F3 pcb group buy...

[gabkw]

I am looking at the PS for the F3 (I think) - It shows a 2 section symmetrical section with a +V rail, GND, and a -V rail with a thermistor seperating GND from Chassis ground. So how do you wire this up to get the +50V rail needed for the F3?

Rewire the two 18VAC secondaries of the transformer so that you get 36VAC and just use the upper section of the PS board?

Or ???

Also - Is there a parts list available for the F3 PS?

Gab

[jarthel]

where do you plan to get the loveltech part? their website seems to non-existent and searching the net doesn't turn up any other corporate website.

[Magura]

Originally posted by jarthel
where do you plan to get the loveltech part? their website seems to non-existent and searching the net doesn't turn up any other corporate website.

Try the search button.....works wonders

Magura

[h_a]

@Gab: as I pointed out previously the psu schematic of the F3 is not correct. It's just copy and paste of the F4. However it's not faulty itself, just the wiring is not correct for the F3. So instead of wiring the trafo secondaries 18-0-18 you wire the symmetrical halves of the pcb identically, use a different transformer (or the same, but the windings in series) and get - tada! - 50V.

That's exactly the reason why Peter pointed out we could reuse the F4 psu-boards, which is a nice thing, but the requirement of twice the voltage ratings of the F4 are expected to not permit this, only in case there's enough space.

Cheers, Hannes

PS: @jarthel: even if I spoil your searching experience, GRollins is selling them, but unfortunately only within the US. But better look into the specific thread (I'm sure you'll find that one yourself), I think there are also some other volunteers which send them to other countries.

[jarthel]

Originally posted by h_a


PS: @jarthel: even if I spoil your searching experience, GRollins is selling them, but unfortunately only within the US. But better look into the specific thread (I'm sure you'll find that one yourself), I think there are also some other volunteers which send them to other countries.

thanks h_a

My mistake was to search on the internet and not in the forum

[SMathews]

Hi Peter,
For your ZV9, you had all the PCB/fets mounted on a copper plate and attached to the heat sink using thermal grease. I guess one could re-use the heat sinks by swapping the ZV9 board and copper plate, with a F4 board and copper plate. Also using your "universal power supply board", will allow one to re-sue the power supply components too. Not to forget the chassis for the amp. Any thing I'm missing here?

Simmonds Mathews

[marsupialx]

Looks like F3 amp boards and PS boards are in the works. Thanks, Peter!
(post #339) in WTB F4 board thread.
WTB: F4 PCB boards

[Peter Daniel]

Here's the revised layout of Zv9. It is basically F3, with exception of R13 which I didn't include (in that case P1 becomes 10k).

Please check for any errors. I will try to finalize the matching PS board tomorrow. It will be the same size as two channels F3 PCB and will accept caps up to 2" dia.

[jameshillj]

Peter,
If it isn't too "late in the day" for changes to the pcb design, could room be squeezed in for "small" bipass caps on all the electrolytics such as 1uF MKP/65v Wima, Rifa 425, etc.
Could this also be extended to the powewr supply?

My F3 has been upgraded with Propylene (MKP-10) and some Styrene (Rifa pfe 216) including the P/Supply and it has dramatically improved the sound of this amazing amplifier.

... jh

[Peter Daniel]

There are few reasons I did not include additional bypasses:

1 I wanted to keep the board size same as previously and there are 2 additional electrolytics now which make layout tighter.

2 I also wanted to be as close to original F3 schematic as possible, and Nelson did not implemented bypasses either (except for triplets at the output, which I also did).

3 I could probably still squeeze ROE MKP 1837 (10nF) at C2, C5, C6, C7, but so far I never found bypassing electrolytics as an improvement. Sure, the tonality changes, but it always happens at the expense of "purity" and "freshenss" of the sound. So whenever I modify older equipment, bypasses are first to go. But I'm very particular what type of electrolytics I'm using.

I tried adding 0.1uF V-Caps to 10,000uF Jensen at the output in my initial version of Zv9. It improved highs, adding more resolution and air, but I still wasn't sure if keeping just the Jensens wasn't overall a better approach. In the end I went with a single Siemens MKV for a tweeter and BG N 330/100 for midrange driver.

If you like bypasses, you can still add them soldering underneath the board directly to the eletrolytic pins, that would be probably also the best way to implement them.