Ear tips: silicone, foam or SpinFit

An IEM is a tiny speaker that plays into a closed space: your ear canal, closed off by the tip. Only when that space is sealed can the driver build up pressure, and that pressure is what you hear as bass. If air leaks past the tip, the bass goes first. The treble then sounds sharper, simply because there's less underneath it.

That's why the same IEM can sound full to one person and thin and shrill to the next. Most of the time it isn't the IEM, it's the fit. A pair of tips costs a fraction of a new IEM, so it's the first thing to try when something sounds off.

You'll come across three kinds of tips.

• Silicone: what comes in the box with almost every IEM. Easy to clean, lasts long and leaves the sound as the maker tuned it. The downside: if the size isn't quite right, it leaks.
• Memory foam: you squeeze it thin, put it in and it slowly expands to fill your ear canal. It seals and isolates best, often adds a little bass and softens the treble. It wears out faster and needs a bit of patience every time you put it in.
• Hybrid designs such as SpinFit: still silicone, but built differently. The SpinFit CP100 has a core that bends and rotates with the curve of your ear canal, so the tip stays sealed where a standard tip folds or tilts.

Most IEMs in our range come with silicone tips in S, M and L, usually with M already fitted. That's the average size, not necessarily yours. Take five minutes to try them.

1. Start with M in both ears and play a song with a steady bass line.
2. Press the IEM in gently with a finger. If the bass gets clearly louder, the tip doesn't seal on its own: go one size up.
3. If the tip presses or the IEM slowly works its way out, go one size down.
4. Do this per ear. Many people have one slightly wider ear canal, so S left and M right is perfectly normal.

Also check that the tip sits firmly on the nozzle of your IEM. A tip that slides on too easily can stay behind in your ear when you take the IEM out.

Foam only works if you give it time to expand. Done in a hurry, it feels like it doesn't fit at all.

1. Roll the tip thin between your thumb and finger.
2. With your other hand, pull your ear gently up and back. That straightens the ear canal.
3. Put the IEM in and hold it with a fingertip for 20 to 30 seconds while the foam expands.

Foam absorbs a little of the treble. If your IEM sounds sharp to you, that's a bonus. If it already sounds dark, foam can make it a bit dull.

• Foam: when it springs back quickly instead of slowly, turns hard, tears or stays discoloured. With daily use that's usually after a few months.
• Silicone and SpinFit: when the silicone tears, loses its shape or still feels sticky after cleaning.
• Any tip: when the bass sounds thinner than it used to and nothing else has changed.

Clean silicone tips every week or two. Take them off, rinse them in lukewarm water with a drop of mild soap and let them dry completely before you put them back. Don't rinse foam: wipe it with a dry cloth. While you're at it, check the nozzle of the IEM for earwax.

From our own stock: the SpinFit CP100 and memory-foam tips from KZ and TinHiFi. They're sold per pair, except the KZ set with four pairs in red, grey, black and blue, which is handy if you want spares.

FiiO's tip sets ship from the distributor and come in a storage box:

• HS18: thin, clear silicone with a wide bore. Six pairs, S, M and L twice, for nozzles from 5.0 to 6.5 mm.
• HS19: twelve pairs in five types. Balanced, vocal and bass silicone tips in S, M and L, two pairs of memory foam and one pair of double-flange tips. Handy if you don't know yet which kind suits you.
• HS20: soft liquid silicone that seals well. One pair each of S, M and L.