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juma 5th June 2010 11:46 AM

F5 with 2SK2013/2SJ313
I got interested in Toshiba's 2SK2013/2SJ313 MOSFETs last year when estman, a forum friend, sent me generously a set of dozen j313s. They impressed me with their superior linearity of transfer characteristics but not until recently (when I got the N-channel complements - k2013) I could not try them in classical push-pull circuit.
Using them in F5 (3 pairs per channel at +/-20V, 400ma per MOSFET for total bias of 1.2A per channel) transformed it into amp that leaves no wishes open.

Schematics and pics are here:
Novi amp sa 2SK2013/2SJ313 -

jacco vermeulen 5th June 2010 01:49 PM

I'm sure the Mastah will also enjoy your creativity.

Can't help mentioning the 6 amp peak output current limit, 5 pairs would be costly but balance the SK56 more, which is also expensive.
(If Dorian Grey would still be around he'd likely start a lengthy itinerary about 10 pair/ch balanced TXF5. :clown: )

:Olympic: Bravo again, the dirty dozen rules the forum galaxy.

EUVL 5th June 2010 02:02 PM

Maybe we should also try 100 pcs ZVP/ZVN3310 in parallel ....



zhoufang 5th June 2010 03:57 PM

Just like other Japanese trannies, they are actually quite cheap if you buy in sufficient quantity.
The price of this pair I get from Avnet is even quite a bit cheaper than IRFP240/9240.
So everyone should be able to easily afford a dozen unmatched pairs without dropping a sweat.

juma 5th June 2010 04:02 PM

Thanks Jacco,
yes, 3 pairs per channel seems thin, but it's all I got right now ;)
Nevertheless, amp drives happily my speakers (Canton ct-1000 and Epos M5 which go down to 3.5 Ohms) and in burn-in test (24 hours at max power - 18Vpeak, driven with 10khz sine wave and loaded with RCL combo of 3.5 Ohms) temperature on MOSFETs never rose more than 26 degrees Celsius above ambient, so I think it's safe to build and use this amp.

Hi Patrick,
remember, we are still waiting for the result of "beast with 1000 JFETs" ;)

juma 5th June 2010 04:07 PM


Originally Posted by zhoufang (Post 2208018)
Just like other Japanese trannies, they are actually quite cheap if you buy in sufficient quantity.....

ZhouFang, Zen Mod contacted you already about these MOSFETs.... ;)

EUVL 5th June 2010 04:55 PM

You cannot use JFETs in the F5 output stage without large changes.
But you can parallel Zetex devices without problems.

But if you really want a detailed yet punchy F5 with lots of reserves, you should try UHC Mosfets.


juma 5th June 2010 05:49 PM

After this one, I tend to even more agree with device's-linearity-is-everything philosophy, and I finally have not a slightest complaint about the amp.

I might yet build a SuSy circlotron with LU1014 out of curiosity, but fiddling with ZVP/ZVN and similar small devices is definitely not my thing ;)

Zen Mod 5th June 2010 08:03 PM



Vix 5th June 2010 08:33 PM

:worship: :cheers: :cool:

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