Plethora of Pinjatas / SET P amp(s)

[Zen Mod]

Finally, Plethora of Pinjatas, origin of P series of amps

These (P) being more or less derivatives of my recent M2 derivatives ........and you know them , so no need to go in detail

So, active FE instead of buffer+autoformer FE; biasing mech. being more or less same (current sense in rails), only - with help of current mirrors, being sorta flipped upside down, vs. previous optocoupler based one

even if optocoupler based biasing is more than good, believe me, this one is even better ...... in anything you can remember to ask about

Iq and Offset stability is bespoke, in any domain I can think of - time, temperature, rails change ( mains fluctuation), no even slightest pops during Power On and Power Off

everything to embrace Square Law OS

(aha, this one being origin, even if its bigger brother - Babelfish XA252 been made first)

OK, straight MOS being real Plethora of Pinjatas ....... (is it Mini Babelfish XA252?)

SET P being then same pcb with twist - upper mosfet in Schade arrangement (is it Mini Babelfish XA252 SET ?)

pretty close to point where I can't even follow my self, go figure

'nuff babbling, some usual pics

schm is cumulative; down will post separate ones

 

[Zen Mod]

Now what ...... some pic of Pudding.

 

[Zen Mod]

pics above are Plethora of Pinjatas, basic one for these pcbs:

 

[Zen Mod]

Proof of Da Pudding

Iq 185mV across 0R11 current sense resistors, so 1A68
Rails +/- 23Vdc

Load 8R

 

[Zen Mod]

everything same, Load 4R

 

[Zen Mod]

That done; Spooky sounding ...... but familiar - as I said - Mini Babelfish XA252

now - few more parts added, so sch. is as this and name changed accordingly, to SET P:

 

[Zen Mod]

some pics of that in action

 

[Zen Mod]

This one being Cheapskate SIT ........ or SIT Emulation, whatever

Schaded Mosfet - giving not just same wakoo current distribution between output parts as in DEFiSIT, but also having practically same output power as SissySIT - around 18W ..... after that level, everything is going Berserk

again, Proof of da Pudding;

Iq 195mV across 0R11 current sense resistors, so 1A77
Rails +/- 23Vdc

IRFP240 Ug +4V35
IRFP9140 Ug -4V78
DN2540 Ug +4V25
all ref to spk out

Load 8R

 

[Zen Mod]

Same, Load 4R

 

[Zen Mod]

I like this pic

It reminds me of all my amps

Set P also sounding Spooky, even with slight addition of Sugar

It's boring now, all my amps are sounding similar

 

[Zen Mod]

ha, just for your amusement ....... funny pic

as with all pcb construction programs, first and logical step is to draw schm, hopefully imputing exact physical packages ( size, power, voltage) of parts one is going to use

when that is done, you have *sch file, with missing counterpart *.brd file

getting to that is easy step - File-Switch to pcb

then Eagle (old one, I'm working with.... for me as old sock) ask for confirmation "to create from schematic?", you give it

and outcome is something reaaaaallly frightening

see, what's posted in #1, first was looking as:

 

[nicoch58]

well done ZM

 

[Zen Mod]

build anecdote:

was sorta late;
after all THD and whatnot tests I did, final thing I wanted to measure and include here, is Ug table (post #8)

lazy but, or rather lazy brain:

black probe on spk out,
red probe on 9140 gate, easy
red probe on 240 gate, easy
then red probe to DN2540 gate - tricky, head leaned, which one is gate ....... probe slipped , shorted D to S

hehe, instead of moving but from chair, and put red probe on C113 positive .... plenty of room , nothing close around

outcome - both IRFPs Dodo, pair of 0R22/2W Dodo

nothing else

replaced IRFPs, all four 0R22, redial Iq , case closed, up to listening position

moral of the story - do not work late and if you are, move your but - helps keeping brain active





btw.

tried lately to buy IRFP240 (or 9140 or 150), for sane price ... and (God Forbid!) in any decent quantity?

it seems Pa is again in situation having at least half World's stock

 

[lhquam]

The distortion plots are excellent. Do you have any estimate of the open-loop gain of the front end?Looking at the schematic(s), the voltage gain stage provided by T106 and T107 appears to have a very high open-loop gain, since there is no load resistor of the collectors and the only load is the base currents of Q101 and Q102.

 

[Zen Mod]

no estimate........ I was eye-balling that (contemplating what to do) and doing mental comparisons with FE stages for which I know they're sounding good - how OLG is high and where to keep it

anyway, in some things I'm trusting Pa, avoiding to be Chicken in everything

it's stable and behaving, Freq. range muchmuch better than my measuring setup ( none of this recent amps is going less than 100KHz strong), it sounds good ...... ultralow THD is name of the game, for change

of course, I investigated OLG in sims. but really can't remember figures and lazy to do that

and, what's wrong if I want to make MC phono from amp?



aha - you can see that I started very conservative with pF caps position and values

 

[Samuel Jayaraj]

DN2540 in TO220 pack is out of stock everywhere. Any substitutes? DN2535 in TO220 is available, however.

 

[Zen Mod]

same part practically, just a little lower max voltage, in this case irrelevant

go for it

 

[Samuel Jayaraj]

same part practically, just a little lower max voltage, in this case irrelevant

go for it

Thank you, Zen Mod!!!

 

[August]

Where did you hide the distortion? I might plunder the IRFP240's from my ACA now

 

[Zen Mod]