Inadequate heatsinks?

[Tripmaster]

Hi

I am currently putting together a chipamp for my father. I would like know if these side panel heat sinks will dissipate enough heat from a pair of LM3886 chips?...I assume not. The chips are being supplied with 36vdc, and the amp will be driving a pair of Hemp FRC8 full range speakers (Circa 95.5 dB SPL at 1w/1m).

Here is the manufacturers website modu








I built a similar amp earlier this year and use a pair of these heat sinks which remain tepid with use. I could use the same heat sink but I am trying to mount everything into one case to reduce cost.



I understand any advice maybe pure guess work, but it would be helpful if someone has tried something similar.

Thanks

Richard

[star882]

A good design should not need much heatsinking anyways. Check out TI's hybrid digitals if you're looking at a new design.

[Juergen Knoop]

That's a nice looking case, I would give it a try.

A good design should not need much heatsinking anyways. Check out TI's hybrid digitals if you're looking at a new design.

LOL!
Regards

[sangram]

Your speakers should be sensitive enough that the chips will not require to deliver more than a few watts (I assume).

The sinks should be sufficient. Temps of up to 60 degrees on the sinks should leave you with sufficient operating margin.

[raypalmer]

Yeah I've got 36vdc into 3886 monoblocks driving far less sensitive speakers. 89db ish? My heatsinks get to about 55-60 centigrade and they're fairly diminutive. Those big aluminum walls should be fine...

[Geoffroy]

Unrelated to heatsinking I'd like to say thank you for finding the Modus website as I was looking for a nice looking case for not too expensive!

Which dimensions is the case you bought? It seems to be about 330 mm by 330 mm...., isn't it?

Cheers

Geoffroy

[AndrewT]

the high sensitivity speakers are a big help in keeping output power down.
The chassis side per 3886 should stay cool enough to keep the internals of the 3886 as close to 25degC as possible.

Go and look at the 3886 datasheet and find the graph that shows power dissipation vs output power.
Note how the dissipation is high for low output powers >5W. Even at 2W of output the dissipation is still above 10W, whereas @ 60W of output the dissipation is 27W

[star882]

Originally Posted by Juergen Knoop

LOL!
Regards

You have clearly never actually worked with the TIs before. The smaller ones (such as the TPA3122D2) don't need any heatsink at all even when operating at maximum power rating and the bigger ones only need a small heatsink.

[Tripmaster]

Originally Posted by AndrewT

the high sensitivity speakers are a big help in keeping output power down.
The chassis side per 3886 should stay cool enough to keep the internals of the 3886 as close to 25degC as possible.

Go and look at the 3886 datasheet and find the graph that shows power dissipation vs output power.
Note how the dissipation is high for low output powers >5W. Even at 2W of output the dissipation is still above 10W, whereas @ 60W of output the dissipation is 27W

Hi Andrew

Thanks, I'll go and have a look.

I didn't want to hack away at the case if side heatsinks are too thin. I suppose I can always add one or two 5mm strips of aluminium between the chip and side wall if they become too hot.

Richard

[Tripmaster]

Originally Posted by Geoffroy

Unrelated to heatsinking I'd like to say thank you for finding the Modus website as I was looking for a nice looking case for not too expensive!

Which dimensions is the case you bought? It seems to be about 330 mm by 330 mm...., isn't it?

Cheers

Geoffroy

Hi Geoffroy

I purchased my cases from here Autocostruire il negozio degli autocostruttori

This is the order code GX 388

80mm x 330mm x 280mm