SONIQS SAX 'polarity'!

[little eddy]

I've just bought a pair of these initially as bypass caps in the second stage of my CLC power supply. They have come with a red and black tails. Logic would suggest that the black leg is connected to 0V but is this the recommended orientation?

At sometime I may true to use these as dc de-coupling caps so again the same question where my logic would be that the signal flows from the red to the black tail.

Anyone any experience or inside knowledge?

[andrew ivimey]

hm, annoying I know but I have used, am using these caps and I like them. I have deliberately swapped them round both as couplers and in PSUs and I can't hear any difference.

Perhaps I have cloth ears!

[Richard]

The black lead is connected to the outer foil of the cap winding. Connecting this to ground, or the earthiest end of the circuit it's in, will create a faraday shield for the inner winding and thus reduce the effect of stray capacitances.

If you have any of those plastic film trimmer caps you'll see they have stators and rotors like a tuning cap. The cap will work connected either way round but by connecting the outer elements to ground the inner ones are shielded, thus the legs may be marked as they are often used at RF.

The effect is only likely to matter at many MHz, where the reactance of a couple of pF may be significant, well out of the audio band, and I think it unlikely you'll find any difference in an audio coupling application.

Found this for anyone wanting a bit more, II Stray Capacitance about halfway down, http://www.analog.com/library/analogDialogue/Anniversary/21.html