#1
So I'm replacing EL34 tubes with 6L6GC tubes. I have a Peavey JSX, inside there is a switch labeled "Bias Select", with the options EL34 and 6L6GC (it's currently set to EL34). There's also some sort of know labeled "Bias Adjust". Will setting the switch it to 6L6GC be all I have to do, or is there anything else I need to worry about? All I know about bias is that if something is wrong with the bias something bad happens, so I need some help...
Last edited by __Pent__ at Jun 17, 2010,
#2
Well just switch it to the 6L6 setting and see how it sounds. Biasing the tubes higher makes the tubes run hotter, produces a somewhat better tone, and yields a shorter lifespan. Biasing the tubes below the factory number gives better life but sacrifices tone to a small, if barely noticeable extent. Especially with Peaveys, you might not even have to bias the tubes regardless of if it has a fixed bias or not. In my 5150II I have changed tubes dozens of times, but when I check the bias, the bias is always near the factory recommended number.
#3
the tubes will need to be biased, so that they work more efficiently and make the amp sound better overall
#4
Wow i didn't know that amp had that switch. But I would probably have it biased anyway. I suggest SED Winged C's 6L6 tubes they sound great.
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#5
Also, you may want to invest in some electrical cleaner to kinda clean out the sockets. Make sure your hands are clean before touching the tubes also. Grime on your hands could get on the tubes and once the tubes get hot, the grime or grease will start to fry (so to speak) and you may end up screwing up a tube.
#6
Quote by guitarmack1
Also, you may want to invest in some electrical cleaner to kinda clean out the sockets. Make sure your hands are clean before touching the tubes also. Grime on your hands could get on the tubes and once the tubes get hot, the grime or grease will start to fry (so to speak) and you may end up screwing up a tube.

To that end, I would recommend wearing thin latex gloves to avoid getting fingerprints and other junk on the tubes.
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#7
Quote by britishsligean
the tubes will need to be biased, so that they work more efficiently and make the amp sound better overall


ignore that

TUBES aren't what you bias

to continue…

i'd just use the switch and forget the re-bias (as someone else suggested) - the difference that the switch is making will affect all tubes equally. what it's doing is changing the resistance to match the labelled tubes (there's no need to go into too much detail about defining bias), the thing to consider is that different classes of tubes i.e. el34 compared to 6l6 are rated to perform "best" at different voltages. if you pop in 6l6 tubes with the switch in the "el34" position, the tubes will run WAY too hard/hot - if you run the 6l6's with the switch saying "6l6" then they should be well within specifications REGARDLESS of what tube batch you got (unless you have a rarer 6l6 that is meant to dissipate or run higher or lower)


trust me, you shouldn't need a re-bias, unless something is wrong with your amp or you want the tubes to be running "perfectly" in spec. (if that's the case, then you will have the amp 're-biased' EVERY time you change the tubes - which a lot of people would rather not do)

hope this helps
Last edited by infectedmusicac at Jun 17, 2010,