FirstWatt J2

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#121
R-K Rønningstad said:
BTW are your Pumpkin named after the ugly 4.7 uFs http://www.diyaudio.com/forums/attachment.php?s=&postid=1318777&stamp=1191699119 😱
Click to expand...

nope ,in fact ;

I wrote to someone , as answer on same Q - main reason is that I just like how pronouncing Pumpkin is sounding , then :Pumpkin: is funny creature , then Pumpkin ( I realized similarity much later) is really made for pumping juice in F4 and similar lazy bstrdz .....

besides that - main reason is that entire (leave Papa's brainchilds out) world of FiFi and FiEnd is just sick serious , pompous and greater than life .
so we must use any chance to mock it

Mods - sorry for OT

:rofl:
 
#126
Burning amp as front end?

Nelson Pass said:
Item 3. You already have plenty enough information in
the simplified schematic. Go forth and fill in the details
yourselves.


😎
Click to expand...

What I will ask, and it's probably more complicated than I can figure out without substaintial help. The simplified schematic looks close to the BA-1 and BA-2 front ends.:bulb: Is it possible with some tweaks (maybe from the master and other giants) to use the BA-1 front end here to build a nice sounding amp?
 
#130
So I want to post my comment on the "special 6-pin, lateron 8-pin" device: It's an OpAmp! It is used to care for 0 Volt dc offset.

But I want to throw in another idea: Why not using 2 F3 Amps, throw out the coupling cap, and build a dc correction via OPAmp??? Next could be the removal of the regulated supply, if used in this operational mode... Well, needs sym input, but who cares...
 
#134
The update being mentioned for current F2 users... is that a straight swap... i'm sitting on the fence wondering if I should join that semisouth GB, build an F2 and use the JFET.

Mr. Pass, you already recommended buying some of those sony JFETs. Is there an article in the pipeline with them in mind? 🙂
 
#136
Yes, there will some sort of project based on them, although
I expect a limited DIY participation due to the scarcity of
the parts.

I bought 10 pair from

Acronman Electronics <acronmanelectronics@gmail.com>

and the service was quite good.

They appear to be genuine, however I have only tested
one of each so far, and I haven't had time to build a proper
output stage to see what the performance is likely to be.

Maybe tomorrow...

😎
 
#138
Oh, I think my proposal to use J-Fet devices for a circlotron output stage was really stupid. The Circlotron has no voltage amplification, because it works as a follower. Therefore, It would be better to stick to ordinary mosfets. In that case, I would prefer the use of 2 F3's, where a symmetrical source is required to drive them. I would leave the couplings caps out, and build an op-amp based circuit, that ensureres the same dc potential on both outputs...
 
#139
HVfanatic said:
Oh, I think my proposal to use J-Fet devices for a circlotron output stage was really stupid. The Circlotron has no voltage amplification, because it works as a follower. Therefore, It would be better to stick to ordinary mosfets.
Click to expand...

That's three wrong statements:

1 Not stupid

2 Who said a Circlotron can't have voltage gain?
(I've got one right here)

3 The "therefore" does not follow from 2 wrong premises

😎
 
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