An externally hosted image should be here but it was not working when we last tested it.
I saw some other op-amp biased fetamp so I thought I would post this one. No bias circuitry is drawn in the picture. Just the basic amp. As it is now it runs in class C. Not any sweetsounding but its just an idea.
Any thoughts or comments????
Bias will be really tough unless you run class A or L-MOS.
B+ maximum for outputs is about 44V (about 60W/8R) for the OPA2604 running off ±24V.
Higher voltages may be used but it can get very complicated.
B+ maximum for outputs is about 44V (about 60W/8R) for the OPA2604 running off ±24V.
Higher voltages may be used but it can get very complicated.
Looks like Sumo Nine(+), except mosfet output, deseign by James Buongiorno.
http://photobucket.com/albums/v58/aparatusonitus/?action=view¤t=Sumo9.jpg
http://photobucket.com/albums/v58/aparatusonitus/?action=view¤t=Sumo9.jpg
Very much so except:
The variable bias scheme should not be tried with FETs.
The high voltage LF 353s were obtained by selection for ±20V. An OPA2604 sounds better and will work at ±24V without selection.
Bongiorno says the AD823 selected for ±20V use is even better.
The variable bias scheme should not be tried with FETs.
The high voltage LF 353s were obtained by selection for ±20V. An OPA2604 sounds better and will work at ±24V without selection.
Bongiorno says the AD823 selected for ±20V use is even better.
Check this out
Its an opamp driven N- channel vertical mosfet amplifier
http://www.qscaudio.com/support/library/schems/pl90.pdf
Its an opamp driven N- channel vertical mosfet amplifier
http://www.qscaudio.com/support/library/schems/pl90.pdf
Why should bias be tough?
Perhaps the following completes the picture:
This is a modifcation from a design in "Radio" August, 1984 issue, pages 35-37.
Don't ask about the sound, because I never got around building the first time I saw it and later I found Renardson's 7-transistor amplifier, which is technologically superior to DIY.
Perhaps the following completes the picture:
An externally hosted image should be here but it was not working when we last tested it.
This is a modifcation from a design in "Radio" August, 1984 issue, pages 35-37.
Don't ask about the sound, because I never got around building the first time I saw it and later I found Renardson's 7-transistor amplifier, which is technologically superior to DIY.
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