2. amps-preamps
  3. 170297-163603

Anyone try using a 5751 in place of a 12AT7?

I'm running a Jolida Fusion 3502P amp, with a pair of 12ax7s in the preamp stage, a pair of 12at7s in the power driver stage, and 4 KT88s in the output stage.

I've been rolling the smaller tubes obsessively (as one does), and while I've settled on my favorite 12ax7s, I've been experimenting with 12at7s and their variants (6201s, 12BH7s, 12av7s, etc), and it never occurred to me until recently that while most substitutes for 12at7s have nearly the gain of a 12at7, it suddenly occurred to me that a 5751 is the only 12xxx tube that has 70% gain (as opposed to the 12at7s 60%). Thought if it didn't sound distorted, it might just add that little tiny bit of punch this amp lacks.

And it did!

So now, of course, I need to stock up on even more tubes.

Oh well.
jsbw

Showing 2 responses by jsbw

jsbw OP
14 posts
 
The 12bh7 was just an experiment, without impressive results (but not unimpressive...just, meh).

No, the main question here is, has anyone used a 5751 in place of a 12at7, especially in a power driver stage? 


jsbw OP
14 posts
 
The amp’s a Jolida Fusion 3502p running in ultralinear, with KT88s. All power tubes are still within bias spec with 5751s as power drivers.

Seriously, the 5751 seems to add a bit of detail. Especially in the higher frequencies.

(Tbh, the difference may be negligible)

But as we all know, it’s the combination of tubes that matters.

I’m working on a spreadsheet with different combos.

I’m just surprised no one else has tried this. Seriously, am I the first guy to sub a 5751 for a 12at7?
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