HELP: Coil for capacitorless cd players output

Hallo everybody, first of all excuse me for my poor english :) .

I would remove capacitors from the output signal in my cd player.

Is it possible, in your opinion, use an induction coil beetween + and ground output, to erase the DC component?

Do you have idea about the sizing of the coil?

Thank you for your help


Paid Member
2002-08-14 1:47 pm
You can probably anwer your own question by a simple experiment. Load the output by a small variable resistor and see at what resistance value the offset is as low as you would want it to be. Then calculate a choke size which will not unduly load the output, ie have impedance above 10k or so @20Hz. Some output stages may be able to work well into lower loads but 10k seems like a fair average.

Even without doing the calcs i feel you won't be able to get a choke of sufficient inductance with low enough coil resistance.
No matter how big or small a coil used, if it is connected from output+ to ground, it will be a short circuit to any dc. So, if there is any dc offset on the output line, you will overheat the output stage circuit & possibly destroy it.
However, in most cd players, unless they run on a single V+ power supply, the output capacitors are not needed. All you need to do is measure the dc voltage at each capacitor pin while a cd is playing. If you see no more than 0.05V DC, then you can simply remove the capacitors & replace with wire jumpers. No other work needed.