Simple Symetrical Amplifier

[PauloPT]

Hi,

If I use 2SJ201/2SK1530 instead of 2SJ162/SK1058 (different pin out) what other changes sould I do to the circuit?

Has anyone thought about having a professional etched pcb and organizing a group buy?

Thanks.

[coolet]

hi shaan do you use tone control?

[shaan]

Originally Posted by coolet

hi shaan do you use tone control?

Nope.

[PauloPT]

Originally Posted by PauloPT

Hi,

If I use 2SJ201/2SK1530 instead of 2SJ162/SK1058 (different pin out) what other changes sould I do to the circuit?

Has anyone thought about having a professional etched pcb and organizing a group buy?

Thanks.

OK, I now can answer my own question. The 2SJ201/SK1530 are vertical mosfets and not lateral as I first thought. Therefore they can't be used without some changes to the circuit like a VBE multiplier. As I have some around I added 3 more diodes for more bias and because the 2SJ201/SK1530 don't suffer from thermal runway (however they are vertical) it worked. I could then taste the SSA sound and it really sounds very very good! The cymbals, the piano notes, sound impressively natural without any hint of harshness and in a sweet presentation. Curiously, the SSA sound signature is very similar to the SYMEF, the same lively and sweet presentation, very very similar.

[Lazy Cat]

Hi PauloPT

Glad you like it, enjoy.

[Salas]

Simple rule of thumb we should remember because many datasheets don't clearly mention category by the way: Laterals are never GDS pin out. They are GSD.

[PauloPT]

Originally Posted by Lazy Cat

Hi PauloPT

Glad you like it, enjoy.

Thank you Lazy Cat for designing this wonderful amp!

I'm going to order some 2SK1058/2SJ162 to make a proper build. I have some questions about it:

1) Is it completely stable, no worries about?
2) The input filter cap is only 22pF, shouldn't it be about 10 times higher?
3) Can I use it with 4 ohms speakers? How much power would I get safely?
4) Has anyone mesured THD, just curious I'd like to know TDH at 20KHz.
5) My home made pcb's always look like something out of an horror movie. I would much prefer to have a nice professional etched pcb, is a group buy for pcb's out of the question?

Sorry for so many questions...

[Esperado]

Originally Posted by PauloPT

2) The input filter cap is only 22pF, shouldn't it be about 10 times higher?

May-i recommend-you to set the input filter with a FC of 200Khz ?
Or to do-it listening: More you filter EMI and residual distortions from previous stages, better it is. The limit is to keep the phase right at 20KHz.

[PauloPT]

May-i recommend-you to set the input filter with a FC of 200Khz ?

If my noobie calculus is right with 1k resistor I'll need 796pF instead of 22pF. Is this right?

Thanks.

[Esperado]

Bingo !
You can set-it to 750pF to let a little margin to the source impedance