Thanks OS ,so you didn't recommended empty holes for these CLc,Cvs 1/2?So you get the very best listening impressions.
C7 = 33p
Clc= 2.7p
Cvs1/2 = 47p
don't make Clc too big .. like 5p (peaking) .. better to be small (2pF)
(below) is the ideal bode with the values above. A VERY
well behaved amp (stability wise)
PS - you can bring this amps unity gain up over 2mhz and it will
still be "well behaved".
(C7 = 22p Clc= 3.3p - 2.1mhz UG)
You can also reduce R9/R10 to 33R for 72db CLG with still ... plenty of
margin .... VERY wide range while being very stable.
The only way to get any ringing on SW was to go (C7 = <15p) or
to use a forbidden 10p+ for Clc ....
OS
PS is it possible give some current(mA)measurements for Ltp and VAS ?
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Thanks OS ,so you didn't recommended empty holes for these CLc,Cvs 1/2?
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?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
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
Attachments
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Ok ,now it's time for testing.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"
OS
I will report again.
Thimios.
I mean 1uf in place of these 2u2.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"
C9/10 ?? (11?) any reasonable value will be good for the local IC decoupling.
OS
1uf in place C12,C13?
R26,R27=1M?
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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
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.
Attachments
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Hi my friend ,i have built all these amplifiers without any matching!
Thimios.
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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