12AX7 vs. 5751

Typically you can use 5751s where 12ax7s are called for. The 5751s having less gain just gives your volume control a little more flexibility, ie you can turn your volume control without a little adjustment giving you a big volume increase as 12ax7s give in some applications. With my preamp there is a noticable difference in gain between these two tubes. 5751s were speced for the military and are very rugged. They also sound very nice, IMHO. I too like their air and detail and I would add bass response. Just to make sure, send altavista an email, they are the experts on Counterpoint equipment.

There are no guarentees it will sound better with a 5751 set ...Each peice of equipment is a little different,so the only way to know is to try..I tried and like the RCA 5751 black plate ( circa 1962 ). Not much gain loss and gorgeous mids with good bass..Didn't like the Mullard ( to dark for my set up ) .I did however think the Tungsram 12ax7 ( Hungary ) is one of the best 12ax7 nos tubes I have ever tried...( available at Tubemonger.com )To me if I were going to try rolling I would suggest try either one of those tubes mentioned. Both great but slightly different..And as mentioned by Davt ,the Mullards work great for some also..Its a crapshoot!

I have used both A LOT and never noticed the gain difference in 5751s. But they sure sound different. The right tubes will depend on your tastes and equipment.

Arthur

I have an additional question.

Can a 12ax7 be used in place of a 5751?

the preamp is speced for a 5751 in the line stage.

gentlemen:

in many cases you may substitute a 12ay7 for a 12ax7, with a gain difference. i have done this with a cj premier 3, audio note cd2, cary slp 94, mcintosh c220 and nobis proteus preamp--phono stage .