Mesa boogie 50/50

[Tom Phillips]

Pre-amp tubes don't require a bias adjustment if that's what you are asking.
Just use tubes that sound good to you.
Due to the high gain MB circuit you will need to use good tubes that are low in microphonics in the the front end of the pre-amp.

[Steve Conner]

Be that as it may, when the original bias voltage is altered far enough, it will compensate for the tube's abnormal performance and the correct amount of idle current flow may then be restored. Clearly this is something most repair techs should not attempt.

Surely Randall Smith meant to say "There's nothing better than an amp with permanently installed cathode resistors brought out to jacks on the chassis for plugging in a voltmeter, and a bias pot for each power tube with a wide range of adjustment too, so you can stick in any old tubes you found at a flea market and let them rip"

[stokes]

Yeah, he should have said a lot of things.Mostly he should have kept his mouth shut.I cant believe someone with his background would make some of the statements he made in that paper."Clearly this is something most repair techs should not attempt".That is absolutely absurd.This "paper" was obviously directed towards people who have no idea what goes on in their amps,and scare them into using his tubes and putting amp techs out of business.

[jak0lantern01]

In light of the statement everyone is complaining about, shouldn't there really be more issues with Mesa amps? I mean, is everyone really using THEIR tubes or throwing non-Mesa tubes without properly adjusting the bias? Something just doesn't add up here. Plus, there is the reality that two authorized Mesa techs told me don't bother with Mesa tubes, it's all about the name and that's it. As I stated earlier, the non-Mesa tubes they tossed in sound great and haven't yet experienced trouble. Since we're on the subject of tubes, I wanted to get an opinion on how many hours people run their tubes before replacing (Pre and power). I'm sure you're not all waiting for failures before swapping. I average anywhere from 6-8 hours a week at jam-level volumes (I have to hear over the drums and everyone else).

[stokes]

A lot of tube suppliers are selling tubes that are tested and graded to fit Mesa's bias range.GT has been doing it for years,in fact Mesa endorses the use of GT's.I have heard that Eurotubes and KCA are doing the same.I would have to think or at least hope the Mesa techs you mentioned are using tubes that fall into the peoper range,in which case you would be safe.I think you can attain better performance out of your tubes if you fine tune the bias.Even if I were inclined to use the Mesa system I would still have to check the bias to see where they were idling,which would just force me to tweak it anyway.

[steelhorse]

How would you bias a Boogie amp? I have a buddy who has one and he doesn't care for the tone and I suggested re-tubing and checking the bias then I remembered as a former MKIII owner I never did bias but I did always use MB tubes.

[kurtdaniel]

ive seen a thread about a Bias mod on a 50/50.. but its on another forum.. can i post the link here?

[Jazz P Bass]

Sure.
But start a new thread.

[kurtdaniel]

orayt!! tnx..

[kurtdaniel]

ive seen a thread about a Bias mod on a 50/50.. here it is.. The Boogie Board • View topic - Bias mod on a 50/50 : how to do.. this will surely improve our amps performance and how we are playing guitar..