks would be a good idea too ala peavey XXX.
just plain old biasing is done via resistors installed at the tube sockets.

[Dreamland_Rebel]

Re: Biasing a Rectifier. Worth it?

well not to start and argument, but when i got my .50 cal used it had groove tubes in it. i had them replaced with a new set of groove tubes and had it rebiased for that set of tubes. no bias pot was installed, just a few resitors in the power tube sockets. now its sounding great and i won't have to adjust it if i use grove tubes with the same specs. granted this boogie like all boogies do not have an "ajustible bais" that is why the resistors have to be changed instead.


yes installing a bias pot would make changing tube ratings/types easier, but it is not mandatory. (but a good tech is! hehheh)

~JW

[Chuckracer]

Re: Biasing a Rectifier. Worth it?

Never mind.

[khabibissell]

Re: Biasing a Rectifier. Worth it?

I called my tech and he quoted me $55 to install a bias pot. Not too bad, so I'm gonna do it.

Now... Any opinions on the best sounding EL34's? I use Mesa branded Svetlana's (STR-447) now. Any opinions on pre's?

[charvel750]

Re: Biasing a Rectifier. Worth it?

Biasing is only about $25 at most shops, so as long as you provide the tubes, it's pretty darn cheap, and well worth the price to get not only the optimal tone from your amp, but also to keep it running efficiently and smoothly.

[Chuckracer]

Re: Biasing a Rectifier. Worth it?

The problem is these heads, the Rectos and the 5150 are a fixed bias...there is no adjustment pot on the board, so you'll need a tech with his act happening to mod the head with a bias pot, THEN properly set the bias.
From the factory, both these amps are set cold as hell cause longer tube life means less warranty claims for them, to hell with what it sounds like.

I hate both of those companies for that.

[LRGman]

Re: Biasing a Rectifier. Worth it?

Buy from the tubestore.com-good prices and overnight delivery for 12.95-call them they will answer any questions. You can buy the same svetlana's for half the price as mesa. Oh but they don't have the mesa logo and haven't been tested to mesa's standard [img]graemlins/puke.gif[/img] [img]graemlins/laugh.gif[/img]


They are aware of where tubes can run for fixed bias and will send you a hot set if you want.

Mesa and Groove tubes are the biggest rip ever. GT are the worst tubes I ever had in any amp-burnt right after warranty