Successors for V-FET SONY-Yamaha-TOKIN 2SJ28, 2SJ18/2SK60, 2SJ26/2SK76 and 2SK180 - Page 4 - diyAudio
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Old 14th April 2010, 07:44 AM   #31
tvi is offline tvi  Australia
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Digital-Do-Main go to the trouble getting the devices made for them, their patents mention a company called SYSTEC KK as co-applicant.
Could be: Systec Research, Inc

Some of their patents
Dual Static Indution Transisitor in Adjacent Arrangement Within Chip & Power Amplifier Circuit for Audio Using the Same

Push-Pull Using Static Indution Transisitor of the Same Conductive Type

Current Setting Circuit of Power Amplifier Circuit Using Static Indution Transisitor

And this might be of interest
High Speed, High Voltage, and Energy Efficient Static Induction Devices

Rgds
James
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Last edited by tvi; 14th April 2010 at 07:47 AM. Reason: formating
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Old 31st May 2010, 06:58 PM   #32
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Quote:
Originally Posted by roerdomp View Post
The extremely rare 2sj28/2sk82 for the TA_N88b and the 2sj18/2sk60 are offered on ebay all the time. I own a ta-n7b working with the 2sj18/2sk60 ranking 52 and 53 and works perfectly. So are the even rarer sansui Ba-1000 NEC v-fets (2sj20/2sk70). My Sansui Ba-1000 has been slightly modified to work great with sony 2sj18/2sk60 v-fets.
At my opinion it would be the best way to emulate the V-FETs with today's available parts.
Anywhere a discrete op amp was created with same PCP surface sizes than a normal integrated version (somewhere here on the forum has been explicite reported, but I don't know the exactly title of the subject)

Actually the same must be possible for the vintage V-FETs.

The PA02 e.g. from Apex Precision Power offers IC's in a TO-3 like outline:
http://www.cirrus.com/en/pubs/proDatasheet/PA02U_O.pdf
I read here, that this are no monolitic versions but thickfilm-technology, that is similar to SMD
PA02 pdf, PA02 description, PA02 datasheets, PA02 view ::: ALLDATASHEET :::
Some pics of this devices you will find by post #4 about
Thick Film Hybrid (not monolithic) Integrated Circuit Amplifier - Overview

If I order this Apex TO-Devices empty (i. e. without their thickfilm-PCB) and I have a circuit topology that create the right character so as appropriate power SMD FETs for solder on the TO3 die surface to get the typical V-FET Characteristic by higher realibility at the same time, then I have a good solution.
Ideal must be a jFET from Lovoltech together with cascode MOSFET/IGBT, but a commonly power MOSFET (even enhanced mode version) with Sziklai cascode consists of small signal 2SK170 jFET & BjT + BjT HV cascode transistor must us also bring to the wished targed function.

All the other possibilities have the disadvantage, that the Sony devices are hard to find and if I have success, I get still used devices.

Last edited by tiefbassuebertr; 31st May 2010 at 07:09 PM.
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Old 31st May 2010, 07:52 PM   #33
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I have been playing with some of these parts. When you
talk about using or emulating them, the key question is "What
characteristic of the Vfets or SITs is of greatest interest to you?

For me, it is the characteristic of the output (Drain) conductance.

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Old 1st June 2010, 09:04 AM   #34
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Quote:
Originally Posted by Nelson Pass View Post
I have been playing with some of these parts. When you
talk about using or emulating them, the key question is "What
characteristic of the Vfets or SITs is of greatest interest to you?

For me, it is the characteristic of the output (Drain) conductance.


I would generally prefer that characteristic, that makes at one hand expect nearly the same distortion behavior, but at other hand the least possible change in the amplifier topology itself (concerning the model, which is to repair).
The fact, whether the threshold voltage (Vgs) is in the positive or - as in the original V-FET device - in the negative area is located, is less important.
Much more important is an quite identical curvature of all transfer characteristic curves itself - this is the main challange - so I think.

Last edited by tiefbassuebertr; 1st June 2010 at 09:07 AM.
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Old 29th December 2010, 04:21 PM   #35
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New SONY V-Fet reliability problem discovered ! - AudioKarma.org Home Audio Stereo Discussion Forums
I read by last post #19 from "Mr. V-FET" follow (written five years ago):
V-Fet emulation:
I worked on that for a while and I found that it is possible to
bring a 150W V-Fet emulating circuit (including a MOSFET as power device) completely into a TO-3 can.
But the end price for such a device would end up at perhaps 50$ per piece at 1000 pcs.
Who would be willing to pay such a price for a 150W transistor ?
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Old 29th December 2010, 04:28 PM   #36
Telstar is offline Telstar  Italy
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I would if they would be closely matched by production.
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Old 4th January 2011, 01:52 PM   #37
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Quote:
Originally Posted by tiefbassuebertr View Post
about
New SONY V-Fet reliability problem discovered ! - AudioKarma.org Home Audio Stereo Discussion Forums
I read by last post #19 from "Mr. V-FET" follow (written five years ago):
V-Fet emulation:
I worked on that for a while and I found that it is possible to
bring a 150W V-Fet emulating circuit (including a MOSFET as power device) completely into a TO-3 can.
But the end price for such a device would end up at perhaps 50$ per piece at 1000 pcs.
Who would be willing to pay such a price for a 150W transistor ?
The diyaudio member Jon Lord tell me similar conditions concerning V-FET's from SONY and Yamaha, but however - he is also able to do this - go to #145 about
Densen amp
to look his profile
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Old 18th September 2011, 10:01 AM   #38
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Quote:
Originally Posted by tiefbassuebertr View Post
are there successors from currently production in the meantime?
in this case this thread could be of interest:
First taste of Papa's new devices

The brand "Power Integrations Inc" about
http://www.powerint.com/en/design-su...lication-notes
is able to create intelligent MOSFET's like follow example for switching applications:
http://www.datasheetcatalog.org/data...int/TOP202.pdf
This means for me, that this brand is probably also able to introduce intelligent V-FET's, suited as improved successors for all V-FET's from Sony, NEC and Yamaha, but with very enhanced reliability in all respects.
In opposite to the old ones there must be a "built in" protection.
The question is only, which quantities for order are at least necessary so as wich flate rate costs for the singular developement costs.

Last edited by tiefbassuebertr; 18th September 2011 at 10:18 AM.
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Old 21st September 2011, 11:12 AM   #39
Shinja is offline Shinja  Japan
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Hitachi's HA-500f employed 2sj20/2sk70 too.
HA-500f is more rarer than sansui's one even in japan.
I have gotten and maintained it but sold at auction yet.

Hitachi discontinued V-FET soon because they invented famous MOS-FET 2SJ50 2SK135 series...
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Old 21st September 2011, 12:58 PM   #40
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Quote:
Originally Posted by Shinja View Post
Hitachi's HA-500f employed 2sj20/2sk70 too.
HA-500f is more rarer than sansui's one even in japan.
I have gotten and maintained it but sold at auction yet.

Hitachi discontinued V-FET soon because they invented famous MOS-FET 2SJ50 2SK135 series...
mean you this amp from Lo-D ?? - go to follow URLs:
Lo-D HA-500F
http://audio-heritage.jp/LO-D/amp/ha-500f.html
http://www.niji.or.jp/home/k-nisi/ha-500f.html
http://www.hifidiy.net/index.php?act...ead-tid-337714
http://www.real-audio.ru/measurements/shop/s-amp.html

Last edited by tiefbassuebertr; 21st September 2011 at 01:04 PM.
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