#1
hey everyone. so i recently got a blue voodoo and i haven't given it a retube yet.
i was wondering what would you do first? preamp or poweramp change.

the whole amp is loaded with groove tubes. im planning on taking the amp in for a tech to do the power amp tubes. but the preamp tubes i can do. the power amp tubes light up just fine and all is well so far. i plan on doing the power amp tubes within a month or 2.

i know they dont die very often but i have just been wanting to test out a new set of preamp tubes to see what sounds i get.

i have been looking at jj ecc83-s and electro harmonix 12ax7eh.

is it worth the 40ish bucks to get new preamp tubes?
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#2
new preamp tubes made a world of difference in my amp. Removed 99.99% of the fizz from the gain and smoothed things out. I would say preamps first.

EDIT: and they were the JJ's. I tried the two EH's I had lying around with one of the new JJ's, as all I had were two spare EH's and the sound was a little harsh/fizzy for my taste, the JJ's were smoother and nicer sounding to my ears.
Last edited by Chad11491 at Apr 14, 2011,
#3
Yes it's worth it. How old are the power amp tubes? If 6 months or more change them.
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#4
Quote by rawkandrowl
Yes it's worth it. How old are the power amp tubes? If 6 months or more change them.

6 months? I usually change mine every year, and that's with heavy gigging. 6 months seems a little too soon. It would probably explain why my amp has been sounding a bit lifeless lately though .
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#5
im really not sure how old any of the tubes are. i was gonna replace all of them and start with a clean slate. i was also planning on keeping them all and just putting them aside as back ups to the back ups lol.

im most likely gonna go with JJ's i was looking at some tung sol preamp tubes but they are a bit more expensive than the jj's.

so far the judgment is go for it? sounds like a plan. thanks guys
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Last edited by iheartgun at Apr 14, 2011,
#6
When your power valves blow it can damage other parts of the amp. When preamp valves die it doesn't usually cause any real damage. For this reason alone, I'd say it's most importat to keep your power valves fresh.
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#7
the power tubes are going to be replaced within the next 2 months or sooner. for now they are fine. nothing out of the ordinary here! knock on wood.

i personally cant wait to get those replaced.
any recommendations? i have been looking around on tube depot all day.
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#9
There's no reason you have to use all one brand. Figure out what kind of preamp structure your amp uses and you can mix and match based on desired outcome. I use a combination of Tung Sol, JJ, and Shuguang tubes in my Mark IV. When I retube again, I might just go all Tung Sols or try some Electro Harmonix tubes.

For power tubes, I'm currently running Ruby -- they're a little sweeter on cleans than the stock Boogie tubes. I think I'm going to go with some Winged =C= 6L6s next, perhaps mixed with Svetlana EL34s. Winged =C= tubes have a reputation for being good in higher gain applications.
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#10
I'm not sure if I follow you there . What do u mean preamp structure ?
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#11
I think he mean what tubes do what. Some are gain structures, some are reverb driver, phase inverter and so on. Certain tubes do certain things better than others.

For example, Sovtek 12ax7lps makes good phase inverter. Tung-Sols are good for gain and tone.
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#12
I spend a bit of time selecting the right valve for each position in my main amp (the Abbey). Granted, I am spoiled and have a bit of a collection of NOS 12AX7 valves, but it demonstrates that you choose what's best, you don't try to match brands/types.
If you really want to get the most out of your amp I strongly suggest hunting down NOS valves for the preamp. You can take your time about it and just replace one or two at a time. Hunting down that valve you want on Ebay can get a bit addictive I have to admit - but I do have some nice valves in my amps and lots of nice spares.
You can still score JAN Phillips 12AX7's for around $25 and they are a great valve and well worth that money. They'll outlast a modern valve by about 5X or more and sound better doing it.
As for the power valves. JJ are a good choice. SED =C= are very good but cost a bit more. I have NOS Brimar 6L6's myself but I scored them for a crazy cheap price during my Ebay stalking period.

Groovetubes can be anything. You have to look at the end of the part number. If it ends in a C it's Chinese (Shuguang), S it's Slovakia (JJ), R is Russian (Sovtek).
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#13
Quote by iheartgun
I'm not sure if I follow you there . What do u mean preamp structure ?

Some amps use one or two preamp tubes per channel, and those tubes are dedicated, so when you select that particular channel, you're hearing one (or two) specific preamp tubes. Some use a "cascading" system where more tubes are added as you add more preamp distortion, so the tubes aren't isolated from one another, per se. And then there's the matter of phase inverters and reverb, of course.
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#14
thanks for explaining that to me guys. that helps alot.
i guess its time to start the research.
the manual for the blue voodoo only says 4 12ax7's so that doesnt help at all. even the schematics that come with it say that so off to google i go.

i have already been searching ebay for a couple days and i can see how it gets addicting.
from trying different tube amps and doing a good amount of reading. and having my local "tech" charge 20 bucks per power tube i will not put those in my amp again.
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#15
Quote by stratman_13
6 months? I usually change mine every year, and that's with heavy gigging. 6 months seems a little too soon. It would probably explain why my amp has been sounding a bit lifeless lately though .


Every year, are you mad? I change mine every 3 years, and I gig 2 times a week running my amp well over 2 hours each time, that's not including how often I record or practice.

I would change the preamp tubes first, then power tube. Your tube choices are ok, but you can do better for the same amount of money.
Last edited by ethan_hanus at Apr 15, 2011,
#16
so i have been searching through google and i cant find a thing about the preamp stages or anything remotely close. also there is talk of a phase inverter....... what in the heck is that?

some people say replace it with a 12ax7 some say 12at7
wtf?
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#17
Quote by iheartgun
so i have been searching through google and i cant find a thing about the preamp stages or anything remotely close. also there is talk of a phase inverter....... what in the heck is that?

some people say replace it with a 12ax7 some say 12at7
wtf?



Phase inverter, lets see if I can explain it right, a phase inverter takes your signal, and hits it with a out of phase signal to do something to it, and it's supposed to make everything sound smoother. You usually want like a Long plate tube in the phase inverter position because it works the hardest.

I like the Sovtek LPS 12AX7 in a phase inverter position, seems to work rather well.


I'm no amp expert, so take what I say with a grain of salt.
#18
im not too sure which one is the phase inverter just so i know. doesn't it go

v1:closest to guitar input
v2
v3
v4: farthest away from input?

so which one is the phase inverter? it sounds important and if i swap out the tubes id like to know which one it is so i can mark it and replace it if i dont like the sound.

oh and by the way. thanks alot to everyone who has responded you guys have been really helpful on this.
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#19
Quote by iheartgun
im not too sure which one is the phase inverter just so i know. doesn't it go

v1:closest to guitar input
v2
v3
v4: farthest away from input?

so which one is the phase inverter? it sounds important and if i swap out the tubes id like to know which one it is so i can mark it and replace it if i dont like the sound.

oh and by the way. thanks alot to everyone who has responded you guys have been really helpful on this.


Where it is in relation to the input does not always mean it's what you think, you have to get a wiring diagram to see what is what, but usually the phase inverter is the very last tube in the chain.
#20
oh gotcha. im gonna go look at the diagrams i have.

essentially if all the tubes are 12ax7 groove tubes and i replace them all with jj's or mix and match everything should be peachy? regardless of which one is the phase inverter?
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#21
Quote by iheartgun
oh gotcha. im gonna go look at the diagrams i have.

essentially if all the tubes are 12ax7 groove tubes and i replace them all with jj's or mix and match everything should be peachy? regardless of which one is the phase inverter?


Yeah, it'll all work fine, what everyone is just saying is that certain brands of tubes in certain spots can make it sound better or worse, but throwing all of the same new tubes in the wont hurt it or make it sound bad per say, but you can actually mold your tone better if you pick and choose what you put in.
#22
this is gonna be fun. im gonna mess around with this quite a bit when my tubes get here.
thanks for all the help.
my wife is gonna hate me. hahahah
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#23
First of all there's high voltage present in the amp so don't touch the sockets with your fingers nor the pins while plugging in. the 12ax7s will have a pin missing and that's your guide, match it to the socket.

Ok, the 12ax7 that's next to the power tubes are usually the phase inverter (V4). This tube is what drives your power tube so you choose a tube for that purpose. It'll work better if you choose a tube with a matched set. The 12ax7 is really two triodes in one making it a pentode. A sovtek 12ax7lps with matched set is ideal for the PI.

The V1 determines the tone as it's a start of the signal chain and amplified thereafter so choosing a 12ax7 with musical properties will enhance the tone. V2 and V3 may be gain tubes also for channels (if any) and/or FX drivers.
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#24
Try to get a balanced 12AX7 for the phase inverter.
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#25
im pretty sure for right now ill be leaving the phase inverter alone till i get the right tube.
the other 3 are gonna get messed with

i was looking on thetubestore.com and they are saying something about mached preamp tubes.

would a matched tung-sol 12ax7 work well as a phase inverter?
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Last edited by iheartgun at Apr 15, 2011,