#### JimL11

##### 1000+ Head-Fier

The CCS amplifikation is quite high and the bandwith also. I have not calculated on the poles so I don´t know the phase margin. When i got time I want to do a spice simulation. Anyway the decoupling worked well.

Reagarding the 150H choke. A choke supply will generate an opposite current and voltage, that in turn will feed the headphone. Giving 3dB higher voltage swing or 6dB more power than just a CCS. The voltage out can actually swing higher and lower than the power supply.... Thats way the headroom gets bigger. And as I said the secon adwantage is that at high frequencies where the impedance of the CCS is increasing, thats where the choke comes in... at 10kHz the 150 H choke will have an impedance of 10Meg ohm.

Um, no. A choke by itself can have the voltage swing higher and lower than the power supply voltage, but if you put a choke in series with a CCS, the CCS forces the choke to have a constant current through it, so there is absolutely no voltage variation across the choke whatsoever. The whole idea of the CCS is that it forces the current through it to be constant regardless of the voltage across it. When you use a CCS as the load for an output device, that means that any voltage variation pushes all of the current variation through the transducer.

Second, the CCS impedance does decrease somewhat at the highest frequencies, but since it is likely over 100 megohm anyway, the extra 10 megohm doesn't make that much difference (and remember that is assuming a perfect choke, real chokes generally have leakage capacitances that will drop that value significantly).

Choke loading can be useful on its own, and actually I use chokes in my power supplies all the time. It's just not particularly helpful in conjunction with a CCS - the CCS just turns it into a very expensive resistor. Another way to think of a CCS which may be useful is to look at it as an extremely high value resistor. If you have a bazillion ohm resistor in series with a choke, the choke really doesn't make any difference - it's the resistor that determines the behavior of the combination.