#1
I own a Music Man RD50. It's a two channel amp, one clean, one overdrive. Solid state preamp with 12ax7 driver, and 2-6L6 tubes in power amp.

I read on harmony central that you can change the sound of the amp buy changing this driver: http://reviews.harmony-central.com/reviews/Guitar+Amp/product/Music+Man/RD+Fifty/10/1
Thanks to the 12ax7 driver tube, you can get a whole lot of different amp sounds from the amp, just by changing that tube with another. For a more metal sound, use the 12ax7wa, for a more full fidelity sound, use the 12ax7wb, for a harsh all mids rock and roll sound, use the 12ax7wxt. Depending on the tube, it has quite a bit of preamp gain...

This sounds wrong to me but I'm not tube expert. So what does this 12ax7 driver do, and can it really change the sound of my amp?
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#2
i think it's the preamp tube in your amp

Whodicted



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#3
I dunno what it does, but the poster above me is wrong.

My Peavey XXX has 3 preamp tubes, and 2 powertubes which are driven by a 12AX7


?????
Quote by It'sForTheBest
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Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#4
all that's left then is the recitfier tube

Whodicted



Quote by stevo_epi_SG_wo
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#5
Quote by hendriko
all that's left then is the recitfier tube


No, it is probably the reverb tube.
#6
So basically by changing they reverb tube its supposed to change they way my amp sounds?
I don't buy it.
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#7
Quote by FrenchBread
So basically by changing they reverb tube its supposed to change they way my amp sounds?
I don't buy it.


Are there any other effects on the amp? Tremolo, etc?
#8
Mine doesnt have any effects, just a spring reverb.
Quote by It'sForTheBest
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Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#10
Quote by greenbox
http://www.schematicheaven.com/newamps/musicman_rd50a.pdf
http://www.schematicheaven.com/newamps/musicman_rd50b.pdf

The reverb is solid state. It the tube handles the distortion channel. If you're running pure clean, then changing the tube isn't going to change anything.

So your saying that's the over drive tube, now it makes sense.

So how drastically will it change my distortion?
And do these tubes need to be changed like regular tubes do?
Quote by mr_hankey
Are there any other effects on the amp? Tremolo, etc?

No, only reverb and distortion.
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
Last edited by FrenchBread at Mar 4, 2007,
#11
Tubes are cheap, and there is only one way to find out how much it'll change it .


There are people around these parts that say changing the tube in their Vox Valvetronixes made it sound a lot better.


Might as well give it a shot if you aren't happy with your tone.
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Quote by utsapp89
^I'd let a pro look at it. Once you get into the technicalities of screws...well, it's just a place you don't want to be, friend.
#12
Quote by FacingUsAll
Tubes are cheap, and there is only one way to find out how much it'll change it .


There are people around these parts that say changing the tube in their Vox Valvetronixes made it sound a lot better.


Might as well give it a shot if you aren't happy with your tone.


Yea, I was actually thinking about buying a bunch of 12ax7 drivers and switching em up to see what sounds best. Its really an amp that sounds best on clean [seeing as its basically a fender], but I'm not a clean player. And though I normally use my processor, from what I gather at UG I could get better tone if it came from a good tube than any processor.

I could possibly buy a Mesa tube... lol then it would be quite the 'mutt' of an amp.

EDIT: If I do swap, I'll definitely post back to let you all know how much a difference it made, and how they are different.
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#13
Quote by FrenchBread
I own a Music Man RD50. It's a two channel amp, one clean, one overdrive. Solid state preamp with 12ax7 driver, and 2-6L6 tubes in power amp.

I read on harmony central that you can change the sound of the amp buy changing this driver: http://reviews.harmony-central.com/reviews/Guitar+Amp/product/Music+Man/RD+Fifty/10/1
Thanks to the 12ax7 driver tube, you can get a whole lot of different amp sounds from the amp, just by changing that tube with another. For a more metal sound, use the 12ax7wa, for a more full fidelity sound, use the 12ax7wb, for a harsh all mids rock and roll sound, use the 12ax7wxt. Depending on the tube, it has quite a bit of preamp gain...

This sounds wrong to me but I'm not tube expert. So what does this 12ax7 driver do, and can it really change the sound of my amp?


That 12AX7 acts as a driver for the power tubes. People change them because they can, not because it makes a huge difference. There is a difference, but not enough that you'd do anything more than just find one you like and use it. Just put a good tube in that hole and play.

Great classic amp.
#14
12AX7's are the preamp tubes. The preamp tubes are what shapes your tone. The 6L6's are the power amp tubes.
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#15
Quote by jerm__
12AX7's are the preamp tubes. The preamp tubes are what shapes your tone. The 6L6's are the power amp tubes.

I thought it was the gain for the power amp tubes.
Now I'm getting conflicting answers.

Anyway, I'm thinking about replacing it anyway because the 6L6's were orignal [like at least 1980's] before I replaced them, so I guess it wouldn't hurt right?

And will any 12ax7 driver work or are the certant kinds [like that match the voltage/wattage of the amp?]
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#16
Nope. 12ax7s are 12ax7s no matter what. They dont need biasing either.
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#17
Is the Peavey XXX 40 watt combo self biasing?

There is a switch that you have to select either 6L6 or EL34 power tubes, but I dunno if its self biasing or not
Quote by It'sForTheBest
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Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#18
Quote by FrenchBread
I thought it was the gain for the power amp tubes.
Now I'm getting conflicting answers.

Anyway, I'm thinking about replacing it anyway because the 6L6's were orignal [like at least 1980's] before I replaced them, so I guess it wouldn't hurt right?

And will any 12ax7 driver work or are the certant kinds [like that match the voltage/wattage of the amp?]


The 12AX7 is a twin triode, that means it is basically two tubes in one bottle. In this amp, one of those tubes is used as the final gain stage, this is the last preamp section before the master volume control. The other half of the 12AX7 is a phase inverter - that's where the signal goes after the master volume and before it hits the power tubes. Your amp with a pair of power tubes that work in what is called push- pull - the output of one tube goes low while the output of the other goes high. For that to happen they have to get a signal that is out of phase from the other - this half of the 12AX7 is used to do that and is called a phase inverter. Since it is the last component to push the power tubes it is also called a driver. Anyway, you were right, half of this tube provides gain for the power tubes, the other half splits the phase for them. Here's the schematic for anyone who wants: http://www.ernieball.com/mmonline/techinfo/old_amps/2100-65.pdf

Anyway, this tube has a harder life than your average preamp tube. It's standard practice to also replace the driver if a power tube blew or had a problem. And it used to always be recommended for routine tube replacements to do the driver at the same time as the power tubes. Some of the old stock tubes in amps like that Musicman were so excellent and there have been so many crappy modern tubes that people often waited until there was a problem before replacing that driver.

You might want to try replacing it and seeing if it does sound better. Tubes don't cost that much and it'll be good thing if you have a spare. Nothing special about that tube, you can use most any brand (though I still prefer to avoid Chinese stuff) out there. I've gotten good results with the 12AX7EH, great all around tube and reasonably priced.

Have fun with it, that's a great amp you got there.
#19
When the amp specs say

3 Preamp 12AX7

2 Power Tubes 6L6 driven by 12Ax7

does that mean there are a total of four preamp tubes or three? Ive looked and only have seen 3.
Quote by It'sForTheBest
Those cameras are really cool. I'm watching a parking lot right now.



Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#20
Quote by Ronsonic
The 12AX7 is a twin triode, that means it is basically two tubes in one bottle. In this amp, one of those tubes is used as the final gain stage, this is the last preamp section before the master volume control. The other half of the 12AX7 is a phase inverter - that's where the signal goes after the master volume and before it hits the power tubes. Your amp with a pair of power tubes that work in what is called push- pull - the output of one tube goes low while the output of the other goes high. For that to happen they have to get a signal that is out of phase from the other - this half of the 12AX7 is used to do that and is called a phase inverter. Since it is the last component to push the power tubes it is also called a driver. Anyway, you were right, half of this tube provides gain for the power tubes, the other half splits the phase for them. Here's the schematic for anyone who wants: http://www.ernieball.com/mmonline/techinfo/old_amps/2100-65.pdf

Anyway, this tube has a harder life than your average preamp tube. It's standard practice to also replace the driver if a power tube blew or had a problem. And it used to always be recommended for routine tube replacements to do the driver at the same time as the power tubes. Some of the old stock tubes in amps like that Musicman were so excellent and there have been so many crappy modern tubes that people often waited until there was a problem before replacing that driver.

You might want to try replacing it and seeing if it does sound better. Tubes don't cost that much and it'll be good thing if you have a spare. Nothing special about that tube, you can use most any brand (though I still prefer to avoid Chinese stuff) out there. I've gotten good results with the 12AX7EH, great all around tube and reasonably priced.

Have fun with it, that's a great amp you got there.


First off, thanks for taking the time to respond with an in depth answer, thats why I love UG.

So how much do you think it will change my tone?

[ac/zeppelin/dc i'm not ignoring you, but I obviously don't know about this stuff]
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#21
haha...apparently no body does
Quote by It'sForTheBest
Those cameras are really cool. I'm watching a parking lot right now.



Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#22
Quote by AC/zeppelin/DC
When the amp specs say

3 Preamp 12AX7

2 Power Tubes 6L6 driven by 12Ax7

does that mean there are a total of four preamp tubes or three? Ive looked and only have seen 3.

There's only 3.

It might not change them a whole lot. Different tubes will give you different gain and a slightly different tone. It won't make your amp sound like a completely different one, but it should have some effect.

You should be going for more power amp distortion anyway. If you want more gain, go with a tube with more gain. It only has one tube so it wouldn't be too bad to buy three or four different types and try them out. I have to buy 4 new preamp tubes just to replace one set, you only need to buy one!
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#23
So one of the three 12AX7s drive the power tubes.

How do I tell which one it is? They are all labelled the same on the chassis.
Quote by It'sForTheBest
Those cameras are really cool. I'm watching a parking lot right now.



Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#24
Quote by andrew7667
There's only 3.

It might not change them a whole lot. Different tubes will give you different gain and a slightly different tone. It won't make your amp sound like a completely different one, but it should have some effect.

You should be going for more power amp distortion anyway. If you want more gain, go with a tube with more gain. It only has one tube so it wouldn't be too bad to buy three or four different types and try them out. I have to buy 4 new preamp tubes just to replace one set, you only need to buy one!


I wonder if I bought a mesa 12ax7, if the distortion would be mesa-like. Considering I'm basically going from a Fender driven distortion to a Mesa driven distortion, that's pretty opposite. I realize it won't sound completely different, but I'd expect the gain to at least sound different in some ways.

I have 3 more questions:
1. Any other brands I should check out?

2. And earlier someone recommended a 12AX7EH. Well mesa just says its a 12ax7 so if i bought a Marshall 12ax7, that could also be an EH so it could produce almost identical results as the Mesa 12ax7. So what I'm getting at is, is there some kind of marking on the tube that will tell me the exact version?

3. Where is a good place to buy tubes, I was just gonna buy from www.mesaboogie.com , but if there is one place I can get a bunch of different tubes it would save time and $$.

EDIT: I take it that means I can't use a 12AT7, because I'm guessing though they have the same function they aren't built with the same specs?
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
Last edited by FrenchBread at Mar 5, 2007,
#25
Quote by AC/zeppelin/DC
When the amp specs say

3 Preamp 12AX7

2 Power Tubes 6L6 driven by 12Ax7

does that mean there are a total of four preamp tubes or three? Ive looked and only have seen 3.


Yeah, three 12AX7s. Inside each glass bottle are two sets of tube elements. If you look on a schematic you'll see six tubes drawn.
#26
Quote by FrenchBread
First off, thanks for taking the time to respond with an in depth answer, thats why I love UG.

So how much do you think it will change my tone?

[ac/zeppelin/dc i'm not ignoring you, but I obviously don't know about this stuff]


Depends. Probably not a lot, but it might be a very worthwhile change. Especially if your tube's worn.
#27
Quote by Ronsonic
The 12AX7 is a twin triode, that means it is basically two tubes in one bottle. In this amp, one of those tubes is used as the final gain stage, this is the last preamp section before the master volume control. The other half of the 12AX7 is a phase inverter - that's where the signal goes after the master volume and before it hits the power tubes. Your amp with a pair of power tubes that work in what is called push- pull - the output of one tube goes low while the output of the other goes high. For that to happen they have to get a signal that is out of phase from the other - this half of the 12AX7 is used to do that and is called a phase inverter. Since it is the last component to push the power tubes it is also called a driver. Anyway, you were right, half of this tube provides gain for the power tubes, the other half splits the phase for them. Here's the schematic for anyone who wants: http://www.ernieball.com/mmonline/techinfo/old_amps/2100-65.pdf

Good stuff but... i don't think that's his amp...

http://www.schematicheaven.com/newamps/musicman_rd50a.pdf
http://www.schematicheaven.com/newamps/musicman_rd50b.pdf

that looks more like it... I could be wrong though. But it looks like the 12ax7 is purely used for the gain/overdrive in the overdrive section preamp. But i didn't review the schematic that carefully anyway.
Last edited by greenbox at Mar 6, 2007,
#28
Quote by FrenchBread
I wonder if I bought a mesa 12ax7, if the distortion would be mesa-like. Considering I'm basically going from a Fender driven distortion to a Mesa driven distortion, that's pretty opposite. I realize it won't sound completely different, but I'd expect the gain to at least sound different in some ways.

I have 3 more questions:
1. Any other brands I should check out?

2. And earlier someone recommended a 12AX7EH. Well mesa just says its a 12ax7 so if i bought a Marshall 12ax7, that could also be an EH so it could produce almost identical results as the Mesa 12ax7. So what I'm getting at is, is there some kind of marking on the tube that will tell me the exact version?

3. Where is a good place to buy tubes, I was just gonna buy from www.mesaboogie.com , but if there is one place I can get a bunch of different tubes it would save time and $$.

EDIT: I take it that means I can't use a 12AT7, because I'm guessing though they have the same function they aren't built with the same specs?



mesa tubes won't give you mesa tone. mesa doesn't make they're own tubes, i believe they just print MESA on ruby tubes. go to the tubestore.com and talk to doug or eurotubes and talk to bob to find some good tubes.
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#29
Quote by greenbox
Good stuff but... i don't think that's his amp...

http://www.schematicheaven.com/newa...icman_rd50a.pdf
http://www.schematicheaven.com/newa...icman_rd50b.pdf

that looks more like it... I could be wrong though. But it looks like the 12ax7 is purely used for the gain/overdrive in the overdrive section preamp. But i didn't review the schematic that carefully anyway.


Whoa, that is a different animal. In that design, the tube is used purely as a gain device. I've actually never met one of these. All the MM amps I've met that had a tube used it as a driver/PI as in the schems I linked.

So please, OP, what model is your amp?
#30
Quote by soybomb
mesa tubes won't give you mesa tone. mesa doesn't make they're own tubes, i believe they just print MESA on ruby tubes. go to the tubestore.com and talk to doug or eurotubes and talk to bob to find some good tubes.

I know it won't completely change my tone, but I would expect some differences in the distortion. I will have to check out those sites.


Quote by Ronsonic
Whoa, that is a different animal. In that design, the tube is used purely as a gain device. I've actually never met one of these. All the MM amps I've met that had a tube used it as a driver/PI as in the schems I linked.

So please, OP, what model is your amp?


Who is OP?
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#32
Oh, got ya.

Its the Music Man RD50 head [it's not a combo because they made a 50RD combo i think]
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#34
Well I'll probably buy at least one 12ax7 just to see how much the difference is. But like it was said above, back then the tubes were made so good people tended to not replace them if they weren't broke, so I might end up liking the original 12ax7 driver better.

I'll definately report back to let you all know.

Thanks for your time,

FrenchBread
Quote by CL/\SH

Quote by sanitarium1
...for the gigs im going to be playing its going to be 60% tone and 40% stage look, and I'd like the look of my rig to be able to back up its sound.

No.
No.
NO.
GOD DAMMIT NO.
#35
How do I tell which of the 3 is the driver??
Quote by It'sForTheBest
Those cameras are really cool. I'm watching a parking lot right now.



Quote by SynGates7X
alright, you need to tell me how you get the shits to come out
#36
AC/zeppelin/DC:

I get the feeling you're talking about a completely different amp... but I'm too lazy to check this thread for which amp. If you have a 3 tubes, my best guess is v1 and v2 are preamp tubes, and v3 is a phase inverter (v3 being the closest to the power tubes). So your first two tubes would be the "driver tubes"... I guess.