Sony VFET Amplifier Part 2

[Nelson Pass]

Through the kind generosity of Armin Paya (VP of Engineering at Eltek)
we have some samples of genuine 2SK60 and 2SJ18's, procured many
years ago from Jim Bongiorno. At some point I will document their
performance in this circuit.

 

[Michael Rothacher]

The input capacitance is a good bit lower, which is nice (said in Bill Murray voice)

 

[Zen Mod]

if those eenyweenies were good enough for ZM's F6 VFet bstrd , they're good enough for anything ....... originating from Mithrandir's Kitchen

 

[Soundhappy]

Would a single 2sk60/2sj18 pair serve as a headphone amp?

Thanks

Bob

@ Bob
You can try build modified version of the head amplifier like this one

http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-112.html#post4339556

http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-113.html#post4340288
It's easy with 2SJ28 from Acronman just reverse psu polarity and bias.

Best regards

 

[luvdunhill]

Seems like you could create an output board that would work for CSX2 and VFET part 2. The later has a slightly better PSU reference and a couple extras (R41, Z3, etc.) that probably would just fine on CSX2. Then a cable over to either a transformer or the VFET part 2 front end.

... Sort of a BAx approach. This would allow paralleling devices in the CSX2 and/or using smaller VFETs if we can get a good source for them.

 

[flocchini]

@ Bob
You can try build modified version of the head amplifier like this one

http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-112.html#post4339556

http://www.diyaudio.com/forums/pass-labs/253411-article-sony-vfets-part-1-a-113.html#post4340288
It's easy with 2SJ28 from Acronman just reverse psu polarity and bias.

Best regards

thanks soundhappy

 

[luvdunhill]

Any interest in an OS PCB? It would have two pass mosfet and three of each VFET, so a total of 8 TO-3 devices. It would have a few resistors and a connector of some sorts, and perhaps some small diameter capacitors. I would imagine the board to be around 11.5" * 2" and cost $15 each.

 

[CeeVee]

Through the kind generosity of Armin Paya (VP of Engineering at Eltek)
we have some samples of genuine 2SK60 and 2SJ18's, procured many
years ago from Jim Bongiorno. At some point I will document their
performance in this circuit.

.....i did try my best to get my hand on some at the time juma published his amp with them.....to no avail.
Maybe now i can .....juma had some very nice things to say about them.

 

[2 picoDumbs]

What is this I just found?

 

[2 picoDumbs]

Oh Yeah. I've struck gold.

 

[Zen Mod]

just pretend you didn't found them ........ and send them to OPLDF

 

[2 picoDumbs]

What would they go for on Ebay?
Bidding starts at $1000
Hahahaha

 

[Soundhappy]

What would they go for on Ebay?
Bidding starts at $1000
Hahahaha

Oh no !
Build Vfet push-pull are priceless

 

[gadut]

I have 3 pairs of 2SK82 KD33 which was originaly bought for SIT L'amp, can i use 2SJ28 KF33 in this circuit which acronman still sell? does it matter if the batch is different for push pull?

notes: if anyone interested on JA33, do not hesitate to contact me

 

[Soundhappy]

...can i use 2SJ28 KF33 in this circuit which acronman still sell ?....

Yes is goood for push-pull vfet amplifier
K is batch name
F is February
D is December
month's of production letter
Vp=33 is pinch-off voltage
Yours have the same rank on both sit's
Enjoy

 

[gadut]

@soundhappy

that's interesting, never knew about this rank naming, so it's more important to have same 33 instead of KD or KF.

 

[Soundhappy]

@ Gadut

Yes Vp=33 is important parameter and write in this Sony documentation.
But maybe i ignore other data ?

Kind regards

 

[gadut]

each pair K82 from acronman have different Rds which are 0R7, 0R9, and 1R1, it seems acronman matched them

while 4pcs K82 JA33 have 1R1, 1R4, 1R6,1R9. another J28 JA33 have 1R5, 1R7, 1R9, 2R1

well, K60 datasheet says output resistance Rd ~ 16 ohm at 20V 1A, is this equivalent to Rds measured by dmm?
there is a chance that JA33 is original, not relabelled K60

 

[gadut]

just forget it, brush JA33 with isoprophyl alcohol completely remove the label, only 1 time brush. while KD33 have been brushed mutiple times but no degradation on the label

www.diyaudio.com/forums/solid-state/241272-what-do-sony-v-fets.html#post3606182

 

[WalterW]

Ah, finally 'On semiconductor' is producing VFETs

You can't compare the 20V 1 Ampere value (16 Ohm)with the one measured with your digital multimeter.
How ever your dmm shows that a 2SK82 has 2 dies inside, and thus half the resistance of one 2SK60 ( which your fakes probably are).

@ Soundhappy: Which month is my KE-33 ?