Let me lite fire - Nelson Pass F1

[jh6you]

Crying like a baby, one small girl was afraid of walking into the operation room . . . I said it's a small thing . . . I pushed her back into the room . . . It was not a cancer, but something under the skin . . . Mmm . . . she was born with it . . .
Waiting outside . . . I was thinking about . . .
Pass Zens and the First Watt . . .
Yeah, it's time . . .


Here is my concept darwing.


I will not draw any details . . . I am afraid of Nelson Pass . . .


My target is 5W@8ohms and 10W@4ohms.
A-class of efficiency about 5%.
Of course, the current source amplifier.

Nelson Pass, is the concept feasible?

Will it drive normal 2-way 90dB speakers too?
Or, should I change the x-over network?

Or, should I go with the efficient single unit speakers?

Regards
jH

[gl]

Hi JH,

Mr. Pass has already given away most if not all of the F1 design in the form of small hints on this board and in the ZEN articles on PASSDIY. I would start off by doing a search on the subject.

I have built a transconductance SOZ from this information. I am still debugging a few things but it does work and it does make music. Some other people have already had good luck converting some of the other Zen's to work as current amps, if you need something right away.

Your other questions on 2 way speakers and crossovers are already answered in the current source amplifier and crossover papers on the PASSDIY website.

Cheers,
GL

[thorstenlarsen]

Hi jH !

The schematic you have shown looks like an X-SOZ, without any series resistor at the input. It will have a very low input resistance, because of the feedback from drain to source.
If you add a series resistor at the input, the amp will turn into a voltage amplifier.

Thorsten

[acaudio]

I thought a little about this:

Adam

[Nelson Pass]

Well guys, if you're going to second-guess the F1, you'd
better hurry up, as the service manual will go up next month
or so.

[JEKYLL]

Yyyyyyyeeeeeesssssss!!!!!!!!!!!!!!!!!!!!

[gl]

Mr. Pass,

I noticed that Mark Sammut has added a note to his site that says that he will run out of F1's by the end of this month. I took that to mean the current batch he had on hand, but I guess it means for all time.

GL

[Nelson Pass]

The F2 is out, and there will be poop up on the web site
www.firstwatt.com in a couple of days.

Probably I will close out new F1 availability sometime next
month, although RenoMark is anticipating some trade-ins on
F2's and subsequent product.

[jh6you]

Oh . . . the limited number of the first edition is almost slod out . . . ?
In one month . . .


gl, I will read his writings.
Thorsten, thanks for the hint about the input R.
acaudio, mine is almost the same as yours. Did you build it?


Actually, mine was inspired by Zen V6 and Zen V7 . . .
I will go out to find IRF240 and collect them and others . . .


Regards
jH

[jh6you]

You are right.
The simplified Fi schematic is already at www.firstwatt.com . . .
So, mine is found as feasible . . .

Yeah . . . Nelson Pass gives no sanwer . . . Often it means yes . . . I know . . .


Regards
jH