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Nordic 19th September 2005 12:58 PM

Case idea to make you resin-ate
Ok, while I'm waiting for the parts to arive, I am building and rebuilding this silly little 3875 amp over and over in my head... bet I can do it without the circuit diagrame by now...

Now as I had this whole amp constructed and suspended in space (in my mind) It reminded me of a clear casting-resin paperweight I made in primary school in class with components in...

So I was thinking, asuming I could make a jig/mold to encase the whole amp and all its components (except the powersupply) in a resin square... I could even do it so the bottom of the chip sits flush with a side so it could still screw into a powersupply

Do you think it could work, in terms of dissapating heat, so that the resin would sorta act like a big heatsink, drawing the heat out evenly, and provide a larger surface area for cooling of.

or do you think it will end up as another paperweight.

we are talking about a unit here that will not be repairable...if it breaks, its a paperwieght.

owen 19th September 2005 03:03 PM

I cant see a significant reason why you shouldn't do this.

The chips will need heatsinks. Use the heatsinks to form the 2 sides - have the chips mountedto the heatsinks before you begin.

Then using some sheet acrylic, make a u shape that will form the mould. Secure on the outside using some hot melt glue.

Now is the tricky bit - suspend the power supply jacks, the RCA inputs and the speaker outputs from a jury rigged frame, at the final level of the back of the amp. Fill the mould with resin to the finished level on the back, and wait for setting.

carefully peel the mould from your unique crystal gainclone...

Do let us see the finished product!


elementx 20th September 2005 02:33 PM

I would like to see that! Just curious, what kind of "resin" do you use? Can you give me any brands or webpages that have that stuff? I know exactly what you're talking about, but I have never come across it in a store. thanks!

Nordic 20th September 2005 03:42 PM

Just google for Clear casting resin, the stuff looks like glass when you are done... Oh you get dyes too.. so you could have clear, blue, red, amber etc... You also get opage resin, but I can't see why you'd want to use that.

Ok got most of the parts, and a few weak substitutes, hope to have it all working in a day or so....

Would still be a little while before I do the casting though, as I need to get some better parts from overseas

analog_sa 20th September 2005 03:58 PM

HI Nordic

Careful with the resin. Around 1980 i sold a few MC step-ups based on LM394 (not that it matters). Due to extreme idiotism and paranoia i poured some epoxy on top and bottom of the PCB in an attempt to make reverse engineering impossible. Once the epoxy set and i powered it up i had a shock. The sound was practically unlistenable. Don't know if it was a change in dielectric absorption due to impurities in the epoxy but it certainly thought me a lesson. Those 394s were not cheap.

Even if DA is not an issue the dramatic change in structural rigidity and damping will have quite an effect on sound.

One thing a chipamp does not need is improving the heat dissipation.

elementx 20th September 2005 04:39 PM


Originally posted by analog_sa
HI Nordic

Careful with the resin. Around 1980 i sold a few MC step-ups based on LM394 (not that it matters)....Once the epoxy set and i powered it up i had a shock. The sound was practically unlistenable.

So this was in 1980's? Do you think there has been an improvement in the resin to this date? I think that would be so cool to have your amp enclosed in a resin cube, or sphere even! Maybe it's worth trying. Even as a paper-weight it would look pretty cool!

dnsey 20th September 2005 04:58 PM

If I remember correctly, casting resin cures a little cocave and tacky on the 'open' face, so you will need to arrange things so that this face can be filed and sanded flat.

tvi 20th September 2005 05:31 PM

2 Attachment(s)
Should match with this Ice cube CD player


Nordic 20th September 2005 06:06 PM

Yeah, I believe, there are quick setting resins on the market now, but last time I did this, the resin had to sit a good few days to crystalise properly, and then the hard part starts, sanding it all down....

rif 20th September 2005 06:19 PM

What about this stuff:,190,42942

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