F4 power amplifier

[Babowana]

Originally posted by GRollins


What'd I miss?

Yes, you are missing my interest.
I'm a bit tired of doing DIY these days, and busy.
I will not care of any scratch on the surface
as long as there is the original finger-print of Nelson Pass.
What is the retail price for the F4?
Much much higher than 2.5K USD . . . ?

I'm serious!

[EUVL]

> I don't have the datasheets for the input JFETs with me at the moment

Identical to 2SK170/2SJ74, only not TO92.

Patrick

[juma]

First stage (complementary JFET pair) is just an input buffer and it's not that critical. Any favourite low current buffer stage with appropriate voltage swing capability can be used.

I think that I would build F4 as na integrated amp, in the same box with Aleph L or Aleph P.
In that case the input JFET pair could be left out of the circuit.

2N4736 should probably be 1N4736 (6.8V 1W Zener)

[jacco vermeulen]

Originally posted by juma
probably be 1N4736

General Pass must have had his mind wander off to exotic wave braking shores for a bit longer.
(irish wolfhound playground)

Curious me: what to expect for the rise time of this beauty ?

[mpmarino]

This one looks fun.

A couple of things please! Thanks in advance.

I remember seeing a reference that the IRFP140 is a better complement to the IRFP9240 than is the IRFP240. Is this true? Would anyone have spare IRFP9240? I have spare IRFP140 I would like to trade off for 9240. maybe we could help each other.

Amongst the guys that know jfets - Please don't be shy in suggesting suitable replacements (and hashing out which is best, and why). I am sure more than myself could benefit in how you come to the conclusions you come to.

heatsink on the jfet?

I promised myself no more amps. This one will be the last

Thanks Nelson!

[adolphe]

Would this be suitable as an amp for the AKG K1000 headphones?

[Zen Mod]

Originally posted by adolphe
Would this be suitable as an amp for the AKG K1000 headphones?

certainly;


for who's ears?

[Vix]

Originally posted by mpmarino
I promised myself no more amps.

Hehehe....I have built ZEN V9 and an F2 lite. Great! Very friendly amps to fullrange speakers. At least I don't need another amp! But...what could be better than a fullranger on the Open Baffle, driven by Zen v9 or F2?
Uhm....you bet-F4 driving big woofers on OB!

But...Yea, no more amps....

Someone on diyaudio once said "Stop pushing my Woo-woo button!"

[Jon Ver Halen]

Very, very nice amp. It has the JFET sweetness, like the F3, but also has push pull control and is direct coupled. An awesome little amp for those you can live with it's limitations (low gain and low power).

If your system does not work with these limitations consider this amp to be a great excuse to build a better pre-amp and get into high efficiency speakers. Yes, it is that good.

[Zen Mod]

mebbe yes
mebbe not

( probably not)
this variant for my 16E 15"

not btw :
Papa,tnx again .........no more no less than for inspiration