ZM's 2SK2087C musings, phase one (SissySIT as cradle)

[Zen Mod]

Well, as Greedy Boyz did share (tnx!!!!) some interesting info in https://www.diyaudio.com/community/threads/odd-sit-vfet-2sk2087c.385288/ , frenzy is there and who know how it will end

Yeah, impossible to keep low profile, but lets just hope that price isn't going to sky and over

So, officially - parts are Iznogood, everything above 2$/pc is steal and overpriced

Anyway, CodyT sent me few, and they arrived pronto

Have some more arriving, sent from friendly Greedy Boy from Japan, but they are still collecting dust in my Customs , that will be covered ( along with my official gratitude) when I see them

pics of package sent by CodyT, along with basic Ugs measurements (Uds 24Vdc, Iq 1A8, Igate~20uA (0mV2 across 100R gate resistor)

more specific info can be seen in thread linked above

 

[Zen Mod]

basic schematic shown in SissySIT R.3 thread, also enclosed here

everything the same as original ( THF51S) , meaning 24-ish rails, Iq 1A8

even level shifter resistor (R115) having same (120R) value, resulting in Ug for IRF510 (M101) and IRFP9140 (M102) being both around 4V7, ref to speaker output node

2SK2087C Ug (in amp) of course being in range of value on sticker , again ref. to speaker output

 

[Zen Mod]

now, Proof is in da Pudding

8R load pics

compare them directly to THF51S , post #7 : https://www.diyaudio.com/community/threads/sissysit-r-3.371272/post-6626308

 

[codyt]

Looks like we got ourselves a winner!

(though I should wait until ZM's official assessment 🙂)

 

[Zen Mod]

4R load pics

compare them directly to THF51S , post #8 : https://www.diyaudio.com/community/threads/sissysit-r-3.371272/post-6626310

 

[Zen Mod]

Conclusion:

2SK2087C, very Iznogood part!

in SissySIT - comparing to ( origonal THF51S iteration) :

-same DEFiSIT-ish THD Spectra

• slightly smaller power
• evidently lower THD in entire power range, except on clipping

-same benign character regarding Iq and DC Offset stability ( nothing to write home about, in time/temp/rails fluctuation domains)


as I said in origin 2SK2087C thread, I have intention to try them in already (so-so) ready-to-do circuits

- Singing Bush ( why not, combined with IRFP150, little SE)
-Choked Singing Bush ( hopefully that one not being speaker killer during power On cycle)
-Lazy Singing Bush

now just to find some time, soon

Life is Fun

 

[codyt]

Bravo! Good news for those having the parts. FWIW I've seen these starting to pop up again on the internets, so keep eyes peeled (same hesitancy regarding real vs scam applies of course)

 

[Zen Mod]

Mighty ZM being faster than Pa!!

my Crystal Ball is telling me that he's busy making again some toy-easy-to-make amp for Spoiled Greedy Boys (are two or three pleonasms there?)

 

[codyt]

Looks like its time for SissySIT boards with a second to-247 (to-3pl) footprint??

(I know, I know – looks easy enough to bend a few leads... 🙂)

 

[Zen Mod]

no way Jose



no new pcb for these

 

[Zen Mod]

oh, yes, didn't said how it sounds ...... pretty much the same as SissySIT with elevator SIT

maybe because this one is made for small elevators ......

 

[flocchini]

per mighty ZM

"as I said in origin 2SK2087C thread, I have intention to try them in already (so-so) ready-to-do circuits

- Singing Bush ( why not, combined with IRFP150, little SE)
-Choked Singing Bush ( hopefully that one not being speaker killer during power On cycle)
-Lazy Singing Bush"

Babelfish XA252 -2SK2087C?

 

[Vunce]

Disappointing these are Soooo Iznogood, Hehehe

 

[Zen Mod]

......

Babelfish XA252 -2SK2087C?

as Plethora of Pinjatas is practically Mini XA252, more likely 2SK2087C will be tried in that one

XA252 is made so you can go wild, and for that - puck size is much more suitable

 

[flocchini]

as Plethora of Pinjatas is practically Mini XA252, more likely 2SK2087C will be tried in that one

XA252 is made so you can go wild, and for that - puck size is much more suitable

I like wild 😇

 

[Zen Mod]

Looks like its time for SissySIT boards with a second to-247 (to-3pl) footprint??

(I know, I know – looks easy enough to bend a few leads... 🙂)

one who knows what curses of curious mind are

even if I said that there will not be special pcb, I couldn't resist to see what's exact name of case in question

and no - it isn't regular TO3P ..... and I can't even find it by designation nor I can even dream of finding one as Eagle package

luckily, I did learn previously how to make Eagle part packages ( did that for Singing Bush pucks etc.), so making one for 2SK2087 is going to be nice evening fun

where it'll be utilized, time will tell

though ....... there is slight glimpse of possibility that completely DC coupled SissySIT with 2SK2087C is one interesting thing to make ......... so yes, even puny 10uF Silmic (in between autoformer and OS) can be tossed out

huh...... as world is needing another 15W A Class amp, fully DC coupled, without loop NFB

 

[codyt]

Curiosity killed the cat… but rewards the audio designer 😀

 

[Zen Mod]

I was cheating

DC coupled version being in my pile of files for several months already

didn't pursue it mostly because there is not any significant sound difference

besides, DC coupling done in Papastyle, just another on list called Zillion Ways of Mocking Audiophools

so, making 2SK2087C Eagle package was trivial, cradling it in already made pcb file same level of complication



just another one on the list .......

 

[flocchini]

You are omniamazing

 

[codyt]

SOLD, I’ll take it! 😀