Hovland musicap capacitor: What does it do?

This sounds like a silly question and my inexperience shines right through, but I'm curious as to what they do exactly? I've recently received my Merlin speakers and they come with two pairs of musicaps. Because I'm running single wire, I only need one pair and has a spare pair sitting around. I've tried them on my sub-woofer but couldn't notice any differences one way or another. I might try the spare pair on some other places but I would like to know what they are designed for. My thanks in advance.

This is what is known as a Zobel network (a capacitor and resistor in series). I am not exactly sure what it does (meaning I do not wish to be corrected numerous times if I try to explain it technically!), however, if you do some searches on this website or AudioAsylum (or just ask Bobby himself) you will turn up many competent threads.

In a nutshell: a Zobel compensates for a driver's voicecoil rising impedance with frequency. They are most often employed on midbass drivers. But they can also compensate for a harsh sounding tweeter.

I'm sure someone will give you a more technical explanation, but -- in simple language -- a Zobel network prevents an amplifier from going into oscillation when driving some speakers (fortunately a very small number). Zobel networks can also be used at the speaker end of speaker cables -- Alpha Core, for example, offers Zobel networks since its cables can induce amplifier oscillation with certain speakers.