F4 power amplifier

[Babowana]

Originally posted by Nelson Pass


Commenting on the particular mis-match of the complementary
types, notice that the distortion is primarily second harmonic
on the amplifier and that the distortion vs power curve looks
just like a classic single-ended amp.

This imparts a particular sonic signature different from the
usual push-pull arrangement where the character is 3rd harmonic.

Thanks, I will go with mismatchd stones as I have had experience
of it with Zen V5. I will re-fill F1 having a bit higher rail voltages.
I would try to adjust R values, if necessary. I might be able to
manage this within few days when I get jfets, not using PCBs, but
applying P2P as usual. ~ ^^

[jimmyd53]

Papa and Jon,

I am curious, since you are the only two who have listened to all the First Watt amps with Lowthers, as to which amp you personally like best ? Thanks.
James

[Ipanema]

Commenting on the particular mis-match of the complementary types, notice that the distortion is primarily second harmonicon the amplifier and that the distortion vs power curve looks just like a classic single-ended amp.

If I prefer more second harmonic, should I use higher mismatches device between PMOS and NMOS?

Mr. Pass, may I know why you prefer to use TL431 in place of the usual Vgs multiplier, which is more common in the push-pull stage with the added benefit of temperature feedback? How does F4 overcome the temperature instability?

I've just completed F2 and SL10. It just sound marvelous driving my Coral Flat 8A and now I'm addicted to build the F4. Thanks a lot Mr. Pass.

[Jon Ver Halen]

I am curious, since you are the only two who have listened to all the First Watt amps with Lowthers, as to which amp you personally like best ?

Aha! Down to the meat of it all. There is no right answer, and it is part dependent on your taste, part on your music, and your source.

The F1 is super clean and dynamic. If your source is lean, your music will be lean. If your source is rich, your music will be rich. It is the real truth machine, with nothing taken out and nothing added. Ruthlessly revealing.

The F2 adds some 2nd harmonic to this. On lean source material this sounds better than the F1. It is putting a little color in your music, and on dry material it is a pleasant addition. Some like that additional color, some do not. Your choice.

The F3 sounds has a very light touch of sweetness. Sounds more like a great tube amp than any solid state amp I have heard, except that it has the same basic tonal characteristics from highs to lows - something most tube amps dream about.

The F4 sounds like a cross between the F1 and the F3. Cleaner than the F2, a touch of sweetness, but the truth is still front and center. I have not heard this amp in my system (yet), so my thoughts about this may change. It is a very exciting product.

Nelson, with his greater experience, may be better able to describe all of these amps. But as to which is best? That is like saying vanilla is better than strawberry - it is a matter of what you enjoy. All of these bring something different to the table.

Not sure if that helps, but it is the best I can do.

[apassgear]

Jon, nice round up for the lot, I appreciate...Thanks

[Vix]

Originally posted by Jon Ver Halen
The F4 sounds like a cross between the F1 and the F3. Cleaner than the F2, a touch of sweetness, but the truth is still front and center.

Uhm....Being just a follower, it shuold be cleaner than the F2. Jfet input brings a touch of sweetness, mismatched output devices bring some 2nd order harmonic, so it sounds a bit like single-ended....

Not having input Jfets at the moment, I was thinging about ways to make a simple buffer with irf610/irf9610 or similar, but..than it may loose a bit of sweetness. Using matched ouput devices should make it a bit more "clear" while unmatched provide more"romantic" sound?

Have I gone too far?

[Zen Mod]

Originally posted by Nelson Pass
Commenting on the particular mis-match of the complementary
types, ..................

Papa talk about mismatching between 240 and 9240

seems that everybody else talk about matching (or not ) between devices ;

this is -still-preferable............

[bogdan_borko]

Great thanks to mr.Pass for shearing one of his ideas with us!


As I can see, the bias current trough the resistors network for the mosfets gates is about 1.4mA. Some wold say that`s funny! You have to drive the gate`s capacitances (3*IRFP240). How do you expain this mr.Pass?

Cheers!

[Zen Mod]

Originally posted by bogdan_borko
Great thanks to mr.Pass for shearing one of his ideas with us!


As I can see, the bias current trough the resistors network for the mosfets gates is about 1.4mA. Some wold say that`s funny! You have to drive the gate`s capacitances (3*IRFP240). How do you expain this mr.Pass?

Cheers!

AC or DC current ,when you think about gates?



anyway-look what's common there.........source or drain.....

[GRollins]

Originally posted by Jozef
Voltage is almost same as this linestage.
On one PCB maybe ?

If that tube will run well at that voltage, then by all means give it a try.

Grey