[amb]

The HS-TWS is a bit undersized for the amount of heat the dynahi puts out. But as long as your case has good ventilation it should be ok.

 

[steinchen]

What's the heatsinks K/W rating ? Did you happen to measure the heatsinks temperature ? You may consider to reduce the bias a bit, e.g. 70mA per tranny.

 

[Kruemelix]

@steinchen

don't think that will help much. While adjusting the trimpots on the boards, some of the boards ran at only 65mA - and got also hot. I am just thinking about mounting two 40x40mm fans with reduced speed on each of the heatsinks. The small additional noise won't bother me much and it should work fine...
But good to know that the heatsinks are too small

 

[digger945]

So how is it goin with everyone?
Just wondering.

 

[Energy jobs]

hi,
what does the sound originate? No matter how good the rest of your stuff is, if you're running off a 128CBR Mp3 through a terrible motherboard RealTek AC97 DAC, you're going to get terrible sound output quality. At the least, you owe it to your ears to get the Chaintech AV710 PCI sound card. Using "High Quality Mode" outputs the sound through the rear DACs, which have a SNR of 106dB and a very low THD figure. Let me be clear, here: a lovely source will RUIN your listening experience. You don't have to go absurdly all-out, but pay attention to the figures and get something that isn't going to suck the life out of the rest of your setup

 

[Pars]

What? Nice 1st post in a completely unrelated thread

 

[digger945]

Odd post.
Well I finally have all the parts to build mine

Can't wait, as I have probably read every post in this thread alone 3 times already.

 

[Kruemelix]

finally everything works well. I mounted two 60mm fans on each heatsink (with reduced speed). As a consequence, they never get above hand-hot. Nevertheless, another problem occured: When plugging in my AT W5000 I always hear a small background hum that doesn't increase with bigger attenuation. I have to admit that this only occurs with the ultrasensitive W5000 and only with the Dynamight. When being plugged into the headphone jack of my preamp I hear nothing.

Any explanation?

 

[digger945]

You have a pic?
You think maybe having two fans close to the amp may have something to do with the hum?

 

[FallenAngel]

So I got my 2-channel Dynahi build and playing beautifully (though running pretty damn hot - 8 hours of straight and with the heatsinks bolted to the bottom of the steel chassis, the bottom plate gets too hot to comfortably hold).

Now I'm planning for a DynaMight and just ordered a set of heatsinks off eBay. I had these cut to 2.5" lengths (well, height - the length is 5 3/8").

My question is about the L brackets. I got some aluminum brackets from the local hardware store (couldn't find a good choice online) and I'm wandering on the thickness requirements for them. They will be actually taking all the heat from the transistors and spreading it to the heatsinks and I'm worried that they'll just get too hot themselves before dispersing the heat to the heatsinks. The thickness of the brackets is 1/8" I think and it feels like very lightweight aluminum. Would (or could) this be a potential problem. I don't really want to spend a lot of time with them if they will ultimately hold back the heat dissipation.

Is there a minimum (or optimal) thickness for the brackets? Good place to get them?

Thanks in advance.

 

[digger945]

I cut mine to the exact width of the pcb. I wouldn't go any longer unless I knew for sure I would have room in the case.
I don't think you will have a problem with this method, the heat travels pretty fast in the L bracket. I used thermal compound between the bracket and HS and lapped the two on a piece of plate glass with 440 grit sandpaper.
I read Kevin say he had seen this done literally hundreds of times. Can't remember where but I'll look for the link.

Aluminum angle 1/8" thick and 1"X1", I cut them on a Makita power miter saw with a carbide blade. I cut really slow so the edges would be smooth. I used Thermasil III stick on pads and trimmed them with scissors after sticking them to the outputs. Bolted everything together first then soldered the legs in place.

 

[Pars]

Very nice job on the brackets digger! You wouldn't want to make another pair would you? PM if so. When you say you lapped the bracket and the heatsink with 400 grit, did you place the piece to be lapped on top of the sandpaper on top of the glass? I assume wet?

 

[digger945]

The glass was a door on a stereo cabinet, very thick. I have a roll of adhesive backed sandpaper disks and just stuck them to the glass, sometimes two side by side(never overlapping) and rubbed the parts(bracket or HS) on the glass dry. To test the fit I put a drop of oil on the bracket and stuck it to the HS and if it was almost impossible to get the two apart I was satisfied it would work great with just thermal compound.
All 4 brackets(balanced amp) had to be numbered as the holes were peculiar to each position. I actually mounted the brackets to the HS's with rubber washers to allow the bracket to expand and contract with heat but using the Conrad HS's everything stays pretty cool. Only the top of the actual outputs get kinda hotish.

 

[FallenAngel]

Sorry, I meant "optimal/minimal THICKNESS" to the brackets, not "width". Thanks

 

[Pars]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif The glass was a door on a stereo cabinet, very thick. I have a roll of adhesive backed sandpaper disks and just stuck them to the glass, sometimes two side by side(never overlapping) and rubbed the parts(bracket or HS) on the glass dry. To test the fit I put a drop of oil on the bracket and stuck it to the HS and if it was almost impossible to get the two apart I was satisfied it would work great with just thermal compound. All 4 brackets(balanced amp) had to be numbered as the holes were peculiar to each position. I actually mounted the brackets to the HS's with rubber washers to allow the bracket to expand and contract with heat but using the Conrad HS's everything stays pretty cool. Only the top of the actual outputs get kinda hotish.

Thanks. Did you buy the L bracket material online or Home Depot, etc.? Same for the carbide blade? I have a radial arm saw, but cutting the brackets would be the biggest problem for me; I have a drillpress, etc. so drilling them and the rest of the work would not be a problem.

As for the mounting hardware, I assume you used probably 4-40 stuff for the output transistors and for mounting the boards to the L bracket? As for mounting the L bracket to the heatsink, I would guess 8-32 from your pics?