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WTB: F4 PCB boards

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#781
Thanks Phillipe
1K then.
I must have missed V3 of the bom .
Looks like quite a few of the values have changed slightly from the F4 circuit in the original user manual pdf .
I'll stick with the original circuit in general .
I think I have some BG NX 680u/35 that will do nicely for the C5-C6 caps .
I just found eight-off 220u/25V Cerafines in my stash that should do OK for C1 to C4 , but I notice the ratings on the BOM have increased to 63v on these. Does anyone have an accurate figure of what these caps 'see' in the built circuit, as a percentage of the + and - rails ? - obviously 35v would be better but the options reduce a lot from 25v to 35v .

Mark
 
#784
IslandPink said:
I just found eight-off 220u/25V Cerafines in my stash that should do OK for C1 to C4 , but I notice the ratings on the BOM have increased to 63v on these...
Mark
Click to expand...

The F4 PSU delivers about +/- 24V.
IMHO it will be safer using caps voltage rating bigger than 24v.
If you don't they could be damaged... risky :xeye:
35v is recommended, more is Ok too for the F4 boards.
63v is a typo... this value may not fit on the F4 board because of the cap size, it increases according to the V rating supported.
 
#785
Well, none of those caps sees full rail voltage, just did some rough calcs ; I reckon C3 is the most vulnerable seeing about 0.87 x rail so that would be 19V for 22V supply and 21V for 24V supply . I agree that's a bit marginal .
Hmmm...
I'll use the cerafines for C1/C2 and find some 35V rated for the others .

Mark
 
#787
Peter's F4 & PS boards & components

Hiya Guys

Please can anyone supply the following:

3 x F4 amp boards (for mono-blocks + 1 spare)

3 x PS boards (as above)

A kit of premium bits including tightly matched output devices

Also would consider paying someone to supply & build up for me....

Much obliged
 
#789
chrismercurio said:
I have 2 sets of output devices...but really if you need/want 3 of them and are willing to pay someone to build them, why not just buy a genuine First Watt F4 used?

Regards,

Chris
Click to expand...

Thanks Chris - I only need two sets of components, the third board is in case I balls something up lol

Yes, I've priced up a pair of F4's but I'm living in Italy and it's over $700 for shipping from the US plus the customs charges at this end plus the endless Italian bureaucracy... takes the sweetness out of any deal!!

I assume your 2 sets are sufficient for 4 channels ie 1 pair of monoblocs?
 
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