[sdiy] (Electrolytic) Capacitors in audio coupling

[René Schmitz]

Hi Seb and all,

Seb Francis schrieb:

> In one place there is only a very small DC potential difference, but in 
> the other places there is 2.5V or so across the capacitors.
> I've read that if there is no DC difference one should use non-polar 
> electrolytics for lower distortion.  Not sure how true this is .. I'd 
> rather use the same capacitors throughout as I have to buy the MOQ.

One possible solution could be to use two polar caps back to back, if 
you have the space. And you can even tie the center point to some higher 
potential via a high value resistor to keep the cap "biased".

Other than that, I'd like to point out that you should perhaps look into 
wether you really need those high values at all.  No need to buy an 
extra bass octave, which your speakers can't reproduce anyway. If you 
can make inputs of higher impedance you only need smaller caps, and 
might get away with foil caps. And I think its often that your load is 
minimum 10k or so, where you get into the region of 680n for a 25Hz 
lower corner. If you must use the higher values however (think driving 
600ohms), you can improve the high frequency behaviour by paralleling a 
smaller cap to the electrolytic, as its also often done with power 
supply decoupling.


Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159