ZM's 2SK2087C musings, phase two - SissySIT (42) as a cradle

[Zen Mod]

copy/paste from Big DiyA

 

Preceding thread here : https://www.diyaudio.com/community/threads/zms-2sk2087c-musings-phase-one-sissysit-as-cradle.386654/

What was logical precursor/reason to dust off schematic I'm having for some time and to implement it in form of new pcbs, arranged so both Tokin Pucks and Tokin 2SK2087 can be used

Novelty - reason enough for playing with, is full DC connection from input to output, and also current-mirrors based biasing circuit

Nota Bene that DC connection between FE and OS is typical Cheating Papaway - anyway, see it by yourself, draw your own conclusions

Changes vs. SissySIT R.3 - none regarding sound (had my time with farting elephants, life is simpler after that), even steadier output DC Offset and Iq stability, vs. time, temperature, mains fluctuation

As I can see, there is some better drive (shown in clipping level for Big One) but these differences are strictly academic ones, sorta pity that this amp is never going to be considered by Audiophools, having all pizzas for great Drek-selling Story :devilr:

as always, basic pics first

[Zen Mod]

today's funny pics

as you can see, done it all first with THF51S in output, so I can compare measurements of these with measurements with 2SK2087C in place

logically, 2SK2087C in place for second set of measurements

 

 

[Zen Mod]

Now, battery of tests

Will post same measurement of THF51S and 2SK2087C in same post, trying that THF51S is on left side pic; anyway, THF51S related are not having type note, while for 2SK2087C I remembered to include note in caption

go figure

general trend, already established in thread liniked in first post, small one is having lesser THD levels than big one, all the way to clipping , and small one is having lesser power than big one

in all cases - dual rails, 24Vdc-ish, Iq 1A8-ish

1W@8R

 

 

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5W@8R

 

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10W@8R

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15W@8R

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small one is done with power

20W@8R THF51S:

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Freq. 8R

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THD vs Freq. 8R

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Now, comparison of graphs, load 4R

starting with 1W@4R

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5W@4R

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10W@4R

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15W@4R

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20W@4R

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Small one is done with power @4R

25W and 30W@4R of big one

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Freq. 4R

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THD vs. Freq. 4R

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So , some conclusion(s) - 2SK2087 is worthy one in SissySIT cradle, whichever revision is in case

Have plans to try it soon in Common Source and Common Drain circuits, both Mu and Choke loaded, very soon; first one should be most likely Warbler, nothing else than choke loaded source follower stage, with all bells and whistles of proper biasing and buffer and yadayada

35Vdc-ish single rail, Iq 3A-ish for Big Tokin, 2A-ish for 2SK2087C

'nuff for today

and yes, it seems SissySIT (42) is now official edition (Caliph instead of Caliph, (42) instead of R.3)

problem is , I'm feeling as living Groundhog Day ...... whatever I'm doing, it always seems as same amp

Iznogood ( Caliph):

 

[Zen Mod]

[Mikorist]

Radio slušaš ?  

[Zen Mod]

kad nema ko da mi napravi DAC

 

[zerowaf]

pre 52 minuta, Zen Mod reče

Ono radiona...majstor tu nesto radi, a u pozadini alibabina pecina.
Kao one fotke iz garaza u kojima vidis 250GTO ispod hrpe nekakvih kartona (RCA) , Alfu Giuliu Coupe pokrivenu tonom prasine i po njoj poslagane kante od Jupola (Revox) i M3 kabrio koji, sudeci po prasini, nije paljen desetljece i pol (FW).
Majstora to nista ne obadaje. To je tu tako...steta da se baci, pa neka stoji.