Heatsinks for Power Amps

[magma]

I have had a couple of PM's asking me to procure some sinks
so heres a thread where intrested members can work on a group buy

you have the following choices
EDIT : sink types have been renumbered according to weight and heat dissipation characteristics

Following sinks can be procured by me ONLY in 6 foot lengths due to reasons ive mentioned earlier in my amp chasis build threads here
http://www.hifivision.com/diy/12016-amp-enclosures-chasis-cabinets-9.html#post178826

-


Type 1



Specs
8 inch extrusion with a 1 inch gap at the centre , very handy in chip mounting
Base is 5.5 mm thick
and fin height is 42mm
Weight 8.35kgs/metre

This sink is probably best for class AB amps upto 100rms/channel i think

Lengths can be cut as you want ( as long as there are enough buyers to hit 6 feet)
Though i had bought 6 feet for my use i cannot offer pieces from those since they are booked for my builds




Type 2



This is a beautiful flower design heatsink that is already doing F5 duty in a cab .Hence it is a tested F5 sink ( However the type 3,4 will probably dissipate as well and even better )

Specs
7 inch extrsion
weight : 16kgs/metre

However there is one rider when using this sink
- since this sink(unlike the ones above) is only a 7 inch extrusion one would require 10 inches length per channel for an F5
this translates to a case that is 10 inch + high and only 7 inches deep (Fins kept vertical )- which looks odd for any amp

However i do have a workaround for this problem which i have used when i built the cab
But this can only be done provided im building the cab since it involves a bit of work
A power amp F5 using this sink ends up with dimensons of 18 inch wide , 15 inch deep and 6 inch high

Note : This sink cannot be loaded with fins horizontal - theres no heat dissipation at all especailly from the lower half of that sink in that position


Type 3 - Exclusive

Specs
8 inch extrusion
15mm thick base
75mm fin height
weight 23kgs/metre

PICS - imagine this sink to be identical to the type 4 but of smaller fin dimensions as mentioned , however this sink is one piece pure HINDALCO extrsusion and quite exclusive being their top end heatsink
A 7 inch length ( which will become the height of the case ) will be enough for an F5 per channel
Alternatively a 7 inch lenght will probably also be enough for BOTH channles of a 100rms/channel class AB amp/chip amp
(though i advice you do the calculations yourself.im not very good at that.)
This is my favorite sink but i myself cannot buy it since im forced to buy a 6 foot length

Type 4

Specs
10inch wide extrusion,
16mm thick base and
82 mm fin height-
However this is precut at 6 inch lengths ( which is enough anyway)
That makes your case 10 inch deep and 6 inch high! - perfect size
weight - 27kgs/metre




This is actually a heatsink made by two 5inch extrusions that have been auto welded at the centre
However after anodizing you may never notice.Cant make out easily from the pic can you? The base is absolutely flush and level
Also function wise it has no drawback whatsoever since lazer fusion welding is done automated with pure Al ingots only
This sink is an exclusive customized product with the thickest base and the longest fins , most ideal sink for an F5 or a 125rms/channel class AB- i may probably work with wither this or another flower pattern one in one of my builds later


Once again i re-iterate
i have no commercial intrests in sinks, im not a dealer nor a manufacturer just a fortunate guy who has access to customised extrusion owing to my regular work
I am doing this only for members and for sinks that are hard to get as help to all WITH the permission of the extruder ( since these may be patented sinks which may or may not be for retail sale in the market)

 

[gobble]

I would like some type 1. Anything with a flange?

Cheers

 

[cmsajith]

It would be good if you could list down the prices for each type.

 

[gautamz]

Hi,

Depending on whichever group buy pans out... I would want either,
1) 4 six inch pieces of Type 1
or
2) 4 nine inch lengths of Type 3


Please do let us know the reference prices for these.

Thanks,
Gautam

 

[magma]

prices i will not discuss on the forum for obvious reasons
(and i would appreciate that no one discusses them on the forum too once they get the prices from me too - for the same reasons)


Only Serious group buy members please PM me your cell nos.
i am not going to give out prices to anyone who is just enquiring

best regards
Ali

Rahul
i will try and find out about that flange, but why dont you load the PCB directly onto the sink vertically?(instead of on the base plate)

 

[gobble]

prices i will not discuss on the forum for obvious reasons
(and i would appreciate that no one discusses them on the forum too once they get the prices from me too - for the same reasons)


Only Serious group buy members please PM me your cell nos.
i am not going to give out prices to anyone who is just enquiring

best regards
Ali

Rahul
i will try and find out about that flange, but why dont you load the PCB directly onto the sink vertically?(instead of on the base plate)

Vertically requires a crazy "S" backbending style for the legs of the chip which may not be at the flush corner of the PCB. A straight right angle bend at the PCB with the chip horizontally placed on the flange is best and simplest.

You already have my number ... or you can email me

Cheers

 

[magma]

Vertically requires a crazy "S" backbending style for the legs of the chip which may not be at the flush corner of the PCB. A straight right angle bend at the PCB with the chip horizontally placed on the flange is best and simplest.

You already have my number ... or you can email me

Cheers

workaround
Fabricate a 6 mm Aluminium Flange ( basically a 6mm pure extrsion plate only - not one cut from 6mm AL sheet - theres a big diff between the two in terms of purity)
Slot mill the sink by 3mm on the base to locate the flange
Screw on for location - Aluminium braze the joint to make airtight
and hey presto you have a flanged heatsink

Prices of all types have been worked out (GROUP BUY situation only ) except type 1
will contact all intrested parties

 

[gobble]

workaround
Fabricate a 6 mm Aluminium Flange ( basically a 6mm pure extrsion plate only - not one cut from 6mm AL sheet - theres a big diff between the two in terms of purity)
Slot mill the sink by 3mm on the base to locate the flange
Screw on for location - Aluminium braze the joint to make airtight
and hey presto you have a flanged heatsink

Prices of all types have been worked out (GROUP BUY situation only ) except type 1
will contact all intrested parties

Magma
I strongly suspect such a method will reduce heat transfer - I believe it needs to be one single block of Alu in order for a heatsink to be effective.

Maybe somebody more knowledgeable can comment?

Thanks

 

[magma]

Dear all

please note heatsink types have been renumbered according to weight and heat dissipation characteristics
Prices are accordingly

 

[magma]

Magma
I strongly suspect such a method will reduce heat transfer - I believe it needs to be one single block of Alu in order for a heatsink to be effective.

Maybe somebody more knowledgeable can comment?

Thanks

huh?
when you weld/braze the flange to the sink it basically does become the inherent heatsink
IT IS one single block of AL
i think youve misunderstood what ive said

 

[magma]

A member has shown intent to get 32inches of Type 1
Another has intent to get 24-30 inches of type 3 or type 2 (still undecided)
will wait for more to complete a group buy

 

[gobble]

huh?
when you weld/braze the flange to the sink it basically does become the inherent heatsink
IT IS one single block of AL
i think youve misunderstood what ive said

I was thinking at the molecular level like in single crystal oxygen free copper ICs ... the audiophile neurosis is spreading hyeah:

Will PM you later ... been busy all evening with no end in sight even right now.

Cheers

 

[gobble]

Hi All

Please take 15mins to speed read this at the least ESP - Heatsink design and transistor mounting

Esp for you Ali - there is some real valuable advice on how to mount heatsink with diagrams as you scroll down ....

Edit: and a section of DIY heatsinks http://sound.westhost.com/articles/diy-heatsink.htm

Cheers

 

[magma]

dear rahul

that DIY heatsink can be very easily built no problem
but i wouldnt bother with it anyway
Firstly it will not work as well as a pure extruded one
Secondly it will turn out more expensive if i build it

about the transistor mounting and actaully about MOST stuff
Im a very hands on guy
Though i have studied engineering i rarely give more importance to theory over experience and just pure gut feel

i would rarely read an article and believe everything
this is how i would mount, and i think most DIY guys mount it this way too

First mount thechip on the sink
bend legs a bit
lower the PCB on the bent legs
screw on PCB
solder legs

of course this way only works when chip is independant of PCB

if chip and PCB is integrated
mount like so


P.S : courtesy of pics and advice - a good friend

 

[gobble]

dear rahul

that DIY heatsink can be very easily built no problem
but i wouldnt bother with it anyway
Firstly it will not work as well as a pure extruded one
Secondly it will turn out more expensive if i build it

about the transistor mounting and actaully about MOST stuff
Im a very hands on guy
Though i have studied engineering i rarely give more importance to theory over experience and just pure gut feel

i would rarely read an article and believe everything
this is how i would mount, and i think most DIY guys mount it this way too

First mount thechip on the sink
bend legs a bit
lower the PCB on the bent legs
screw on PCB
solder legs

of course this way only works when chip is independant of PCB

if chip and PCB is integrated
mount like so


P.S : courtesy of pics and advice - a good friend

The 2nd pic is a really neat job!! Although I recall seeing it online before, its a great benchmark for comparing ones work with.

Cheers

 

[trittya]

Hey Guys
Can we not get the same kind of sinks in copper?
IMO alu is no patch on copper when it comes to heat transfer but the problem is that it gets tarnished due to inevitable oxidisation. can anyone suggest an electrolytic coating for copper which will keep it from tarnishing and not affect its heat transfer properties.
Help and advice being earnestly sought please.

 

[captrajesh]

Can we not get the same kind of sinks in copper?
IMO alu is no patch on copper when it comes to heat transfer but the problem is that it gets tarnished due to inevitable oxidisation. can anyone suggest an electrolytic coating for copper which will keep it from tarnishing and not affect its heat transfer properties.
Help and advice being earnestly sought please.

Yes, you can and you are right about copper being superior but the only problem is, it is 10 times more expensive.

In spite of that if you are keen on copper but are wary of the tarnishing part, you can get em electroplated with nickel.

 

[trittya]

Yes, you can and you are right about copper being superior but the only problem is, it is 10 times more expensive.

In spite of that if you are keen on copper but are wary of the tarnishing part, you can get em electroplated with nickel.

Hi Sir
Firstly, Your coursemate Capt Murali will be helped as much possible.
Next, thanks for your advice, had considered the same but I think the nickel/chrome plating wil trap heat like a thin film of oil/p jelly would or for that matter as even oxidised/tarnished cooper would, not to mention the dust that accumulates. Still looking. . .
Regards

 

[captrajesh]

Hi Sir
Firstly, Your coursemate Capt Murali will be helped as much possible.

Hi Trittya,
Thank you very much. I deeply appreciate that. He was worried as to how to go about & I remembered your generous offer.

I think the nickel/chrome plating will trap heat like a thin film of oil/p jelly would or for that matter as even oxidised/tarnished cooper would

IMO, it may not be that bad. Doing some research would be worth it.

not to mention the dust that accumulates.

That would hold good for any material.

Still looking

You may have to contact Dan D'Agostino. Now dont ask me, Dan who? Check him out below: -
YouTube - Dan D'Agostino Discusses His New Momentum Monoblock Amplifier

 

[magma]

heres a heatsink that arrived today for an F5 Turbo amp cab build
its a monstrous 6feet long extrusion
absolute killer