F6 Amplifier

Just a matter of ordering them from Profusion. Little expensive, but great deal less than SS.
Two I would recommend.
ECW20N20-Z
ECW20P20-Z
Interesting that these MOSFETs specifically target audio power amplifiers. Claims of high thermal stability will make them useful in diyF5s. If desired a DIYer may build a diyF6 with P-MOSFETs for the right channel and a diyF6 with N-MOSFETs for the left channel of the stereo system. Complementary diyF6s.
 
No problem with tempco. Use Rs to stabilize the bias and connect to lower end of the transformer windings to the source pins. Thus the AC drive is not degenerated by Rs. The only negative effect of Rs is to slightly limit the maximum current drive to the FET. In a build using the R100s, someone do a test using switches across Rs to see if there is a detectable sonic difference. It would surprise me if there was.

The main issue with the Cree is the temp coefficient. It wil not allow for low or no Rs on the outptut fets. I ebelieve it may be a better alternative than IRF. It will get closer than the Exicon on the gain/Yfs front, but I personally feel that the dropping of Rs is one of the things that defines the sound of this amp. I am working on an output board for the Vfet's. We will try 2sk82 first.
 
What about these:Cree CMF10120D or these CMF20120D Mouser has them in stock.
Will they do? What is the difference between these and the SemiSouth?
Rush
I think the Cree 20120 is probably going away in favor of the new Z FET 80120? just a guess on my part though.
Skipping down the datasheet of both, the new Z FET and the SS, noting the parameters that are good for amps, or at least I look for (Not necesassarily needed in the F6):
Id - SS 17A, 30AMax
80120 20A, 60AMax

Rthjc - SS 1.1 max
80120 .65 max

Pd - SS 136W
80120 208W

C - SS 670pf, 103pf, 97pf, Ciss, Coss, Crss
80120 950pf, 80pf, 6.5pf

Of coarse a real amp listening test would be the ultimate test???
I'ld like to here what others think or have done in this regard. For instance Nelson? have you tested these babies??? 😎

I'm not quite ready to pull out a Benjamin Franklin + for 4 of these guy's just yet but, if we could get the cost down???

There are other parameters I'm forgetting but, the overwelming one is that the 80120 should be available for ~$17 ea. The SS is almost unobtainium 😉
 
I think the Cree 20120 is probably going away in favor of the new Z FET 80120? just a guess on my part though.
Skipping down the datasheet of both, the new Z FET and the SS, noting the parameters that are good for amps, or at least I look for (Not necesassarily needed in the F6):
Id - SS 17A, 30AMax
80120 20A, 60AMax
10120 13A, 49AMax

Rthjc - SS 1.1 max
80120 .65 max
10120 .82 Max

Pd - SS 136W
80120 208W
10120 134W

C - SS 670pf, 103pf, 97pf, Ciss, Coss, Crss
80120 950pf, 80pf, 6.5pf
10120 928pf, 63pf, 7.5pf

Of coarse a real amp listening test would be the ultimate test???
I'ld like to here what others think or have done in this regard. For instance Nelson? have you tested these babies??? 😎

I'm not quite ready to pull out a Benjamin Franklin + for 4 of these guy's just yet but, if we could get the cost down???

There are other parameters I'm forgetting but, the overwelming one is that the 80120 should be available for ~$17 ea. The SS is almost unobtainium 😉

I added the Cree 10120 part:
Id - SS 17A, 30AMax
80120 20A, 60AMax
10120 13A, 49AMax

Rthjc - SS 1.1 max
80120 .65 max
10120 .82 Max

Pd - SS 136W
80120 208W
10120 134W

C - SS 670pf, 103pf, 97pf, Ciss, Coss, Crss
80120 950pf, 80pf, 6.5pf
10120 928pf, 63pf, 7.5pf

They are available at Mouser $20.62, Newark $14.07 each.

Rush
 
--left picture amp with splitted resistor network in the PSU according to F6 talk

--right picture amp with not splitted resistor network in the PSU

I see no visible difference concerning the higher harmonics of the 50Hz fundamental.....

my 100Hz is fairly high....does anyone know what to do and what is the influence to the sound?

The 50Hz hum is high because of Kimber cables not shielded and the USB sound card itself.

The third picture is from the Masters device, like always much better, how does he do that? He gets better 100Hz and 200 Hz values without any splitting.... ha, ha!

:devily::devily:
 

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I know in tubes, the issue of balance and hum is always more present and dealt with in interesting ways. Also I tihnk about ZV7 and his comment about how many transformers are not truly balanced on their secondaries and in that particular amp, he talked about trimming it. I guess it is reasonable to believe that the nicer the transformer, the more testing they do and perhaps, this is a request of Nelson to them when making them. I am eagerly waiting to hear the Primrose transformers, as they are suppose to be higher quality. I would hope, winding balance is part of that improvement. Still guessing though.