Will this keep me cool enough?

[littlerick]

I got my case for my first project now.. just wondering if anyone can tell me if this layout will be enough to keep chips cool.. I can lay it so chip is attached to bottom if it would be better.

Im trying to keep it compact but would like to fit toroid in there too.

http://img190.imageshack.us/img190/7...cture015iw.jpg

I have two large heatsinks, but if I use them I will need seperate power suppy box.

[paulb]

It depends on how much power the chips need to dissipate, which depends on the power output, speaker impedance, and power supply voltage.
But, probably not.

[littlerick]

I am planning on using a 300VA 2x22v toroid... but it sounds like I may need the heatsinks so maybe 2 boxes would be better option.

[star882]

A modern hybrid digital design would not need much heatsinking if any.

For your existing design, you can mount the heatsinks outside the case.

[littlerick]

I dont think it will go on the outside.. it is as wide as the box and as deep, takes almost 1/4 of the inside space up. Maybe if I can find a smaller heatsink it will fit along the bottom under the speaker and inputs.

Im working on the cheap as it is my first go.. well as cheap as i can anyway.. Already on course to blow £100 if it doesnt work... but ya cant learn unless ya have a go.

The 4780 was maybe a bit of a dive in for a complete noob, mkII is gonna be a 3875!

[danielwritesbac]

You'll also want the heat to get out of the enclosure, so this means vent holes in the bottom for cool air to get in and vent holes at or near the top for hot air to get out.

Perhaps a pair of inexpensive chrome 80mm fan grilles on bottom and another pair on top (or as high as possible on the each side)?


That enclosure material is too thin to heatsink those chips all by itself. You could try a nice thick bit of aluminum bar stock from the hardware store as a heat spreader. Thermal paste between chips and aluminum bar stock and also between aluminum bar stock and enclosure. A Big piece of the flat (or right angle) stuff on the inside and a Big piece of the flat (or right angle) on the outside (sandwiching a lot of the enclosure material in-between) may be enough to conduct the heat into the enclosure material (thus conducting the heat out of the amp chips).
It'll take a lot of thermal paste too.
I'd rather suggest to use a good size heatsink; however, heat spreaders are a popular alternative with gainclones.

[lanchile]

Originally Posted by littlerick

I got my case for my first project now.. just wondering if anyone can tell me if this layout will be enough to keep chips cool.. I can lay it so chip is attached to bottom if it would be better.

Im trying to keep it compact but would like to fit toroid in there too.

http://img190.imageshack.us/img190/7...cture015iw.jpg

I have two large heatsinks, but if I use them I will need seperate power suppy box.

you will need for sure a heat sink. the chassis it is not enough to dissipate the heat.

[AndrewT]

start by building your PSU. A sheet of plywood or chipboard could be used to mount everything on temporarily.
Power up the transformer through a bulb tester and check you have the correct voltage.
Add on the rectifiers and check voltages again.
Add on capacitors and check voltages again.
Build up one channel of your chipamp. Bolt it to your large heatsink.
Connect it to the tested PSU. Check voltages again.
Build up your second chipamp. Bolt it to the heatsink. Swap it for the tested chipamp. Check voltages.
Add both chipamps to your PSU. Check voltages.
Now look at your tested temporary assembly and work out if it can be fitted inside your box.
Buy a big enough box.

[jimbo1968]

How big is that box?
Are you trying to make something pretty or just functional?

If you can cut aluminum you could make 2 thick aluminum sides from something like this: ALUMINIUM SHEET 150.mm x 200.mm x 12.mm THICK on eBay (end time 04-Jan-10 18:30:15 GMT)

[danielwritesbac]

Originally Posted by AndrewT

. . . Buy a big enough box.

Yes! Like that! A bigger box can get the transformer a farther distance away from the overly sensitive amplifier chips. And of course a bigger box will fit your heatsink.

You can use a nicely grounded heatsink as a barrier (shield) in-between the transformer and the amp chips--amp on one side, transformer on opposite side.