Preamp Tubes Help

[James Rock]

Can u use 2 different brand preamp tubes in the same amp.
I want to imporve the tone of my Fender Pro Junior (want to tame the harsh mids and make it cleaner and more articulate as well as chimier)
I thought maybe using a a combination of the GE JG-5751 http://www.thetubestore.com/jange5751.html (for less gain), a JJ ECC83-s and a Ei Elite 12AX7E. I only need 2 tubes but i want to try different combinations for tonal options.
What r comments on using different tubes especially these ones?

[James Rock]

Re: Preamp Tubes Help

Do I need to know the bias for the power tubes (is it fixed bias or cathode)

[Duke of Metal]

Re: Preamp Tubes Help

hey James,
Yep.. you can mix and match preamp tubs no problem at all. 5751 type tube has less gain then a 12ax7/ECC83. So which result in a bit cleaner tone.

Another choice you can look into if your not concerned about he Overdrive channel is 12AT7 and 12AU7 type tubes. the AU7 is very clean type tone. not alot of gain, but will clean up very very nicely.

The JJ ECC83s is a nice tube. I've been using that tube (but highgain graded) for a long time. It had this "dark" touch to it that will help remove some of the harsh highs and a bit of smooth yet aggressive mids, specially when used in highgain distortion. Very tight sounding tube and low on noise also. Never tried the GE or the EI, so i couldnt comment on those.

For power tubes biasing, i would suggest using this:

http://www.webervst.com/tubes/calcbias.htm

all you need to know from your amp is the Plate Voltage of the amp and do the calculation for the bias per tube using the 1st calculator on that page. Your dealing with high voltage here, so be careful if your going to be doing it your self. if not, then I suggest paying a tech to do the bias on your amp. Should cost you no more then between $30 & $50 but atleast you'll be alive after .

Hope that helps!