I posted a question the other day and it went unanswered. The question is does anyone play with GT 6l6S tubes ( I know that they are JJ's ) because I just bought 4 of them played some shows and by the end of the night the midrange was overpowering and they really sounded bad. Early in the night they sounded great. Does this sound like I may have got some bad tubes or is this how they should sound after getting hot. By the way I play a Boogie Mark I and it does not need to be biased, this is straight from 3 different people from Boogie.
6l6 Problems
- Thread starter rgreen11
- Start date
Re: 6l6 Problems
boogies are designed to run boogie tubes. the tubes that boogie sells are all in a certain range and the amps come biased at the optimum level for those tubes.
if you switch to different tubes the amp will probably need to be biased to sound its best. biasing a boogie is not an easy task as it requires either a bias pot be installed or at least a resistor be changed.
as tubes heat up they sound different, especially if they are biased hot
boogies are designed to run boogie tubes. the tubes that boogie sells are all in a certain range and the amps come biased at the optimum level for those tubes.
if you switch to different tubes the amp will probably need to be biased to sound its best. biasing a boogie is not an easy task as it requires either a bias pot be installed or at least a resistor be changed.
as tubes heat up they sound different, especially if they are biased hot
wixedmords
New member
Re: 6l6 Problems
Jeremy is 100% correct rgreen11.
Boogies are "fixed biased" meaning they have a bias circuit that needs to be set to a specific bias. This is the opposite of "cathode bias" which has a circuit that allows the bias to run within a range compensating for tube differences.
What Boogie wants to do is supply you cold biased tubes that will run within safe specifications inside their amps. Think HP and ink cartridges. If you buy other brand tubes you would need to make sure they are cold tubes and then I would check the bias to make sure they are within a safe range. If you added a bias pot as Jeremy said, you could adjust that bias.
My best guess is that the tubes are running too hot as their sound seems to change drastically throughout the night, as a cold bias is less likely to change the sound and should stay more static. If your tubes are running really hot you are taking some chances with your amp and at a minimum are reducing the tube life.
Jeremy is 100% correct rgreen11.
Boogies are "fixed biased" meaning they have a bias circuit that needs to be set to a specific bias. This is the opposite of "cathode bias" which has a circuit that allows the bias to run within a range compensating for tube differences.
What Boogie wants to do is supply you cold biased tubes that will run within safe specifications inside their amps. Think HP and ink cartridges. If you buy other brand tubes you would need to make sure they are cold tubes and then I would check the bias to make sure they are within a safe range. If you added a bias pot as Jeremy said, you could adjust that bias.
My best guess is that the tubes are running too hot as their sound seems to change drastically throughout the night, as a cold bias is less likely to change the sound and should stay more static. If your tubes are running really hot you are taking some chances with your amp and at a minimum are reducing the tube life.
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Sludgenutz
New member
Re: 6l6 Problems
Groove Tube sells tubes that are in-line with Mesa's tube "bias" concepts, as long as they are within the Groove Tubes' range 4/5/6:
http://forum.grailtone.com/viewtopic.php?t=3718
I hope this helps more than confuses.
Groove Tube sells tubes that are in-line with Mesa's tube "bias" concepts, as long as they are within the Groove Tubes' range 4/5/6:
http://forum.grailtone.com/viewtopic.php?t=3718
I hope this helps more than confuses.
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