12AX7A preamp tubes - ribbed vs smooth plate

I read a lengthy comparison written years ago about 12AX7s and the writer felt that the 5751 gave a more engaging presentation.

The 5751 is a lower gain, quieter version of the 12AX7.  So I tried a Sylvania black triple mica NOS and I agree with him.  I find I lose interest in the music easily, even with a $275 12AX7, compared with the 5751.  With the 5751 in my 300B integrated amp, I can’t stop listening.  Have to force myself to get up and walk away.

And I don’t notice any difference in gain.

GE Black Plate 5751 are great tubes and I've used them a lot over the years. Late 60's Mazda 12ax7 WA silver plate however are the finest small sig tubes I've iused in my current preamp. Have run through Amperex, Tele, Brimar, Mullard & I find the  Mazdas are legit - right in my lane. Just my opinion.

dinov

I don't think the answer (I'd need to ask my friend, we didn't make notes), and it would not be applicable to other phono/pre/amps in any case.

I would search for 'rectifier tubes' see what info comes up. perhaps ask Brent Jesse audiotubes dot com for advice.

If you find a good article about rectifier tubes, please let us know.

An amplifier modulates the power supplied. All things being equal, the better the supply, the better the sound. 

I thought rectifiers were rectifiers, nothing to do with the sound.