VTL Tetrode/Triode

Yeah, that is somewhat strange. But everyone needs to make a living, I guess. I emailed VTL about prices but haven't received a reply yet (maybe because I bought my amp used, so I'm not exactly a priority customer for them).

On another note, I listened to Sonny Rollins "Way out West." Here is my take: Everything sounds more similar in tetrode vs. triode than on the Brahms piano trio No.3, mentioned in a previous post (maybe because that piece has more of a dynamic range?). However, track 4 (Wagon Wheels) does sound better in triode (at the same loudness settings), even ravishing, especially at the beginning, but maybe it is almost too pretty. On other tracks, especially track 1 (Old Cowhand), I can make the bass lines out better in tetrode. But from the midrange on up, triode preserves the harmonic structure a little better, and there is more air between the players (if I don't crank up my pre-amp too much).

It's almost as if triode makes the music slow down a little, and you can hear more into the internal fabric of the instruments. In tetrode, everything appears a little faster, with better rythm. I noticed I foot-tapped more in tetrode mode, and listened more closely in triode.

One thing I've been doing lately is to use different input tubes for each mode with certain types of recordings. For triode mode, the brighter, more incisive Telefunkens make a good match, while in tetrode the darker, fuller Mullards complement nicely. I agree (I think it's agree) that the Shelley Manne intros to those SR tunes generally sound more natural in triode, but when Ray Brown kicks in the pendulum swings toward tetrode...space is also presented differently in each mode, but there I tend to prefer whichever mode I'm listening to at the moment ;^)

Even if your input tubes display no audible microphonics, I urge everybody to try some sort of tube dampers here (I'm using Herbie's); for a nominal investment, you'll probably hear the amps cope better with stuff like vocal sibilants, plus truer tonality and more stable imaging, with 'quieter' spaces between performer images. Everything gets a bit less edgy and a bit more listenable, especially at higher volumes (not that transient impact is smoothed out - actually, HF transient tracking fidelity is increased, because there's less tizz and overhang). The improvement isn't huge, but neither is the cost or hassle.

Zaikesman: Isn't that a pain? Flipping a switch on the back of the amps is one thing, but unscrewing the covers, pulling out the two input tubes, and replacing them? Or do you leave the covers open? Maybe, in that case, it is not too bad.

Well, anyway, that's an interesting thought. Enjoying the music is what this is all about.

he probably leaves the tube cages off as I also do

Yep, I leave'em off, if for no other reason than I like to check the bias more often than I want to deal with the covers. But playing with input tubes is a more fun reason.

I'm also just paranoid enough that I prefer an unobstructed view of, and access to, the tubes in case one should give a hint it's beginning to act up; a few times in the past (not always with these amps) I've caught stuff out of the corner of my eye which likely saved me bigger headaches within moments - including smoke wisps emanating from around transformers - that you're not going to notice as easily with covers on. Have you ever done the jump-up and across-the-room-sprint when a tube started in with a light show? :-) And although I think the amps look better with the covers in place, I assume that heat dissipation - and therefore tube life - probably gets slightly improved running naked.