How do my output boards look?

[punchpeanut]

Here is my first try at output boards for the Aleph X. The same board sould work for and Aleph as well. Each has 4 fets and I mirrored connections on both sides of the board with the idea that boards could be daisy-chained for higher output.

4 boards 16 fets
8 boards 32 fets
12 boards 48 fets
16 boards 64 fets

If I did it wrong please critique, I've got some pretty thick skin.

peanut

[Taco]

It looks oke to me, but I should put more space between the fets to get better cooling.

[punchpeanut]

Maybe I should drop it to a 3 fet per board design. Since I'm using the freeware eagle I can only go 4 inches wide. That way 12 boards would yeild 36 fets which is pretty close to the Pass XA200 that has 32.

[punchpeanut]

Here's the 3 fet version.

[hifimaker]

Here's some existing art from W. Sankey's gallery page on passdiy.com.

Outboard art is at the bottom of the .pdf page:
http://www.passdiy.com/pdf/a2-p1-pcbs.pdf

Picture of finished boards:
http://www.passdiy.com/images/aleph%...y/a2-p1-f8.jpg

This might be helpful if you need larger boards.

-David

[tiroth]

Thick heatsink backplates really spread the heat. If you want to go to 3 or are really pushing the limits in terms of dissipation versus delta T then go for it, otherwise 4 should be fine.

It also depends a bit on the geometry of your heatsinks; if they are crazy long/wide then there is more incentive to even out the spacing.

[punchpeanut]

Thanks guys, The pdf link dw8083 is great! I wanted to make an aleph 2 and that is compete. Since the software I'm using only lets me have a max width of 4 inches I can't add more fets. Otherwise I'd also make a 6 and an 8 fet version too.

Thanks also to tiroth, I didn't even think about that. I will be using sinks from Conrad, they should be fine since I am thinking of doing a 32 fet amp with each fet running at 5 - 8 watts. The 4 fet board should be fine.

[OliverD]

The gate resistors should be as close to the FETs as possible - I did it almost exactly like you in my own design, but I was told every mm matters

[K-amps]

I'd go with 4 myself assuming that good heatsinks will be used with the Aleph's. Its a trade-off between number of boards vs. ease of installation vs. cost of boards vs. thermal spacing etc.

I like your 4 device version and especially the ability to daisy chain them!!

[punchpeanut]

Here is a 4 fet version with the gate resistors almost on top of the fet leg, thanks for the advice! I will also post a bare image of just the traces. I'm kind of proud of myself for thinking of the daisy-chain thing .