An 808 that shakes your studio monitors can vanish completely on a phone. Phone speakers are tiny, and most of them give up somewhere around 100 Hz or higher, depending on the model. The deep fundamental of an 808 sits well below that, so the phone simply doesn't play it. Since a lot of listening happens on phones, laptops and cheap earbuds, your bass has to survive there too.
Why deep bass disappears
A typical 808 is close to a pure low sine wave. A pure sine at 45 Hz has almost nothing above it, so when the speaker can't reproduce 45 Hz, nothing is left to hear. The track sounds thin, and the beat feels like it lost its floor.
There is a useful trick of hearing, though. Your brain can work out the pitch of a bass note from the higher overtones, even when the lowest part is missing. If the 808 contains harmonics in the range a phone can play, the listener still hears the note. Your job is to give the 808 those harmonics without destroying its weight on a proper system.
Your studio can also mislead you. A room with a boosted low end makes the bass sound stronger than it is. Don't judge the 808 only from where you sit.
Add harmonics with saturation
Saturation, soft clipping and gentle distortion create harmonics from the signal that is already there. That is exactly what you need.
- Put a saturator on the 808 channel. Tube, tape or soft-clip modes are a good start. Add a little at a time and compare with the bypass at the same loudness.
- Try a parallel copy. Duplicate the 808, filter the copy so the deepest sub is removed, distort it more heavily and blend it in under the clean one. The clean track gives weight, the copy gives audibility.
- Use a multiband approach. A multiband saturator lets you add harmonics only to the upper part of the bass and leave the sub clean.
- Tame the top. If the distorted layer sounds buzzy, roll off its highest frequencies so it stays warm instead of fizzy.
Be careful not to overdo it. If the 808 has turned into a growl and lost its pitch, you've gone too far.
Choose notes with phones in mind
Very low notes are mostly felt on good systems and barely heard on small ones. For reference, the lowest string of a bass guitar is about 41 Hz, and a note like A1 is about 55 Hz. Both are below what a phone can play, so what the listener hears is their harmonics.
- Tune the 808 to the key of the song. An out-of-tune 808 clashes with every other instrument, and it's more obvious on small speakers.
- When the song's key puts the main note very low, consider moving parts of the bass up an octave, or layer an octave above the original, so the pitch is clear on small speakers.
- Slides and glides add character, but a very long slide through the low range just gets lost. Keep them short and deliberate.
- Shorten long tails with the envelope so each note ends before the next kick.
Kick and 808: who owns the low end
The kick and the 808 compete for the same space, and when both are loud the result is mud. Decide which one leads in each part of the track.
- Sidechain or duck. A short duck on the 808 whenever the kick hits keeps both clear.
- Give them different jobs. A short, clicky kick with a defined attack and a long, round 808 is a classic split. On a phone, the click of the kick carries the rhythm even when the sub is missing.
- Keep the low end mono. Deep bass should sit in the centre. Wide sub bass can cancel on some systems.
- Check the pitch of the kick against the 808, so the two don't fight each other.
Checking on small speakers
Don't trust one monitoring setup. Listen to the mix in several places:
- a phone speaker, with the case on and off
- cheap earbuds
- a laptop
- a car or a small Bluetooth speaker
- mono, with a low volume as well as a high one
A simple simulation is to roll off everything below roughly 120 Hz with an EQ and listen. If the bass line is still recognisable, the harmonics are doing their job. If the track suddenly feels empty, add more harmonics.
Compare against a finished release in your genre, at the same loudness. Your 808 shouldn't be louder than theirs, only as clear. Take breaks too: after an hour of mixing, your ears will tell you everything is fine.
Do these checks before you export the final WAV, not after the release is live. Bass that works on a phone is part of making the track sound like you meant it.