Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans

[Samuel Jayaraj]

Thanks ZM. I am trying M2 Output in another amp.

 

[Michael Rothacher]

Mr. MR , have you SJDP model , too ?

and , just now , I'm having an idea of trying it with cascoded LU ...... it would allow full blast (meaning regular FW range of PSU voltage ) version of amp

will sim tonight ....... and just dream when I'll have time to try it in vivo

Sorry, ZM. I don't have that one.

 

[Zen Mod]

Sorry, ZM. I don't have that one.

Silly ZM ...... I have it in my LTSpice , imported in JFet library eons ago

so , here it is , with SJDP

it needs speaker delay relay , having startup peak , about 10V in first 50uS

at least according to sim .... worth checking in vivo , with soft start etc.

 

[generg]

.subckt SJDP120R085 D G S ; 1200V 100mohm TO-247

Rd D Di 35m tc=9m, 5u ; requires tempco

Rs S Si 35m tc=9m, 5u ; requires tempco

Rg G Gi 500m tc=-3m ; requires negative tempco
Cds S Di 1p ; direct Cds is almost zero

Cgd G Di 2.5p ; Cgd overlap capacitance

Ji Di Gi Si SJDP120R085
.ends SJDP120R085



.model SJDP120R085 njf; Rd, Rs not used (no tempco)
+ Vto=-5 Beta=8 B=0.2 ; dc curves

+ Lambda=.31314 Vk=2k5 Alpha=20u ; voltage influence

+ Is=1e-020 N=3.5 ; sets fwd GS diode curves

+ Isr=1e-020 Nr=1.5 ; sets rev leakage

+ Cgd=500p Cgs=200p Pb=1.6 M=1 ; nonlinear Cs

+ Kf=1f Af=1 ; flicker noise

+ VtoTC=-2m BetaTCe=-0.25 Xti=35 ; tempcos

.ends SJDP120R085

 

[Zen Mod]

tnx Bruder

 

[Zen Mod]

so

have no time right now to try any of these ......

anyone here , having both - time and 2Sk180 , or SJDP , or LU ?

we can call it M2DEF ......... or TNA 1

 

[Skorpio]

Can the Lundahl LL1517 trafo be used here or in B1 with gain?


http://www.lundahl.se/wp-content/uploads/datasheets/1517.pdf

 

[Zen Mod]

yup , classic repeater

enough info in Papa's talk at BAF , regarding B1 T , same as in Iron Pre thread (what's wrong with the kiss , boy .....)

 

[Skorpio]

Thank you

 

[Skorpio]

ZM > anyway , M2 and DEFiSIT - close cousins ..

Similar and different beacause Pass SIT-1 and Cinemag etc.
M2 without input and output capacitors.
Curious about Your first music play with DEFiSIT

M2 has loading on trafo secondary, DEFiSIT has not....due to different trafos?

 

[Zen Mod]

yup

 

[Zen Mod]

Silly ZM ...... I have it in my LTSpice , imported in JFet library eons ago

so , here it is , with SJDP

it needs speaker delay relay , having startup peak , about 10V in first 50uS

at least according to sim .... worth checking in vivo , with soft start etc.

latest iteration of LuDEF sim , much closer to pure DEFiSIT ideal ..... no source degeneration for IRFP9240 , while entire combo consisted of LU. it's source resistor and IRFP240 cascode should be considered as poor man's SIT substitution

hey , it gnawed just right on me ...... one can try even poorer man's SIT Substitution (as fast & furious taste of Real McKay) ..... using verbatim M2 circuit , but connecting upper mosfet with Shade thingie (1K+10K) ........ will try that sim pronto

mild and slow thump (under 400mV) during startup , most probably even lowered due to action of (commonly used in Papamps) NTC softstart

 

[Zen Mod]

this one is sooooooooo nutz ........ it can be called M2 SEF (M2 Shade Enhanced Follower)

mild negative 450mV thump during startup

 

[thiagomogi]

this one is sooooooooo nutz ........ it can be called M2 SEF (M2 Shade Enhanced Follower)

mild negative 450mV thump during startup

I like

 

[juma]

Output is taken from Source pin, there is no gain and no AC on Drain, so there is no Schade feedback, just DC biasing...

 

[Zen Mod]

maybe German Mosfets are so self aware , so they know where load is attached ..... to their head , or their A$$

modulation at Shaded mosfet (not necessary German one) gate is clearly 10/11 of modulation present at input of entire Shebang

 

[juma]

O. H. Schade was a German and that's the only (and totally unimportant) fact that connects the subject to Germany, so no need to accentuate the "German" part so loud. Even I'm not a German, it's just the place where I live at the moment.

What really matters is this:
http://www.clarisonus.com/Archives/TubeTheory/Schade 1938 Beam Power Tubes.pdf

 

[Zen Mod]

gotten backwards or not , effect of Shade feedback is there .


however , besides spending some time with simulator , catch 22 is in last paragraph on p.363 of document you linked

had a copy of it in my hands 30 years ago , even if I didn't understood a yota of it

 

[juma]

There is no AC signal on the drain of the MOSFET (the drain is grounded AC wise through the PSU) so there can be no feedback that way (nothing to feed back, just a static DC bias conditiion).

The last paragraph on that page speaks only about cathode degeneration as the form of feedback that lowers the distortion and it's irrelevant from the "turn penthode into triode" point of view.

 

[indra1]

Perhaps of interest, still in sim, a 6SN7 seems suitable as input to the Valdef output stage. ~24.4W at clipping 0.1% THD at 1W negative phase H2.