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

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Zen Mod

Zen Mod

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few more , with 6db autoformer inline , so somewhat higher THD;

however , who cares for numbers , I'm interested in general trend here
 

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O

obh

Member
Joined 2016
Paid Member
my thf-51s models

I measured my four thf-51s (manually) and used MRs xls solver method in gnumeric to
make models for each of them. This is the first transistors I've measured and made
models for but I get a feeling that each thf-51s is unique part.
I got these from watanabetomoaki asking for low voltage part (20v-60v) .

.SUBCKT thf51-1x0063 D G S ; Drain Gate Source
+ PARAMS: MU=43.571 X=1.494 K=1.339 N=0.902 VCT=0.831 RG=5MEG
*--------------------------------------------------
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
*FOR MULTISIM COMMENT OUT ABOVE LINE (*) AND UNCOMMENT NEXT LINE
*B1 D S I=K*PWR(MAX((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU)),0),X)
R1 G S {RG}
CGS G S 5000P
CGD G D 5000P
CDS G S 0P
.ENDS thf51-1x0063


.SUBCKT thf51-1x0066 D G S ; Drain Gate Source
+ PARAMS: MU=41.136 X=1.853 K=0.755 N=0.878 VCT=1.212 RG=5MEG
*--------------------------------------------------
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
*FOR MULTISIM COMMENT OUT ABOVE LINE (*) AND UNCOMMENT NEXT LINE
*B1 D S I=K*PWR(MAX((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU)),0),X)
R1 G S {RG}
CGS G S 5000P
CGD G D 5000P
CDS G S 0P
.ENDS thf51-1x0066

.SUBCKT thf51-1x0067 D G S ; Drain Gate Source
+ PARAMS: MU=46.667 X=1.271 K=1.507 N=1.046 VCT=0.634 RG=5MEG
*--------------------------------------------------
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
*FOR MULTISIM COMMENT OUT ABOVE LINE (*) AND UNCOMMENT NEXT LINE
*B1 D S I=K*PWR(MAX((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU)),0),X)
R1 G S {RG}
CGS G S 5000P
CGD G D 5000P
CDS G S 0P
.ENDS thf51-1x0067

.SUBCKT thf51-1x0069 D G S ; Drain Gate Source
+ PARAMS: MU=56.181 X=1.412 K=2.257 N=0.609 VCT=0.525 RG=5MEG
*--------------------------------------------------
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
*FOR MULTISIM COMMENT OUT ABOVE LINE (*) AND UNCOMMENT NEXT LINE
*B1 D S I=K*PWR(MAX((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU)),0),X)
R1 G S {RG}
CGS G S 5000P
CGD G D 5000P
CDS G S 0P
.ENDS thf51-1x0069
 
Zen Mod

Zen Mod

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Joined 2003
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Paid Member
it'll be clearer to you , hopefully tomorrow when I (hopefully) finish the other channel and post exact schematic

in principle , schematic is same as Babelfish M25 , with few changes in resistor values , few (protection) diodes missing , one added , one resistor less etc.

didn't measure gate leakage currents ....... maybe I will , but if build of other channel goes without troubles , most probably not ...... :rofl:
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
looking at graphs in SIT-3 user manual , and comparing them with THD values I got for SissySIT , I'm observing few things :

-funny , due to nature of PapaSIT , THD in 4R load is lower than THD in 8R load , while this is not the case with THF

-also funny - regarding THD , SissySIT is on par with SIT-3

few things more , to think of :

-should I measure THD spectra ( and whatnot) of ZM's DEFiSIT specimen , and what conclusions , dumb as I am , I can get from that ;
-should I try THF51-S in SEF amp cradle , so SIT being slightly tamed with some source resistance ...... I'm not scared of work involved , but grumpy of necessary critical listening later , to decide which one is better ......... hate critical listening ......... I like normal -greenaroundmyhead music enjoyment :snoopy: ......
 
C

Chul

Member
Joined 2003
Zen Mod said:
-should I try THF51-S in SEF amp cradle , so SIT being slightly tamed with some source resistance ...... I'm not scared of work involved , but grumpy of necessary critical listening later , to decide which one is better ......... hate critical listening ......... I like normal -greenaroundmyhead music enjoyment :snoopy: ......
Click to expand...

If I may say what I felt from 2SK82 experience, in a subjective term(what else?:D), the sound without Source R was like a sharper knife.

The difference with and without Souce R was also similar to the bass frequency of ported and sealed speaker enclosure. When an amp becomes more flat, on assumption, then the uneven character of a speaker is revealed. The rather strange size and shape of my Altec Valencia is revealed, I imagine.

On other posts Nelson said;
"I personally find the undegenerated output more interesting sonically."

It was not 'better' but 'interesting' and I feel similar. Please keep going, many are following you.....;););)
 
Last edited:
L

lhquam

Member
Joined 2010
obh said:
I measured my four thf-51s (manually) and used MRs xls solver method in gnumeric to
make models for each of them. This is the first transistors I've measured and made
models for but I get a feeling that each thf-51s is unique part.
I got these from watanabetomoaki asking for low voltage part (20v-60v) .
Click to expand...

The capacitances shown in your models are very high which will require a lot of drive to the gate.
 
O

obh

Member
Joined 2016
Paid Member
thf-51s capacitance

Got values from soundhappy
http://www.diyaudio.com/forums/pass-labs/269379-live-lab-hangout-1-1-posted-6.html#post4234184 post #51 5000pf

I've not yet measured capacitance of thf-51s. Did not managed to
do that before I had to clean the lab (when daughter arrived back from university for summer holiday and relaimed her room :). But it is on
todo list (together with temp drift, and double check RG). Any link you can
share how to measure ciss, crss, coss?
 
Soundhappy

Soundhappy

Member
Joined 2012
All " wild horses " 300 to 1K watt´s Tokin SIT's or hockey pucks IXYS mosfets input junction capacitance is high
, amplifier input needs buffer with 25 Ohm impedance output if not high frequency response roll off very quickly.
Cinemag, Jensen or Edcor transformers frequency response have his limits as well
Mr Pass talk about this solution presented similar 2SK77B Digital-Domain SIT, video starting 00:20:37
BAF Presenter Nelson Pass
 

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