Mesa's~ are all models self biasing?

[cellardweller]

Specifically I was looking at a 50 Caliber head.
The documentation details the changing of tubes, but nothing about biasing, so I assume by this omission that it is self-biasing

I REALLY need a small tube amp, and since there is not a reliable amp guru in my area, self-biasing is a neccessity.

[Outlaws]

Originally Posted by cellardweller

Specifically I was looking at a 50 Caliber head.
The documentation details the changing of tubes, but nothing about biasing, so I assume by this omission that it is self-biasing

I REALLY need a small tube amp, and since there is not a reliable amp guru in my area, self-biasing is a neccessity.

I never thought of 50 watts being small, but okay...

[Tadpui]

I think that Mesas are fixed bias, meaning that there's no way to adjust the bias. If this is the case, then you'll need to replace the tubes either with the exact same ones that Mesa put in there in the first place (don't they have their own "brand"?), or find replacement tubes that have the same specific characteristics.

But yeah a 50 watt tube amp is going to be blisteringly loud, not much different than an 80 or 100 watt. Maybe 5-15 watts is more of what you're looking for? Those can still get pretty darn loud!

[HangDawg]

Originally Posted by Tadpui

I think that Mesas are fixed bias, meaning that there's no way to adjust the bias. If this is the case, then you'll need to replace the tubes either with the exact same ones that Mesa put in there in the first place (don't they have their own "brand"?), or find replacement tubes that have the same specific characteristics.

Ahhh that's bullshit. Any good matched set from say, eurotubes.com, will work fine. They mesa's are biased cold and benefit by getting bias resistors put in. I've had my DR for 12 years and haven't had problems with using any available tubes.

[GONZO-X]

fixed bias, mine is...

it's a 1981 mark2b 60 watt head...

i've never put anything in it but mesa 6L6's....

but i'm curious to put some yellowjackets in it, to go with the el84, and see how this circuitry sounds with a completly different tube set...

but, i can't find any shorty yellowjackets... my head case is the small footprint one....

[Tadpui]

Originally Posted by HangDawg

Ahhh that's bullshit.

A simple "that's not true" would've done. But thanks for sharing your experience with us, veiled as it was in unnecessary attitude.

What is it about this board that brings out the worst in people? Jeez.

[joro]

Hi have a Nomad 55 and it has a bias switch for two different kinds of tubes....
I don't have it here...or I would tell you the numbers....
I do know that if you have it set wrong...you can fry your tubes.....

[Outlaws]

Originally Posted by joro

Hi have a Nomad 55 and it has a bias switch for two different kinds of tubes....
I don't have it here...or I would tell you the numbers....
I do know that if you have it set wrong...you can fry your tubes.....

Thats not the same thing. The biasing in this thread is for new tubes of the same type, but that are rated slightly different than the previous set.

[joro]

Originally Posted by Outlaws

Thats not the same thing. The biasing in this thread is for new tubes of the same type, but that are rated slightly different than the previous set.

ahh..
I see....

check out this article from Mesa on the Bias adjustment issue....
I think it may answer the question...

http://www.mesaboogie.com/US/Smith/biasadjust.html

[Light]

Mesa's ARE fixed bias, but that doesn't mean they are self-biasing (which is cathode biasing). Any amps with a bias pot, like most Marshalls and most Fenders, are fixed bias. All the fixed means is the bias voltage doesn't change depending on how you play. But you don't need a bias pot in a fixed bias amp. Randall Smith at Mesa decided he didn't want people messing with the bias on his amps, probably because he thought that most people are idiots and will fuck something up (and he's probably right). So, instead of a bias control, he put in bias resistors to set the bias permenently. In order for his amps to work properly, he tells people to only use Mesa tubes which are picked to work with Mesa amps. Adding a bias control is actually pretty easy, but should only be done by someone who knows what they are doing.

If you don't have a bias control on your fixed bias amp, you need to be very carful what tubes you put in it.


Light

"Cowards can never be moral."
M.K. Gandhi

[ggunn]

Originally Posted by Light

Randall Smith at Mesa decided he didn't want people messing with the bias on his amps, probably because he thought that most people are idiots and will fuck something up (and he's probably right). So, instead of a bias control, he put in bias resistors to set the bias permenently. In order for his amps to work properly, he tells people to only use Mesa tubes which are picked to work with Mesa amps.

Or maybe he wanted to make more money for Mesa by making everyone afraid to use anything but Mesa tubes in his amps. Cynical? Why, yes, I am... ;^)

[soundchaser59]

Originally Posted by Tadpui

A simple "that's not true" would've done.

Yes it would.....

Originally Posted by Tadpui

What is it about this board that brings out the worst in people? Jeez.

"This" board? I got news for ya....it aint just THIS board..... go over to Harmony Central and get banged up a few times, this place is fresh air compared to some of the others....

[ggunn]

Originally Posted by soundchaser59

"This" board? I got news for ya....it aint just THIS board..... go over to Harmony Central and get banged up a few times, this place is fresh air compared to some of the others....

Ain't it the truth. Folks on forums and (especially) Usenet hide behind anonymity and separation to say things to others which, if they said them in person, would earn them a bloody nose or worse. Kinda like they act in cars - no manners.

[punkin]

Originally Posted by GONZO-X

fixed bias, mine is...

it's a 1981 mark2b 60 watt head...

i've never put anything in it but mesa 6L6's....

but i'm curious to put some yellowjackets in it, to go with the el84, and see how this circuitry sounds with a completly different tube set...

but, i can't find any shorty yellowjackets... my head case is the small footprint one....

Give Ed at THD a call...he might be able to hook you up.

[Psyko]

I have Mesa/Boogie Mark IV Amp with fixed bias. It is 9 years old and always has unoriginal tubes in it.
Now I play on JJ tubes and all works perfectly. I don't believe that good other brand tube can damage your amp.

In instruction manual is written that I can put also EL34 or Fender 6V6 tubes in it. If this is not harmful to my Mesa... nothing isn't.

Conclusion: 6L6 means that tube has some sort of power characteristics and I don't believe in so much difference between tube brands.

[ermghoti]

Originally Posted by joro

ahh..
I see....

check out this article from Mesa on the Bias adjustment issue....
I think it may answer the question...

http://www.mesaboogie.com/US/Smith/biasadjust.html

A lot of self-congatulatory talk in there, and I like Boogies.

I wonder if he still has the Sylvanias lurking around? I had a pair in my MkII, and they sounded like a supermodel whispering dirty words into my ear.