SissySIT

Member
Joined 2003
Paid Member
Huhboy...So, this is same board as I will receive with M25 kit? It will fit pre drilled protocol for store's deluxe 4 and Deluxe 5 chassis? If so, I better pay more greenies and get another board set?

Oh! where do we find the THF51-S units? Easy to find or semi unobtainium?

Russellc
 
Last edited:
ZM is here... :)

It's not easy following ZM in every angle. All I do is just read and wonder.. :D

Now I am blessed and cursed at the same time.
Blessed with SIT-3 and cursed by lack of ability(and many other things) to get near the sound of Nelson with my build..

Nelson said there is "you will find that it has a happy character with the top end of the AER and is otherwise a very musical amplifier" :):)
 

Attachments

  • 2018-08-25 12.51.56.jpg
    2018-08-25 12.51.56.jpg
    390.4 KB · Views: 1,710
Official Court Jester
Joined 2003
Paid Member
of course

edit: from my limited batch of THFs , but also from every testing results available around , I have strong feeling that pretty much every THF , randomly taken , will fall in SissySIT circuit and work , those with biggest value of Ugs maybe just demanding some choosing of P mosfet Ugs

illustration - one IRFP9240 in my T-Bed is having -4V1 , second one is having -4V5 for same conditions

practically , if optocoupler is covering 10V gate voltage window in M2 , and it work covering 600mV window in SissySIT prototype , it'll cover everything in between ...... in worst case with resistor or two value correction
 
Last edited:
Official Court Jester
Joined 2003
Paid Member
Regarding mechanismus of circuit itself , it's really hard to re-tell shortly everything spoken of in two threads linked in first post of this one ........ so ,I believe it's worth going back and re-read them , if you missed it .
However , for starters , to quote my self from Babelfish M25 thread , because circuit around DEF output stage is pretty much the same :

Or - Honey , did I just made World's first amp biased through little bugs in rails ???


Yup , we had some good time , having fun in http://www.diyaudio.com/forums/pass-labs/314822-greedy-boy-defisit-papas-koans.html#post5244007 thread .

While we were contemplating of various things , mostly how to get PapaSits cheap and in unlimited quantity , we tossed more than few ideas how to make DEF amps - pure or little less pure , using parts we can lay our greedy hands on ... (Antoinel is playing with his own ideas in his own threads but , I'm not so talented to keep up with everything ..... or just too lazy , dunno )

Trying sims with various depletion parts (old stash from Semisouth Was Here era ) , Shaded mosfets , Japanese SITs etc.

More than few sims exchanged , more than few interesting ideas ; I believe few amps can be made ditto from LTSpice sshots shown there .

One of ideas was to keep , by any cost , sources of parts in question non-degenerated , as one of important "details" in Papa's purest DEFiSIT specimen(s) ; however , as zillion of sims showed , there is no way to keep source of any of these parts (or - to be more precise - compound pairs) clean , simply because THD spectra of said combos is simply not satisfactory , and some shaping of part behavior is easiest to do with source resistance , and strategic arrangement of same , regarding output node.

Anyway - anyone interested in all these examples , can read there.

One of real special moments was indra1's finding , brainstorming about biasing issue sans source resistors, that there are interesting Hall effect based chips , intended for current sensing ....... fact of , frankly , I was strictly and utterly ignorant .

So , again , I owe indra1 not just one big Thanks.


As some of you already know - M2 is my fave Papamp; not best one , not best made , not best sounding , not most versatile ...... but schematic of M2 is worthy of square mile big Poster ....... breathtaking example of wit , humor and brilliance . Besides that , it sounds bloody well .

Yup , we also had some special and good time , in F4 Beast Builders thread ..... about another specimen of Papa's enormously rewarding use of quality and fun time ; one of main characteristics of said amp (PL XA25) is non-existence of source resistors in output . That means pure square-law of transfer characteristics of output stage ..... in layman terms - Sparrow's fart is commanding to welding apparatus :rofl:.
I also have Babelfish XA25 in making , but low on schedule stairs .

So ..... indra1's idea was tempting .... tnx to meine Bruder Generg , I obtained ACS723LLCTR-05AB-T2 chips without too much fuss ..... already done some extensive simming of some possible iterations of M2 and XA25 bstrd

We know that work with big puck mosfets demands not just big heatsinks but also seriously big Cojones ; Mighty Moi , ZM , being jut tinytinytiny version of Papa (as we all are trying to be ) , recanted of pucks , and resorted for usual small bug output parts , already seen in regular M2

OK , 'nuff writing for first post , spell checker in my Firefox is already unconscious , not able to cope with ZMEngrish :)

edit :

Few lines about intention of experiment:


1. to pursue possibilities of using small bug cased 2SK2145BL Toshiba JFets , of present production , instead of more and more rare Toshiba complementary oldies or always scarce LS JFets ........ in both usual SE configuration and in Papa Borbely's White Cathode Follower transpose in JFet realm ;

1. to make possible usage of Edcor , Jensen and Cinemag xformers of final user's choice ;

3.to pursue possibilities of current sensing in rails , to avoid source resistor in output...........



So , 4 or more intentions realized , Mighty ZM fully satisfied .

Am I same as Brave Mickey The Tailor ? :clown:
.......