#2
You should bias it.

it isn't hard if you can use a screw driver and a multi-meter
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#3
Every time you change power tubes, it'll need rebiasing. Unless you use a brand that rebrands tubes with specific power ratings like Mesa boogie, then you set the bias for those tubes, and you won't need to bias it again so long as you use those tubes.

I always take that route because I'm lazy and have a ton of amps, but only if they're quality brands like JJs. Companies like Boogie and Ruby rebrand some SHITTY tubes, so you've gotta look for remnants of the previous label.
I'm always screwing with my rig. Muh chilluns:
Warmoth NRFR strat JB/Jazz
Mesa Boogie Royal Atlantic, Diezel 2x12
Turbo tuner, J Cantrell wah, Alesis 3630
Green Rhino, Wampler Velvet, Strymon ElCap/Lex, Phase 45
#4
This should help you a great deal. http://profile.ultimate-guitar.com/311ZOSOVHJH/blog/80083/
It basically got me from zero knowledge to confident at servicing my own amp, which is really how it should be, change your own car oil yada yada

But yeah be careful and all that... measured my plate voltage the other day after reading about vintage marshalls apparently having higher PV's etc, mine (reissue) was 493v, which will hurt you a bit!
#5
Quote by Guy_Mitchell
Every time you change power tubes, it'll need rebiasing. Unless you use a brand that rebrands tubes with specific power ratings like Mesa boogie, then you set the bias for those tubes, and you won't need to bias it again so long as you use those tubes.

I always take that route because I'm lazy and have a ton of amps, but only if they're quality brands like JJs. Companies like Boogie and Ruby rebrand some SHITTY tubes, so you've gotta look for remnants of the previous label.

Actually Mesa tubes tend to be very reliable, maybe not the best sounding, but deff reliable. The same goes for Ruby they are put through tests and the bad tubes are weeded out.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#6
What's in it EL34's or 6550's?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
Quote by Robbgnarly
Actually Mesa tubes tend to be very reliable, maybe not the best sounding, but deff reliable. The same goes for Ruby they are put through tests and the bad tubes are weeded out.


Where I live, a lot of the Boogie tubes I find are either EHX or Sovtek.

I can't remember what the website is, but there's some guy that will give you a great mix of preamp tubes depending on what amp you use. Like a mix of 12AX7 and 12AU7 or something similar to tame the fizz of the top end in a dual rec or reduce the noise of a 6505.
I'm always screwing with my rig. Muh chilluns:
Warmoth NRFR strat JB/Jazz
Mesa Boogie Royal Atlantic, Diezel 2x12
Turbo tuner, J Cantrell wah, Alesis 3630
Green Rhino, Wampler Velvet, Strymon ElCap/Lex, Phase 45
Last edited by Guy_Mitchell at Jun 4, 2014,
#9
Quote by juliusxxrock
EL34's
Dunno the brand, I've never opened it too take a look
And which JCM800?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#10
Quote by Cathbard
What's in it EL34's or 6550's?

I'm not being facetious, I'm actually curious, in this case why does it matter?
#11
Well, if it's a 2203 I can tell you a quick easy way to bias it without needing a bias probe right off the top of my head.. They came out with both 6550's and EL34's. I'm just trying to ascertain what you actually have so I can help you properly. I need details.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#12
Quote by Cathbard
Well, if it's a 2203 I can tell you a quick easy way to bias it without needing a bias probe right off the top of my head.. They came out with both 6550's and EL34's. I'm just trying to ascertain what you actually have so I can help you properly. I need details.

Hi, sorry for not responding.

I have a JCM 800 2204.
#13
Ok then. You can get the bias into the ballpark (ie safe) if you adjust the bias trimpot until you get -30V on the grid. (pin 5). If you go for EL34L tubes you can go a bit hotter, say -29V maybe even -28V. After you're done watch the tubes closely for redplating but you shouldn't get any. It's worth watching though just to be sure.
Now be very careful, you should probably wear gloves. You have to work on a live circuit containing close to 500V so be VERY ****ing careful. You have to remove the chassis and sit it on something like two stacks of books so you can turn it on with the tubes hanging free and not touching anything so you can get at the internals easily. Don't forget to plug the speaker back in before you start.
It is better to use a bias probe so you can accurately measure the plate current but if you have -30V on the grid you should get away with it.

JJ EL34L are a fantastic tube btw. Best way I can describe them is EL34 with the bottom end of a 6L6. That's what I'd be putting in there.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band