"Sander deWaal" wrote

Go with a reputable vendor like Ned Carlson
www.triodeelectronics.com

Thank you.


or perhaps Willie "Lord Valve" if you can stand his attitude :-)

I know Willie... thanks, I'll pass .


These guys don't just sell, but can also advise you better
than anyone in this newsgroup, including myself.

BTW Powell, 12 AX7s in a microphone amp, are you
seriously looking for noise and microphony? :-)

I'm interested in increasing the timbre and micro-dynamics
resolution particularly in the 80 to 500 Hz range. I'm looking
for a similar resolution to that of my ARC pre-amp.

Here's an interesting comparison of 12AX7 design types:
http://store.yahoo.com/thetubestore/12ax7review.html

And a description of design use:
http://catalog.rell.com/scripts/SkuS...chtotal=% 2D1

Information on NOS tubes, too.
http://www.soundstage.com/tubeor/tube4.htm


In any case, when the design calls for AX7, try 7025 RCA.

And, I understand it ECC83, which is very pricey:
http://store.yahoo.com/thetubestore/12ax70ectyp.html


For a microphone amp, a better choice would be EF86 in
triode, IMHO.

I didn't see where the EF86 was a 12AX7 substitute... are
you sure it is? And it appears appears to be a pentode
design.

I'm leaning toward a highly sorted RAM tube because
of the noise factor. Or maybe purchase both the
Sovtek 12AX7LPS and Ei12AX7 types... can't justify
all three purchases, unfortunately.
http://www.tubeaudiostore.com/tubes.html

Interesting article by Roger Modjeski on "why sound
changes when you change tubes:
http://store.electron-valve.com/soundandtubes.html