12AT7.. Is it a 12AX7 killer?

[Faust2016]

So I recently tried out many different tubes in my Framus Dragon. I was playing around with a 12AT7 in the PI. This made the sound much clearer and more midrange-y. Before there was a Tung-Sol 12AX7 in there, the 12AT7 was a balanced EH tube.

Since I was experimenting I thought lets put this tube in other positions as well in V1 I found the it made the amp sound like it had wayyy less gain and the overall character became too tame. I tried it in V3 as well. In here I liked it best.

The tubes I have in there right now are:

V1,V2 Shuguang C9 12AX7

V3 EH 12AT7

V4,V5 Tung-Sol 12AX7

V6-V9 Shuguang EL34-B

 

Ok well everything is fine, I played for a few hours yesterday and today I played for maybe half an hour until I got into doing some shit on the PC.. I leave my amp on and when I reach for my guitar again I strum a chord and thought the guitar volume was down, cause I was on Ch3 with a boost and there was a very weak clean sound.. So I want to put it back up but it is already all the way up. I switch to Ch2.. Same thing. Ch1 on the other hand is totally fine. I thought it's probably a preamp tube. So I take the V2 tube out and put another one I had lying around in there et voila.. The sound is back as it should be.

Now is my question: I read that 12AT7 tubes have an output of 10 mA as opposed to the 1 mA of 12AX7 and some other :blah:

Could it be that the tube went south because I had the 12AT7 in there? Oh and the tubes were pretty new.. A few weeks old maybe.

[AL30]

12AT7's have less gain than a 12AX7 so it can clean up a stage. Whether or not that's a good thing depends on your ears.

 

The 12AT7 sounding more "mid-rangy" probably has less to do with it being a 12AT7 and more to do with the brand of the tube(s) you're comparing.

 

A tube swap in V1 generally has the biggest overall effect on tone. That's usually your first gain stage.

 

Can't comment on your tube problem. It's hard to tell without seeing a schematic of the amp.

 

AL

[Faust2016]

12AT7's have less gain than a 12AX7 so it can clean up a stage. Whether or not that's a good thing depends on your ears. The 12AT7 sounding more "mid-rangy" probably has less to do with it being a 12AT7 and more to do with the brand of the tube(s) you're comparing. A tube swap in V1 generally has the biggest overall effect on tone. That's usually your first gain stage. Can't comment on your tube problem. It's hard to tell without seeing a schematic of the amp. AL

 

I knew all that That's exactly what I found out swapping teh tubes

[Mr. Awesome]

The 12at7 has more drive which is why it was used to drive the transformer in in the early Fender amps. When Fender created the Bassman (maybe Blues Deluxe?) guys would put 12at7's in their amps only to experience problems later on. The problem was Fender went on the cheap (getting worse all the time) and put something like 1/4 watt resistors in the amps. These resistors could not handle the extra current and fried out over time.

 

If you have a decently made amp chances are a 12at7 will do no damage, if however you have something which is made less robustly you could have issues. I wouldn't think a Framus would be one of these.

[CenturyStanding]

I would agree 100% with this thread. 12AT7 is a brighter tube with less gain. I don't really care for it in actual gain stages, as it can get a bit harsh and trebly. However, in the PI section, the extra current really helps to push the power amp. If you take an amp that likes to be pushed (like my Savage) it will give you more of that cranked poweramp sound at lower volumes with much more clarity and openness. Good stuff.

[OverDriven]

The 12at7 has more drive which is why it was used to drive the transformer in in the early Fender amps. When Fender created the Bassman (maybe Blues Deluxe?) guys would put 12at7's in their amps only to experience problems later on. The problem was Fender went on the cheap (getting worse all the time) and put something like 1/4 watt resistors in the amps. These resistors could not handle the extra current and fried out over time.

 

Whatttt???? No. While hiliarious, your reply just spreads BS.

[guitarbilly74]

The 12at7 has more drive which is why it was used to drive the transformer in in the early Fender amps. When Fender created the Bassman (maybe Blues Deluxe?) guys would put 12at7's in their amps only to experience problems later on. The problem was Fender went on the cheap (getting worse all the time) and put something like 1/4 watt resistors in the amps. These resistors could not handle the extra current and fried out over time. .

 

*sigh*

[guitarcapo]

AT7's have less gain. I've been told by amp techs that the only place they should be put is the PI slot because they are "functional tubes and not audio tubes" (their words not mine). I've used them in the V1 slots and never thought they sounded bad. Sort of like a 12AY or some other lower gain preamp tube. Really I don't notice much difference in the PI tube with tone, especially when playing clean. I think at best it effects the degreee and tone of breakup, sometimes better, sometimes worse. When it's bad, it's sort of a spongy out of phase wimpy tone (hard to describe) When it's good, it's that square wave crunch. A lot depends on the overall amp design. Experiment and see.

[CenturyStanding]

 

AT7's have less gain. I've been told by amp techs that the only place they should be put is the PI slot because they are "functional tubes and not audio tubes" (their words not mine). I've used them in the V1 slots and never thought they sounded bad. Sort of like a 12AY or some other lower gain preamp tube. Really I don't notice much difference in the PI tube with tone, especially when playing clean. I think at best it effects the degreee and tone of breakup, sometimes better, sometimes worse. When it's bad, it's sort of a spongy out of phase wimpy tone (hard to describe) When it's good, it's that square wave crunch. A lot depends on the overall amp design. Experiment and see.

 

 

It doesn't sound bad in a tone spot, but if you want to lower the gain in V1 or a gain stage, you are better off with a 5751. It is WAY warmer and much more balanced tonally. None of that piercing high end.

[AL30]

I knew all that That's exactly what I found out swapping teh tubes

 

Well, there's no subsitute for experience.

 

This may help

 

http://thetubestore.com/gainfactor.html

 

 

AL

[guitarcapo]

 

It doesn't sound bad in a tone spot, but if you want to lower the gain in V1 or a gain stage, you are better off with a 5751. It is WAY warmer and much more balanced tonally. None of that piercing high end.

 

 

 

I mostly play clean and LOVE that piercing high end sparkle. I'm always fighting mud with my amps. Probably doesn't help that my ears are shot....

[Hanglow]

Here's a quote from the excellent aiken amps website

 

"Q: Can I substitute a 12AT7/12AU7/etc. for a 12AX7?

A: Yes and no. While they are the same pinout, the tubes are very different with regards to internal plate resistance, bias current, gain, etc. It won't usually hurt anything to substitute them, but it is not a fair tonal comparison if you don't also change the cathode and plate resistors to optimally bias the tube. A straight swap without regard for circuit operating conditions will lead to incorrect conclusions regarding the characteristic tone of the tube."

 

 

might be of some interest. might not.

[Weathered]

 

Could it be that the tube went south because I had the 12AT7 in there? Oh and the tubes were pretty new.. A few weeks old maybe.

 

 

I doubt that the 12AT7 caused V2 to go south.

 

Evne new tubes can go bad in short order - I wouldn't rule out the fact that the tube in V2 just wasn't really a good tube.

[Faust2016]

I would agree 100% with this thread. 12AT7 is a brighter tube with less gain. I don't really care for it in actual gain stages, as it can get a bit harsh and trebly. However, in the PI section, the extra current really helps to push the power amp. If you take an amp that likes to be pushed (like my Savage) it will give you more of that cranked poweramp sound at lower volumes with much more clarity and openness. Good stuff.

 

I didn't find it overly bright at all But this might be because the Dragon itself is a lot less bright than the Savage as it is. What brand of 12AT7 did you try and what brand of 5751 would you recommend?

[Faust2016]

I doubt that the 12AT7 caused V2 to go south. Evne new tubes can go bad in short order - I wouldn't rule out the fact that the tube in V2 just wasn't really a good tube.

 

Yeah I just want to make sure as I'm a little hesitant to turn my amp on as I don't want to fry more tubes

[Weathered]

Yeah I just want to make sure as I'm a little hesitant to turn my amp on as I don't want to fry more tubes

 

If you're hesitent, swap it back to a 12AX7. I logically, though, I think that the risk would be downstream from the AT, and not upstream.

[Mr. Awesome]

*sigh*

 

This is what I read in the Gerald Weber books. I'm not talking original Bassman either only the first repros. Supposidly he serviced a bunch of them which had burned up 1/4 watt resistors in the gain stage. If I'm wrong blame Weber, but I'll take a kick in the shins as well if this is not true.

[Weathered]

 

This is what I read in the Gerald Weber books. I'm not talking original Bassman either only the first repros. Supposidly he serviced a bunch of them which had burned up 1/4 watt resistors in the gain stage. If I'm wrong blame Weber, but I'll take a kick in the shins as well if this is not true.

 

 

Maybe you picked the wrong word then. You said "created", which isn't quite right, being that the originals were built ~30 years before the RI.

[CenturyStanding]

I didn't find it overly bright at all But this might be because the Dragon itself is a lot less bright than the Savage as it is. What brand of 12AT7 did you try and what brand of 5751 would you recommend?

 

This is true. For a high-gain head the Savage is VERY bright. I don't think my treble or presence have ever been above like 4 at any given time. With something like a Recto or Diezel or something with less high-end the 12AT7 might sound better in a gain spot. I did just find the 5751 to have more detail in a tone spot than the 12AT7. I don't know how to explain it. I think I just found the 12AT7 to be sort of dynamically lacking in V1 compared to a 5751.

 

I use a NOS Mullard 12AT7 (going rate is about $15-20 per tube, not bad for a NOS). The 5751 I used was either a JAN Philips or a NOS GE, I don't remember exactly, they weren't actually mine. Again, for NOS tubes they are reasonably priced. Also between $10-20 a piece.

[C-4]

I pulled a 12AX7 from V-1 and V-2 in my Einstein and placed in NOS Mullard 12AT7's.

I got a very sweet distortion and the gain knobs can now be turned up all the way without choking off the clearer tones mixed in with the distortion a 12AX7delivered.

 

With a 12AX7 in those slots, at about 2 o'clock, the clarity and sweetness of the distortion disappeared and was replaced with pure distortion...way too much for my desired tones.

 

Now the distortion has the complexity of a SLP running dimed, which is much more to my liking.

[Heineken]

I think you got it backwards dude. 12AX7 is the 12AT7 killer. That's why 99,9% of the amp makers put 'm in their products. It's not like they are more expensive to make or something and the only reason they are less common is because there's no market for them.

[Faust2016]

I think you got it backwards dude. 12AX7 is the 12AT7 killer. That's why 99,9% of the amp makers put 'm in their products. It's not like they are more expensive to make or something and the only reason they are less common is because there's no market for them.

 

[Weathered]

 

+

 

This thread isn't about what sounds better.

[WRGKMC]

This site has a proper explanation of the gain and variations of the 12ax7 tubes. http://www.vacuumtubes.com/12ax7.html

 

It does say the 12AT7 has a gain of 70 but I think its a littel higher

in a proper circuit, properly biased.

The 5751 has a gain of 70

The 12AX7 has a gain of 100

 

I use the 5751 tube in my Marshall Valvestate preamp. Made the overdrive channels much more useable.

I also used a few in a mike preamp that was too gainy and sacrificed some gain for a more usable range of volume controll.

 

I think Stevie Ray Vaughn used the 5751s in his Fender amp along with some mods to get his sound as well

[Heineken]

+ This thread isn't about what sounds better.

 

(damn... i should have read the post before getting all over the thread title....)