best replacement tube in a tube overdrive pedal.

If I have a distortion pedal (by Tubeworks) that has a 12AX7A vacuum tube in it, what would be a good replacement tube that wouldn't give so much heavy distortion?

Jim has a point. There are so many factors that affect your overdriven tube tone- pickup type, pickup output, pedal gain, preamp gain, power amp gain, tone control settings (on the pedal and the amp)... ETC.

What works for one setup might not work for another. For example, I had a Tubeworks Real Tube pedal at one time. I used it with a Strat and a Lab L7 solid state amp. It sounded a little too heavy with the stock 12AX7 tube, so I switched to an EH 12AU7. It sounded beautiful- it could go from a Buddy Guy type blues tone to a Ritchie
Blackmore-ish rock sound. But then I switched to a silverface Fender
Pro Reverb amp, and it sounded weak and tinny. Now I'm using a reissue
DOD 250 overdrive (solid state pedal) with the Fender.

I agree with what others have said. Use your ears. Try pedals with your own guitar and amp. Buy what sounds good to you. Don't be afraid to try something different (the DOD 250 is not really a popular pedal, but I like it)

I'm having trouble reading this... the comments are separate and jumpled. Do you have an easier to read format you could post?

Go to www.thetubestore.com
Plenty info there.. EH has some really good 12a's
http://community.webtv.net/smittyjr/BandOfThieves

Different brands of 12AX7’s will sound different. Which one is best for you can only be found by trial and error.

The following is a list of some of the favorite tubes that will operate in
12AX7 circuits, their gain factor (how much amplification they provide) and comments on each.

Tube Number
Gain Comments

12AX7 100

12AX7A/

ECC83*/CV4004** 100

Later version (began production about 1960) of the

12AX7 with lower noise and hum.
7025 100

Lowest noise version of 12AX7. Recommended by

Fender for V1, V2 and V4 preamp tubes.
5751 70

Industrial number which is essentially interchangable with 12AX7’s. It has slightly lower gain but don’t let the number fool you. Moving from a gain factor of 100 to 70 is not very noticable (in loudness) to the ear.
These are fantastic as first preamp tubes in many amps. They tend to be a little mellower in tone than some 12AX7’s can be. Also work well as reverb drivers (V3 in most Fender amps). Stevie Ray Vaughan is rumored to have used these in his phase inverter socket.

12AY7/6072 ?

This was the stock first preamp tube in some Fender tweed amps from the 1950s.
The famous ’59 Bassman amp (most often used for lead guitar) used one. These have a gain similar to 5751’s and tend to distort at lower volume settings which is why they’re favored by some blues players. They also have a nice mellow top end.