F6 Amplifier

[Soundhappy]

I guess the F6 he reviewed was the newer one with IRF MOSFETs?

We see he opened F6 new from box on video and i think you are right
yes this is First Watt amplifier with IRFP Mosfets new product.
Extract from F6 manual :

 

[Zen Mod]

gimme a brake

13:55 of yanking with 25W on wimpy cones , speaking as serious

naah ..... mission missed 110%

 

[labjr]

We see he opened F6 new from box on video and i think you are right
yes this is First Watt amplifier with IRFP Mosfets new product.
Extract from F6 manual :

Just wanted to be sure the review was of the newest F6 version since it was also produced with Semisouth JFETs.

 

[Nelson Pass]

I avoid sending "pilot run" pieces to reviewers as it just creates trouble,
unless the production is the same, which it is occasionally.

😎

 

[labjr]

Thanks for clarification.

I'm wondering if you've experimented with bipolar input stages since JFETS are becoming rare?

 

[aoc]

LSK are available

 

[palstanturhin]

And, 550/560 Diamond THD 0.013% 1kHz 1W 8R.
Which is nice...

🙂

 

[Phil Townsend]

This time I did something different... I bought with cash money an F6 from Mark at Reno HiFi.
No solder slinging, no parts roundup, no chassis punching, just unpack the damn thing and plug it in.
Well I did have to take off the lid and see what was inside... had to look at the layout, the wiring, the PC board artwork, the white greasy spots for the 240's...yep, it looked like an amp. Screwed the lid back on and plugged it in. Turned on the DAC (iFi from Thorsten) tuned in the streaming from Classic and Jazz in Paris Hey it works... There is something to be said for ready to play electronics. Not that I haven't bought ready made stuff before but amps and speakers are what I like to build.
Ill cut to the chase cause I'm hungry and Christine has breakfast ready... (she said something about homebrew scones)
This is one very seriously great amp... No ****!
Im about to pull out my Feastrex speakers and let the F6 put the spurs in that driver. Yikes folks this is one fine machine.
Hunger... food ... scones...
Phil
Santa Fe
K5SSR

 

[Zen Mod]

 

[Michael Rothacher]

Congratulations, Phil

Have we ever determined if the "F" stands for First Watt, or Ferrari Fund? 🙂

 

[Phil Townsend]

Well it was Semi South vs Enzo Ferrari... and look who won.

Oh and By the way or BTW...
I forgot "Bad words" are stricken from the posts... One can not type words like XXXX or XXXX or XXXX.
GRAB...generally recognized as bad.

Anyway breakfast was stunning... Scones good.

Looks like I'm gonna have to build an F6 for my wife... She came in my room/shop/lab/shack yesterday and started crying. yeah, the F6 is really good.

Phil
Santa Fe
K5SSR

 

[anilva]

My problem continues in one channel only, where the output has a big swing before settling in. Could it be a problem with C1 or C2 (1000 mfd) caps? The power supply capacitor bank is common and does not seem to be the problem as the other channel is behaving well at startup.

There is absolutely no problem in sound reproduction, gain or any other matter.

Thanks in advance.

Cheers.

Hi,

I changed the C1 & C2 to high quality caps and the still in one channel there is a big swing on my fullranger cone at the time of power-on and then it settles in. There is no such behaviour in the other channel.

I don't know if my fullranger is going to get damaged with such a huge cone suck out in the beginning.

I am completely out of depth to trouble shoot this problem. Need some help here.

Thanks in advance.

Cheers.

 

[Nelson Pass]

Im about to pull out my Feastrex speakers and let the F6 put the spurs in that driver.

My D9nf's like it very much.

😎

 

[Phil Townsend]

I built a system for a women here in Santa Fe a few years ago using the 9Dnf and the Eminence 4015...OB... Using your Pass Labs 30.5 to drive the whole thing... Wow!
I have the 5Dnf (the cheap ones) and plan to put back into service.
Also those Lowthers with the field coils... (The ones Dave wound) Those drivers made their way back to New Mexico. The deal was, I got the drivers after Dave, Jon and god knows who fooled with them. I bought the raw drivers from Jon and handed them over to Robert who machined them up at the lab in Los Alamos... Your tax dollars going to something good.
Anyway the 5Dnf and the 4015 should really be happy with the F6... I love that sweet midrange of the Feastrex. Wonder what happened to those guys? (Feaster that is?)
Ill get to it next week.... right...

 

[anilva]

Hi,

I changed the C1 & C2 to high quality caps and the still in one channel there is a big swing on my fullranger cone at the time of power-on and then it settles in. There is no such behaviour in the other channel.

I don't know if my fullranger is going to get damaged with such a huge cone suck out in the beginning.

I am completely out of depth to trouble shoot this problem. Need some help here.

Thanks in advance.

Cheers.

Some kind soul on this forum pointed out that this could be do with gate stopper resistors and parasitic oscillation at the time of start up and he also pointed out to Papa's talk in BAF during the F6 discussion. Will pursue that line and check.

Thanks.

 

[6L6]

I'm using 220R gatestopper in my amp.

 

[wdecho]

Was there a problem with your amp just using 47 ohm resistors? In another post your said to go with 110 ohm. Share with us your findings and the problem you were having if any.

 

[6L6]

I was not having any issue, I just selected a bigger gatestopper right away... Mainly as I've had issues before with gatestopper too small.

Yes, I misspoke, I used 110ohm

Gatestopper can be any value from 47r to about 680r

 

[wdecho]

Thanks for satisfying my curiosity. I went with 47r and so far no problems. Oh by the way, I went with the .62 resistors (R1) for Q1 and it sounds great. I may play around with R1 and R2 at a latter date.

David

 

[palstanturhin]

Diamond F6

There...

I think I am ready to close the lid now.

I still have 4 PCBs left to those lucky ones who wish for a low distortion F6.
18$/pair + shipping...
PM if interested...