Thanks OS ,so you didn't recommended empty holes for these CLc,Cvs 1/2?😱
PS is it possible give some current(mA)measurements for Ltp and VAS ?
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You can start with just C7 ... you will have a "ampslab" basic amp (or a
REAL big NE5532) 😀.
Add the Clc/Cvs later .... they "mold" the sonic signature. (FFT says so).
OS
Is it possible give some current(mA)measurements for Ltp and VAS ,so i can trim?
R26,R27=1M
C9,C10=1uf Is this ok?
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Exactly 3V (3ma) across R8 will give 4.8ma VAS current.
Depending on your rail voltage , R11 and 13 might also need adjustment
to supply the "hungry" 😀 zeners with enough current.
C9/10 ?? (11?) any reasonable value will be good for the local IC decoupling.
PS- so we are on the same page ... I made labeling mistakes early on.
(below is the latest).
OS
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That what I changed ... the servo caps ...
Yes ! 1 meg / 1uf will bring you close to the .2-.3Hz servo fc. Good !
(actually .5hz ... but still good).
OS
Good Job Thimios
i expect from this simple topology amp perfect 100 khz square wave at last full p-p.
i expect from this simple topology amp perfect 100 khz square wave at last full p-p.
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Now it's time for test.
See measurments on shematic
photos.
1)1KHz/12vRMS/8R
2)10KHz/12V RMS/8R
3)20KHz/12V RMS/8R
4)20KHz/27V RMS/8R just before clipping.
5)20KHz clipping /29V RMS out/8R
6)20KHz hard clipping/31V out/8R
SQUAREWAVE
7)1KHz 28V OUT/8R
8)10KHz out 13V/8R
9)20KHz
See measurments on shematic
photos.
1)1KHz/12vRMS/8R
2)10KHz/12V RMS/8R
3)20KHz/12V RMS/8R
4)20KHz/27V RMS/8R just before clipping.
5)20KHz clipping /29V RMS out/8R
6)20KHz hard clipping/31V out/8R
SQUAREWAVE
7)1KHz 28V OUT/8R
8)10KHz out 13V/8R
9)20KHz
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the rest
1)50KHz
2)100KHz
-3db doun to 2.8Hz
up to 200KHz (tested at 20v RMS) (-3db 14.4v)
All PNP small signal trans.=TCSA970. All NPN (except vas)=2sc1845
Output transisstors 2sa1943,2sc5200 (one pair).
PS Many guys ask me about listening test.
This is the most difficult.
I haven't good speakers so i can't hear difference at so hi quality amplifiers.
Is on my plan to have a listening test when my friend repair his kef speakers,or my other friend Nikos call me into ARTA.
Thimios.
1)50KHz
2)100KHz
-3db doun to 2.8Hz
up to 200KHz (tested at 20v RMS) (-3db 14.4v)
All PNP small signal trans.=TCSA970. All NPN (except vas)=2sc1845
Output transisstors 2sa1943,2sc5200 (one pair).
PS Many guys ask me about listening test.
This is the most difficult.
I haven't good speakers so i can't hear difference at so hi quality amplifiers.
Is on my plan to have a listening test when my friend repair his kef speakers,or my other friend Nikos call me into ARTA.
Thimios.
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i like your measurments Thimios promise good sound.
Now pull out the servo ic and measure the dc offset to see how matced are the ltp and not olny .
Now pull out the servo ic and measure the dc offset to see how matced are the ltp and not olny .
Hi my friend ,i have built all these amplifiers without any matching!
Thimios.
The first fire up is good .pull out the servo and measure , if measure big value of volt its nesesery to match the LTP and you get more sound detail .
Very good !
I do notice "sticking" on clip. Try increasing main VAS cascode LED current
(R16)... try 33-47K here (>2+ma led I).
Square wave is excellent ... this amp has the "slew" !
OS
Hi OS ,i will try this afternoon.
You mean this R16 from 100K to 33-47K SO I led=2mA?
Which is the recommended out idle current(one pair)?
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