12AX7 or 5751

[tomas_almeida]

NOTICE: I WROTE 12AX7 ON THE THREAD TITLE BUT IT WAS SUPPOSED TO BE 12AT7


Hey TBers!

I have a Traynor YBA200-2, and I want to replace the preamp tubes. I have read all the threads about this subject, but I can't decide on one thing.

Should I buy a 12AT7 or a 5751 to put on V1?
I read many people saying that the 12AT7 had good results, but also read lots of things saying that 12AT7s shouldn't be used on the V1. They say that the sound gets very thin with a 12AT7, that you should use a 5751 instead.

My goal is to get the most possible clean headroom, tame the excessive highs and high-mids (the very high ones, between 1.5kHz and 4kHz), and if possible to get some more lows and low-mids.

I sit here patiently awaiting for suggestions.

Cheers

 

[B-string]

You def. don't want a 12AT7 there! You will loose gain with the 5751 but the tone maybe what you are looking for?

 

[johnk_10]

5751's are great replacements for 12AX7's if you want to have a little less gain and more headroom in your first preamp stage. they are very smooth sounding tubes, whereas the 12AT7's are, in my opinion way too thin/brittle/stiff sounding

 

[mr.redpants]

I can't tell from the OP what the goal is - based on my limited experience, if (1) you want sweet low end and quieter overall (less hiss) and max volume isn't an issue, 5751 will be good, if (2) you want headroom I think you want the strongest signal to your power tubes, that's a 12ax7.

 

[tsunami1052]

I have had good luck with the JAN-Philips 5751 in a couple of my tube preamps.

 

[johnk_10]

I can't tell from the OP what the goal is - based on my limited experience, if (1) you want sweet low end and quieter overall (less hiss) and max volume isn't an issue, 5751 will be good, if (2) you want headroom I think you want the strongest signal to your power tubes, that's a 12ax7.

in a way, you're correct, but in actual use, you get more headroom with a 5751 since it will have less chance of overdriving the subsequent stages.

 

[tomas_almeida]

I see that the concensus seems to be that a 5751 is a better option. However, I have seen people that used 12AT7s for my purpose in this specific amp and claimed to be very happy. This confuses me...

And my goal, sonically, is decribed in the 3rd paragraph in the first post.

EDIT: I mean, 4th par.

 

[B-string]

That's why we are saying the 5751 and not the 12AT7! But you don't have to believe the people that have been doing this for decades

 

[tomas_almeida]

Ok, don't take me wrong, I'm a natural skeptic . I'm more inclined to order two 5751s now. However, I would still like to read some opinions form people who have modded this amp.

 

[Calaverasgrande]

usually 5751's do best as the last tube before the power section. That way the tube you are driving the big tubes with has more current, less gain, more headroom!

 

[B-string]

I've only modded two, Johnk_10 may have done more? I'm sure others will speakup as well.

 

[johnk_10]

i've used them extensively in Fenders and a Traynor YBA-200-2 and they work awesome. IMO, 12AT7's do not sound anything like a 12AX& when substituted for one. believe me, if you're going for a smooth and full tone, with a large and wide 'soundstage', use a 5751.
IMO, that's the same reason that Stevie Ray Vaughn used them in his Fender amps.

 

[tomas_almeida]

Sorry that I only answered now guys, didn't have time to come here and see the responses.

I guess I'll be going with two 5751s then. However I'm a bit confused by this:

usually 5751's do best as the last tube before the power section. That way the tube you are driving the big tubes with has more current, less gain, more headroom!

Isn't the last tube before the power section usually a very low gain tube like a 12AU7??

 

[B-string]

I was a little confused by this also? It is a low gain/high current stage, the 12AU7 is capable of much higher current. All I can say is I never tried one in that position....yet.

 

[main_sale]

I've had great luck with the Tungsol 12AX7. It's a very musical tube that I regularly use in V1 in several of my amps.

 

[MAMMOTHvolume]

Sorry that I only answered now guys, didn't have time to come here and see the responses.

I guess I'll be going with two 5751s then. However I'm a bit confused by this:




Isn't the last tube before the power section usually a very low gain tube like a 12AU7??

normally a 12ax7 but a 12at7 or similar gain valve will do a much better job there.

I normally run 12au7s throughout the preamp, they normally still have enough gain to push the power amp but with a much lower n/s ratio and do a much fatter cleaner sound.

 

[tomas_almeida]

That does sound very interesting, I'll try to get some more info into that.

And oh, I only noticed now that I I put 12AX7 on the title, should've been 12AT7. Sorry.

 

[Calaverasgrande]

5751=low gain high current.

 

[testing1two]

In all honesty, these are relatively cheap tubes. Get one of each, do a real world listening test and post your subjective results here. At the end of the day we all have opinions but only one of them matters...

 

[wave rider]

I've always enjoyed the notion that JAN5751s were made to be used in ICBMs. If they won't go microphonic in a missile, a bass rig should be easy street...

=wr=