This month, Brian O'Shaughnessy gets slap happy with a bass guitar and a rhythm track. Laugh? I could have DI'ed...

The bass guitar is significantly different to 6-string guitars in more than just size, number of strings or pitch. The role it has to play involves working with the drums, to tie them to the rest of the music, and underpin the track. So, unlike a lead guitar, say, the bass part needs to sit rhythmically and precisely with the drum part.

The first prerequisite for this is a bass player and drummer who work well together — suffice it to say that in my experience, the weakest link in most young hopeful bands is usually the rhythm section. A solid backing track can have all sorts of looseness on top of it and still feel good, but a shaky rhythm track will always feel uncomfortable, and the whole track will sound shambolic and amateurish. How to put together a good rhythm track is outside the scope of this series of articles, but we can do our best to help the tightness of the track, by making sure the rhythm guitars and bass are as well played and recorded as possible.

DI recording

In the first electric guitar article (THE MIX, January 1995) I did my best to discourage you from using Direct Injection to record guitars, but for bass it's the other way round. If you really feel you need an amp sound then use one, but always use a DI as well. A good DI bass sound will give you definition, clarity and punch at the mixing stage, which you may find difficult to achieve if you've only got an amp signal.

I generally try to record the bass at the same time as the drums, with the bass player in the same room as the drummer, to give good visual contact between them, and so help to achieve a tight, coherent rhythm track. Any small imperfections in the bass part can be repaired, once you've got a performance with a good overall feel. So long as the bass hasn't spilt onto the drum tracks — as good an argument as any for using a DI — if I want an amp sound. I generally assemble a good take (as above), and then feed the signal back off tape into a bass amp and rerecord it. More on this later.

All my comments about the condition of the guitar in previous articles apply equally to bass, with the possible exception of new strings; these can sound a bit too lively — boingy and twangy — but beware strings that are too old; they'll sound dead and will be harder to get properly into tune. I usually ask the bassist to set the tone controls the way they normally have them, and work with that.

I would, however, caution you against turning the treble right down and the bass right up at this stage — Okay, it will sound nice and deep and subsonic, but if you find in the mix that the bass lacks definition, you'll be forced to push the upper-mid frequencies very hard, to try and get it back. Of course, this will add loads of tape hiss.

Right then, let's plug the bass into an active DI box, get the bassist to play along, set a reasonable level and listen. It should sound fairly good, and really only needs a gentle EQ tweak at this stage. Frequencies to look out for include:

50-100Hz: A boost adds depth and warmth, but don't overdo it, or it will get woolly and boomy.

300-600Hz: If it sounds nasal, a cut in this range should sort it out.

600-900Hz: Boosting in this range adds growl.

900Hz-2.5kHz: If the sound needs definition, here's where to find it.

3khz +: There's not usually much of any use for bass here, so I usually roll some of the top end off, to reduce line noise.

It's in the nature of bass guitars, regardless of how good the player is, that some notes will sound louder than others. The lower strings, being heavier, will inevitably generate more signal at the pick-ups, and if you're adding bottom-end, this will exacerbate the problem.

Also, if the playing is slappy, you'll get a lot of notes popping out. So, once you're happy with the EQing, it's time to compress. Patch a compressor across your bass input channel (post-EQ), set the ratio to about three, and adjust the threshold until the compressor is reducing the output gain by 5-10dBs: if you have variable attack and release controls, then they need to be set to fast.

Compression is a vital but subtle tool in the studio armoury, and nowhere more so than for bass guitar — if you've got the compression right, the bass will sound more even and punchy — so make sure to A/B the compressed signal with the original and try to hear the difference; overdoing the compression will result in the signal pumping, and the bass apparently getting louder after the note has been plucked — try to avoid this.

Amp sound

If the project is of a rockier or grungier nature, then you will probably need the dirtier, more overdriven sound that an amp can give. Modern bass rigs usually have quite sophisticated controls including graphic EQ and compression, which can be a bit of a minefield if you haven't encountered them before; I usually ask the bassist to set the amp the way they normally have it, and only change settings if I don't like the sound. Remember, though, that the player has a sound that he/she likes for live situations, and is relying on you to get a sound that works on tape.

My general approach to recording bass amps is pretty much the same as for guitars. One good quality dynamic mic, or a bass drum mic such as the AKG D112, not more than six inches from the speaker. If the source sound is good, then you shouldn't have to do too much EQing, but the general guidelines I gave you above for DI sound will still apply; use your compressor in the same way. Any bass rig that's being driven will cause anything loose in the room to resonate, thus generating lots of stray rattles and buzzes — it's for this reason I don't usually bother with ambient miking techniques for bass guitar.

Re-amping

Assuming you've got a good take of the bass part DI'ed on tape and you want a ballsier amp sound, then just bring the bass part up through a channel on your desk, turn the level right down, and feed the channel output into the amp. Roll the tape, and gradually increase the bass channel level until what's coming out of the amp sounds reasonable. Remember the amp is designed to accept an input signal of the order of a few millivolts, whereas the desk channel output will certainly be much higher (100 times or so) than this.

The other thing to beware of is mains hum, caused by an earth loop between the mixer and the amp. This can be cured either by reversing the earthing on the amp (many modern amps have an earth lift switch on the back somewhere), or by disconnecting the earth in the mains plug of the amp — this is safe, because as long as the amp is connected to the mixer, it's getting an earth from there. Don't, whatever you do, forget to reconnect the earth as soon as you've done the re-amping — a dead bass guitarist doesn't look too good on the CV.

So, in summary, bass guitar is a lot simpler to deal with than 6-string. Just make sure, however you record it, to take a clean DI signal as well — it's worth the extra track, and 9 times out of 10 you'll end up using some of it. In my next article I'll talk about some different techniques for mixing guitars, but, meanwhile, enjoy that funky groove thang!