A real Vendetta?

[Algar_emi]

Maybe the Bordely FET Preamp schematic can give you some idea for the Vendetta FET substitution.

[john curl]

You can use 2SK170-J74 parts for input and second stage parts if you wish.
Many of you do not understand that BEFORE the Japanese devices, there were the J series parts. You know: J107,110, 113, 203, 274, etc. This just meant that the parts were plastic encased, instead of metal, not the polarity of the device.

[jacco vermeulen]

Mr Curl,

As i can not think of anyone more knowledgeable on Japanese parts, what is your view on the outlook for audio grade semiconductors ?

It looks to me like the top grade Japanese parts manufacturing had a 30 year timeframe, ended as the internal demand in Japan for such parts has diminished in favor of the 'digital/switcher' era.
The concentrated development of high quality semiconductors seems to be shifting back to the roots.

ps: hope my "sense" of humor is still acceptable => @

[Algar_emi]

I found few errors in the last SCM-2 last version. C13 is 10uF, C15 is 100nF

[john curl]

Jacco, I don't know what to think of the Japanese parts situation. It is NOT good! I don't understand it, and why Toshiba would pull successful parts from the inventory.

[EUVL]

> why Toshiba would pull successful parts from the inventory.

Successful maybe in the technical sense.

They don't bring enough financial return. Better to use the same production capacity to run higher valued parts.


Patrick

[GRollins]

John,
Assuming that the schematic posted herein is correct, or close to it, why do you use a current source to set the operating voltages for the output cascode? Given that you have flogged the DC rails to within an inch of their lives, a resistor would seem to give as stable an operating voltage and presumably be quieter. Is the output run hard enough that you're using Q17 to thermally stabilize the voltages across R26 & R33?

Grey

[lumanauw]

What's the MC stage of Vendetta looks like? Is it still differential or single ended ?

[h_a]

From my understanding of the datasheets, the 2SK240 and 2SJ75 can be replaced by the 2SK389 and 2SJ109 which still exist on earth (however the datasheets state a significantly higher current capability for the 2SK240, also higher dissipation...so one should check that).

Just a thought for the guys who probably want to build this amp.

Cheers, Hannes

EDIT: seems the 2SK140/2SJ75 can still be found somewhere, as are the other parts!

[jacco vermeulen]

Originally posted by h_a
seems the 2SK140/2SJ75 can still be found somewhere, as are the other parts!

Depends which Idss grade.
I have eight pairs of 2SJ75BL/2SK240BL, the usual grade to be found is GR.
Same goes for the 2SJ72/2SK147. Grandata and Mark5 still offer these for a pound and a half the piece, GR grade ones.
I've got more than 50 of the 2SK147GR, finding them in BL grade is difficult.
Why Erno BoBo takes you to the cleaners if you need a BL pair.