Vfet / SIT Amplifiers

@atmasphere 
maybe there is some enthusiasm in @kitr statement but it is not inaccurate. Most vfet amps will ride right along the top 1%-5% of the amps build new or old, in terms of sound finesse and detail.
True, none will win any races for driving difficult loads (much below 4 ohms), but for average to efficient speakers, they are extremely difficult to match by other SS amps and some of the vfet amps do just fine against vacuumed glass.

If you have the opportunity, you should try to pickup something like a B-3 or a B-2. For the B-2, I would send you something that would take care  of the "stuff" in the signal path, so that there is nothing between the rear input and the driver board.
B-2, B-3 are DC amps. Most of the ancillary circuitry is about protection, which actually works quite well, hence the high survival rate of these amps after 40+ years.

Don't worry too much about too many stages or other "old school" amp design. If you have the opportunity, try getting one and if it is still kickin' even in original condition the sound is extremely engaging. With some proper TLC, they are world-class amps.

There's no 'maybe', there is an enthusiasm in that statement :)

However, an enthusiasm or not these amps are amazing. I wouldn't call them exactly cheap, but you can hardly find anything better in their price range, or any price range really.

The only problem is, if the transistors go, you won't find a replacement, only another working amp (maybe).

What the VFETs have going for them is two things.


The first is that its possible using them to design an amplifier that will make the lower ordered harmonics (2nd or 3rd) as the primary distortion component, in enough amplitude to mask the higher orders. This results in a smooth sound and might be an order of magnitude lower than a tube amp of the same power (and lower output impedance too).

The 2nd advantage is that of soft clipping, but this is somewhat ameliorated by the fact that nearly all the designs *manufactured* employ feedback, and when you do that soft clipping isn't a thing so much.

You can build other kinds of amps that can get the same distortion signature. One key element is to insure that whatever the distortion signature is, its consistent at 100Hz, 1KHz and 10KHz. Some of the VFET designs seem to do this (so do zero feedback designs regardless of tube, traditional solid state or class D, so long as the bandwidth is wide enough).


It is nice when you get get an amp to perform that way as the improvement is easily heard and the system sound is all about the music- you can forget about the system making it.

Well, I just want to share my latest experience with the V-FET.

My mate just bought two Starkrimson monoblocks from Orchard, which are supposed to be one of the best amps out there, at any price level. So, we pitted them against the B-3s.

Weeeeeeeeeeell..... I have to say, it was really interesting. Before he came, I was wondering if I'll get rid of the B-3s and buy a new amps.

1. The Starkrimsons were certainly a bit cleaner. Nothing I'd kill for, but they were.
2. There were more details. Again, nothing to kill for, but I heard some details I couldn't with the B-3s. Which was pretty good.
3. Instrument separation was on par.
4. The imaging was miles better on the B-3s.
5. The B-3s have a bit deeper and nicer bass.
6. And the most important thing... The Starkrimsons sound so boring, it was almost painful. With the B-3s, the sound is so nice, you don't want to turn the music off, you just want to keep listening whatever you're listening.


So, the conclusion is, I am not getting rid of the B-3s anytime soon. If these two were combined, the clarity and details from the Starkrimsons and the imaging and the warmth that's coming out of the B-3, I'd get that for sure.

@kitr 
thanks for sharing and I am not surprised. The B-3s along with its vfet family produce very engaging listening experiences when in working order.
Get those B-3s fully restored, bump the bias up to 50-60mv. if you like them so much now, you will love them even more after.