2. amps-preamps
  3. 168760-163603

Replace a 12at7 with a 12av7?

I have a Jolida Fusion 3502P and I've become an obsessive tube roller in the last six months.

The stock configuration is 12ax7s in V1 and V5 preamp sockets, and 12at7s in the V2 and V6 power driver sockets.

It's a fairly robust amp, but am I risking my pricey 12ax7s if I replace the 12at7s with 12av7s? I've found a few NOS 5965s in my stash, and honestly, I prefer the sound!
jsbw
oddiofyl's avatar
oddiofyl
3,783 posts
 
I don’t know if you tried them, but NOS Mullard 6201 are a great 12at7 variety and they sound incredible in my preamp
tksteingraber's avatar
tksteingraber
607 posts
 
Should be fine but be aware the 12av7 is a hotter tube. It uses 150 mA more on the heater grid.  A pair of tubes isn’t a lot.  Gain is 41 vs 60 on the 12at7 so it may need a little extra power.  Your ears are the answer...if it sounds better to you then so be it. Good luck.
tksteingraber's avatar
tksteingraber
607 posts
 
Fyi the best sounding 12at7 that I have heard is a 70’s Tungsram with square metal getter  supports.  Unusual design for sure and hard to find.  These are amazing better than mullards, amperex, telefunkens etc....there is a pair on eBay with the orion brand on them.  I would pick these up if you are a chronic roller like me. I would but I don’t need to hoard.. cheers!
jsbw OP
14 posts
 
" I don’t know if you tried them, but NOS Mullard 6201 are a great 12at7 variety and they sound incredible in my preamp "

I've been using some NOS GE 6201s and I really like them as well.

Picked up som NIB Mullard CV4024s...how different could they be?
johnss
569 posts
 
the 12AV7 is lower gain than the 12AT7. Should not hurt anything if you try it, but you may want to measure the plate voltage first with the AT7 in place. Then re-measure plate voltage with the AV7. Depending on how stiff the power supply you may get some voltage sag with the AV7 so may need to change the plate and cathode resistors to bring the voltage back up.  
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