First taste of Papa's new devices

jacco vermeulen · 2011-09-15 7:50 pm

Nelson Pass said:
By the way

Pronounced in Ruskian much nicer as SHJEET (CИT) :clown:

(Yamaha datasheets say SIT, Sony preferred V-FET)

Jon Lord · 2011-09-15 8:41 pm

A short V-FET/SIT story

Indeed very nice !

Yamaha and Sony also marketed the amplifiers as VFET or V-FET amplifiers, this is strange but also understandable.

The name "Static Induction Transistor" was certainly created by a genius in Physics but not by a good English speaker.

There is certainly nothing static inside, nor is electromagnetic induction taking place in the traditional sense (But Nishizawa probably already envisioned GHz-Applications ..).

He probably wanted to say "Electrostatic Field Induced Voltage Transistor" "EFIVT" but ended up with "SIT". I'm sure the marketing people at Sony and Yamaha understood the principle quite well, but spoke a better English,and thus came to the point.

Nishizawa also wasn't really the inventor of the SIT, this can rather be attributed to Julius Edgar Lilienfeld, who filed a patent on the idea in the late 1920ies, just about 20 years before some future Nobel Price winners at Bell labs discovered the bipolar transistor, by trying and failing to implement Lilienfeld's idea ...

Strange also that patents expire exactly after 20 years, isn't it ?

What's wrong with the following sentence:

"SITs are a paticular breed or Power J-FETs like Triodes are a particular breed of Power Pentodes"

Jacco, we should get in contact, V-FET-lovers should unite !

Sorry for robbing this thread ! I get the V-FET blues from time to time ...

Zen Mod · 2011-09-15 9:08 pm

jacco vermeulen said:
Pronounced in Ruskian much nicer as SHJEET (CИT)

(Yamaha datasheets say SIT, Sony preferred V-FET)

so - you can use some drek voltage-augmented sillyfunnysmallcurrentcrippled F5 ( or simply cascoded BA3 FE) and use it as FE for superdupersimple complementary SIT amp .

w./wo. servo

simple , iyam .

:clown:

Jon Lord · 2011-09-15 9:32 pm

Yes indeed, what did you think !

In order to avoid biasing problems, just explant all electronics from a readily working F5 and implant a Hiraga V-FET Class A circuit using NEC or SONY V-FETs or some circuit from Evolve (Japan), this will be fun ...

OK some of us posted in the wrong forum

Our all father :santa:

should forgive us our sins :angel:

Nelson Pass · 2011-09-15 10:37 pm

Jon Lord said:
Nelson,

Please find enclosed a picture, which shows the two dies of an opened 2SK82.

I also appended a list with V-FET data I collected in the past. Please don't see the data to be definitive or up to date.

Cheers for that. Interesting, I actually have a sheet that calls it out at
4mm die and 65 watts. Since I have a small supply of these, I'm perfectly
happy with 95 watts.

To my mind though, SE Class A is the raison d'etre for SITs, and is
where they really shine, although the 2SK82 has pretty low gain driving
8 ohms common-source. My SIT-1's have a pretty good balance on that.

I have some nice push-pull and se follower examples, but nothing else can
deliver voltage and current gain with a high input impedance, low output
impedance and good distortion without feedback and/or degeneration.

Zen Mod · 2011-09-15 10:53 pm

vdi_nenna said:
In that case, would a BA-3 front end and a single-ended all Jfet R063A or R100A power stage be possible? They have 500 and 1200 pF input capacitance.
Or, will that be the BA-4?

if you want to use high gain FE ( as BA3 FE is ) , you must use follower on output

Jon Lord · 2011-09-15 11:47 pm

Thank you that you forgave me ...

I don't like to imagine, how much your "little supply" is, if you invested a few $100k in SIT-1 ...

Since they are very much like Triodes, SITs certainly also shine, where Triodes shine and this can be SE-Class A, no question.

But they also shine at places, where thermionic Triodes tend to fail: They were available complementary (at least some of the classics) and they didn't need output transformers, which gave new possibilities for simple thinking developers, possibilities which at least were partially used.

You really should give a refurbished TA-5650 a try, only the power amp stage (the pre amp is sh.t). For me the SIT devices show also something magical in these rather simple 70ies topologies.

Don't forget these Classic V-FET amps run in Class B in the sense of minimum combined output gm variations (300mA .. 500mA Bias current in such an amp is pure Class B, thanks to the low inherent gm). Here Class B works better than in any other amp: The devices are almost free from switching delays and the bias is almost totally temperature independent, a feature Class B and Class AB designs of today still can only dream of, with their thermal induced distortions, carrier storage, gm-doubling etc..
This distortion reduction effect is even existing with complex loads, a thing, which can't be said about SE-Class A, where IMO distortions can only be minimized for a given, preferably pure resistive load.

For me the fact, that with these transistors a smooth sounding and revealing Class B operation without any annoying crossover distortion and pretty high power is possible, sounds even more promising than their potential in the direction of SE-Class A with a very few Watts, but this is my personal taste.

Michael Rothacher · 2011-09-16 12:27 am

I have a few hundred hours on mine by now and I expect they'll still be in service long after we've all moved on to the next big thing. They've certainly given me more than $48 worth of fun already. I always buy a couple extra for personal warranty stock. This is DIY and we are ABFAB.

Jon Lord · 2011-09-16 1:38 am

Michael,

I didn't bring up another aspect, which makes me angry and afraid as well.

These devices might work on a DIY basis, but unfortunately building them into DIY projects on a "hype basis" and hunting after a new "Fashion" a few months later, lets the people, who really need them (Owners of the original amplifiers) left with no spares available anymore.
You should think about it like follows: The existing classic amplifiers already made indefinite (>30 years) listening fun to their owners and they will do another 30, if the spares are not depleted by DIYer and DIY pack rats. This track record will never be reached by any DIY, First Watt and PASS Labs project.

$48 might be OK for one pair, but for a destroyed TA-N88B you need two pairs per channel ! These classic amps are worth to preserve them, but some day nobody can afford anymore spares for these, or the spares are completely depleted.

I would even bet, that any classic V-FET amp sounds better than your single ended designs, but this is only one of my lesser fears ... :bawling:

From my point of view DIYers using the complementary classic V-FETs are wasting a precious resource by playing around with half cooked stuff for fun and burning them away in festivals of the very same name ...

Why don't you or Nelson bring the SIT-1 to all us DIYers, that we don't need to flee into "substitution drugs" like the precious and scarce Classic V-FETs ?

Woudn't that be fair for everybody:

- The SIT-1 is seemingly the better transistor
- You help to push a new audio hype (SIT and SiC) much faster
- DIYers find spares for their SIT projects, if they need them ...
- The DIYers keep their hands away from precious spare parts for Sony and Yamaha amplifiers.
- People like me, who are Hifi collectors and DIYers, would be happy twice.

But this will be only a dream, at the end not "DIYer's fun" will prevail, only commercial interests and a self made monopoly will be left over.

If this appeal does not help, probably the following one:

Buy you a Sony TA-5650 for $200, tweak a little bit on it and have pure listening fun, these V-FETs are enjoyed best in their natural environment !

You or NP can send me a PM, if a further discussion is OK.

NYCOne · 2011-09-16 2:25 am

Jon Lord said:
Michael,

I didn't bring up another aspect, which makes me angry and afraid as well.

These devices might work on a DIY basis, but unfortunately building them into DIY projects on a "hype basis" and hunting after a new "Fashion" a few months later, lets the people, who really need them (Owners of the original amplifiers) left with no spares available anymore.

This concept is no borne out in audio or any other area of life. The price of VFETs may change, but that's going to happen according to need whether DIYers or Sony owners want them. If the price gets high, folks "find" these devices sitting in basements or attics in defunct amps, or perhaps a box that was taken home from a lab.

Additionally, who's to say a Sony owner has more "right" to a VFET than a DIYer?

While free markets can have sharp edges, they work.

Michael Rothacher · 2011-09-17 1:43 pm

Jon Lord said:
Michael,

I didn't bring up another aspect, which makes me angry and afraid as well.

A lot could be said here, but you seem like a very friendly and knowledgeable person who is clearly passionate about the classic V-FET amplifiers.

But honestly, you vastly overestimate my influence and the size of my readership.

That’s really all I have to say about that. I think we’ve jumped the shark, so let’s return to our fun discussion about these awesome new devices.

Nelson Pass · 2011-09-17 7:01 pm

Whether or not these single-stage no feedback efforts sound don't sound as
good as the original designs would be a subjective judgement call. I don't
tout them as operating in the same performance domain.

Just as likely that current interest in these devices will renew interest in the
old Vfet amplifiers. It is not likely that Sony and Yamaha will take notice,
but new versions of the Yamaha parts exist now (I have a few), and there
is a decent stock of NOS Sony parts. More of my parts or other variations
can be made - it just takes $$$,$$$.00

In any case, what is of interest to me is that SITs are just about the ideal
sort of part for the Common-Source mode minimalist no feedback
amplifiers that I find interesting. They beat the crap out of every other
single-transistor amplifier I have made, and you can't even try this with
triodes.

Everyone who has heard them so far has been pretty amazed, and some
of these people are not fans of little simple amplifiers.

Michael Rothacher · 2011-09-17 8:39 pm

The PASS-SIT-1 is probably one of only a few parts with the right specs to build a practical single stage amp with a selector switch for zero feedback, degenerative feedback, and loop feedback.

Of course, I realize that's not the point, but has it been done experimentally?

tiefbassuebertr · 2011-09-18 10:40 am

jacco vermeulen said:
Pronounced in Ruskian much nicer as SHJEET (CИT)

(Yamaha datasheets say SIT, Sony preferred V-FET)

In which electronic magazine you have found this?
perhaps in the magazine "Radiohobby" (Радио хобби) - go to post #13 about
http://www.diyaudio.com/forums/soli...rrently-available-electr-audio-magazines.html

Nelson Pass said:
In any case, what is of interest to me is that SITs are just about the ideal
sort of part for the Common-Source mode minimalist no feedback
amplifiers that I find interesting. They beat the crap out of every other
single-transistor amplifier I have made, and you can't even try this with
triodes.

For me it would be of interest, in which kind the audible differences were noticeable, e. g. against a good designed "ZEN" ?
Was compared at the same speakers and at the same power supply?
Independend of this results perhaps I must modify several exist "ZEN" power amps like that one from
http://www.diyaudio.com/forums/pass...itional-op-amp-ultimate-sounding-phl1230.html
And what about Andrea Ciuffoli's power follower about
http://www.audiodesignguide.com/my/Follower_99c.gif ???

An explicit comparable amplifier test that used SIT and ordinary IRF's in both "common source" and "source follower" topology highly appreciable.

jacco vermeulen · 2011-09-18 1:37 pm

tiefbassuebertr said:
In which

Not magazine, top part of page 195 of pretty OK bookie.

Nelson Pass said:
what is of interest is that SITs are just about the ideal sort of part for the Common-Source mode minimalist no feedback amplifiers

Minimalist altogether is probably the key word.

vdi_nenna · 2011-09-19 8:18 pm

I got a quote from jack at electa-print @ $150 each.
How close does the Nemisis get to the S2 in sound quality, not as interested in power comparison. How much can the arch Nemisis evolve?
I ask because my next step is to grab some R085s and/ or R100a jets.

tiefbassuebertr · 2011-09-19 10:09 pm

Tea-Bag · 2011-09-19 11:39 pm

The SJEP120R063A is just a R100 on steroids, with somewhat more input capacitance - about twice the cost.

ra7 · 2011-09-19 11:51 pm

What are you guys' thoughts on the R550? Anybody got any listening time on it? It is listed as an option in the Arch Nemesis, with not too bad distortion numbers. It's the cheapest option at Newark and I'm hoping to get two pairs for less than $50 to get started.

Nelson Pass · 2011-09-20 1:15 am

The R550 certainly has the most bandwidth, particularly if your want to drive
them from a higher source impedance.. If I were to try describing the
difference, I think I would say that the R550 leans in relation to the
R100 somewhat in the way a lateral Mosfet leans in relation to a vertical.

It certainly is worth trying, and I bought a few, but I bought a thousand of
the R085's because I can get lower distortion out of them.

First taste of Papa's new devices

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