#1
hi,

basically my amplifier hasnt got as much gain as id have hoped for.

ive been doing a bit of research but most of it is rather confusing for me, however, it sounds like as long as you keep with the same type of tube it is a cheap way to change the sound of your amp.

my amp has:
x2: 12ax7
x2: el84

now this is where i get confused, which tubes are the preamp and which are the power.

also, can someone explain what the difference is betweenthe two?

thanks in advance
#2
i have a vibro champ with a 12ax7 and a preamp gain tube. im pretty shure the 12ax7 is the main tube while the other is for your preamp. im having same problem as you. i wont more of a hard rock edge in my sounf but my amp is either to clean. ( which i like alot) or to distorted or heavy metelish
Last edited by travs2448 at Feb 22, 2009,
#3
12AX7 - preamp
EL84 - power amp

The power amp tubes have a much larger influence on tone than the preamp ones. 98% of all tube amps will have 12AX7 preamp tubes anyway.
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#4
ah..right...so are the power tubes in the silver case or not?

and can someone recoment any good high gain power tubes.

are the EL84 from electro harmonix any good?
#5
so basically to try and get more gain out of an amp, someone should look at changing the power amp tubes versus the pre-amp tubes?
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#6
Changing the power amp tubes won't necessarily give you more gain, definitely not a lot more. The only way to drastically change your tone by switching power amp tubes is by switching the type that you use. You have EL84s, which are famously used in Marshalls. They help give the mid-range crunch Marshalls are famous for. Mesa/Boogie uses 6L6 power amp tubes, which add a deep and warm quality to the amps.

You want more gain. Don't switch tubes.

You can either buy an overdrive pedal (or distortion if you want) or cut your losses and admit you bought the wrong amp for you.
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#7
btw...whilst im on the subject,
one of my power tubes (i prosume those are the ones NOT in a silver case) doesnt glow as much as the other.

now ive had the case of my amp off and had a look at them and it looks to me like the filament (or whatever) is sitting slightly lower in one tube than the other so this, i prosume, is whats making it appear to glow less.

does this mean the tube is faulty?.....my amp sounds alright but its my first valve amp and im not sure if its supposed to sound any different to what it does.

would there be some sort of iregular noise if something was wrong?
#8
Get a pair of JJ 12AX7s and a pair of JJ EL84s. Can't go wrong.

Don't worry about the filament thing...most tubes vary + or - 20% of a certain value...that's a lot of variation.

If you want more gain, try JJ ECC803s, they're similar to a 12AX7 (ECC83) but with a bit more gain.

http://www.tubedepot.com/jj-ecc83.html
http://www.tubedepot.com/jj-ecc803s.html
http://www.tubedepot.com/jj-el84.html
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#9
You can try replacing the 12ax7 tubes with 12bz7. They don't have the exact same ratings but I have heard of many people doing it with quite a lot of success.
#10
JJ's are for sure a better bet.
The power tubes are the bigger ones. They're also the ones labled "EL34" if you wanna be a jerk about it. DO NOT change them with 6L6 tubes. That would ruin your amp unless you get it rebiased.
If the amp only has 2 EL34s than it can't be much more than 50 watts, right? Just crank it!

What kind of amp is it?

Travs, there is no way you will get a good gain sound out of a Vibro Champ. Thats not what its made for.
#11
Quote by inkandlead
JJ's are for sure a better bet.
The power tubes are the bigger ones. They're also the ones labled "EL34" if you wanna be a jerk about it. DO NOT change them with 6L6 tubes. That would ruin your amp unless you get it rebiased.
If the amp only has 2 EL34s than it can't be much more than 50 watts, right? Just crank it!

What kind of amp is it?

Travs, there is no way you will get a good gain sound out of a Vibro Champ. Thats not what its made for.


He's got 84s, not 34s...different base and whatnot, no way to fit a 6L6 in there.

Also, you need to do more than a rebias if switching from EL34s to 6L6s...the pin arrangement on the base is a tad different.
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#12
Quote by DLrocket89
He's got 84s, not 34s...different base and whatnot, no way to fit a 6L6 in there.

Also, you need to do more than a rebias if switching from EL34s to 6L6s...the pin arrangement on the base is a tad different.

Aha. So he does. I'm not an amp guy. Just a guy who thinks he knows everything. Ha.
#13
Quote by inkandlead
Aha. So he does. I'm not an amp guy. Just a guy who thinks he knows everything. Ha.


I'm worse, an amp guy who think he knows everything.

Oh well.
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#14
ok....so going on what you've all said im considering on buying a pair of JJ Tesla EL84's.

do i need to buy a pair of JJ Tesla 12AX7's awell or can i just stick with the 12AX7's ive already got?

does anyone know if the JJ Tesla EL84's have a good distortion sound?...ive been looking at reviews and most people are rating it nearly 10/10....but they just say 'it sounds great'
#15
Quote by Doodleface
12AX7 - preamp
EL84 - power amp

The power amp tubes have a much larger influence on tone than the preamp ones. 98% of all tube amps will have 12AX7 preamp tubes anyway.



Actually, you're wrong. The tone stack is in the preamp. This is where your signal is shaped. Your preamp has a much larger influence on tone than your preamp. Especially for high gain.
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#16
If you want more gain swapping tubes is probably NOT the way to go. High gain tubes have more gain, but can be quite noisy.

What kind of amp do you have exactly?
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#17
Quote by inkandlead

If the amp only has 2 EL34s than it can't be much more than 50 watts, right? Just crank it!

So not true....


Travs, there is no way you will get a good gain sound out of a Vibro Champ. Thats not what its made for.

Wrong. Why do people think that Fenders are not supposed to be overdriven?
Last edited by al112987 at Feb 22, 2009,
#18
Quote by Doodleface
Changing the power amp tubes won't necessarily give you more gain, definitely not a lot more. The only way to drastically change your tone by switching power amp tubes is by switching the type that you use. You have EL84s, which are famously used in Marshalls. They help give the mid-range crunch Marshalls are famous for. Mesa/Boogie uses 6L6 power amp tubes, which add a deep and warm quality to the amps.

You want more gain. Don't switch tubes.

You can either buy an overdrive pedal (or distortion if you want) or cut your losses and admit you bought the wrong amp for you.


EL34's are famously used in Marshalls, EL84's are what Vox's are known for. I agree though, get an overdrive. It will probably be less than a tube swap anyways, and will have better results. Check out the DigiTech Bad Monkey for only $50.

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#19
Quote by Kevin Saale
If you want more gain swapping tubes is probably NOT the way to go. High gain tubes have more gain, but can be quite noisy.

What kind of amp do you have exactly?

+1