So my amplifier uses 6 of these tubes and I have noticed that in the first two slots 12AX7A and 12AX7B is used and in the rest the 12AX7C is used. I was wondering what is the difference because if it comes to future re-tubing of these tubes to just 12AX7 without the A, B, or C designation, I will be more confident doing so, unless I have to specifically use tubes with such designations... and I only found Chinese tubes that are separated like that. Other brands are just branded as 12AX7.
Pre-Amp Tube 12AX7
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TwilightOdyssey
Darkness on the edge of Tone
Re: Pre-Amp Tube 12AX7
Won't make a diff. You can use any type of 12AX7 or AX7 variant/substitute, and even mix/match them depending on your personal preference ...
Won't make a diff. You can use any type of 12AX7 or AX7 variant/substitute, and even mix/match them depending on your personal preference ...
TwilightOdyssey
Darkness on the edge of Tone
Re: Pre-Amp Tube 12AX7
I'll have a look at the Tube Substitution Handbook tomorrow and get back to ya!
I'll have a look at the Tube Substitution Handbook tomorrow and get back to ya!
Chickenwings
Alnico 6/8
Re: Pre-Amp Tube 12AX7
with sovteks the 12ax7wa is the cheapest, then b has a slightly higher s/n ratio and so on with the c. The Lps is their best one. Im pretty sure fender mostly use gt branded sovtek 12ax7wbs for the majority of their amps coming out of a shop.
The first tube in the line is the one that has the biggest effect on your sound so when you go retubing make sure you get a good one. The sovtek lps is good. The EH 12ax7s are very nice in marshalls. For thin sounding amps jjs are great cos they add a bit of bottom end, and for dark amps the tungsols are excellent to add a bit of top end bite. In the end it all comes down to preference, but if i could only choose one 12ax7 for any/all applications it would be the EH.
Oh yeah...a lot of amps use 12aT7s as the phase inverter...so if you see that designation on one of your 6 tubes then replace it with the same type.
with sovteks the 12ax7wa is the cheapest, then b has a slightly higher s/n ratio and so on with the c. The Lps is their best one. Im pretty sure fender mostly use gt branded sovtek 12ax7wbs for the majority of their amps coming out of a shop.
The first tube in the line is the one that has the biggest effect on your sound so when you go retubing make sure you get a good one. The sovtek lps is good. The EH 12ax7s are very nice in marshalls. For thin sounding amps jjs are great cos they add a bit of bottom end, and for dark amps the tungsols are excellent to add a bit of top end bite. In the end it all comes down to preference, but if i could only choose one 12ax7 for any/all applications it would be the EH.
Oh yeah...a lot of amps use 12aT7s as the phase inverter...so if you see that designation on one of your 6 tubes then replace it with the same type.
Last edited:
Brown Note
New member
Re: Pre-Amp Tube 12AX7
There are something like 10 tube manufacturers in the entire world and I'd say that 7 or 8 of them makes preamp tubes. Those that are still there, atleast a couple ex jugoslavian tube manufacturers use the same factory building! Almost every tube out there is just a renamed version of someone else's tubes and these have different kinds of ratings based on how they are priced, whether the rating makes any sence or not. Most of them don't even tell how they rate or calculate their ratings and are thus probably just a marketing skeme.
Worst thing is that most companies, ruby tubes for examble, use tubes from several manufacturers, all labeled with same name and this makes buying these tubes a bit of a quesswork. They do have tolerances with which they sell their product, but I'm more comfortable knowing that if a Tung sol tube sounded great, the next tube that I buy is also a Tung-Sol instead of something else.
There are something like 10 tube manufacturers in the entire world and I'd say that 7 or 8 of them makes preamp tubes. Those that are still there, atleast a couple ex jugoslavian tube manufacturers use the same factory building! Almost every tube out there is just a renamed version of someone else's tubes and these have different kinds of ratings based on how they are priced, whether the rating makes any sence or not. Most of them don't even tell how they rate or calculate their ratings and are thus probably just a marketing skeme.
Worst thing is that most companies, ruby tubes for examble, use tubes from several manufacturers, all labeled with same name and this makes buying these tubes a bit of a quesswork. They do have tolerances with which they sell their product, but I'm more comfortable knowing that if a Tung sol tube sounded great, the next tube that I buy is also a Tung-Sol instead of something else.
guitfiddle
firstlessonologist
Re: Pre-Amp Tube 12AX7
Lots of luck. Re-branding has been going on from the very beginning of tubes.
Lots of luck. Re-branding has been going on from the very beginning of tubes.
Re: Pre-Amp Tube 12AX7
I took out all of the Ruby tubes on my 6505+ and put in V1 GT 12ax7 gold, V2 GT 12ax7gold, V3 Ruby 12ax7, V4 GT 12ax7 gold, and the V5 phase invertor an EH 12ax7-R. It is now much smoother, less harsh. I can ring out tap harmonics all day on the rhythm channel and the lead channel just kicks ass.
I took out all of the Ruby tubes on my 6505+ and put in V1 GT 12ax7 gold, V2 GT 12ax7gold, V3 Ruby 12ax7, V4 GT 12ax7 gold, and the V5 phase invertor an EH 12ax7-R. It is now much smoother, less harsh. I can ring out tap harmonics all day on the rhythm channel and the lead channel just kicks ass.
The JEM Ghost
New member
Re: Pre-Amp Tube 12AX7
As for tubes produced by SOVTEK, the A, B, and C designates the gain these tubes have, A has the least gain, B has a little more, and C has some more compared to B and is their highest gain tube.
Take into account that these designations only are for SOVTEK tubes! I know other manufacturers use A, and B and so fort as well, but often those are Chinese ones where the letter designates the generation of tubes produced and has nothing to do with their gain.
As for tubes produced by SOVTEK, the A, B, and C designates the gain these tubes have, A has the least gain, B has a little more, and C has some more compared to B and is their highest gain tube.
Take into account that these designations only are for SOVTEK tubes! I know other manufacturers use A, and B and so fort as well, but often those are Chinese ones where the letter designates the generation of tubes produced and has nothing to do with their gain.
TwilightOdyssey
Darkness on the edge of Tone
Re: Pre-Amp Tube 12AX7
Even classic-era Mullard 12AX7s can be rebranded Philips!
Truth!
Even classic-era Mullard 12AX7s can be rebranded Philips!
TwilightOdyssey
Darkness on the edge of Tone
Re: Pre-Amp Tube 12AX7
It's probably the combination of the gain of your amp and the valves combined. I'm using an old stock GE 5751 in the V1 slot of my Studio 2, and I have no problem getting great crunch tones from the amp. With a 12AX7 of any description in there, I get CRAZY amounts of gain!
Stef
New member
Re: Pre-Amp Tube 12AX7
lower gain indeed:
T-12AX7B-CHINA
Preamp Tube - 12AX7B Chinese made
9 pin miniature preamp tube (Amplification Factor = 100). The Chinese 12AX7B is very similar in tone to its standard Chinese cousin, but the B’s seem to average in at slightly lower gain and noise.
http://www.amplifiedparts.com/products/tubes/12AX7B-CHINA
another good description:
You can be sure of a linear response that produces a clear, crisp, warm tone that gives a smooth sustain when overdriven.
http://www.voc-rock-guitars.com/Valves-Tubes/Shuguang-12AX7B-valve-BA.html
lower gain indeed:
T-12AX7B-CHINA
Preamp Tube - 12AX7B Chinese made
9 pin miniature preamp tube (Amplification Factor = 100). The Chinese 12AX7B is very similar in tone to its standard Chinese cousin, but the B’s seem to average in at slightly lower gain and noise.
http://www.amplifiedparts.com/products/tubes/12AX7B-CHINA
another good description:
You can be sure of a linear response that produces a clear, crisp, warm tone that gives a smooth sustain when overdriven.
http://www.voc-rock-guitars.com/Valves-Tubes/Shuguang-12AX7B-valve-BA.html
wahwah
GumbyLoveologist
Re: Pre-Amp Tube 12AX7
That's where the date and manufacture code comes in...if a Mullard has the 'B' in the date code, it wasn't made in a Philips factory, it was made at the Blackburn Mullard plant. The label alone is never a reliable indication of a tube's origin, only the date and factory codes.
Cheers........................................ wahwah
That's where the date and manufacture code comes in...if a Mullard has the 'B' in the date code, it wasn't made in a Philips factory, it was made at the Blackburn Mullard plant. The label alone is never a reliable indication of a tube's origin, only the date and factory codes.
Cheers........................................ wahwah
Gearjoneser
Gear Ho
Re: Pre-Amp Tube 12AX7
I don't remember the details, but I think they're all Chinese and vary in gain with A being the hottest.
Years ago, I started doing two things....well 3 things to get good tubes.
1. Every time I go to an Amp or Tube show, I buy 1 really good pre tube, which I expect to be great in the 1st position of my amps.
2. Anytime I sell an amp, I make sure to raid any good tubes from it and put my cheapest stuff in it.
3. If you ever come across tube audio gear being thrown away, check to see if there's old stock pre tubes in it. This is a rarity, but I thought I'd mention it, since I've raided many Mullards from old movie cameras in a dumpster.
I don't remember the details, but I think they're all Chinese and vary in gain with A being the hottest.
Years ago, I started doing two things....well 3 things to get good tubes.
1. Every time I go to an Amp or Tube show, I buy 1 really good pre tube, which I expect to be great in the 1st position of my amps.
2. Anytime I sell an amp, I make sure to raid any good tubes from it and put my cheapest stuff in it.
3. If you ever come across tube audio gear being thrown away, check to see if there's old stock pre tubes in it. This is a rarity, but I thought I'd mention it, since I've raided many Mullards from old movie cameras in a dumpster.
Brown Note
New member
Re: Pre-Amp Tube 12AX7
Tube names aren't just random. The european ecc83 when broken down means
e=6.3V filament
c= triode(two 'c's mean two triodes)
83 = the tube has 9 pin socket
http://www.associatepublisher.com/e/m/mu/mullard-philips_tube_designation.htm
the "retma" naming system that's used in USA, is similar
12 = 12V filament, though it can be used in parallel so that it's 6V
AX = probably refers that the µ of the tube is 100 and is indirectly heated
7 = number of active elements
the AX part is just a sequence bearing no standardized meaning as far as I know.
All tubes bearing the same name have roughly the same amplification, though it decreases a *bit* when the tube ages. Also, aside from cascode connection(used sometimes in some HIFI audio) the tube never has it's full amplification, nor does it need to. If it did, a 4 gain stage preamp would have amplification of 100000000, which is quite a lot. In dB that would be 160. The gain of the tube does indeed make a difference, but not that much that it would perceivably be "hotter", than some other tube. I'm assuming that there is some quality control, of course if the tube is dud then the tube won't probably have the µ of 100.
Tube names aren't just random. The european ecc83 when broken down means
e=6.3V filament
c= triode(two 'c's mean two triodes)
83 = the tube has 9 pin socket
http://www.associatepublisher.com/e/m/mu/mullard-philips_tube_designation.htm
the "retma" naming system that's used in USA, is similar
12 = 12V filament, though it can be used in parallel so that it's 6V
AX = probably refers that the µ of the tube is 100 and is indirectly heated
7 = number of active elements
the AX part is just a sequence bearing no standardized meaning as far as I know.
All tubes bearing the same name have roughly the same amplification, though it decreases a *bit* when the tube ages. Also, aside from cascode connection(used sometimes in some HIFI audio) the tube never has it's full amplification, nor does it need to. If it did, a 4 gain stage preamp would have amplification of 100000000, which is quite a lot. In dB that would be 160. The gain of the tube does indeed make a difference, but not that much that it would perceivably be "hotter", than some other tube. I'm assuming that there is some quality control, of course if the tube is dud then the tube won't probably have the µ of 100.
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