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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
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Old 16th April 2018, 11:58 AM   #281
First Watt Guy is offline First Watt Guy  Viet Nam
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Quote:
Originally Posted by Zen Mod View Post
I made sim with SJDP

tonight with SJEP , OK ?
Thanks , sir
But how can I search for SJEP with the same vgs as IRFP ?
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Old 16th April 2018, 02:41 PM   #282
Zen Mod is offline Zen Mod  Serbia
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
you need SJDP if you want to pair it directly , without additional bias circuit , and I can't tell you is that even possible , because I didn't make any analysis regarding biasing voltages at desired current

make distinction between enhancement devices (SJEP , IRFP) and depletion devices (SJDP , JFets) ......... then you'll understand why you need SJDP for possible direct pairing with IRFP
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Old 16th April 2018, 05:51 PM   #283
Zen Mod is offline Zen Mod  Serbia
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
Default as promised - SJEP , so no DEF but EEF

Attached Images
File Type: jpg schm.jpg (108.9 KB, 308 views)
File Type: jpg spectra.jpg (46.3 KB, 305 views)
File Type: jpg thd.jpg (25.6 KB, 287 views)
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Old 16th April 2018, 07:35 PM   #284
Samuel Jayaraj is offline Samuel Jayaraj  India
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Originally Posted by Zen Mod View Post
SEF

this one goes in prototype
Zen Mod, I experimented with your SEF circuit. I left R7 at 220E as in original M2. R1 & R2 was made by a string of 0.18E X 3, 5watt each. But they got too hot in just a few minutes.

I couldn't get offset below 4 volts. Hence, used a 4700uF cap to connect the speaker.

Sound was fuller, more organic, forward and airy. But the liquid character of M2 was sacrificed.

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Old 16th April 2018, 07:37 PM   #285
Samuel Jayaraj is offline Samuel Jayaraj  India
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The SEF circuit is in post #264.
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Old 16th April 2018, 08:10 PM   #286
Zen Mod is offline Zen Mod  Serbia
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Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans
any of these amps made with DEFiSIT as role model , will have greater THD than M2 , so it is logical to sound less clean , erring on sweet side

regarding values in any of shown sim schematics , they're exactly that - simulations , so some value tweaking in vivo is inevitable

setting correct Iq ( look at Pd per device - 35 to 40W) and offset is trivial thing , done in 20min or so

so , fear no more but no less , you'll need to wait for (slow) Mighty Moi , to show in vivo values , in case that you can't fix them by your self
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Old 17th April 2018, 03:21 AM   #287
Samuel Jayaraj is offline Samuel Jayaraj  India
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Thank you Zen Mod for your response. I could try setting offset etc. What is the dissipation in R1, R2 & what wattage would be appropriate? Thanks.
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Old 17th April 2018, 08:33 AM   #288
Zen Mod is offline Zen Mod  Serbia
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Quote:
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Thank you Zen Mod for your response. I could try setting offset etc. What is the dissipation in R1, R2 & what wattage would be appropriate? Thanks.
everything is on schematic

top of R1 is 1.01V , bottom of R2 is 3.8mV

so , I=U/R

1.01/(2x0R27)= 1A87

dissipation in resistor P=I^2 x R

P=1A87^2 x 0R27=940mW
3W resistor will do

so , you need to have one voltmeter across any of 0R27 to observe and set Iq , and second voltmeter across output to observe and set offset

write here what your results are and I can tell more precise what to do
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Old 17th April 2018, 03:21 PM   #289
Samuel Jayaraj is offline Samuel Jayaraj  India
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I didn't bother to change R7, and it remains at 220E.

My R1, R2 combination is 0.54E. Voltage drop across this resistor is 1.26 volts. To be sure, I put an Ammeter in the positive supply line and measured a current draw of 2.36 Amps.
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Old 17th April 2018, 05:34 PM   #290
Zen Mod is offline Zen Mod  Serbia
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well , bother

('till you get 1V across 0R54)

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