F5 power amplifier - Page 287 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 11th February 2009, 09:19 PM   #2861
sekess is offline sekess  United States
diyAudio Member
 
Join Date: Feb 2006
Location: NJ
Default spreader

Once again -- nice work Peter.

I see that copper has almost twice the thermal conductivity than that of aluminum. Using a copper spreader makes a lot of sense - theoretically. In practice, I would be a little concerned with the aluminum-copper joint.
As Uriah stated before, if you can get smooth and flat surfaces and use grease to fill in the imperfections, this sound's like a great idea.


Steve
  Reply With Quote
Old 11th February 2009, 09:35 PM   #2862
rhysh is offline rhysh  United Kingdom
diyAudio Member
 
rhysh's Avatar
 
Join Date: Sep 2008
Location: Southampton
Send a message via MSN to rhysh
How about an all copper heatsink
  Reply With Quote
Old 11th February 2009, 09:38 PM   #2863
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
One other solution to prevent aluminum/copper corosion would be application of alodine to untreated aluminum surface, that what's being done in aircraft industry: each part is treated with alodine, then primer painted: http://www.caswellplating.com/kits/a...1a978ceee525b1
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 11th February 2009, 09:40 PM   #2864
labjr is offline labjr  United States
diyAudio Member
 
Join Date: Apr 2003
Location: MA
Quote:
Originally posted by rhysh
How about an all copper heatsink
Copper dissipates the heat too slowly
  Reply With Quote
Old 11th February 2009, 09:51 PM   #2865
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Quote:
Originally posted by labjr


Copper dissipates the heat too slowly

If you are talking about conductivity: wrong
If you are talking about emissivity: can easily be corrected by dark coating

But price for copper for this use would be way out of line. Using it for a spreader gives much better cost/benefit.
  Reply With Quote
Old 11th February 2009, 10:07 PM   #2866
labjr is offline labjr  United States
diyAudio Member
 
Join Date: Apr 2003
Location: MA
Quote:
Originally posted by pooge



If you are talking about conductivity: wrong
If you are talking about emissivity: can easily be corrected by dark coating

But price for copper for this use would be way out of line. Using it for a spreader gives much better cost/benefit.

I don't know the exact physics. But have you ever noticed how quickly aluminum cools compared to copper. I guess the convection is better. I'm not sure painting it black would make it as good or even close to aluminum.
  Reply With Quote
Old 11th February 2009, 10:47 PM   #2867
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Aluminum has less mass, thus having less energy for a given rise
in temperature.
  Reply With Quote
Old 12th February 2009, 12:47 AM   #2868
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Nomograph from a defunct electronics magazine -- you can see the tradeoffs. International Rectifier has an application note describing how black-coating will improve emmissivity.

Click the image to open in full size.
  Reply With Quote
Old 12th February 2009, 01:03 AM   #2869
udailey is offline udailey  United States
diyAudio Member
 
Join Date: Mar 2008
So copper dissipates more heat. Makes sense since it will spread out through the sink faster. But it looks like vertical mounting, for instance like Peter mounted his sinks, actually dissipates more heat. This doesnt make sense to me. You would think you would want the large surface area of the sink facing upward. Well, I would think that anyway
Uriah
__________________
purchase LDRs anytime Also try my Resistor Replacers or LDR based Input Selector Email me. diyldr@gmail.com
  Reply With Quote
Old 12th February 2009, 02:01 AM   #2870
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Quote:
Originally posted by udailey
But it looks like vertical mounting, for instance like Peter mounted his sinks, actually dissipates more heat. This doesnt make sense to me. You would think you would want the large surface area of the sink facing upward.
http://en.wikipedia.org/wiki/Natural_convection:

Natural convection is a mechanism, or type of heat transport in which the fluid motion is not generated by any external source (like a pump, fan, suction device, etc.) but only by density differences in the fluid occurring due to temperature gradients. In natural convection, fluid surrounding a heat source receives heat, becomes less dense and rises. The surrounding, cooler fluid then moves to replace it. This cooler fluid is then heated and the process continues, forming a convection current; this process transfers heat energy from the bottom of the convection cell to top. The driving force for natural convection is buoyancy, a result of differences in fluid density. Because of this, the presence of a proper acceleration such as arises from resistance to gravity, or an equivalent force (arising from acceleration, centrifugal force or Coriolis force), is essential for natural convection. For example, natural convection essentially does not operate in free-fall (inertial) environments, such as that of the orbiting International Space Station, where other heat transfer mechanisms are required to prevent electronic components from overheating.

Natural convection has attracted a great deal of attention from researchers because of its presence both in nature and engineering applications. In nature, convection cells formed from air raising above sunlight warmed land or water, are a major feature all weather systems. Convection is also seen in the rising plume of hot air from fire, oceanic currents, and sea-wind formation (where upward convection is also modified by Coriolus forces). In engineering applications, convection is commonly visualized in the formation of microstructures during the cooling of molten metals, and fluid flows around shrouded heat-dissipation fins, and solar ponds. A very common industrial application of natural convection is free air cooling without the aid of fans: this can happen on small scales (computer chips) to large scale process equipment.




Click the image to open in full size.
Papers blowing due to air current from radiator

__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  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
Rockford Fosgate Power 20001 bd amplifier power rating?? pachoorion Car Audio 8 8th May 2011 10:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 10:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 08:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM


New To Site? Need Help?

All times are GMT. The time now is 11:33 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