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In Reply to: RE: Own a Rare First Watt VFET/SIT Amp posted by Cappy on October 05, 2016 at 08:54:04
I had a siony vfet amp, and sold it as soon as I found out the vfets were "unobtanium".
Follow Ups:
Pass Labs now handles First Watt distribution and support. I'm sure they'll keep a stock of VFETs on hand for the long term.
You can read all about it on DIYAudio.com
Its a lot of reading, but in a nutshell the SIT was available for a while as a new product, made for Nelson Pass. The company making them went out of business and it does not look like the SIT will see new production again anytime soon. It also appears that the recent stock made is nearly gone. So its back to finding NOS devices from years ago, of which Nelson managed to find quite a few.
So much in fact that he based a new kit on them. But the supplies are limited!
Very informative guys. NP is the MAN!
Are these amps similar to the ones recently used at Audio Shows?
However it is very well received and may be one of the best sounding solid state amps made. Since its also a kit, a caveat must be included- as long as it is built properly.
Exciting- I sure would like to audition one of these amps.
I am pretty sure that Nelson has someone making them for him. I don't know if they will retrofit into a Sony or Yamaha VFET amp.
Dave
Retrofit? I was talking about Pass Labs support in the unlikely case the VFETs needed to be replaced someday.
And Dave was talking about fstein's post in which he specifically says he had an old Sony VFET, so his point about retro-fitting was entirely valid.
Semiconductors are made in BATCHES, sometimes thousands at a time.
The number of devices made depends on 4 things:
1. Yield. If they get few good ones relative to the number started, that's BAD.
2. Size of Silicon wafer used. Area goes up 4x faster than diameter.
3. Economies of Scale. Batch size can be 25 wafers on UP.
4. Order size = desired number of transistors to be delivered.I'm certain that if each amp uses a dozen per, and he wanted to make 100 amps, that he'd order DOUBLE the number of devices needed.
There is nothing 'exotic' or 'weird' about the fabrication of these devices. Final cost depends on the above factors PLUS getting a mask set made, running prototypes to zero in on performance parameters and profit margins. IF the company making the devices can find OTHER markets for them and are NOT forbidden by contract, than lots of costs can be written off over a large production run.
I would NOT worry about such devices becoming 'unavailable' any time soon. Pass has a bunch of these devices in a nice, safe place. They'll last nearly forever, unless exposed to REALLY excessive temps or cosmic rays.
The linked auction and photo shows 6 TO5 devices per side. I see 2 smaller and very slightly headsinked devices per side. The 'blurb' says 2 output devices per side. Those would be the small heatsinked devices? Given class 'A' bias and all, I don't see those 2 pair being the output devices.
Does anyone have any better information?
Too much is never enough
Edits: 10/05/16
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