Powersupply: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 trensient 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 blindtests.
The Caps (repalcement for C10):
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 performence 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 defenetly 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 pleasent. Next I added (parallel to the Panasonic
1000uF) a Vishay 15nF capacitor. The highest frequencies are marvelous. No
harshness, no detail is smeared. Realising that adding a smaller capacitor
cleans and speeds up the sound and also supports a more colorfull performance (rigth now at high frequencies), I switched in a third one, a
Mundorf MCap-ZN 2.7uF. I was hopeing 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. 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 sonore 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 definitiv solution is as follows:
|