VTL Tetrode/Triode

When I first got my MB-450s, I played around with it. I managed to make it a difficult lean to get around to the back of them so I have since usually switched only once every couple of months - usually when I'm listening to large scale symphonic works or opera. The rest of the time it stayed on triode.

Recently I got a pair of MUCH more efficient speakers so have no use for the added "stomp" that tetrode provides.

FWIW, I agree that piano and almost all single instrument classical or chamber music, jazz, and vocal is better done on triode. Tetrode really shines with music with "impulse" dynamics - things like Holst's Planets, Beethoven's Fifth, above-mentioned Mahler symphonies, and good feisty operas (Carmina Burana, Don Giovanni, etc).

I agree with your assessment. There are some surprises, however. For example, certain Reggae pieces (Bob Marley, Rastaman Vibration) sounds better in triode, not tetrode (as I originally thought it would). Vocals are a lot clearer, and it sounds more real, live.

On the other hand, take Vivaldi's Four Seasons with Salvatore Accardo on Philips, and it sounds better on tetrode (more liquid, smoother, soaring highs on the massed strings), at least to my ears. Weird.

Hi Hgabert

In my experience (Manley 200/100 Mono's, very similar circuit to your MB's)), in absolute terms, the amps always sound better in triode: much more refined sound, better detail, less grundge, etc., etc. Tetrode becomes advantageous when your system, wether because of your speakers' efficiency, or your preamp's gain characteristics, benefits from the extra power. If your speakers are efficient enough to meet all of the needs of every type of music that you listen to, at every loudness level that you listen at, with the amount of power that triode has to offer, triode may always sound better to you. It sounds like they are not; few are.

I found that in my system, with many speakers, tetrode not only allowed the speakers to play louder, with more bass, but more importantly, it let the speakers unravel complex orchestral passages, it let a string section sound like many individual players as opposed to one large mass of "string" sound; probably why the Vivaldi sounds better in tetrode. Most reggae, while "bassy", is not particularly complex music; so will probably tax the amps less. The problem became that I missed the purity and sweetness in the highs that triode offered. The solution for me was two-fold: get used to listening at slightly reduced volume; this taxed the amps (and my hearing) less, in triode mode, and experiment with the input tubes. I found that with the right NOS 12at's (for me it was W.German Amperex or Tele's), there was enough of an improvement in the detail and treble extension departments, in tetrode, to bring the sound close, if not quite, to the level of triode sound with run-of-the-mill 12at's. This allowed me to enjoy tetrode mode when I absolutely had to have the extra watts. Of course, the sound in triode became that much better also; and this is why it is called "audiophilia nervosa" :)

Good luck.

Hi Frogman,

thanks for your response. I'll try the German Amperex or Telefunken 12AT7, that's a good idea.

But what about the 6350 tube (phase splitter)? Any suggestions there?

And the output tubes (Russian 6550C) are probably ok, right? (I don't think you can change them anyway, even if you wanted to).

Right now the rule of thumb for me is: Anything from solo instrumental, up to seven or eight players, use triode. Anything above, use tetrode (this is also what T_bone mentioned above).

BTW, i use B&W N803 speakers (90 db sensitivity).