I am always erring around,
anyway I found these depletion mosfets:
At around 2 amps they need some Rs but then they are fine
1) IXTH6N50D2 Stable with 1.1Ω, Ciss = 2.8nF; at 4.5S ; Stable (Example Rs 0.5Ω+0.56Ω; 1.2Ω//20Ω). Good tempco ... € 13/Mouser
2) IXTH16N20D2. Ciss = 5,5nF Vgs = -2,2V @ 2Amp, 12S; Ron 80mΩ Take a Rs=1Ω or 1.2Ω €22/Mouser. Slight pos tempco, but with such a Rs that is moot.
The second looks like a powerhouse to me. The first one looks very useable too.
How to simulate these? Any models floating around? Any on-hand experience?
With these, it looks like the 'original' F6 with R100 looks like obtainable!
anyway I found these depletion mosfets:
At around 2 amps they need some Rs but then they are fine
1) IXTH6N50D2 Stable with 1.1Ω, Ciss = 2.8nF; at 4.5S ; Stable (Example Rs 0.5Ω+0.56Ω; 1.2Ω//20Ω). Good tempco ... € 13/Mouser
2) IXTH16N20D2. Ciss = 5,5nF Vgs = -2,2V @ 2Amp, 12S; Ron 80mΩ Take a Rs=1Ω or 1.2Ω €22/Mouser. Slight pos tempco, but with such a Rs that is moot.
The second looks like a powerhouse to me. The first one looks very useable too.
How to simulate these? Any models floating around? Any on-hand experience?
With these, it looks like the 'original' F6 with R100 looks like obtainable!
Attachments
how about this KISS?
the potmeter 5Ω allows skewing of the working points and hence the balance / phase of H2. which one I don't know yet;
once determined it should remain stable.
[I had such skewing on a balanced preamp in the nineties]
the potmeter 5Ω allows skewing of the working points and hence the balance / phase of H2. which one I don't know yet;
once determined it should remain stable.
[I had such skewing on a balanced preamp in the nineties]
what's the point of making an amp with OS parts so heavily degenerated?
OK, I'm biased, having extrastrong fetish for pure SQL OS, but anyway?
I'm just not seeing it - with all those compromises, none possible better than with good old IRFP
OK, I'm biased, having extrastrong fetish for pure SQL OS, but anyway?
I'm just not seeing it - with all those compromises, none possible better than with good old IRFP
I totally agree. all degeneration will destroy the vibration.
and putting a big .1 - 1F across it helps little probably.
note the F6/IRFP has 0.47Ω or 0.56Ω.
This beast has 1Ω. What is the difference?
here the degeneration is as variable as the sloppy drawing of a potmeter to its wiper the capacitor is attached.
top = little; bottom a lot (up to 1 or 1,5dB difference) - theoretically impossible to hear.
or have the other half use this; enfin you know the trick.
A bias V- would be more comfortable and is easy to make for the top. attach a green led (yes green please!?) to earth and the V- and presto you have some -1,7V bias for the wiper to scratch.
Or a fixed-Voltage-device of 2.5V .
Then no degeneration on top.
But then you will have to test the harmonics of the whole with only degeneration at the bottom. . and that might switch the phase around (It is all in my head now, sorry)
and putting a big .1 - 1F across it helps little probably.
note the F6/IRFP has 0.47Ω or 0.56Ω.
This beast has 1Ω. What is the difference?
here the degeneration is as variable as the sloppy drawing of a potmeter to its wiper the capacitor is attached.
top = little; bottom a lot (up to 1 or 1,5dB difference) - theoretically impossible to hear.
or have the other half use this; enfin you know the trick.
A bias V- would be more comfortable and is easy to make for the top. attach a green led (yes green please!?) to earth and the V- and presto you have some -1,7V bias for the wiper to scratch.
Or a fixed-Voltage-device of 2.5V .Then no degeneration on top.
But then you will have to test the harmonics of the whole with only degeneration at the bottom. . and that might switch the phase around (It is all in my head now, sorry)
@triode_al
I understand the joy of experimenting with different devices however, in case you missed that post, Nelson said that his F6 test listeners preferred the MOSFET version over the JFET's.
https://www.diyaudio.com/community/threads/f6-amplifier.216616/page-285#post-3910852
I understand the joy of experimenting with different devices however, in case you missed that post, Nelson said that his F6 test listeners preferred the MOSFET version over the JFET's.
https://www.diyaudio.com/community/threads/f6-amplifier.216616/page-285#post-3910852