#1
So I have an old (10 years or so) Peavey XXX 2x12 that needs re-tubed. The tone is flubby, flat as hell, and I'm getting wild noise on standby on/off and power off. This is no surprise, as I've never swapped tubes as of yet, and I bought it second hand.

So, I know I can go with EL34 or 6L6, and I'm pretty ok to to just go with EL34 again, which I believe are what came stock in the amp to begin with. I've also read that preamp tubes rarely need changed, but I don't know much about this, which is why I've come here. You guys have been helpful in the past, and frankly, I've read so many contradicting explanations presented as facts that I've got a headache.

So I'm hoping you all can help me cut through the BS and I can learn how often power tubes/preamp tubes need replaced with moderate use, and whether or not the amp is self biasing/fixed bias/will need biased. I've been digging for forty minutes and haven't come up with a solid answer yet.

Thanks in advance.

“We’re built of contradictions, all of us. It’s those opposing forces that give us strength, like an arch, each block pressing the next. Give me a man whose parts are all aligned in agreement and I’ll show you madness. We walk a narrow path, insanity to each side. A man without contradictions to balance him will soon veer off.”



silentfall.bandcamp.com
#2
The stock tubes in the XXX was 6L6 with the ability to run EL34 tubes.

Tubes can last years, or tubes can last minutes there is no set length of time.

If you want to go EL34 then JJ E34L are nice and so are the JJ KT77 (I used them in a bugera 333 which is a XXX clone)

JJ Ecc83 are a decent preamp tube and the Sovtek 12ax7LPS is a great PI tube.
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
Quote by Robbgnarly
The stock tubes in the XXX was 6L6 with the ability to run EL34 tubes.

Tubes can last years, or tubes can last minutes there is no set length of time.

If you want to go EL34 then JJ E34L are nice and so are the JJ KT77 (I used them in a bugera 333 which is a XXX clone)

JJ Ecc83 are a decent preamp tube and the Sovtek 12ax7LPS is a great PI tube.

+1

I'm going to back all of this up that Rob said and add a few things myself.

Yes, you should bias the amp. I suggest getting an external bias probe so you can plug it into a multimeter to get more accurate readings. I have a blog in my profile on how to do this if you are interested.

Also, wasn't the first run of XXXs 6L6 only? There was a small mod you had to do to run EL34s. Snip a grid resistor out or something. You'd have to research that further. If your amp has the 6L6/EL34 switch then your good.

I think JJ EL34Ls would be a good choice and JJ 12AX7 (ECC83) would be my choice too. Also consider a JAN 5751 NOS drop in replacement tube as well that works good in V1 and the PI.

I found a couple of good articles in this list:

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=biasing+a+Peavey+XXX

For bias probes you can use a cheap one like from Eurotubes or spend a bit more and get a better one from www.taweber.com
#4
Awesome, thanks to the both of your for the information.

“We’re built of contradictions, all of us. It’s those opposing forces that give us strength, like an arch, each block pressing the next. Give me a man whose parts are all aligned in agreement and I’ll show you madness. We walk a narrow path, insanity to each side. A man without contradictions to balance him will soon veer off.”



silentfall.bandcamp.com
#7
Quote by monwobobbo
Peavey amps are for the most part fixed bias so you don't need to do that.

That is not accurate. You do need to bias the amp. The amp actually has test points and bias knob right on it I believe. The problem with the XXX, like most Peavey amps, is that the test points cannot be trusted and knob does little.

Now. If you bought a matched set of tubes with the MilliAmp range designated by Peavey for that plate voltage would it work fine? Maybe.

I suggest getting a bias probe and doing it correctly. Your tubes will last longer and your amp and ears will thank you. 60-70% plate dissipation from the tubes is probably ideal but also may be a bit on the cool side. You want the bias up just to the point of cross-over distortion but not over that point.

The whole 'Fixed' bias thing is confusing though I'll give you that. The industry has not helped either.

Fixed Bias = means the amp needs to be manually biased. It is adjustable. By you the consumer*

Non-Adjustable Fixed Bias = means that not only do you not need to bias the amp but you actually cannot unless you modify the amp to do so.


Many Peavey amps and Marshall type amps are fixed bias.

Many Mesa amps and the Peavey Valveking are non-adjustable fixed bias.

(Think of fixed as meaning it has a fixed range you need to be in based on the plate voltage.)


*Opening up an amp can be dangerous to your health. Read up on the dangers so you can safely navigate around the insides and never touch things with your bare hands or while the amp is on.


Edit: first couple of links on here from places like Peavy, Eurotubes, Ultimate-Guitar will help:
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=Is+the+Peavey+XXX+fixed+bias%3F
Last edited by 311ZOSOVHJH at Dec 14, 2015,
#8
i just picked up and retubed a JSX. i realize that they are somewhat different, but the biggest difference was a 12AT7 or 5751 in the PI.

i would try a new production mullard, will do you well in one of the preamp. move it around where you like it.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#10
Quote by 311ZOSOVHJH
Just keep in mind that new production Mullards are nothing like the old Mullards. I still say a JJ 12ax7 and JAN 5751 is what I'd buy for preamp tubes.


I tried all jjs in it, but I preferred the Mullard in the one of the spots.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#11
Quote by 311ZOSOVHJH
That is not accurate. You do need to bias the amp. The amp actually has test points and bias knob right on it I believe. The problem with the XXX, like most Peavey amps, is that the test points cannot be trusted and knob does little.

Now. If you bought a matched set of tubes with the MilliAmp range designated by Peavey for that plate voltage would it work fine? Maybe.

I suggest getting a bias probe and doing it correctly. Your tubes will last longer and your amp and ears will thank you. 60-70% plate dissipation from the tubes is probably ideal but also may be a bit on the cool side. You want the bias up just to the point of cross-over distortion but not over that point.

The whole 'Fixed' bias thing is confusing though I'll give you that. The industry has not helped either.

Fixed Bias = means the amp needs to be manually biased. It is adjustable. By you the consumer*

Non-Adjustable Fixed Bias = means that not only do you not need to bias the amp but you actually cannot unless you modify the amp to do so.


Many Peavey amps and Marshall type amps are fixed bias.

Many Mesa amps and the Peavey Valveking are non-adjustable fixed bias.

(Think of fixed as meaning it has a fixed range you need to be in based on the plate voltage.)


*Opening up an amp can be dangerous to your health. Read up on the dangers so you can safely navigate around the insides and never touch things with your bare hands or while the amp is on.


Edit: first couple of links on here from places like Peavy, Eurotubes, Ultimate-Guitar will help:
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=Is+the+Peavey+XXX+fixed+bias%3F

Thank you 1 million times over for the info - I learned a lot and it cleared many things up for me.

“We’re built of contradictions, all of us. It’s those opposing forces that give us strength, like an arch, each block pressing the next. Give me a man whose parts are all aligned in agreement and I’ll show you madness. We walk a narrow path, insanity to each side. A man without contradictions to balance him will soon veer off.”



silentfall.bandcamp.com