Can L25D amps share a common large heat-sink? - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th March 2012, 02:03 PM   #1
diyAudio Member
 
Join Date: Nov 2005
Location: Coventry
Default Can L25D amps share a common large heat-sink?

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
  Reply With Quote
Old 17th March 2012, 08:50 PM   #2
diyAudio Member
 
Join Date: Nov 2005
Location: Coventry
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
  Reply With Quote
Old 18th March 2012, 01:39 AM   #3
gmarsh is offline gmarsh  Canada
diyAudio Member
 
gmarsh's Avatar
 
Join Date: Apr 2004
Location: Halifax, NS, Canada
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.
  Reply With Quote
Old 18th March 2012, 11:09 PM   #4
diyAudio Member
 
Join Date: Nov 2005
Location: Coventry
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
  Reply With Quote
Old 21st January 2013, 08:07 PM   #5
diyAudio Member
 
Join Date: Nov 2005
Location: Coventry
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
  Reply With Quote
Old 21st January 2013, 08:35 PM   #6
diyAudio Member
 
theAnonymous1's Avatar
 
Join Date: Feb 2004
Location: Anonymityville
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.
  Reply With Quote
Old 21st January 2013, 09:10 PM   #7
diyAudio Member
 
Join Date: Apr 2010
Location: Brisbane
Quote:
Originally Posted by jaistanley View Post
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
__________________
If you measure, you know; if you guess, you don't
  Reply With Quote
Old 21st January 2013, 09:38 PM   #8
diyAudio Member
 
theAnonymous1's Avatar
 
Join Date: Feb 2004
Location: Anonymityville
Quote:
Originally Posted by theAnonymous1 View Post
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.
Attached Images
File Type: jpg amp2.jpg (163.7 KB, 193 views)
  Reply With Quote
Old 23rd January 2013, 12:51 AM   #9
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Hey theAnonymous1,

How much does that sucker weigh? With those 4, fairly large trafos, it must tip the scale!
__________________
redjr
  Reply With Quote
Old 23rd January 2013, 02:47 PM   #10
diyAudio Member
 
theAnonymous1's Avatar
 
Join Date: Feb 2004
Location: Anonymityville
45 pounds!

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

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Heat Sink Heat Sink Sources for Pass Amplifiers manmohan singh Pass Labs 9 16th March 2012 11:37 PM
heat sink khimh Subwoofers 1 8th December 2011 12:50 AM
Heat sink sizing for power amps prairiemystic Solid State 4 5th February 2011 12:00 AM
Is this heat sink OK? portreathbeach Chip Amps 5 28th February 2010 11:56 AM
How much heat sink is necessary? rosss Pass Labs 11 23rd February 2003 05:23 AM


New To Site? Need Help?

All times are GMT. The time now is 09:31 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2