Switchable Tetrode - Triode please explain

It's all inside the tube logic:

Tetrode mode is needed when the dynamic music needs to be reproduced: large orchestras, brass bands and has certainly larger gain than triode.

When the triode mode is used when you need maximum transparency listening to the small instrumental bands, vocals.

Also VTLs having that switchable feature can be used to match different types of speakers depending on their efficiency.

Do not forget to turn it completely off before switching modes!!

The tetrode tends to give the music a more forceful, forward presentation. It also has more dynamics and deeper bass in Tetrode. Triode, on the other hand, may be a bit more laid back and at first may not seem as seem as appealing. Give it a chance. I have been spending a fair amount of time listening to small jazz ensambles and acoustic blues in triode and the sence of realism and of "being there" cannot be matched by the tetrode mode. Acoustic instruments are 3-d and the vocals seem a lot more real. I also get a better sence of the room environment the recording was made in in triode. Triode also works well with string quartets....basically acoustic music in general. The dynamics in triode mode won't take you by storm but if you are critically listening the triode should bring a smile to your face with the less dynamic music. I've left it in triode for some large rock band CDs and it fared well there. As far as using it to match speakers with the amp, i'm not too sure about that. Its an apple and oranges thing. The two different modes produce a different feel to the music as a result of how the tubes work and the amount of power produced. Since triode produces less power it may not work as well with low efficiency speakers if you have a low power amp but if you have a pair of Wotons i really don't think it would matter what speakers you used with what mode. I'm actually starting to think about the VTL 250 triodes. I have the VTL 185 signatures and the 5.5 pre-amp driving a pair of dunlavy athenas now. It's an easy audition so check it out but do power down first or you will fry some tubes (watched the guy at the local shop do just that).

Hi Weiserb; would you mind telling us what differences in sound quality/character you've noted when switching from tetrode to triode mode(s) with your amp? And maybe what speakers you're driving with it? I've been thinking of the VTL 150 myself. Thanks. Craig

why do you have to power down to switch? i can switch mine back and forth without missing a beat. triode is less rated power but i have found it to sound even more powerful than tetrode.

I agree with Kirk930. I have found that triode mode, even though it has less actual rated power, generally sounds more dynamic than a tetrode. It is similar to the way a 300B triode at 7W can sound more dynamic than a 35W push-pull.

I listen to mostly symphonic works and find my 7W Amp more than dynamic enough with my speakers (91db)

Sibelius