F5 power amplifier

[Nelson Pass]

Thanks Mr Pass, look forward to read it, hopefully there will be soon also article like the 6moons or by J Lowther to get a taste of the quality and listener differences between the several models. But may I ask you how would qualify / compare F5 to F1 or F3, if I may.

By the way, do you plan to build & sell some through RenoHifi?

I am not planning a write of up the subjective differences between the
models, but Srajan at 6moons will undoubtedly offer his own opinion.

They will be available from Mark@renohifi shortly, although I probably
should tell him about it.

😎

There will be a short piece on tweaking F5's, and then the next major
article is about buffers.

 

[EUVL]

> I have two (balanced) versions .....
> There will be a short piece on tweaking F5's ....

We all keep our plans on hold then !!!
😉


Patrick

 

[TimS]

High Power Balanced F5

To run the amp at a higher supply voltage, as some one suggested, I tried cascoding the input JFET's but I really couldn't find much advantage. I find just adding resistors fixes the problem and the performance is almost identical.

I think this is my last iteration of this design, I have tried many other variations with not much improvement in the performance. Though I may scale the design down for a preamp.

I think my next step will be to build it. I have the heatsinks, the transformers and most of the metal work for the case. I just need to design a board and find some JFETs.

Cheers

Tim

 

[jameshillj]

Tim,
While you're at your computer, could you possibly scale this cct down to drive a pair of headphones from 32R (grado ) up to 600R (Senn), with matched pairs of k170+j74 and 610+9610? And still have Zin of >100kR?

 

[jackinnj]

F5 sans inquietude thermique:

An externally hosted image should be here but it was not working when we last tested it.

 

[Nicola]

Subjectivty on F5

I am not planning a write of up the subjective differences between the models, but Srajan at 6moons will undoubtedly offer his own opinion.

There will be a short piece on tweaking F5's, and then the next major article is about buffers.

Some "subjective differences" are more subjectives that others 🙂
& i'm pretty sure your comment are factuals. But so far is there some spec that provide an indication on power, damping factor, distortion, as you have been writing on F2, F1, none of them where that subjective.

"and then the next major article is about buffers" avaialable under FistWatt.com ?

Regards

 

[TimS]

Tim,
While you're at your computer, could you possibly scale this cct down to drive a pair of headphones from 32R (grado ) up to 600R (Senn), with matched pairs of k170+j74 and 610+9610? And still have Zin of >100kR?

I could probably do that, I could make it a preamp that is able to drive headphones, but do you realize, you would have to cut the plugs off your headphones and replace them with a 4 pin plug.

 

[Nelson Pass]

Re: Subjectivty on F5

But so far is there some spec that provide an indication on power, damping factor, distortion, as you have been writing on F2, F1, none of them where that subjective.

"and then the next major article is about buffers" avaialable under FistWatt.com ?

FistWatt. I like that. 😎

Suffice it to say that the F5 has more power, more damping,
more current, more bandwidth, lower distortion, and higher
input impedance than the other F's. Many will think it sounds
better.

 

[SCD]

Hmmmmm
Bigger, better, stronger, faster. All the good things in life

You got to like that.
What about lemony fresh?

Why does AxP take so long to get to my house

 

[Nelson Pass]

If you Google "Fistwatt", you will get 9 references.

😎

 

[dfdye]

Somehow we need to work a reference to Chuck Norris's Chin in here, but I can't figure it out.. . .

 

[MEGA_amp]

There is no chin behind Chuck Norris’ beard. There is only another fist.

sorry I couldn't resist

 

[GRollins]

Given some of the connotations and denotations of 'fisting' at this point in history I'm almost afraid to Google it. I might not be old enough to read the responses.

Grey

 

[anubisgrau]

so, has anyone made F5 up and running so far?

 

[dfdye]

"FistWatt" could become the unofficial clone brand of FirstWatt products!

I can see the slogan now:

"FistWatt: My amp beat up your amp!"

 

[Zen Mod]

so, has anyone made F5 up and running so far?

Papa , certainly ........

 

[jameshillj]

Yeah Tim,
Have rewired the 701s (Z=63R) and using an "unbal - bal" adapter that also includes the adjustable series resistors (varies with different amps unfortunately).
[Amazing sound connected directly to o/p of F3 (as unbal)]

Estimate about 350mA thru the 610/9610 fets, and about 5mA thru the Jfets.

Expecting some pcbs for a mini Babblefish J (from ZM) as an upgrade to Marchello Originals [also approx +/- 15v rails].

... Thanks.

Anybody, looking for a 15H (not mH!)/ 350mA+/ <15R choke for the L-C supply - any ideas?

 

[Brett]

"FistWatt" could become the unofficial clone brand of FirstWatt products!

I can see the slogan now:

"FistWatt: My amp beat up your amp!"

In the local NZ dialects, one would be indistinguishable from the other. 🙂

As everyone calls Nelson Papa, I can think of a few slogans that include "Who's yer Daddy".

 

[jacco vermeulen]

I see a whole range of opportunities rising, the merchandising alone takes your breath away.

(you asked for it)

 

[TimS]

In the local NZ dialects, one would be indistinguishable from the other. 🙂

Ma get me my gun..