Can I replace the 12AT7 tube in the bassman with a 12AX7?

[titser_marco]

What differences would it make? Would it ruin the amp?

[deltaslim]

What differences would it make? Would it ruin the amp?

i wouldn't do that i were you.  ang 12at7 is intended for drivers and phase inverters and there's a reason they need a 12at7 to do the job. check mo sa tube chart ano exactly ang purpose nung tube slot na paglalagyan mo; baka naman may naglagay lang ng 12at7 dun.

[titser_marco]

What differences would it make? Would it ruin the amp?

i wouldn't do that i were you.  ang 12at7 is intended for drivers and phase inverters and there's a reason they need a 12at7 to do the job. check mo sa tube chart ano exactly ang purpose nung tube slot na paglalagyan mo; baka naman may naglagay lang ng 12at7 dun.

Acttually, Fender specifies that a 12at7 should be there in the phase inverter. So I guess that means I can't and shouldn't. thanks

[tolits]

Yes you can replace a 12at7 with a 12ax7, wont do you no harm, in fact will give you a little more gain, marshall amps uses straight 12ax7s, you just have to see if you will like the effect.

[skunkyfunk]

Yes you can replace a 12at7 with a 12ax7, wont do you no harm, in fact will give you a little more gain, marshall amps uses straight 12ax7s, you just have to see if you will like the effect.

One time I remember asking tolits to rebias ericbacquiran's silverface twin.  I forgot that the phase inverter and reverb driver should be 12AT7s.  So I gave tolits a bunch of 12AX7s.  So when I got it back, I noticed that the twin sounded way too warm (a little preamp distortion) and the reverb was so boingy.  That was when I figured out that I should have used 12AT7s instead.

BTW, Those NOS RCA 12AT7s rock as Phase inverters!

[markflo]

What differences would it make? Would it ruin the amp?

12at7 has lower gain than the 12ax7, it's perfectly safe to switch though...if you're after that vintage type of tone...

actually, the earlier bassman used 12ay7's, a tube with an even lower gain than the 12at7...

12ax7 100% gain
12at7 70% gain
12ay7 40-50% gain

more or less...

[titser_marco]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

[skunkyfunk]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

Try Watson's along Rizal Ave. in Manila (Chinatown).  Or Deeco.

[deltaslim]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

I might still have some singles, not sure. Will post back here kung meron.

I think you got mixed suggestions here cuz we weren't sure if you need it for a phase inverter or not. Ok lang ang 12at7 (and other 12xxx variants) sa input/preamp if you want cleaner tone. kaso nagiging sterile din ang tunog.

[titser_marco]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

I might still have some singles, not sure. Will post back here kung meron.

I think you got mixed suggestions here cuz we weren't sure if you need it for a phase inverter or not. Ok lang ang 12at7 (and other 12xxx variants) sa input/preamp if you want cleaner tone. kaso nagiging sterile din ang tunog.

Yeah, I was looking for a tube that would functin as a phase inverter. Sorry bout that.

How much would you sell your 12AT7 (or is it a 12AX7) if ever?

[deltaslim]

How much would you sell your 12AT7 (or is it a 12AX7) if ever?

Good news: I've got 2 pairs of NOS 12AT7WCs. One pair is JAN Philips ECG and the other is JAN GE.

Bad news: I can only sell as pair, can't sell a single.  I'm inclined to keep the Philips and sell the GE. PM me if ur interested.

[markflo]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

I might still have some singles, not sure. Will post back here kung meron.

I think you got mixed suggestions here cuz we weren't sure if you need it for a phase inverter or not. Ok lang ang 12at7 (and other 12xxx variants) sa input/preamp if you want cleaner tone. kaso nagiging sterile din ang tunog.

napansin ko din yun meng...kinabitan ko ng 12at7 yung v1 ng fender hot rod deluxe ko dati, mas malinis nga, kaso yun nga, medyo nawalan ng character...tama ka rin na it's MOSTLY used for PI's...

anyway, pahirapan humanap ng tube na yan meng

[skunkyfunk]

Hey thanks for the info -- keep them coming. I asked Audiophile if they had these, and they said they don't. Same with Phasetron. Any suppliers in Manila that you guys know?

I might still have some singles, not sure. Will post back here kung meron.

I think you got mixed suggestions here cuz we weren't sure if you need it for a phase inverter or not. Ok lang ang 12at7 (and other 12xxx variants) sa input/preamp if you want cleaner tone. kaso nagiging sterile din ang tunog.

napansin ko din yun meng...kinabitan ko ng 12at7 yung v1 ng fender hot rod deluxe ko dati, mas malinis nga, kaso yun nga, medyo nawalan ng character...tama ka rin na it's MOSTLY used for PI's...

anyway, pahirapan humanap ng tube na yan meng

I tried using a NOS GE 5751 for the Clean channel's V1 of my old Mesa Boogie DC-2.  5751 = 70% gain version of the 12AX7.  Same plate resistance.  It cleaned up the preamp a bit, and it was shimmery. Also use it with my ART Tube Mic Preamp and it also added some sparkle as opposed to mud of the stock ECC83.

[markflo]

that's because those are nice tubes...5751's are in between 12ax7 and 12at7 when it comes to gain...i dunno...the 12at7 just sounded weird in the v1...it's not just the gain...it's the whole tonality that was different...it works best nga talaga in the phase inverter...where it doesn't change your tone that much but just cleans it up...

[oasgomez-is-banned]

I stick by Tolits on this one.  Just try it out.  It might match your gear better with 12ax7.  What model of a bassman is this anyway?

[deltaslim]

that's because those are nice tubes...5751's are in between 12ax7 and 12at7 when it comes to gain...i dunno...the 12at7 just sounded weird in the v1...it's not just the gain...it's the whole tonality that was different...it works best nga talaga in the phase inverter...where it doesn't change your tone that much but just cleans it up...

yup, i find that 5751s are the only direct replacements for 12ax7s that still retain the orig character of the preamp. what you lose in gain, you get back in headroom and tone. i find them smoother when clipped w/ sweeter harmonics, unlike 12ax7s which can sound harsh and peaky. that's why 5751s are great in guitar tube preamps.

i've tried GE JANs, RCAs, Sylvannias... blackplate double and triple mica, etc. It's hard to go wrong with a 5751, esp if its NOS.

[titser_marco]

I stick by Tolits on this one.  Just try it out.  It might match your gear better with 12ax7.  What model of a bassman is this anyway?

Bassman Ten. 4x10. Thanks

[skunkyfunk]

I stick by Tolits on this one.  Just try it out.  It might match your gear better with 12ax7.  What model of a bassman is this anyway?

Bassman Ten. 4x10. Thanks

This one?

[titser_marco]

I stick by Tolits on this one.  Just try it out.  It might match your gear better with 12ax7.  What model of a bassman is this anyway?

Bassman Ten. 4x10. Thanks

This one?

Korek!

[titser_marco]

Another question: Can I just frop in the new tubes on the bassman (2x6L6, 2x12AX7, 1X12AT7) when I get it and start using it? Or do I have to have it rebiased before I can fully use it? Thanks

[skunkyfunk]

Another question: Can I just frop in the new tubes on the bassman (2x6L6, 2x12AX7, 1X12AT7) when I get it and start using it? Or do I have to have it rebiased before I can fully use it? Thanks

OK with replacing the preamp toobs in no time.  But with the power tubes, you have to bring your amp for rebiasing.  That way you can optimizeyour new tubes by making them run not too hot or too cold.   Now if you're really excited, try replacing the 6L6s and play with your amp for the whole day while observing the tubes.  They must NOT have any glow in the plates.  Should that be the case, have it rebiased so that they won't run too hot.  On the contrary, if the plates aren't running red but the tone is too bland, chances are your tubes are running too cold.  Again you have to bring it for rebiasing.

[markflo]

Another question: Can I just frop in the new tubes on the bassman (2x6L6, 2x12AX7, 1X12AT7) when I get it and start using it? Or do I have to have it rebiased before I can fully use it? Thanks

OK with replacing the preamp toobs in no time.  But with the power tubes, you have to bring your amp for rebiasing.  That way you can optimizeyour new tubes by making them run not too hot or too cold.   Now if you're really excited, try replacing the 6L6s and play with your amp for the whole day while observing the tubes.  They must NOT have any glow in the plates.  Should that be the case, have it rebiased so that they won't run too hot.  On the contrary, if the plates aren't running red but the tone is too bland, chances are your tubes are running too cold.  Again you have to bring it for rebiasing.

korek except that whole glow thing. output tubes do glow but...if skunky means that cherry red almost gonna explode type of glow, yea, that's a bad thing...heheh...

if you're replacing it with the same type of output tubes (same make and model eg Sovtek WXT to Sovtek WXT) it shouldn't be a problem

the bias is basically like the car's idle...it's exactly like that. i mean, your amp will work and all but to rebias it would be like setting the correct idle, like skunky said, for optimization purposes...

[skunkyfunk]

Another question: Can I just frop in the new tubes on the bassman (2x6L6, 2x12AX7, 1X12AT7) when I get it and start using it? Or do I have to have it rebiased before I can fully use it? Thanks

OK with replacing the preamp toobs in no time.  But with the power tubes, you have to bring your amp for rebiasing.  That way you can optimizeyour new tubes by making them run not too hot or too cold.   Now if you're really excited, try replacing the 6L6s and play with your amp for the whole day while observing the tubes.  They must NOT have any glow in the plates.  Should that be the case, have it rebiased so that they won't run too hot.  On the contrary, if the plates aren't running red but the tone is too bland, chances are your tubes are running too cold.  Again you have to bring it for rebiasing.

korek except that whole glow thing. output tubes do glow but...if skunky means that cherry red almost gonna explode type of glow, yea, that's a bad thing...heheh...

if you're replacing it with the same type of output tubes (same make and model eg Sovtek WXT to Sovtek WXT) it shouldn't be a problem

the bias is basically like the car's idle...it's exactly like that. i mean, your amp will work and all but to rebias it would be like setting the correct idle, like skunky said, for optimization purposes...

Thanks for clarifying that Mark.  Yes, I meant the red glow in the plates as if you were seeing those heaters in a bread toaster.  That is the BAD type of glow.  But under normal circumstances it should be blue, purple or sometimes even very dark.  But what makes it better is the smell of burning paint on the tubes.

[titser_marco]

Another question: Can I just frop in the new tubes on the bassman (2x6L6, 2x12AX7, 1X12AT7) when I get it and start using it? Or do I have to have it rebiased before I can fully use it? Thanks

OK with replacing the preamp toobs in no time.  But with the power tubes, you have to bring your amp for rebiasing.  That way you can optimizeyour new tubes by making them run not too hot or too cold.   Now if you're really excited, try replacing the 6L6s and play with your amp for the whole day while observing the tubes.  They must NOT have any glow in the plates.  Should that be the case, have it rebiased so that they won't run too hot.  On the contrary, if the plates aren't running red but the tone is too bland, chances are your tubes are running too cold.  Again you have to bring it for rebiasing.

korek except that whole glow thing. output tubes do glow but...if skunky means that cherry red almost gonna explode type of glow, yea, that's a bad thing...heheh...

if you're replacing it with the same type of output tubes (same make and model eg Sovtek WXT to Sovtek WXT) it shouldn't be a problem

the bias is basically like the car's idle...it's exactly like that. i mean, your amp will work and all but to rebias it would be like setting the correct idle, like skunky said, for optimization purposes...

Thanks for clarifying that Mark.  Yes, I meant the red glow in the plates as if you were seeing those heaters in a bread toaster.  That is the BAD type of glow.  But under normal circumstances it should be blue, purple or sometimes even very dark.  But what makes it better is the smell of burning paint on the tubes.

So you mean to say those tube amp ads are baloney because they feature tubes that have an orangey glow? Do you have some pics of a properly glowing tube? Thanks

[markflo]

well...it's just like those food commercials wherein they exaggerate the picture...hehe