Would you please share what this is?
It's unfair to hint at a potential good story to people like us without you telling the hole story…
This is a known issue. You can find some info here:
https://www.firstwatt.com/wp-content/uploads/2023/12/art_mos_test.pdf
https://www.firstwatt.com/wp-content/uploads/2023/12/art_ba2.pdf
Edit: Good morning Patrick!
https://www.firstwatt.com/wp-content/uploads/2023/12/art_mos_test.pdf
https://www.firstwatt.com/wp-content/uploads/2023/12/art_ba2.pdf
Edit: Good morning Patrick!
@Thypils - It's published / written elsewhere.
See this...
[https://www.diyaudio.com/community/...o-building-an-f5.188691/page-109#post-7193347
and...
https://www.diyaudio.com/community/threads/aleph-5-q-for-kit.381309/#post-6898268
With this article...
https://www.firstwatt.com/wp-content/uploads/2023/12/art_mos_test.pdf
Edited - Dennis and I posted roughly at the same time. Good morning, Dennis!
See this...
[https://www.diyaudio.com/community/...o-building-an-f5.188691/page-109#post-7193347
and...
https://www.diyaudio.com/community/threads/aleph-5-q-for-kit.381309/#post-6898268
With this article...
https://www.firstwatt.com/wp-content/uploads/2023/12/art_mos_test.pdf
Edited - Dennis and I posted roughly at the same time. Good morning, Dennis!
Apparently known since 1992.
https://www.diyaudio.com/community/threads/power-amp-transistor-pairs.174099/post-2312180
"Ask Nelson Pass about the IR P-channel parts. I discovered the problem back in 1992 when I was developing the first Ayre amp......"
See also :
https://www.diyaudio.com/community/...orch-preamplifier-part-ii.146693/post-2635089
Patrick
For a newbie who has only purchased complete kits for builds, I want to confirm that I understand what I'll need to complete this kit if I am able to purchase the F5M Essentials and Completion Kit. Based upon Mr Pass' white paper and other comments in the thread, I'll need the following:
- Chassis (Dissapante, Deluxe 4U or 5u)
- Power supply (Antek Inc. as 2218va-18v or as 3218va-18v) Not sure which is preferable
- Back Panel Parts kit from the DIY store
- Additional wiring? If so, what types? I have both shielded cable and DC wiring from prior projects. Do I need AC wire as well?
- Focus and determination
@TomR. Yes, you have it pretty well understood.
1) A 5U is overkill for this thermally, but has lots of room for future projects if you want to try different things. Also remember Nelson’s famous quote, “there’s no such thing as a heatsink thats too big.” That said, I strongly suggest making a cardboard box mockup of the 5U and seeing if you have room for it, that’s a large chassis.
2) Get any of AS3218, AS3220, AS4218, AS4220… whatever’s in stock.
3) Certainly could be put to good use.
4) I like the wire kits from Remington on Amazon quite a lot. But any suitably-rated wire will do. Yes, you’ll need to do some AC wiring in the chassis as well.
5) Of course. Additionally, patience can be helpful.
1) A 5U is overkill for this thermally, but has lots of room for future projects if you want to try different things. Also remember Nelson’s famous quote, “there’s no such thing as a heatsink thats too big.” That said, I strongly suggest making a cardboard box mockup of the 5U and seeing if you have room for it, that’s a large chassis.
2) Get any of AS3218, AS3220, AS4218, AS4220… whatever’s in stock.
3) Certainly could be put to good use.
4) I like the wire kits from Remington on Amazon quite a lot. But any suitably-rated wire will do. Yes, you’ll need to do some AC wiring in the chassis as well.
5) Of course. Additionally, patience can be helpful.
Hi
One can also look at the amazing work from @6L6 for some detailed construction steps when building such power amp, FW F4 as an example
https://www.diyaudio.com/community/threads/a-guide-to-building-the-pass-f4-amplifier.234355/
One can also look at the amazing work from @6L6 for some detailed construction steps when building such power amp, FW F4 as an example
https://www.diyaudio.com/community/threads/a-guide-to-building-the-pass-f4-amplifier.234355/
To add to e fortier's post read up on all of his build guides here:
https://www.diyaudio.com/community/threads/the-diyaudio-build-guides.260319/page-6#post-7566866
There’s going to be a F5m guide.
I’m waiting on the same thing (PSU board revision) as everybody else is.
I’m waiting on the same thing (PSU board revision) as everybody else is.
Also no degeneration on the jfets, no current limiter on the output devices, no thermistors, slightly different gain value, different output devices...
Also of interest is that the F5m document shows a negative phase second harmonic distortion compared to the third harmonic profile shown in the original F5 article.
Also of interest is that the F5m document shows a negative phase second harmonic distortion compared to the third harmonic profile shown in the original F5 article.
Wasn’t experimentation with harmonic profiles one of Mr. Pass’ original ideas behind the F5?
As I’ve understood the story - The P3 allowed you to fiddle with the bias symmetry in the push-pull stage and thereby change the balance between even and uneven harmonic distortion.
So, when you refer to the harmonic profile of the original F5, wouldn’t it rather be a matter of personal choice?
From my point of view, I kinda miss that opportunity to fiddle with the coloration of the sound.
You might not believe me as I confess that this will be my first class A amplifier, and that I’ve never even tried to listen to a tube amplifier or anyting else single-ended!
The very concept of consciously allowing a 2nd harmonic is very exotic to me!
(What an adventure this is going to be.. 🤓)
The simple answer is yes. But the changes are not totally trivial.
https://www.diyaudio.com/community/...tage-perfectly-integrated.406024/post-7524606
https://www.diyaudio.com/community/...tage-perfectly-integrated.406024/post-7538728
Patrick
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