Can L25D amps share a common large heat-sink?

[jaistanley]

Hi guys.

I have ordered 8 of the L25D boards to make a high power 8 channel amp to run my active speakers.

I understand that the L25D may produce wuite a lot of heat (90% efficiency at 350W is still 35W per amp) when run at high voltages/power.

Could I replace the heatsink provided on the boards and use heat-slugs to transfer heat to a common large ehat-sink? From what I can gather the fets are electrically isolated from the heat sink so this shouldn't be a problem but I don't nkow about the grounding and if eddy currents make induce noise in the amps.

I would quite like the Hifi2000 case with the heat-sinks built in, then use copper slugs instead of the supplied heat-sink to transfer the heat out.

Can anyone help?

Kind regards,

Jai

 

[jaistanley]

Well I've been scoping out work and I can get myself some fairly tasty looking slugs made from solid copper.. I just need to know if there's any reason not to do it???

Kind regards,

Jai

 

[gmarsh]

There might be a tiny bit of capacitance between the FET drains that wasn't there before, but you can calculate that pretty easily. I'm pretty sure it's negligible.

 

[jaistanley]

Thank you for your response. I'm not sure what the means though, at least I don't know what the consequence of the extra fet drain capacitance would be?

Kind regards.

Jai Stanley

 

[jaistanley]

Can anyone else offer any advice on this?

After a bit of time off from my project, I am now thinking about what case to buy. I'd like to buy one very large modushop case with heat sinks down each side, and use slugs of copper to take the heat from each amp module to the case heat sinks.

Is this feasible or will it cause me problems? There is a lot of space in the case when I put four on each side, mounted vertically inside.

Many thanks in advance..

Jai

 

[theAnonymous1]

I think I remember reading in an IRF document that self oscillating amps should not share a common heatsink. Sorry I can't elaborate on that or remember where I read it.

It might be one of those things you won't know unless you try, which I'm sure isn't the answer you want to hear.

 

[doctordata]

Well I've been scoping out work and I can get myself some fairly tasty looking slugs made from solid copper.. I just need to know if there's any reason not to do it???

Kind regards,

Jai

In the reference design 2 channels are mounted on a common heatsink , so why not 8? give it a try on your workbench with an aluminium or copper bar grounded to the PSU GND and see what happens .

Cheers ,
Rens

 

[theAnonymous1]

I think I remember reading in an IRF document that self oscillating amps should not share a common heatsink. Sorry I can't elaborate on that or remember where I read it.

It might be one of those things you won't know unless you try, which I'm sure isn't the answer you want to hear.

Wow, can't believe I completely forgot I have an amp I built with two IRAUDAMP1 ref boards connected to a single heatsink. That's 4 channels self oscillating with no problems.

 

[redjr]

Hey theAnonymous1,

How much does that sucker weigh? With those 4, fairly large trafos, it must tip the scale! 🙂

 

[theAnonymous1]

45 pounds!

I built the thing over 3 years ago and have never even used it. :/

 

[stocktrader200]

how may capacitors are in those banks?

 

[theAnonymous1]

40pcs 820uF per rail (32,800uF). 160pcs total.

 

[joemac2013]

Don't bother?

My L25D's run so cool that I can't imagine a problem if you give them a little air.

Of course I only run mine at 72volts DC a side,, into 8 ohms. I sure love those little amps.... Just keeps sounding better everyday? Speakers breaking in???