Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Construction Tips Construction techniques and tips

Stone as Heatsink
Stone as Heatsink
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 8th January 2018, 02:23 PM   #1
GumGum9000 is offline GumGum9000  Germany
diyAudio Member
 
Join Date: Dec 2015
Question Stone as Heatsink

Hey,

does anybody know if it's possible to use a piece of Stone/Rock as the heatsink for an amp?
Let's assume 100W heat dissipation from the transistors and the size of a common normal heatsink. The transistors would be mounted to a smoothed area of the stone.
  Reply With Quote
Old 8th January 2018, 02:28 PM   #2
globalplayer is offline globalplayer  Germany
diyAudio Member
 
globalplayer's Avatar
 
Join Date: Oct 2014
Location: =)
Stone/rock has a low heat conductivity.

__________________
◢◣◢◣◢◣◢◣◢◣
  Reply With Quote
Old 8th January 2018, 05:01 PM   #3
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Stone only feels cold because it has better thermal conductivity than, say, wood. It is significantly inferior to metals. A stone heatsink might be slightly better than no heatsink at all.
  Reply With Quote
Old 8th January 2018, 05:06 PM   #4
globalplayer is offline globalplayer  Germany
diyAudio Member
 
globalplayer's Avatar
 
Join Date: Oct 2014
Location: =)
Maybe it will work better if it is some kind of ore.
__________________
◢◣◢◣◢◣◢◣◢◣
  Reply With Quote
Old 8th January 2018, 05:24 PM   #5
woody is offline woody
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
Well as said earlier stones would be a bad choice for a heatsink. But as they say there is an exception to every rule and in this case it's diamond ! But that might not be cost effective !
  Reply With Quote
Old 8th January 2018, 05:28 PM   #6
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
GoatGuy's Avatar
 
Join Date: Dec 2012
Location: SF Bay Area
Think about the word: heat-sink. To "sink" or wick away heat. Its purpose (ironically) isn't as a reservoir of heat, no. It is just the opposite: the least amount of "reservoirishness" and the greatest amount of "heat-moving-ness". Heat conduction.

This is why modern super-high end PC's have liquid cooling for the processors: not a huge block of aluminum. The water efficiently comports the produced heat AWAY from the source. The chip. This is also why aluminum is so often used as a heat-sinking building material. Its cheap, per unit mass, it is an excellent heat conductor, and it doesn't offer significant extrusion challenges (for cheap manufacture) into quality sinks.

Oh, you could use all-copper. But it'd cost a king's ransom. Or liquid cooling, but the pumping noise is rather distracting to a fine playback experience. Stick to aluminum. Its really, really good.

GoatGuy
__________________
John Curl's Golden Rule…: 100 kHz bandwidth, 3 μs risetime, 100 W mean output, 100 V/μs slew rate, 2 Ω dynamic load, 20 amp min current source/sink
  Reply With Quote
Old 8th January 2018, 05:29 PM   #7
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
It would be good for heat storage so you wouldn't have to wait for your amp to warm up properly
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 8th January 2018, 05:40 PM   #8
globalplayer is offline globalplayer  Germany
diyAudio Member
 
globalplayer's Avatar
 
Join Date: Oct 2014
Location: =)
Or just use some metal disguised as stone/rock.
__________________
◢◣◢◣◢◣◢◣◢◣
  Reply With Quote
Old 8th January 2018, 06:21 PM   #9
PRR is online now PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Im old Maine, where rock was our best crop, a stone barn was considered "warm" (insulated), not a heat-sink. Of course in part this is because a foot of rock costs little more than an inch of wood board (rock on site and board hauled from sawmill). If it keeps the cows warm (good), won't it keep the chip warm (bad)?

Get some numbers.
Thermal Conductivity of common Materials and Gases
Specific Heat of common Substances

I thought specific heat might play a part in short-term rock fondling, but apparently no real effect.

Thermal Conductivity (more below)

Hand, rock, paper, scissors-
Beef 0.45 (hand substitute)
Rock 2 - 7
Paper 0.05
Steel 43

In the hand, stone sucks heat faster than paper, slower than steel. Cold paper is not real chilly. Cold steel is cold! Cold rock is cold but not like steel.

Air 0.024
Aluminum 205
Copper 401

Aluminum whups stone 50X. Aluminum whups steel 5X. Copper beats Aluminum 2X.

The heat path from a small hot chip to all the air in the world is a pyramid. You need your best stuff at the point. Hot chips use a copper plate to take heat from the chip and spread it about 50X bigger area. Here Aluminum is plenty good and cheaper than copper. Cheap enough to use out to 1,000X the area where we transfer to air. That's a serious mismatch, but nothing else has good conductivity, low cost, and producible in complex shapes. (Actually in larger work we transfer to metal to water and pump to a large water/air heat exchanger- your car radiator.)

The chips are surely designed to pass heat to Aluminum. With stone the heat rise in the first mm away from the chip would be about 50X what the designer expected. "Maybe" you could run a 100W chip at 2 Watts actual output (if it would work on the low voltage).

Also the contact between two surfaces must be INTIMATE. Air voids conduct 10,000X worse than Aluminum. Grease is only slightly better, not a cure. The stone must be finished as smooth as a metal heatsink. Yes, you can get Marble finished finger-smooth, but the surface is pitted.

The engineered path would be chip to Aluminum heat-spreader at least 50X the area of the chip heat pad. Roughly the center of a very good Al sink, fins cut off. Still it will take a LOT of rock to even approach the total surface area of a finned heatsink. It needs to be very much bigger than a finned sink.

Glue some pretty pebbles to 1% of the Al fins and rave about the rock-solid imaging you hear.
______________________
Thermal Conductivity
Air 0.024
Aluminum 205
Beef 0.45
Copper 401
Glass 1.05
Marble 2.08 - 2.94
Paper 0.05
Plywood 0.13
Rock, solid 2 - 7
Softwoods (fir, pine ..) 0.12
Steel, Carbon 43
Stainless Steel 16
Water 0.58
  Reply With Quote
Old 8th January 2018, 07:13 PM   #10
johnnyx is offline johnnyx  United Kingdom
diyAudio Member
 
Join Date: Jan 2004
Location: manchester
There are thermally conductive insulating ceramic washers used for mounting high voltage power devices. Not cheap though.
  Reply With Quote

Reply


Stone as HeatsinkHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Stone Speaker Cases stoneaudio Full Range 18 4th March 2012 03:32 PM
Please don't stone me. . . . Nihilist Tubes / Valves 11 20th February 2010 02:44 AM
How does a stone sound? el`Ol Instruments and Amps 2 4th February 2007 10:10 AM
G Randy Stone Design Help SteveT Solid State 3 25th April 2005 07:05 PM


New To Site? Need Help?

All times are GMT. The time now is 07:50 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki