FirstWatt J2

Official Court Jester
Joined 2003
Paid Member
specs comparable with original (speaking about THD spectra ) , but you know that specs aren't everything

will publish complete schmtc and measurements as soon I have it confirmed in vivo

FE configured for several TO92 , same as for SOT23 JFets , pair or double pair - cascoded , for convenience

cascoded EF in between LTP and OS gate

outputs - whatever one is having - SS , IRFP150 ........ any of Kosher Audio mosfets ..... though -I have no intention to accommodate pcb for different pinouts (IRFP and SS are GDS from left)

we'll see ...... have pretty good feeling about this one
 
IMHO, for such a low dissipation amp with 60W per channel, a small case (340mm width) from ebay, plus a small PCB will be more than sufficient.
PCBs within 100x100mm are very low costs these days.
And you can use both top and bottom layer for power tracks, which can be made very short and compact.

Unless of course one wants to creat the illusion of a carbon copy of a FW product. ;)


Cheers,
Patrick

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Official Court Jester
Joined 2003
Paid Member
Dear Zenny, I love to hear this and I ask you if you can make it possible to use the 2SJ109 in your upcoming design as well. A long time ago I stored a small box in my lab with all parts for two channels of the J2 amp.....

Cheers, Ernst

sorry , no

idea is allowing use of 1 or 2 pairs (by wish) of 2SJ74 , J271 , MMBFJ271,LSJ74 ....... and it'll be major PITA squeezing in pinout for 2SJ109 too
I'm sure that arrangement with 2 JFet pairs in LTP is enabling use of some other "lesser" JFets too
 

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Member
Joined 2007
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sorry , no

idea is allowing use of 1 or 2 pairs (by wish) of 2SJ74 , J271 , MMBFJ271,LSJ74 ....... and it'll be major PITA squeezing in pinout for 2SJ109 too
I'm sure that arrangement with 2 JFet pairs in LTP is enabling use of some other "lesser" JFets too

So I am sorry too - but not too much, as a nice home made adapter would serve.
Or having a look at Jeffs boards :)

Cheers,

Ernst