hi, peranders.
the PCB made by the FHIFIDIY.net,and it drawn by my buddy AEON,its schematic is designed by me.
the post which we build and discuss is on here:
http://www.hifidiy.net/dispbbs.asp?boardID=2&ID=19991&skin=0
sorry,I don't finish drawing of the whole schematic which all in my brain
,but is the basic topology of it show below:
it have two JFET buffers,one for input and perform V/I convert which V/I resistor is R7,another for output and perform isolation.
the middle stage is the current transmission of super-pair and R13 is the volume controler which perform I/V converter.the gain of the pre amp=R13/R7
the pre-amp is Non NFB,in other words,it don't have loop feed back but have strong local NFB .the simulator tell me the distortion in ordinay play level is less than 0.01% and mainly from the JFET buffers.I don't have the distortioner to verified it
,but I have check the BW of it in pratice....the BW of the pre amp is 700KHZ@-3dB!!! when R13(R10 in the pic below) is less than 1K.
the sound of it is very smooth, very detail, much much better than my OPA627+BUF634 pre which show here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35712&highlight=
I continue to modify it now:
the PCB made by the FHIFIDIY.net,and it drawn by my buddy AEON,its schematic is designed by me.
the post which we build and discuss is on here:
http://www.hifidiy.net/dispbbs.asp?boardID=2&ID=19991&skin=0
sorry,I don't finish drawing of the whole schematic which all in my brain
,but is the basic topology of it show below:
An externally hosted image should be here but it was not working when we last tested it.
it have two JFET buffers,one for input and perform V/I convert which V/I resistor is R7,another for output and perform isolation.
the middle stage is the current transmission of super-pair and R13 is the volume controler which perform I/V converter.the gain of the pre amp=R13/R7
the pre-amp is Non NFB,in other words,it don't have loop feed back but have strong local NFB
.the simulator tell me the distortion in ordinay play level is less than 0.01% and mainly from the JFET buffers.I don't have the distortioner to verified it ,but I have check the BW of it in pratice....the BW of the pre amp is 700KHZ@-3dB!!! when R13(R10 in the pic below) is less than 1K.
An externally hosted image should be here but it was not working when we last tested it.
the sound of it is very smooth, very detail, much much better than my OPA627+BUF634 pre which show here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=35712&highlight=
I continue to modify it now:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi, XG,
I study your schematic, and it's actually a Folded Cascode, modified by placing Q11 and Q15 so the output is non-inverting (ordinary folded cascode gives inverting output).
Q1 and Q9 is for helping setting the voltage reference of the diodes?
The folded cascode is Q11 towards Q8.
But one thing is not clear. If the current passing the 220ohm resistor is 6.8mA, how many mA is passing through Q11, and how many mA is passing through Q8? I cannot calculate how many % of biasing current is passing to front path and end path.
I study your schematic, and it's actually a Folded Cascode, modified by placing Q11 and Q15 so the output is non-inverting (ordinary folded cascode gives inverting output).
Q1 and Q9 is for helping setting the voltage reference of the diodes?
The folded cascode is Q11 towards Q8.
But one thing is not clear. If the current passing the 220ohm resistor is 6.8mA, how many mA is passing through Q11, and how many mA is passing through Q8? I cannot calculate how many % of biasing current is passing to front path and end path.
hi,lumanauw
yes.....depend on what you think.maybe it can seen as a special diff stage+ special CB stage+buffer.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25051&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=29750&highlight=
and more:
http://www.diyaudio.com/forums/sear...d=240736&sortby=lastpost&sortorder=descending
PS:Are you a Chinese,lumanauw?
X.G.
lumanauw said:
yes.....depend on what you think.maybe it can seen as a special diff stage+ special CB stage+buffer.
Q1-Q8,Q2-Q9,Q6-Q11 andQ4-Q15 all are super-pair stages....you can see some posts of them in digital area,like this:lumanauw said:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=25051&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=29750&highlight=
and more:
http://www.diyaudio.com/forums/sear...d=240736&sortby=lastpost&sortorder=descending
the current of Q8 is close to Q1, Q11 is close to Q6,and depend on the temp couple.the simulate show something for that,and my experience show the result.I think you can calculate all of them now.lumanauw said:
PS:Are you a Chinese,lumanauw?
X.G.
lumanauw said:
yes,the current of Q1=Q6,and the current of Q1=(Vcc-Vref)/R18......oh! I made a mistake before
,correct it :the current of Q8 is not(!) close to Q1,the current of Q11 is close to Q6.one sample of my experience,IIRC,when Q6=1.50mA,Q11 is 1.53mA,and Q8 can reach to 8mAnow,the total current of Q1,Q8 and Q11 equal to Vref/R1,so you can easily caculate the the current of Q8.
lumanauw said:
oh......I had viewed your post which about FM acoutis and saw your picture....
I know where Indonesia is,of course
,but I don't know where Bandung is
"Anyone remember a common emitter output design called the "Texan" back in the 70s"
My first amp. This was a "Practical Wireless" pre/power amp design by a TI engineer. Very popular because of ease of construction (741/748 op amps throughout + o/p stage). Combined it with a Skingley-Thompson (WW) FM tuner. Made three of them on home made pcb's. Still going strong.
I still have a spare FR4 pcb!
Brian.
My first amp. This was a "Practical Wireless" pre/power amp design by a TI engineer. Very popular because of ease of construction (741/748 op amps throughout + o/p stage). Combined it with a Skingley-Thompson (WW) FM tuner. Made three of them on home made pcb's. Still going strong.
I still have a spare FR4 pcb!
Brian.
Hi David,
i've lived in The Hague for 10 years, you'll find an Indonesian restaurant or Toko on every corner there.
They all have masakan padang, i am very fond of rendang.
Type "sate" in google, that should give you an idea how common satay is here.
Every french fries shop here has satay too, but not as good.
I'm very fond of Thai style satay: thin sliced, folded around the pin, grilled on charcoal.
I've been cooking Indonesian food since i was 10, also do my own sambals and atjars since then.
(and have become sambal badjak addicted, PEDIS !)
www.pasarmalambesar.nl/english/eng.htm
Anyone got a schematic of the Texan ?
i've lived in The Hague for 10 years, you'll find an Indonesian restaurant or Toko on every corner there.
They all have masakan padang, i am very fond of rendang.
Type "sate" in google, that should give you an idea how common satay is here.
Every french fries shop here has satay too, but not as good.
I'm very fond of Thai style satay: thin sliced, folded around the pin, grilled on charcoal.
I've been cooking Indonesian food since i was 10, also do my own sambals and atjars since then.
(and have become sambal badjak addicted, PEDIS !)
www.pasarmalambesar.nl/english/eng.htm
Anyone got a schematic of the Texan ?
A new idea, or only a question:
What if we would use a separated PS for the drivers in the output stage ?
(For the first transistors in the darlington)
Base concept: when the output transistors load the main PS, it
should give a lot of current in a short time, so only a less current
would remain to the drivers in the same time, when the PS is shared.
What if we would use a separated PS for the drivers in the output stage ?
(For the first transistors in the darlington)
Base concept: when the output transistors load the main PS, it
should give a lot of current in a short time, so only a less current
would remain to the drivers in the same time, when the PS is shared.
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