there is no way you have improved performance if those silmic are decoupling caps (well actually at this size they become reservoir caps), you do know that putting the 2 caps in series like that reduces
the capacitance, rather than increasing it right? it only increases the voltage rating, which i'm guessing is not what you were trying to do? you will have created a 'cap' that is more inductive, higher impedance and most likely resonant.
SMD is the superior format for decoupling, hell these days its pretty much superior for everything, yes even audio.
edit: sorry I just read back, I see you know its lowered the capacitance value. it has also increased the impedance, which is now seen in series, so youve doubled the impedance of the silmics, which are already higher than the caps you are replacing.
silmics can be used well in some applications, mostly for if you have to
use an electro in the signal path, which is why you would connect 2 together to make a bipolar cap to handle the AC signal, for DC it serves no purpose IMO (well unless degrading the specs is the purpose?).
it is done because there are not all that many high quality bipolar electros made anymore for audio (probably because most stuff is moving towards being DC coupled these days) and if a bipolar cap is needed for AC signal duties, most will use a film cap.
AC (alternating current) switches polarity twice each 'swing' so a polar cap can distort on the alternate phase, so if for AC signal and film cant be used, this trick was sometimes used to make a nice quality non-polar cap. This has no bearing whatsoever on decoupling DC power supplies.... for power supply reservoirs and decoupling, the SMD polymers you replaced are the better choice.
wow you are replacing ceramic HF decoupling caps with them too? just a little bit of info, even a small 0402 size ceramic capacitor placed directly across pins with via in pad pattern for the PCB (lowest possible inductance and impedance) is only good up to 10MHz.
the silmics are literally pointless for bypassing HF signals, the ceramics were orders of magnitude better for the job and even those were probably too large. For really effective digital HF decoupling, only even smaller SMD parts than 0402 (0201, like a spec of sand), as well as planar capacitance designed into the PCB power and ground planes is effective.
for getting rid of/attenuating such noise, a combination CRCLC is required. Something like the Murata EMIFIL products
it is clear, funnily enough, that audioengine have a better idea about how audio hardware and basic electronics functions than your friend. who woulda thunk that?Edited by qusp - 1/31/13 at 12:25am