VTL Tetrode/Triode

That's what VTL says, although I couldn't find out exactly how the parts are supposed to differ. I also couldn't get TRT to either confirm or deny this assertion of proprietary specification for me. VTL seems to charge around twice as much for these parts as they're generally available for - assuming they'll even sell them to you at all; I've found the company is very loathe to assist in any way owners wanting to do mods on their own or hire outside tech assistance that's qualified and local to them. That VTL charges $200 more for the InfiniCap upgrade than for the MultiCap upgrade raises my eyebrows; that suggests a parts cost increase of over $16 per cap for my amps, way more than the actual retail difference - in fact, it's slightly above the InfiniCap per-piece retail price itself!

They are insistent that the cap mod be done at their CA factory, which I can understand for reasons of quality control and warranty impact, not to mention their own business. Plus, they will perform other updates if needed - such as to the fusing and certain resistors - while the amps are in, and retest them generally and provide you with updated test documentation. But for those of us who don't have a warranty with VTL anyway and live on the opposite coast (and who've already had the factory updates performed), this means shouldering 2-way shipping charges considerably north of $200 (you must ship the way VTL says) for the privilege paying the factory almost double what is commonly charged for this same job done independently. Tell your local tech that the manufacturer wants $1K (not including shipping) to replace 12 (in my case) capacitors that cost about $15 apiece retail (at $50 an hour, this would imply around 16 hours of labor, but since the job should only take about half a day for a skilled tech, well, you do the math) and see what kind of reaction you get... ;^) Add in the associated expenses, risk, and hassle of shipping, plus the extended time the amps will be away from the system, and you can understand why I'm inclined not to worry about VTL's vague claims concerning the InfiniCaps they use.

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