Does a cap in the audio signal path cause delay?

[jivex5k]

Forgive my ignorance here, I've become very interested in learning about circuits and have started playing around with breadboards and following various tutorials. This led me to learn more about capacitors, and to my understanding, they cause a delay in the voltage as they charge. I've been learning about create an analog sawtooth wave oscillator, and it uses a cap alongside an inverter to create the waveform.

This got me thinking, wouldn't  cap in the audio signal path of an amp cause a delay? This doesn't seem to be the case, I have my crack hooked up to my PC and there's no perceptible delay in audio and video. I tried to google the subject, it was hard to find info on this though.

Maybe the voltage + size of the caps makes the delay small enough to be negligable, and instead simply provides current stabilization? Figured I'd ask here since there's so much expertise.

[Paul Birkeland]

We refer to this as phase shift and use degrees rather than actual time.

Sometimes it helps to quantify things you might be concerned about.  If we take the 100uF coupling cap and assume a 300 ohm headphone load, we will have -15 degrees of phase shift at 20Hz (the worst case spot). That is about .002 seconds of delay.  Headphones themselves also have phase shift, and this -15 degrees of shift may actually cancel out what the headphones themselves are doing!  For loudspeakers, it's not all that unusual to see +/-45 degrees of phase shift.

Lots of research has been done on the topic and most of it has demonstrated that we can't hear this very well. 

As I'm writing this I would expect that PJ is authoring a more precise post, this is very much is expertise!

[jivex5k]

Thanks for the answer! That's pretty neat you can use formulas to determine the phase shift amount.

I was playing around with caps yesterday, I picked up a book about electronics and it had me build a circuit to create a self oscillating relay, which turned it into a buzzer which was neat. Then I started adding caps in parallel to the relay coil, it lowered frequency of the oscillations which was cool. I'm happy to say I was able to look up the datasheet for the relay and walk through the concept of how it works to create it without following the guide.

[mcandmar]

Coincidently i fell down the phase shift research rabbit hole the other day, found this RC High Pass calculator which also graphs the phase shift for you..  http://sim.okawa-denshi.jp/en/CRhikeisan.htm

Never did find a definitive answer as to how important it actually is, and what level is generally deemed to be acceptable.

[Paul Birkeland]

Much depends on what your cochlea does with what you're hearing, so there isn't just a magic number that's audible.  It's also frequency dependent.