F6 Amplifier

Official Court Jester
Joined 2003
Paid Member
little forensic work

well - just came to my mind - regarding recent dilemma about Papa's revealing of F6 schm

ZM has been nagging me for information on the F6. I have a very nice
sounding prototype, but the design and the article that accompanies it
have some details remaining.

However, I can afford to put out this teaser:

:cool:



so - Papa is preparing article , and he told us that iin very first post

we aren't just Greedy ........ we are not so rarely even Hysteric Boys

:devilr:
 
Circlomanen: Is the schematic theoretical or does it pertain to a circuit you are already testing?

I have been thinking about a headphone-amp just to test the circuit. I dont have any other depletion mode fets than DN2540 and SK170-BL. Non of them powerfull enough for driving a 8 ohm loudspeaker without lots and lots of them paralell.

If i had som SiC-J-fets this is what i would build. I like this amp a lot. The simplicity and the use of transformers are brilliant. Its a really smart way to get maximum sonic benefits without the drawbacks. Transformers usually gives a very nice sound. Warm, effortless and organic.

Mvh Johannes.
 
What is the point behind using a transformer?

A) gives us the required phase splitting without any active devices
B) allows easy operation of the top half as a common source
C) simplifies biasing

To achieve the above without a tx would take quite a few active devices IMO - take a look at Digital Do-mains implementation of the same op topology - even the simplified schematic is scary ;)
 
Forgot the generator link. Post #4
http://www.diyaudio.com/forums/pass-labs/195430-ro85-zen.html

Another point about the SiC parts. I have had multiple recomendations about trying to minimize the use of source resistors.

That won't work for this.
Since you already have dual rail voltage (+/-) and you want the negative voltage for the lower (negative) SIT, I think you need a more negative supply attached to the negative rail if this makes any sense.
So a small 6 to 10 volt trans rectified and smoothed, Attach the bias positive rail to the negative rail of the main supply and you should have -10 volts or so more to adjust bias from.

Rush
 
What is the point behind using a transformer?

There are a number of tube guys, who have been using transformers for phase splitting for awhile now, have discovered that they work better than almost any other phase splitter known to man. Of course, some disagree.

But really good one's aren't always inexpensive, especially when designed as 'inter-stage'. But if you use a phase splitter as the input transformer where signal levels are lower then it gets slightly easier (less expensive). And it seems to me that the F6 uses the phase splitter as essentially, an input transformer. It just happens to be buffered first (probably a requirement for the series feedback arrangement to isolate the feedback loop from the source impedance???).
 
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That won't work for this.
Since you already have dual rail voltage (+/-) and you want the negative voltage for the lower (negative) SIT, I think you need a more negative supply attached to the negative rail if this makes any sense.
So a small 6 to 10 volt trans rectified and smoothed, Attach the bias positive rail to the negative rail of the main supply and you should have -10 volts or so more to adjust bias from.

Rush

Thanks Rush. Wasnt exactly thinking it through, was I? Got your package. Yours should arrive soon. Thanks again.
 
Official Court Jester
Joined 2003
Paid Member
..... It just happens to be buffered first (probably a requirement for the series feedback arrangement to isolate the feedback loop from the source impedance???).

hardly that that's the main reason

you ned low impdance to drive two so-called 150R windings in parallel , and are you using buffer or preamp to muscle it , it's irrelevant

in this case , logic is that not all ppl are Susumi Sakuma , having preamps with output impedance in sub 100
 
it will work , if you're using two windings-two bridges , as Papa does

Not sure I follow you ZM.
You mean if your transformer has a second winding you are not using to power the output devises? Then yes, that is the same as another transformer.
Or do you mean you can cap couple a rectifier off of one winding and add it to the negative rail? Hum, a digram would help me, not sure about the ground in that case.

Rush
 
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