SissySIT

[cal3713]

Zen, another question as I try to force myself to understand the circuit.

For the voltage source that's added to the signal in the ltsplice diagram. Will just directly connecting to V+ & V- of an amp board work?

(And sorry if this got double posted. I swear I submitted it earlier, but couldn't find it in any of the threads I post in.)

 

[Zen Mod]

V1 in lower pic in #1018 is AC signal source

preamp, CD, TV, phone, whatever

in mentioned amps , there is JFet buffer in place of V1

just general remark - xformers are AC realm beasts

toss enough DC on them, all you'll get is smoke

 

[cal3713]

Thanks for the continuing education.

I was confused by seeing both the voltage source and the "IN" connection. I just got a testing circuit worked out on the breadboard and was able to directly show myself the effects of disconnecting various coils on volume. Super useful for pounding it into the dumb head.

As always, thanks for your patience and help. Super simple once it comes together...

 

[G600]

Some news on the SissySIT front.
It's finally outputting some fine music.
Adjusted a while ago, but waited for some iron to finish my preamp.
I must receive the finished front panel from Schaeffer in a few days.
Two blue LEDs to be installed, and bingo.

Thank you, ZM!

 

[Zen Mod]

if you're happy, I'm happy

 

[pras1170]

I resumed work today, and continue to sell 2SK182ES 2SK180 2SK1058 2SJ162 2SK1530 2SJ201 LM350K MJ21194G MJ21193G MJ21195 MJ21196 MJ15025 MJ15024 MJ15015 MJ15016 THF-51N THF-51 If you need a transistor, integrated chip, you can contact and send @qq.com directly: 378632242@qq.com

 

[mbrennwa]

As always, I am late to the party, and I apologize for not reading every single post of this thread -- it is simply too long.

I have been staring at the SissySIT schematic for a few days now. I don't get it.

The gate of the IRFP9240 at the bottom is driven by the input stage. The gate of the SIT on top is driven by the optocoupler. This looks like the IRFP is the active gain device, and the SIT is part of the current source, that follows the gain device. Shouldn't it be the other way round (SIT = gain device, IRFP = current source / follower)!? What am I missing?

Is there an overview / walk-through of the circuit somewhere? A link to this might be useful.

 

[Zen Mod]

optocoupler's bjt with cap in parallel is firm stick between two gates

signal from xformer is pushing and pulling one end of that stick

other end of stick, naturally, follows

plenty of talk and mumble in link posted in post #1 of this very thread : Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans - Page 62 - diyAudio

 

[mbrennwa]

Hmmm, I screened through that thread, but couldn't find the explanation. I can see how the opto acts as a stick between the gates. If the current through the outputs tries to wander off, the Hall chips will tell the opto to fix the length of the stick in order to keep the current fixed. But if the stick is a proper stick, and the two ends of that sick follow each other, then I'd think that both the SIT and the IRFP are driven by the input stage in the same way. I would have thought the SIT should be the gain device that is driven by the input, and the IRFP should be the current source that follows the SIT. Do you see where my brain goes wrong? I don't.

 

[Zen Mod]

think M2, OS is simple mosfet PP source follower, biased with great sense of humor

now, just replace upper mosfet with SIT, move current senses to rails, so you can remove source resistors

simple as that ....... same stick used in M2 and in SissySIT

 

[mbrennwa]

think

Been there, done that. Does not work.

M2, OS is simple mosfet PP source follower

Push pull? Really!? That would mean you'd want symmetric N and P channel outputs...

now, just replace upper mosfet with SIT

That would kill the symmetry in the output stage, right?

 

[Zen Mod]

read linked thread, everything is explained

reason why Papa deliberately used non-symmetric parts is to get desired THD Spectra

no more, no less

 

[hirscwi]

I'm also late to this game (story of my life).

I have had the kit from ZM for over a year, possibly longer, but have not yet started. I'm ready to dive in but now I read of SissySIT R3. Can someone point me to approximate starting point for that discussion? "R3" is too short string for search engine on this forum.

I'm hoping I can use the original PCB to build the R3 version.

 

[twitchie]

Use that PCB to make M25 instead. R3 is being bred in captivity until there are enough to be released into the wild (not out yet).

Until then, you can add extra green LEDs to make it R1.001 (joking, don't do it)

Any news for R3 would either get posted here or MZM will make a new thread. Don't worry, you haven't missed anything ... except a year of beautiful music from your SissySIT !

 

[Botte]

I don’t know, I think the greenie made it sound much better!

 

[Zen Mod]

I'm also late to this game (story of my life).

I have had the kit from ZM for over a year, possibly longer, but have not yet started. I'm ready to dive in but now I read of SissySIT R3. Can someone point me to approximate starting point for that discussion? "R3" is too short string for search engine on this forum.

I'm hoping I can use the original PCB to build the R3 version.

no, you can't use previous iterations for last one

NB that R.3 is made strictly to enable use of whatever Ugs of SIT

no significant practical and certainly no sound performance changes, so you're loosing nothing

Use that PCB to make M25 instead. R3 is being bred in captivity until there are enough to be released into the wild (not out yet).

Until then, you can add extra green LEDs to make it R1.001 (joking, don't do it)

Any news for R3 would either get posted here or MZM will make a new thread. Don't worry, you haven't missed anything ... except a year of beautiful music from your SissySIT !

time, energy, work, zillion of parallel projects, all in finishing stage..... inevitably being lined up, simpluy because line operator is sole one, even if Omnipresent, Omniachieving, Omnicapable, Omnietc. ZM

SissySIT pcbs fully populated yesterday (got those 0R22 resistors finally), so this weekend have in plan to dismantle LuDEF from T-Bed and put instead (presently populating with parts) Old Soul ......... and to swap R.2 to R.3 boards in my own SissySIT ....... and confirm pcb functionality with final measurements

when any of amps finished, new thread

oh yeah, fun times

 

[BRN]

No I think blue sounds the best!

 

[Zen Mod]

I don’t know, I think the greenie made it sound much better!

just for Botte's eyes, teaser of one amp with P suffix

 

[twitchie]

Iron deficient

 

[codyt]

just for Botte's eyes, teaser of one amp with P suffix

I’m excited to hear more about this one