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What To Do With Those 2SJ28's
What To Do With Those 2SJ28's
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Old 25th April 2017, 08:37 PM   #21
Michael Rothacher is offline Michael Rothacher  United States
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What To Do With Those 2SJ28's
Quote:
Originally Posted by vdi_nenna View Post
I still don't know what to do with my vfet N/P pairs.
If you have pairs, the VFET Part 2 is the amp to build.
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Old 25th April 2017, 08:44 PM   #22
Soundhappy is online now Soundhappy  France
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What To Do With Those 2SJ28's
Quote:
Originally Posted by Nelson Pass View Post
The last generation of Sony amplifiers used SITs to cascode bipolar devices.
Funny guys , was age of engineers crazy experiments.
Mr. Pass never stops

I don't see many designs for small SIT's Sony 2SK79 , they matched pairs are available

http://www.diyaudio.com/forums/vendo...ml#post5053635

With two 2SK79 matched pair can we build useful front-end for stereo 2SJ28 DEF power amp stage ?

http://www.amplimos.it/images/2SK79_data.pdf
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Old 25th April 2017, 10:37 PM   #23
Soundhappy is online now Soundhappy  France
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What To Do With Those 2SJ28's
Quote:
Originally Posted by Michael Rothacher View Post
So, I gather there are a number of orphaned Sony 2SJ28's out there,
so let's use this thread as a scratch pad for ideas to put them to use.
Other concept is SET equivalent like in tube world.
Something to amplify antique radio oh just joke !
Anyway create from the orpfans one family.
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Old 26th April 2017, 05:31 AM   #24
kasey197 is offline kasey197
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What To Do With Those 2SJ28's
my vote goes for an antimatter vfet circlotron
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Old 26th April 2017, 07:02 AM   #25
noelectrix is offline noelectrix  Europe
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with my very cheap and little speakers (20 euro 30Watt open baffle fullrange without crossover) in my studio the ACA-amp almost beats the Vfet (wich hasn´t seen real speakers due to lack of transportable case). It quite like changes with bigger speakers, but i guess it must have to do with SE magic. So I vote for little SE-kitchen-amp
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Old 26th April 2017, 08:51 AM   #26
aspringv is offline aspringv  Australia
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What To Do With Those 2SJ28's
How about a mu follower with the sit in the driving seat and a MOSFET for the other?

... Or did I just take all the imagination out of the BAF schade design of Mr Pass? ummy:
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Old 26th April 2017, 10:46 AM   #27
wdecho is offline wdecho  United States
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Quote:
Originally Posted by noelectrix View Post
with my very cheap and little speakers (20 euro 30Watt open baffle fullrange without crossover) in my studio the ACA-amp almost beats the Vfet (wich hasn´t seen real speakers due to lack of transportable case). It quite like changes with bigger speakers, but i guess it must have to do with SE magic. So I vote for little SE-kitchen-amp
Mating an amp with speakers is the key. The little ACA with a linear supply is almost as good as the BA-1 I just finished. Almost. The V-fet is an extremely good amp with the right speakers but with my horns I lean towards a SE . A good friend with big horns loves the V-fet better. Personal preference comes into play along with the choice of music. I love SE with my horns. The exception would be my F4. Rules are made to be broken. So many more options with efficient speakers. Even a 5 watt amplifier is more than a enough.
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Old 26th April 2017, 01:08 PM   #28
liubincalvin is offline liubincalvin  Singapore
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What To Do With Those 2SJ28's
simonms told me the SIT amp with the 2sk79 pairs are quite good, so I guess STI amp would be a good build with these vfets.

A power amplifier by Shinichi Kamijo:
Amplified triode

and here is a single-end vfet amp with 2sj28/2sk79 from amplimos:
http://www.amplimos.it/images/2SJ28%20SE%20AMP2.bmp
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Old 26th April 2017, 02:38 PM   #29
Circlomanen is offline Circlomanen  Sweden
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SCHADE-BASTODE.jpg

A simple Schade feedback Bastode amp?

I don´t have any spice model for the 2SJ28, so all the resistor values is just guesstimates.

Cheers,
Johannes
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Old 26th April 2017, 02:43 PM   #30
jamahamvui1978 is online now jamahamvui1978  Viet Nam
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All Vfet
V-Fet Single Ended Amplifier - DIY - csináld magad! - AVX Fórumok
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