DIY Amp enclosure for LM3886......

[Anil kumar]

Hi all, i bought all the cabinet material for LM 3886 amp.
Front Aluminum panel is 6mm thick, for top, back & bottom i am planning 1mm GI sheet with perforations. Cabinet dimensions, 17" x 4.25" x 12". Edges of the front panel & heat sinks will be milled by Saturday.

Will update with more pictures soon.

 

[ukjeyaraj]

Impressive start. Looking forward to more update on this

 

[rikhav]

Neat work Done by you Anil Sir

 

[captrajesh]

Anil, the heatsink looks like an overkill. The heat sink that I provided is probably only 1/10 in size. I'm posting a pic here.

 

[gobble]

Anil, the heatsink looks like an overkill. The heat sink that I provided is probably only 1/10 in size. I'm posting a pic here.

Yeah, that other buyer consumed heat-sink enlargement pills hyeah:
Hence the big results

Cheers

 

[magma]

in this case i think the aim here is largely- aesthetics so that the heatsinks can automatically form the side walls of the cabinet

the heatsink is being placed in a completely compromised arrangement
Conventional Heatsink fins are not meant to be horizontal ( but vertical only)
heat dissipation does not work like that
(howver in this case heat dissipation rarely will matter even if the sinks are placed the way they are purely for the reason that theres not much heat to dissipate anyway)
as capt rajesh said - functionally a smaller sink would sufice

this discussion has already been done before on the forum i think in anilvas thread
Anil in the final version of the F5 placed the sinks correctly in order to achive max heat dissipation

hence though the heatsink is overkill anil has probably used them for the reason mentioned above

anil
what i dont understand is why the edges of the front plate and the heatsinks need to be MILLED when a circlar saw can do the same job in probably 1/4 the cost
(provided the milling i am assuming is for clean 90 degree cuts)

 

[kaushik]

cost and addresses

 

[RajeevMurali]

go on anil.....

100W 2x LM3886 Audio Power Amplifier - Home Stereo Amplifier

cheers

 

[CANDUU]

is anil kumar and anilva are same person with different ids?

 

[captrajesh]

Conventional Heatsink fins are not meant to be horizontal ( but vertical only)
heat dissipation does not work like that

Heat dissipation is done in three ways; Conduction, Convection and Radiation. In case of Amps it is done through heat sinks and is achieved predominantly by way of radiation (transferring the heat to the air surrounding the heatsink) and to some extent by convection (by transferring the heat to the moving air)

The fins are there only to increase the surface area to achieve the above objective. No my point is, how does it matter in what way the fins are oriented (i.e. Horizontal or Vertical)

Yeah, that other buyer consumed heat-sink enlargement pills hyeah:
Hence the big results

So that member whom Sriramanujam pointed out did do his biz afterall.

 

[magma]

The fins are there only to increase the surface area to achieve the above objective. No my point is, how does it matter in what way the fins are oriented (i.e. Horizontal or Vertical)

capt
i beg to differ- it matters - it mattera a whole LOT
as you have said heat in amps is mostly achived through radiation
the above orientation allows less heat to be transferred this way
the top most fin blocks all hot air moving upwards
(actaully each fin does this for the fin below it)
Furthermore if you allign horizonatally only one side of each fin is actaully contributes ( to a comparitive extent) to radiation ( if any )
other than that the surface area of the same sink alligned with fins vertically offer far more surfacce area ( provided cut pieces are use side by side)
your sink could well be down to only 20% of its true efficiency


this is only a lay explanation
the technical explanation is long - google it

please check the orientation of heatsink fins on most commercial / pro amps
hell even on active subwoofers
Also check any of the DIY amps On DIYA audio

leaving out a few amps that have horizonatally alligned fins ( and theres an explanation for that too) all amps will have vertically alligned fins only

if the above orinetation worked well people would never have to break their head about sourcing WIDE extrusions
A 4 inch wide ( as used above would serve all purposes when cut to diffrent lengths)


see
here for amateur builds

Chip Amp Photo Gallery - diyAudio

Post your Solid State pics here. - Page 3 - diyAudio

for pro/commercial amps just visit their websites

Anyway
this is derailing the thread
all i wanted to say was this is not correct orientation of sinks

however it should work in the OP's case since the sink is major overkill so he does not have to worry about efficiency
this orientation (IMO) is being used for aesthetics ( so the heatsink forms the side walls of the cabinet) and the build looks cool
The build could have very well be completed by using a sink slightly larger than what capt had posted earlier and installing it INSIDE the cab too(fins vertical only)

 

[captrajesh]

it mattera a whole LOT
as you have said heat in amps is mostly achived through radiation
the above orientation allows less heat to be transferred this way
the top most fin blocks all hot air moving upwards
(actaully each fin does this for the fin below it)
other than that the surface area of the same sink alligned with fins vertically offer far more surfacce area ( provided cut pieces are use side by side)
your sink could well be down to half or less than its efficiency

Thank you Magma for your detailed explanation. Yes, your point is correct, I stand corrected.:thumbsup:

 

[GeorgeO]

Anil Kumar is a different person from anilva-thats the reason why they have different monikors..

 

[Anil kumar]

Thanks to all for the reply.

Dear magma thanks for the info. These heat sinks are largely for aesthetics. I am going for a large vertical heat sink for maximum heat dissipation.

what i dont understand is why the edges of the front plate and the heat sinks need to be MILLED when a circular saw can do the same job in probably 1/4 the cost
(provided the milling i am assuming is for clean 90 degree cuts)

Even after cutting, edges looks imperfect when compared to front side, filing the edges becomes uneven. I always go for perfect finish, in the process i may lose a bit of money.

I am planning to keep volume control in the center, power switch goes back. I already bought 24 step rotary Attenuator Volume Control Pot.

 

[anilva]

Anil,

Very nice set of heatsinks. Should make your cabinet look very good. In the case of gain clone, there is hardly any heat. Does not matter how the heatsinks of this size are aligned. Magma is right about vertical alignment, but becomes mandatory in builds like F5.

I will seek your help one of these days to get some milling help on the front facia of my amps.

Will be keen to see the finished product.

Cheers.
Anil (anilva)

 

[magma]

sorry
post did not contribute so i editted it

 

[Anil kumar]

Hi all, made some progress after a long gap, but still long way to go.

Done 60 hours of burn-in

Milling

Milling of front plate

Machinied volume control knob

Test fit looks great !!!!​

​

 

[gobble]

Anil
Its looking good so far.
I would like to order a volume control knob form your source if you dont mind hyeah:


--G0bble

 

[quad]

Beautiful work! Do you own a milling machine too?
That knob looks nice and heavy. Do you plan to burnish or
anodize the knob and front panel?

 

[anilva]

Great looks with industrial finish.