VTL Tetrode/Triode

The 6350's affect the overall sound less than the 12at7's do. It still pays to experiment, though. This is an American made tube and there are no exotic versions available, to the best of my knowledge. My favorites are the Tungsol's and the earlier RCA's. The RCA's that I have (two different vintages/two different internal construction), sound a bit more relaxed and romantic. The Tungsol's sound a bit more dynamic and alive, with a more prominent top end; this better suited my system. The differences are relatively subtle; but a definite improvement over the GE's that came in the amps. Try "Antique Electronic Supply" as a source of 6350's.

As far as 6550's go, I really don't have an opinion since my amps use 6L6GC's. I will say that the Sovtec 6L6's that the amps came with sound less refined than the NOS GE's that I have. The GE's are not a particularly great tube either, but in my system, a better sound. I hear good things about the Svetlana's; maybe worth a try. By the way as far as the 12at7's go, the Telefunken CCa (a super-premium version of the 12at7) is supposed to be THE tube for these amps. Very expensive, though.

Have you experimented with power cords? My amps definitely benefit from upgraded power cords. I use the old Tiffany "reds". Recommended by the Manley's themselves as the chords for these amps. This is going back several years, however, and I'm sure there are better cords out there for these amps, by now. The improvement over the stock chords was unmistakeable, however. Gutsier sound, with larger soundstage and more refinement. My amps also like to be placed on hard cone-type footers. The soft type makes the same a bit ill-defined and tubby. And finally, VPI bricks on the transformers are a very worthwhile tweak; the tighten up the sound, and make the spaces between instruments cleaner.

Good luck.

Frogman:

whew! I appreciate your insights. Lots of things to try out when it becomes time to re-tube, that's for sure. Right now, I'll enjoy the sound and definitely check out the power cords, and perhaps the other two tweaks you mentioned. Again, thanks!

I'll go along with the generalization of "The less complex, the more fitting the triode works". I have VTL MB-125's and tend to keep them in tetrode most of the time... I prefer the extra gusto and sheer effortlessness. I can find triode intriguing with the right mood which usually entails late nights and some smooth jazz but I'm often dismayed by the less than agile bass if I kick up the volume to any more than moderate levels. I find the increased "3D" addicting in triode but the tetrode always gives me that extra kick. Another generality, (obvious?) : the better the recording, the more it will display the virtues of triode... tetrode can rock to much less sophistication. Oops, does that make me some kind of "Common Joe"? Oh well. Just for the record, my good friend runs his MB 450's (I've got my eye on those someday) and his Wotans (2 separate systems) in tetrode virtually all the time. "Too syrupy", and "not tight enough" being his opinion... . It's sure nice having the option though isn't it ?!! Good listening.

Hi Lissnr:

All larger-scale works that I have played on my VTLs do sound better in tetrode, I agree there. For instance, with a Beethoven symphony (try Karajan's 1963 cycle with Berlin Philharmonic, 9th), triode just can't match tetrode's steady grip, with a totally steady soundstage, all instruments staying in their places, just like you would hear in the hall, especially when the chorus comes on in the last movement.

But listen to some small-scale jazz or classical, and triode just is more real. I attend live music performances quite a bit, and to my ears, there is no contest.

In fact, with tetrode on smaller-scale music, one loses the inner detail, the beauty and air around instruments, and the ambience of the recording venue. It sounds flatter and less involving.

But to each his (her) own. I just wished VTL would make the switching less of a pain. Always having to turn off the amps before switching is inconvenient, to say the least. And they should either have the switch on the front panel, or have an indicator light for triode mode. That would be nice.

I understand the new Siegfried amp does automatic switching.

Try listening at reduced volume, and I think you will find that triode has a decided advantage over tetrode, even with large-scale, complex orchestrations; the issue is simply that to unravel and amplify a complex signal, more power is needed. It's not that tetrode ever has an advantage, per se, it's that when the music is more demanding, the extra power makes up for any loss in transparency that triode provides under ideal circumstances (higher speaker efficiency). Conversely, try turning the volume up, higher than normal, while playing small cale jazz or classical. I think you will find that you lose the detail and purity.

I think that we can all agree that filet mignon is a better cut of beef than sirloin; but if the budget only allows for one pound of filet, and we are trying to feed six adults, would it not be more satisfying to buy two pounds of sirloin, than one pound of fillet. Poor analogy, perhaps, but the point is that I think that if you were to compare tetrode to triode, using something along the lines of a Klipsh corner horn with it's extraordinarily high efficiency, it's unlikely that there would be any advantage to tetrode mode; unless, perhaps, if you were trying to fill some incredibly large space with sound.

By the way, it is not necessary to turn the amps off to switch between the two modes. You simply have to be sure there is no signal running through them: mute the preamp.