Installing new tubes

SLuiCe

SLuiCe

New member
My local shops will take like a month to get it done, so I'm wondering what it would take to do it myself. Is it feasible, or even a good idea? What tools would I need for biasing? Would I need a degree in tubology? CAN'T WAIT A MONTH!

OK, I'm alright. I'm breathing....
 
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I've never changed tubes, so you should probably wait for someone else to respond... But it seems to me that all you do is take the old one out, line up the pins of the new tube and the socket, and push it into place. It helps to have the amp unplugged if you do this!
 
You can change the preamp tubes (the little 9pin ones) without worrying about bias. Unplug the amp, let it cool, pull the tubes with a gentle circular rocking motion. Do 'em one at a time. If it's a Marshall head or any amp with the sockets facing up you'll probably need to blow the dust out first. Don't want that stuff getting in the sockets. Make sure the pins are lined up coreectly when you install the replacements. Check 'em first to make sure none are bent. If they are carefully straighten them first.

It's the big output tubes that could need a bias adj. Not a task for a tube newbie. You don't want to go poking around under the chassis of a tube amp without knowing what you're doing. Large stored voltages in there that can give you a serious jolt or even kill.

You could get lucky on the bias issue. If it were me I would go ahead & install the new power tubes, then watch the amp carefully for an under-biased condition. If there isn't enough bias voltage, the large plates inside will start to glow. If this happens shut it off, you need an adj. to run those tubes. It could take as long as 30min for that to happen, so keep an eye on those tubes for a while.

If the amp sounds weak, and has an unpleasant distortion even at low volume it's over biased. This really won't hurt anything, but you probably won't dig the tone.

There are a few books out there that describe the bias process and what tools you'll need. "The Tube Amp Book" by Aspen Pittmamn is the one I have. Lots of good stuff in that one. Cool pics of old amps & guitars, schematics for tons of amps, care & feeding tips. Even has a section on vintage tube mics. Every tube amp owner should have a copy.
 
What kind of amp?
Also.....what the hell kind of shop would take a freakin' MONTH to change your tubes?

Some amps have fixed biasing so you can't change that anyway.

And even the amps where you can set the bias......it's only to get the last little tiny bit of performance........if the amp has been working right.....then just change the tubes abd screw the bias.
I went for many years not even knowing there was such a thing as bias and all my amps worked just fine.

So I'd change the crap out of them and get the bias set whenever you can.......M.BRANE is right though....biasing isn't something to do yourself unless you're a semi-competent electronics guy......although I'm pretty sure he has it backwards.....if the large plates glow that's too much bias.....but you should be setting it to a specific amperage rather than just looking at the tubes.
 
Thanks fellas.

M. Brane, that's good information man. Thanks. Obviously the biasing is my chief concern. But you've told me that I can at least give it a shot now, and if it needs biasing then maybe I'll have to wait a while for my amp. But it's a chance at least, to get right back to recording guitars. Ya know, I've been playing guitar since I was 13 (16 years) and I still know jack shit about gear. I think it's time to start focusing on that a little. I can't afford a guitar tech. :(

:) Cheers guys!
 
hahah funnny timing steve.

Yea, I guess both of the better stores here are booked right out. But I'm feeling encouraged by what you guys are telling me! Thanks man.
 
Change em on out, dont be scared.
Make sure your preamp tubes are all matched, and look on the web for some simple tutorials on biasing. There may be metal caps over your preamp tubes, those just twist and lock in place, may have a spring load on them too.
Wiggle them out.
Make sure its unplugged, of course.
Dont get in there messing with a screwdriver or anything, there are capacitors in that thing wioth enough stored juice to blow a hole out the back of your elbow.
Book a spot for having the amp biased, and in the meantime change the tubes yourself.
Why a month? damn, ridiculous for a 20 minute job.
 
I was just looking at Mesa's site at their tubes page. The best I could see on the page was a duet match, 5881 STR-425 (6L6 Russian). How would I go about getting 4 of them matched, if that is in fact necessary or recommended?
 
The fine Lt. has given you the motherlode of tube web pages. At the tubestore, you can get a matched quad. Just put 'em in and you'll be fine. Personal reccomendation is the Svetlana's or the Electro-harmonix 6L6. If you order two matched sets, they automatically send you a matched quad.
 
Hmm... I'm such a novice. I read the charts and reviews at that site, and the Svet's appear to be quite good. Do you guys think I should try them over the Mesa's?
 
Sure.....look, Mesa doesn't make tubes anyway and niether does Groove Tube......they just buy them, check and match them and stamp a Label on them. Hell, some of them might even be Svetlanas.
 
> Make sure your preamp tubes are all matched,

This serves no practical purpose whatsoever.

Neither does the recent fad for "balanced" PI tubes.

I would also not replace power tubes in a Marshall without biasing.
 
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