I use the 5751 in place of 12ax7 in my Line Magnetic 518IA and the lower gain hit the mark for me in that amp. Agree with others I wouldn’t substitute it for the 12AT7 unless the amp designer stated that it was okay to do so with his circuit
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.
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.