I've got two small signals, one I want to run through a voltage amplifier (not much gain, maybe 4 or so), and the other one I want to do the same thing, but invert it. I'd like to go discrete for this, with BJTs or JFETs. Now I know how to do it with opamps, but how would I go about it with discrete components?
JoeBob,
Take a look at the second schematic of the thread below and read a little further. If you take the inverting and non-inverting outputs of this preamp they'll both be offset by about +50mV but that should do the trick. If the 50mV offset is too much you could capacitor couple them.
If you were to use the third schematic you would definitely have to capacitor couple the outputs since the offset is about -15V each.
However, if you were going use it as a balanced preamp as I have, you wouldn't have to couple the outputs. (R21 represents the load, which would be the power-amp)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=3001&perpage=15&pagenumber=1
Stephen
Take a look at the second schematic of the thread below and read a little further. If you take the inverting and non-inverting outputs of this preamp they'll both be offset by about +50mV but that should do the trick. If the 50mV offset is too much you could capacitor couple them.
If you were to use the third schematic you would definitely have to capacitor couple the outputs since the offset is about -15V each.
However, if you were going use it as a balanced preamp as I have, you wouldn't have to couple the outputs. (R21 represents the load, which would be the power-amp)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=3001&perpage=15&pagenumber=1
Stephen
Also suggest you look at Pass' Balanced Line Stage and his article on building your own opamps. www.passdiy.com
I was thinking of just using DIY discrete opamps (a la Nelson Pass article), but didn't know if there were better ways...
What! First I have to send you the parts, then you ask for Spice models. Now you want me to design it too? [joke]
I take it that they haven't arrived yet.
Jocko
I take it that they haven't arrived yet.
Jocko
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