Fabian Sigg’s DDDAC 1543 - Power Supply:

Fabian Sigg’s DDDAC 1543 - Power Supply:

I'm using the LM317 as regulator for the TDA-tower. The voltage is set to 8.5V. The datasheet states that the LM317 will work without C10 at all, but a 25uF capacitor is recommended for better transient response. All comparisons were made by using a switch to connect and disconnect the capacitors rapidly and easily to the circuit. By the way, these all were blind tests.

The Caps (replacement for C10):

  1. Black Gate FK, 100uF, 16V
  2. Sanyo OS-CON 25SC47M, 47uF, 10V
  3. BC 56/57, 15'000uF, 25V
  4. Lelon 10'000uF, 25V
  5. Panasonic FC, 1'000uF, 25V
  6. Panasonic FC, 270uF, 25V
  7. Mundorf MCap-ZN, 2.7uF, 100VDC
  8. Mundorf MCap, 4.7uF, 400VDC
  9. Epcos polypropylene, 2,2uF, 400VDC
  10. Vishay Roederstein 1837, 15nF, 160VDC

Results:

Without any capacitor at all the balance between low, mid and high frequency is very convincing. When switching in a Black Gate or a Sanyo, sound is more dynamic and also less harsh, but only at mid and higher frequencies. Some of the bass attack gets lost. The balance turns a little to the bright side. The difference between BG and Sanyo is small. Maybe the BG is less bright. I was not sure what to prefer, with or without cap. Maybe bass performance is not weaker than without capacitor, but the change in relation between mid/top and bass lets the bass disappear a bit.

The Panasonic FC 1000uF is definitely an improvement. The sound is just as balanced as without cap, the before mentioned positive effects are recognizable over the whole frequency spectrum. Bass is substantial, better than with BG or Sanyo and as textured as without Capacitor. The overall performance is very pleasant.

Next I added (parallel to the Panasonic 1000uF) a Vishay 15nF capacitor. The highest frequencies are marvellous. No harshness, no detail is smeared. Realising that adding a smaller capacitor cleans and speeds up the sound and also supports a more colourful performance (right now at high frequencies), I switched in a third one, a Mundorf MCap-ZN 2.7uF. I was hoping  the midrange will follow treble. Well, that's just what happened. Every kind of music is played coherent, relaxed and dynamic. The third capacitor is really needed for optimal performance.
I've also tried a Mundorf MCap 4.7uF in place of the MCap-ZN. I couldn't find any disadvantage when using the cheaper MCap.

The last test was about finding out if a quite large Lelon 10'000uF Elko could still improve something. It turned out to be worthwhile. Music is just more relaxed, more solid and there is no negative side effect.

After these experiences I decided to use four capacitors in parallel in the supply for the chip tower. I tried to keep a constant factor between the capacitance values. My definitive solution is as follows:

  1. BC 56/57 15'000uF, 25V
  2. Panasonic FC 270uF, 25V
  3. Epcos polypropylene, 2,2uF 400VDC
  4. Vishay Roederstein 1837, 15nF, 160VDC

Adding capacitors parallel to the battery:

  1. 6 x Rubycon ZL, 2'200uF, 25V
  2. Wima MKS4, 1uF, 63V
  3. Wima FKP2, 10nF, 63V

Results:

The above listed capacitors I had around and they were placed as close as possible to the DAC board. I did not experiment on exchanging one of the caps for another or adding one more. Switching them in had a positive effect in terms of relaxation and quietness. There is no negative effect when adding them.

Maybe one could try the same solution as done above for C10 replacement or just use much more capacitance.