can I use tin foil for 1543A DAC tower heat sink?

[pburke]

I'm starting to put together a pair of DDDAC1543s (see http://www.dddac.de ) and was wondering about how best to move heat away from the DAC chips without spending a ton of cash on custom machined aluminum profiles as suggested on the DDDAC site.


Here's what I had in mind: Determine the gap between the DAC and fold a 3" piece of aluminum serveral times until it resembles a thin flat strip that's just as wide as the body of the DAC chips. Then I'd place these strips between DAC chips that are to be soldered together, add a little heat conductive material usually used to mount computer CPU's to heat sinks, and clamp it together for soldering of the pins. Repeat for all chips until the tower is complete. At last, take some sharp scissors or an exacto knife and cut along the folded edges of the foil where it extends from the chips, so it can be peeled apart into something that looks like a big fan with a lot of surface area.

Now, this would not have a lot of mass to it, but a lot of surface area. Am I overlooking something here, or are people not doing this because it's too much work?

As an alternative to all this - does anyone know of a REALLY silent 40mm computer fan? The best I can find is rated at 25db, and that's simply too loud unless used in some sort of muffler housing.

But back to the tin foil idea - is there something fundamentally wrong with the use of it as a heat sink?


Peter

[bigparsnip]

the bigest problem that I could see with this is that the fiol will move very easily, and could end up folding back and shorting out the pins on some of your chips (which wouldn't be good).

What may be a safer suggestion would be to use thin (~1mm) aluminium sheet, which you could sandwich between layers as you mention, as this would transfer the heat away more efficiently whilst still probably providinig enough surface area to keep everything cool as long as it sticks out of the ends enough.

[gmarsh]

We use adhesive copper tape at work for odd things, see if you can get your hands on some of that.

It's sticky, it's a bit more thermally conductive than aluminum foil, and you can solder to it (in case you want to ground your 'heatsink', for some kind of shielding effect)

[John Swenson]

I just got my DDDAC up and running a couple days ago, here is what I did.

I got a .25 inch brass strip and a .5 inch brass bar at the local hobby shop. I cut the .25 strip into .75 inch long strips. I then used Arctic Silver Adhesive (I got mine at Frys) which is an epoxy with silver particles added to glue the strips to the bottom of each chip. I built a little jig out of some scratch wood to hold the chip and strip together so they would all be positioned the same way.

When they were all cured I then built the stack with a little more arctic silver between the chips. Put a dab on the top, stack the next chip on top, put in the vise and lightly squeeze together, solder the pins, take out of the vise and repeat untill the tower is done.

I then let the whole thing cure for a day. I then checked the ends of the brass strips and they were not quite lined up, so I used a grinding disc to make all the strips on each side be flush with each other. I then cut up the .5 inch bar into two pieces and used more arctic silver to glue them onto the ends of the brass strips. I was originally going to solder them, but the arctic silver was much easier.

This makes a nice rigid tower which does a good job of getting heat out of the chips. If you need to you can easily add aditional heat sinks onto the brass bars but so far I have not done it.

There was one problem with the design: when I went to put it into the board I found it didn't fit! There was a small cap and trimmer hitting the bars. Rather than use stacked sockets to get it high enough to clear the parts (which really bothers me), I put the two components on the back, which makes adjusting vref a little tough, but its not in a box yet so I don't care! If I were doing this again I would carefully look at the parts around the tower and make the strips the right length so it would fit. I originally left some strip sticking out because I thought it would add some more surface area for cooling.

It seems somewhat complicated but it really was not hard to do at all, it just took a few days because I had to wait for the glue to cure between each step.

The arctic silver adhesive worked very well, it seems to do a very good job transfering the heat, but be careful, the stuff gets all over everything before its cured. I would recommend wearing gloves and clothing you don't mind being permanently spotted with silver!

Unfortunately I don't have a picture handy yet.

BTW I made a few slight changes to the design which significantly improved the sound, see the thread on the Tent clock waveform for details. I added a 50ohm resistor in series with the clock and added a few .1 ceramic bypass caps. Its VERY nice sounding right now and I haven't even started cap rolling yet.


John S.

[pburke]

Originally posted by John Swenson

I got a .25 inch brass strip and a .5 inch brass bar at the local hobby shop. I cut the .25 strip into .75 inch long strips.

I didn't even measure the gap in the chips yet - 0.25" is enough? I'd prefer using something like copper or brass, but the hobby stores around here tend to cater to the cross stitch crowd more than people who work with tools

I'll try a different place tonight - maybe i'll luck out.

Arctic silver adhesive is a good idea - that way the tower will hold together better. I'll get some from newegg today. Obviously, with tin foil there's no way to have the tower stay glued together for very long.

... I then cut up the .5 inch bar into two pieces and used more arctic silver to glue them onto the ends of the brass strips. I was originally going to solder them, but the arctic silver was much easier.

so you're not using any fan to keep it cool? I'm really trying to avoid using a fan, as my enclosure is rather small (PartsExpress heat sink box 2x4x8") - so small, I don't even know how to get a fan to work with it, unless I drill the thing into swiss cheese, which defeats the purpose of this nice looking enclosure.

BTW I made a few slight changes to the design which significantly improved the sound, see the thread on the Tent clock waveform for details. I added a 50ohm resistor in series with the clock and added a few .1 ceramic bypass caps. Its VERY nice sounding right now and I haven't even started cap rolling yet.

I'll check it out. I've been following most DDDAC threads here, but I don't recall this particular subject. I just got a 100 pack of WIMA caps for bypassing - I'll put them anwhere I can find room or reason to place them

Peter

[audionut]

I installed a small 12v muffin fan, blowing air over the chips. The fan runs at half speed...keeps the eight chips at about 40 deg. C.

[Bas Horneman]

Peter,

How is your DDDAC1543 sounding?

I'm in love with mine...wonderful natural spacious sound!

Will post some pics tonight...

Cheers,
Bas

PS...using a 12v 33Ah battery..

[edit] not much to look at but I'll post them anyway..

[pburke]

It's sounding so sweet, especially now after about 50-80 hours of burn-in, that I am having a hard time finding the time to finish the second unit I built for a friend. I just keep listening to music

Regarding this thread's subject:my copper heat sink solution I settled on seems to be quite effective, because when last week I forgot to turn on the fan for 7 hours of playing, the DAC sounded just fine when I noticed it (the heat sink does get pretty warm even after just a few minutes of fanless operation). So now I am undecided regarding the use of the fan. I may add some additional copper fins and completely do away with the fan, since that would eliminate a source of noise (barely audible unless I go close up) and vibration on the DAC.

I have a pile of photos, but since I am not done yet, I'm waiting to post the results on my web site. I'll also get some nice face plates made in the near future, since this DAC is a keeper. Another friend already mentioned he'd want of these DACs, so I may need to build a third one real soon

This weekend I'll be able to compare the first two DACs I built. One is bone stock around the clock chip, while the second one will have a bead on the +5V lead feeding it, plus a 47 ohm capacitor on the output leg, as recommended on Guido's site. The DAC I am listening to right now doesn't have that mod yet, and it still sounds extremely good.

The sound from the DAC right now is extremely neutral, very well defined, and it reveals detail that I never heard before in just about any recording I listen to. It seems almost too "spacious," as you describe it, until you get used to the very sharply defined location of instruments and voices across the sound stage. Some albums have taken on a almost 3D holographic quality - e.g. Roger Water's "Amused to Death" now truly shows of the QSound recoding with dogs virtually barking in my neighbors yard. The boundaries of my listening room completely disappear with many good recordings, and I haven't even done any room treatment...

I'll try to do a more comprehensive review when I get done with the project. One thing I had in mind was to buy the Ack! DAC as a trial and compare, because I really want to know how good the DDDAC1543 is compared to this alleged giant killer DAC. The Ack! has a trial period, so I won't be risking much. Sure would be better if I could find somebody in my zip code to come over for a shoot out (anyone around Madison,WI with an Ack!? I have beer...)

Peter

[Andypairo]

Originally posted by pburke


I have a pile of photos, but since I am not done yet, I'm waiting to post the results on my web site.

Peter

Why don't you post some here? It would be nice to see them.
PS Please enable your www button so we can visit your site!

Cheers

Andrea

[IpsilonSound]

pburke, where did you get TDA1543's? I ordered mine thru MCMElectronics and it's been already 2 weeks of waiting for them to arrive.... Do you know any other place where to order them from? I'm also interested in TDA1541A's. Thanks.