My buddy Ross was nice enough to lend me several preamp tubes to test in my Genz BenzShuttleMAX 12.0. I had done some reading online that led me to believe people had heard a real difference with replacing the stock tube. Others have said that due to design, there won’t be much difference. Having screwed around with preamp tubes before in other pieces of equipment, any differences I’ve heard in the past have been very subtle. But hey, why not kill a few hours and see.

Long story short, the ShuttleMAX was no different. I imagine it’s partly due to the circuit design. I had hoped to find a combination that allowed for earlier breakup and more overdrive. There was a more noticeable difference with one of them, but all things considered, I’ll probably just stick with the stock tube.

I still think it was a worthwhile exercise as it cured my curiosity, and I was able to capture each tube change sonically. The candidates were as follows:

  1. Stock (I believe a re-branded Ruby)
  2. Fender 12AX7
  3. JJ ECC83S
  4. EHX 12AX7
  5. Tung-Sol 12AX7
  6. TAD 12AX7A-C (Tube Amp Doctor)

The recording was done with my Warwickcustom shop Thumb BN 6, into the ShuttleMAX, DI out into my Echo Layla 3G, into Cakewalk Sonar. For each recording, I used the low and high gain settings on the Benz tube channel. The exception of course was the FET channel, which was really just for reference. I decided to play along with a drum track, as I personally find reviews of bass gear where it’s onlythe bass to sometimes be useless. Not to mention I’d rather be playing with a drummer than without. The little ditty is something I came up with on the spot, in order to cover three styles to try and coax more out of the tubes; slap, slow heavy finger, and fast aggressive finger. With all three I tried to throw some chords in, and I also tried to get all six strings in. Each take is one shot, as I wasn’t trying to make anything perfect, just capture the moment. This is most noticeable with the switch-up on the ending triplet figure…it’s at a pretty spirited pace ;)

The amp was EQ’d as pictured in the photo (both channels), which is what I’ve typically been using live lately.  The only thing not accurate in the pic are the gain and volume settings.  I decided to leave the tube channel gain at max, as it was the most likely setting for getting overdrive.  I adjusted the volume on the FET and tube channels so the output into Sonar was relatively the same.  When engaging the high gain switch on the amp, I adjusted the incoming volume on the Layla so as not to mess up the gain from the amp.  I marked my low and high gain settings on the Layla in order try and return to the same position for each tube swap out.  It also tended to preserve the gain differences between each of the tubes, which there was definitely some. 

The mixed down tracks don’t have anything else on the bass, except a limiter to keep the signal from hitting 0 db, and just some slight compression on the drums.  The files were exported as 16 bit wav, POW-R 2 dither, then bounced to mp3 with CDEXat 320 kbps fixed, 44100 Hz (to get the file sizes down).

The tracks:

  1. FET
  2. Stock tube, low gain
  3. Stock tube, high gain
  4. Fender, low gain
  5. Fender, high gain
  6. JJ, low gain
  7. JJ, high gain
  8. EHX, low gain
  9. EHX, high gain
  10. Tung-Sol, low gain
  11. Tung-Sol, high gain
  12. TAD, low gain
  13. TAD, high gain

The only real differences I noticed?  The Fender was fizzier and a bit more overdriven, and the TAD was smoother overall.  Both cases were most noticed at high gain.  There are minor differences between all of them in my opinion, but nothing earth shattering. There’s some additional discussion over at Talkbass here: 5 tubes tested in the ShuttleMAX 12.0

Having said all that…I’m probably just going to stick with the stock tube!