FirstWatt J2

[Zen Mod]

BTW are your Pumpkin named after the ugly 4.7 uFs http://www.diyaudio.com/forums/attachment.php?s=&postid=1318777&stamp=1191699119

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 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

 

[R-K Rønningstad]

That's very good, ZM!
When not playing music or messing with one's own amps, the Papa-forum is a friendly, good place to be. Nice atmosphere here!

 

[Nelson Pass]

Pumpkin on Tricky's Maxinquay album - one of my
favorite recordings (musically) - the recording quality is....

Hmmmm... What's the word.....

FUGLY!

 

[Spooky Electric]

For me Maxinquaye is Tricky's best work (leave out the Massive Attack stuff). Pumpkin is quite romantic!

 

[Zen Mod]

http://www.youtube.com/watch?v=7Mlvk97ySoI&feature=related

ok - even if I hate to watch musak (except concerts )

that's why this one is better :

http://www.youtube.com/watch?v=K6tTqE-71H0&feature=related

 

[Tea-Bag]

Burning amp as front end?

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

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. 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?

 

[Melon Head]

I don't see why not

 

[R-K Rønningstad]

I do have a copy of that in pdf.

BTW Are you an AES member yourself, Nelson?

RK

 

[Nelson Pass]

No.

 

[HVfanatic]

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...

 

[HVfanatic]

And another question: Why use a f2 topology? We could use the famous circlotron and change only the output devices??? This would be better than the srpp...

 

[Tea-Bag]

that's already being discussed in another thread by mrothatcher.

 

[Nelson Pass]

There's a whole world of possibilities.

 

[ra7]

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?

 

[Melon Head]

The question is. Where can you buy the Sony devices from without the fear of getting counterfeit parts?

 

[Nelson Pass]

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...

 

[Blues]

http://www.diyaudio.com/forums/showthread.php?p=1941304#post1941304:spin:

 

[HVfanatic]

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...

 

[Nelson Pass]

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.

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

 

[HVfanatic]

****. All the circlotron otl valve amps I rember have a cathode follower like behaviour. they have gain 1. But how can I change topology that the circlotron has voltage amplification? (I bear in mind, what tubecad has published....)