VTL Tetrode/Triode


I'm just curious if any VTL amp owners (I have a MB-450) with triode/tetrode switchability have any preference for one or the other mode, depending on the type of music one is listening to.

Even though some music is a no-brainer (e.g., a Mozart piano trio sounds much better in triode mode, and a Mahler symphony sounds better in tetrode), sometimes I'm hard pressed to choose. Small-scale jazz or blues can sound good in either mode.

Any thoughts?
hgabert
I'm sure Mejames is right about the 750's, and the comparison is a little unfair not only because of the added power, but also because the Reference amps have an improved input amplifier circuit topology and power supply, not to mention the better parts. Upgrading the coupling caps in my 185's is probably the next step, although going to 250's or 450's could also be in the picture eventually (the Ref amps are too big and too much money for me - and besides, I like to think I can and should be happy without having to have the best :-)

The tube swap to KT-88's requires nothing more than installing the new tubes and biasing as normal. (This is not the case for KT-90's, which need resistor changes.) The driver 6350's are the same as always (there's not much to choose from with this tube, NOS being tough to come by and limited to just a couple of options I believe). I've played with several different input tube varieties of 12AT7's - maybe I'll do a thread on the results sometime.

About your comment that "small-scale" music shouldn't present very taxing power demands, just today I did some comparisons between tetrode and triode using Sonny Rollins' "Way Out West" MFSL CD. Jazz doesn't get much more intimate than this: just a sax, bass fiddle, and a small trap set with a little percussion. No chords at all, and the tunes are taken at easy tempos and volumes, with plenty of space left in between the notes. Still, there are differences to be heard when listening between the two modes - even at moderate levels - that could relate to power, such as bass control and dynamic range. As ususal, those catagories go to tetrode, while overall naturalness of timbre, particularly from the low midrange up, goes to triode. Which presentation sounds more 'real' is a bit of a toss-up, depending on what sonic qualities you prioritize.

I think that to approximate reproducing the true sound of any acoustic instrument or voice, no matter how delicate the music or spare the arrangement, still presents an enormous challenge to any power amplifier, and I tend to agree with VTL's position that a lot of the inevitable compromise is simply related to a lack of available ultimate power. The task, of course, is to make a power amp that can deliver the needed level of clean power and yet do it instantaneously and with good musicality. I guess VTL probably does as good a job of trying to give us this as anybody, but there's a price to paid both monetarily and in size/weight/heat/appearance, and besides most speakers can't take full advantage of dynamically unlimited amps anyway. Most audiophiles will never attempt this, and the SET/horns crowd would pooh-pooh the notion, but my suspicion is that a home 2-channel system utilizing several thousand watts of multi-amped power would not necessarily be overkill strictly from a sonic accuracy standpoint. (You here Sean?... :-)
horsepower wars in sound reproduction, man how reality changes. I remember in the early 80's when i played in a loud rock band (we're talking marshall half stacks running 3/4 by the end of the night)and all we had driving the vocal mains was a lowly crown dc 300 that need a fan blowing over pitchers of ice to keep it cool enough to run. The last band i was in was a pretty quiet blues band and we used almost six thousand watts a side for the mains. My home system is the same deal, i'd love a mb750 for my 14 by 22 room and i'd probably play it quiter than my high school system of klipsh cornwalls fueled by a crown d 150. Headroom is a good thing.
My MB-450 have the MIT caps, I'm not sure if they differ a lot from infini caps in terms of sound reproduction.

I agree, power reserves are crucial. (I just find it astonishing that 220 watts for small-scale music might not be enough). However, all of the clues certainly point in that direction. And I'll give the Sonny Rollins "Way out West" a spin as well in both tetrode and triode. That should be interesting.

So, what to do? Get the MB-750s, or more efficient speakers, or keep everything the same and listen to tetrode mode? The audio hobby just doesn't appear to have an end to it.
Hgabert wrote My MB-450 have the MIT caps, I'm not sure if they differ a lot from infini caps in terms of sound reproduction.
my reply was "If your VTL doesn't have the infini caps currently I would highly recommended you get them installed they are a rather significant improvement in my system for sure." my amps had MIT caps they sound like completly different amps now much better everywhere with infini caps.
Mine don't even have the MultiCaps (MIT caps), they just have the yellow "VTL" caps. I'm trying to decide whether to go with the InfiniCaps, as VTL uses, or the DynamiCaps, both of which are made by TRT. I described where I was sonically and where I wanted to go to both Peter Moncrieff (the manufacturer) and Michael Percy (the retailer) and they unanimously recommended the slightly more expensive DynamiCaps, but that was before I switched to the KT-88EH's and made some changes regarding the input tubes (including adding tube dampers) which went a ways toward addressing the brightness I was hearing in tetrode. VTL officially prefers the Infinis, while Moncrieff's comments seemed to imply that they were flatter in their response than the DynamiCaps, which from his description sound like they're probably a bit more 'tailored' in their response, but in a way that he apparently thinks better serves the music in many circuits and systems...scary choice ;^)