There are two things that I asked Jason about. One is the biasing of the Vali 3 output transistors. I asked specifically about how much is there of an Class A operation region:
“Not very much. Vali 3 really only runs about 30-50mW Class A. But depending on the headphone load, you could be running in Class A most of the time (300 to 600 ohm headphones) or not very often (16-32 ohm headphones). Higher impedance headphones don’t require as much current, so Vali 3 will stay in Class A much longer.”
While this is pretty clear that this is not a big and heavy amplifier, what we could derive from the above is that the higher impedance of the phones, the better. And the last thing, that Coherence topology:
“Yep! Coherence was actually born with Vali 2, refined with Lyr 3, and carried forward to Vali 2++, Vali 3, and Lyr+. It’s a strange topology in that it allows us to direct couple the tube gain stage to the solid state output stage, which is really weird. Usually you’ll need to capacitively couple the tube side to the solid state side. That’s what we did with earlier Lyrs and Mjolnir 2. Using capacitors in the signal path is not necessarily a bad thing, but less is better. Especially if they are relatively pricey and big film capacitors like you’d want to use in such an application. Vali 3 is just the latest version of our Coherence topology, running higher voltage than any previous Vali.”
So, this basically explains it all. What should also be mentioned is that the PSU here is a fully, “100% linear. With a very weird AC wall-wart that provides the 6VAC for the tube heaters and the 24VAC for the HV and mid-voltage rails separately (24V is transformed into 100V and 28V rails via old-skool analog tricks like voltage multipliers and then regulated.”
And before we move to the most important part, which will undoubtedly be the sound, I would like to address just a few practical things. The first one is that this thing is, I will maybe repeat myself here, really cute. I mean both the form factor and the design. And a very practical at the same time, since the small footprint makes it really useful on today’s crowded desktop spaces. There’s a gain selector that may be useful when connecting wider variety of headphones. Hiss was not an issue, at least not with IEMs like Campfire Audio Andromedas. And as for the power, we will address this in the next section, since this is a really a wider subject. Especially since I went all-out and connected really difficult to drive headphones (apart from out usual suspects like Sundaras or Devas), in this case AMT-powered HEDD Audio HEDDphone TWO. Even more, I also used this small thing as a line-level preamplifier, so we will cover that too.
Schiit Audio Vali 3 – the sound
Let me start with something of a digression here. There are actually many stereotypes when it comes to the whole “tube sound” thing. When a certain equipment sports a vacuum tube, people tend to have some expectations. And those expectations are, as you may’ve guessed it, usually based on those stereotypes that usually tend to point in the direction of more or less warm sound and that typical tube timbre that is lush and saturated. The really interesting thing here is the fact that this whole tube sound characteristics is very often imprinted not by tubes themselves, but rather by output transformers that very often colour the sound. I mention this in the very beginning of the Vali 3 sound description because while there are some tube traits in the sound, what can be actually surprising is that the general tonality of this amp is not going too much into the world of adding harmonics to the sound. Or maybe let me put this another way, and from a slightly different perspective.