F5 power amplifier

[Blues]

Let me guess Nelson...the output stage has 3 pairs of mosfets with about 200mA of bias through each pair?

[Nelson Pass]

No, you are looking at all the gain devices in that schematic.

[anubisgrau]

best wishes for the fast recovery, nelson!

it would be great if you could add a few words on what in particular you've wanted to achieve with F5, what's the sound philosophy behind, whom it is aimed for (what kind of speakers).

this is so distinctive about each of FW amps - a strong philosophy behind each and every of them. but one has to be careful where to apply them!

[Zen Mod]

talking about Profet ;
NFB is bloody different

[Blues]

Originally posted by Nelson Pass
No, you are looking at all the gain devices in that schematic.

What!?...WOW!

[Blues]

Isn't that circuit supposed to be Zv10?

[stefanobilliani]

Originally posted by EUVL
All the best for a speedy recovery.

I think R4 should also be 600 ohm and not 0R47.

Yeah , me too

[Nelson Pass]

Originally posted by Blues
Isn't that circuit supposed to be Zv10?

I suppose that ZV10 would have been the F4.

The Zen Variations were intended as single-stage amplifiers
(although ZV4 had a buffer).

The First Watt stuff is distinguished by being commercial product,
and is not limited to single stages.

14 years is a good long run for the Zen series. I may return to it
some time in the future, but I don't have a specific plans.

[stefanobilliani]

Were we talking somewhere of a nice new preamp in the zens ?

[Nelson Pass]

Originally posted by EUVL
All the best for a speedy recovery.

The simplified schematics looks familiar though ?

Profet Amplifier

PS I think R4 should also be 600 ohm and not 0R47.

Such a smarty-pants. Yes, it's 600 ohms (it's correct in the not-
simplified schematic).

I had not seen the Profet schematic before - when the ads came out
I noted that it supposedly "all the benefits of a current source
and voltage source" and I didn't give it further attention.

An email correspondent some years ago also suggested this
topology, a CFP with voltage gain. If I could remember his name I
would have mentioned him. (who knows, maybe it was the Profet
guy...)

Anyway, it's been around for a while. When you read the F5 article,
you will see "The topology is familiar...". Selectronics has chosen to
bridge the circuit and settled on different values.

Given the differences in measured performance from "Chuck"
Hansen's review in AudioXpress, I suspect that they were using the
same kind of gun to shoot at a different target.