OK, it is over 20dB local NFB around the input device!
I have always liked the JLH 10W, actually it was one of the first amps I built back in the -60s. For a long time I have also favoured the buffer version of it with a PNP as phase-inverter together with a tube driver.
Got inspired when I saw the simplicity of the PLH. By changing the IRF610 to a p-channel IRF9610(in the schematic a fqp..... as I didn´t have a working model of the IRF) the PLH is now transformed into a unity gain buffer. By adding a BOZ we are done!
At first I was into a transformer-coupled OCL tubehybrid, with a 6H30 follwed by a Slagle bifilar. But noticing the slight allergy against tubes in this corner of the forum I went for the BOZ😉.
It sims OK with a nice 2nd harmonic domination and a bandwith to over 100k.
I have always liked the JLH 10W, actually it was one of the first amps I built back in the -60s. For a long time I have also favoured the buffer version of it with a PNP as phase-inverter together with a tube driver.
Got inspired when I saw the simplicity of the PLH. By changing the IRF610 to a p-channel IRF9610(in the schematic a fqp..... as I didn´t have a working model of the IRF) the PLH is now transformed into a unity gain buffer. By adding a BOZ we are done!
An externally hosted image should be here but it was not working when we last tested it.
At first I was into a transformer-coupled OCL tubehybrid, with a 6H30 follwed by a Slagle bifilar. But noticing the slight allergy against tubes in this corner of the forum I went for the BOZ😉.
It sims OK with a nice 2nd harmonic domination and a bandwith to over 100k.
So, with the help of a lowdropout regulator we can get rid of the extra +40V. The negative voltage is easier to arrange for, so it stays.
An externally hosted image should be here but it was not working when we last tested it.
That's quite clever.
I suspect, however, that the pot and C10 actually
introduce a small amount of local feedback.
😎
I suspect, however, that the pot and C10 actually
introduce a small amount of local feedback.
😎
The source of M2 isn't going anywhere.
Current cascodes right thru M2 into R1.
Yeah, I think that ends up being NFB...
Current cascodes right thru M2 into R1.
Yeah, I think that ends up being NFB...
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