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Just got my Muse DAC and burning it in after a few mods.
Most of the heat from the DAC is generated by the LM317T voltage regulator. It is cooking using a 12VDC power supply. I think that is the source of the overheat problem, especially in a small enclosure. Using a lower voltage power supply will definitely help significantly in reducing the heat given off by the LM317T. Also the tab of the LM317T is not solder to the PCB plate underneath. I applied some solder and it helps to distribute the heat to the other side of the PCB, away from the components.
The heat from the TDA1543s are minor in comparison. The stock heat sink and compound are not very effective. I mover the four 100nf capacitors to the other side of the PCB and replace the stock heat sink with a spare set of video RAM heat sinks, which work much better.
Added a couple of jumpers, shorting out the stock Silmic 10uf output capacitors.
The red power LED is replaced with a green one.
You sir are 100% correct! I was running my Muse on 9V for so long that I never realised how much heat came from the regulator!
I've whipped up a battery to power my Muse. She's a nice sealed lead acid 17AH jobbie so I think it should last for a while between charges.
I saved a power cord from an old lamp that we threw out a few years ago, as it had a nice long 1.5m lead and an integrated switch. This ended up being perfect the job.
I had the correct plug for the Muse lying around, so I spliced this in and soldered/heatshrinked it. I also added a 3A fuse on the positive wire (as these batteries can put our some serious short-term current if there is a short-circuit downstream).
The battery reads 13V when fully charged, so just within the specified 9-13V range for this DAC. I have to say that I agree... when being fed 12-13V, the regulator gets mighty hot!
I've done some recent mods to the DAC too, as numbered in the pic below:
Fitted a cut-down copper heatsink onto the voltage regulator (1)
Fitted copper heatsinks to each individual DAC chip (2)
Replaced the standard tantalum DAC chip coupling caps with Panasonic stacked film caps (3)
Replaced the previous AXON output caps with some 4.7uf PMC output caps (just for giggles (4)
Replaced the output bypass caps with some vintage NOS polystyrene caps that I had lying around (5)
I've also got a larger power supply filter cap to fit (680uf vs 470uf for the standard item). I'll whack this in there soon.
At present I have the Muse connected to my PC system, which is a $25 Fanmusic SPDIF to USB converter, the Muse DAC, a restored Kenwood amp, and a pair of Usher S-520s. She's sounding quite decent at the moment.
I've got a standard, non-modded Muse here for comparison, so it will be interesting to see how this tweaked DAC sounds against a completely standard unit. The difference between the stocker and my Muse with the AXON output caps was very clear, and I'm hoping the gap has widened further. Time to start listening! Looking forward to dragging this outside to my main system to compare it to my NFB-3 and also to a Pro-Ject DAC box FL that I currently have on-loan (another TDA1543 x 4 DAC).
Check another PSU. It's very poor quality and dies sometimes. 9V positive center at least 500mA
