F5 V3

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You're going to need higher voltage than 18 on your transformer. I'm going to be building F5 V3's for a friend soon when all of his parts arrive. I have the chassis, boards, transformers, and a few other odds and ends in my car that I picked up yesterday.

He ordered one Antek AN-6435 per monoblock. You could kick it up to 800VA or more, too. I'll test both on my quasimodo / oscilloscope to size the snubber resistors. Maybe I can knock that out this afternoon. My experience is that the snubber values are pretty consistent across the same mfr and model number. I'll post the values here when done.


You're going to need higher voltage rated caps in the PSU with the higher voltage rails. He's going with 22000uF 63V Digikey: 565-4899-ND



If you haven't bought Mosfets yet, I'll be matching a ton of them for my buddy's amp, and kitting up more pairs and quads for others. I'll be posting them here as that happens. I expect that will happen sometime in the month of September depending on when he orders his last batch of parts.

One more time. this is a standard 1 pair F5 version 3. not a F5 turbo V3.
 
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I built a Quasimodo jig earlier this year and have used it in building several amps: Aleph Mini J, Aleph J Monoblocks, standard F5's, and now I'm going to build F5 Turbo's for a friend, and SissySIT's for me.
Going through old notes, here's the snubber values I went with.
Antek 4218 - 20 Ohm (SissySIT)
Antek 3218 - 20 Ohm (F5)
Antek 6435 - 20 Ohm (F5 Turbo V3)
Antek 3220 - 18 Ohm, 16 Ohm (Aleph J Mono)
Avel Lindberg Y236607 14 Ohm (Aleph Mini J Stereo)
Today I measured the 4218 and 6435's. For grins I set the pot to 20, and then to 18. The difference between 18 and 20 Ohms on the scope isn't much. I chose 20 because that's what I have on hand. 18 would be fine.



Caps I'm using are:
EPCOS/TDK CAP FILM 0.01uF 63VDC - Mouser p/n: 871-B32529C103K
EPCOS/TDK CAP FILM 0.15uF 63VDC - Mouser p/n: 871-B32529C154J
 

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Those caps will work great.


I have built 8 or 9 amps with the rectifier boards. I'm doing my next 2 with bridges and doing a snubber circuit off some terminal blocks.



Why? The main reason for me is that I have made dual rail power supply boards for caps and resistors, and don't have any more rectifier boards. Plus I have the bridges in a spare parts box. I've read that a snubber on a so-so rectifier circuit beats the best fast/soft rectifier without snubbers. So I'm taking a decent bridge and adding snubbers.



If you have the boards and decide to use individual diodes or Schottky's, you'll need the separate diodes, heatsinks, and hardware (screws, washers, nuts, thermal insulating pad / washer depending on the rectifer.) It's a little more time and money to go for the individual diodes. But it's a DIY project, not a commercial design. Few extra bucks and a bit of time won't be end of the world if you decide to go that way.
 
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I just confirmed that I used 0.5W snubber resistors.


4U chassis should be perfect.



If there is the chance you may want to go for a F5 turbo one day, consider biting the bullet to get a 5U chassis. It will work fine for your F5, and give you room to expand if you want to use the chassis for a larger future build.
 
Thanks for the info.
Have all parts ordered for the boards as they are.
Anyway, I am building this just to have a Nelson Pass design, never had the opportunity to listen to one of his amps and now I am going build one "with my own little hands".
Oh, any tips on soldering the aluminum heat sinks?

Are you thinking of the rectifier heatsinks?

if so, there is 2 pins on the underside of the sinks. Solder dem to the PCB like any other Component. Just remeber to screw down the rectifier diodes to the heatsinks first.
 
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