Mook's Taste Test for 12AX7
INTRODUCTION:I tested 10 different kinds of 12AX7 pre-amp tubes using a Dr. Z Carmen Ghia through a "cheapo" 1x12 cabinet (with alnico speaker) from Ruby Tubes. Vacuum Tube Valley (VTV) did the same in issue #1, Spring 1995, but I have not read their 12AX7 report. I shall do so soon, so as to compare my results to theirs.
The following list of gear is for "comparative" purposes only. This is NOT meant to plug or praise certain manufacturers. The guitar was plugged straight into the amp with a 20-foot Spectraflex cord. Volume and Tone knobs on the guitar were set to full (10).
I listened to EI 12AX7, GE 12AX7WA, Westinghouse 12AX7, Sylvania 12AX7, RCA 12AX7, JJ ECC83, Sovtek 12AX7WB, Ruby 7025-STR, German (perhaps Siemens? Only marking is "G7 L G7"), Sovtek 12AX7WXT+ tubes. I "listened" with the volume knob on the amplifier at 2 different positions - at 50% (medium) and at 100% (full).
- Dr. Z Carmen Ghia (2xEL84, 5751, 12ax7a, 5y3) through a Ruby Tubes 1x12 (alnico speaker) cabinet. As a reference, this amp has been "defined" by many as a cross between an early 70's Marshall and a Fender Tweed Deluxe. For the entire test, I kept the tone knob at the halfway point.
- Heritage Les Paul copy with Seth Lover pickups strung with D'Aquisto nickel round wound size .012-.052.
RAW DATA:EI 12AX7: When played clean, this tube was very chimey and well balanced! Very nice. When distorted, it was still chimey, but fuller. This tube had more of a high-end distortion, so it wasn't quite as balanced when played clean. Very nice and full when distorted, though.
GE 12AX7WA: When clean - seems less high-ended than the WB version (I like the WB better). "Honky" and sterile sounding. Also, very noisy! This tube was the noisiest in the whole bunch! When distorted, this tube was fuller and nicer. Probably OK when used in a Marshall at max volumes.
Westinghouse 12AX7: Balanced and not "honky" when clean. Nice. When distorted, it still retained its evenness and fullness.
Sylvania 12AX7: Very, very "honky" and middy, but not in a bad way. This tube must have higher gain than the others, because it liked to make the amp start distorting when the volume was halfway (clean). When distorted, the amp was very full. Chords were killer. Single notes were a tad piercing. A must for Marshalls!
RCA 12AX7: When clean it was a bit chimey, but also a tad "honky". Good for the neck pickup. When distorted, it was nice and very full, but still a tad "honky".
JJ ECC83: Middy when clean, but also chimey. Very full harmonic content. Excellent! When distorted, very full and still retained good harmonic content.
Sovtek 12AX7WB: Fairly lifeless when clean, not too full. Chords were not bad, though. When distorted, it was still not too "full". Single notes sounded weak and "raspy".
Ruby 7025-STR: Well balanced, decent harmonics and string definition when clean. Extremely quiet (this tube produced the LEAST amount of noise - but that is no surprise). When maxed, the distortion was higher ended like that of the EI. Mids were not as present as in the EI.
German: The only marking on this tube is "G7 L G7". Not as "dark" as the Sylvania, but definitely in that vain. Nice and chimey when clean. When distorted, this tube was very much like the EI and 7025-STR.
Sovtek 12AX7WXT+: Chimey and well balanced when clean. Very good in all pickup positions. When distorted, this tube was a bit brittle and piercing and not as full as some others.
CONCLUSIONS:The definite winners were the EI 12AX7 and JJ ECC83. Both tubes exhibited great chime when clean and good harmonic content when distorted. For my personal application, I like the JJ a bit more; this tube has found it's permanent home in the Dr. Z Carmen Ghia!
Next would be the Westinghouse, RCA, (unknown) German, and 7025-STR. Each tube had decent harmonics and balance. Distortion sounds were also nice, balanced, and full. In the case of the 7025-STR, it was very quiet.
The Sovtek 12AX7WXT+ and Sylvania come next. The Sovtek is better suited for cleaner playing whereas the Sylvania was better suited for distorted playing (Marshall Plexi).
I didn't care too much for the Sovtek 12AX7WB and GE 12AX7WA. Both tubes were sort of "lifeless" and sterile sounding.
Thanks to Kevin Miller aka "Mook" for doing the testing and sharing the results with us in alt.guitar.amps .
Last updated: 05 May 1999
Taste Test copyrighted by Kevin Miller aka "Mook" 1999. Incidentals copyright 1999 Miles O'Neal, Austin, TX. All rights reserved. Miles O'Neal <roadkills.r.us@XYZZY.gmail.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514