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By Bjorgvin Benediktsson
If you have the option of recording both, then take the opportunity and record
both.
DI Recording
Recording direct is great if you're left without an amp. Just plug your bass
straight into your interface, or use a DI box.
You can also record through a pre-amplifier. Instead of the signal going into
a cabinet and out of the speakers, you can just route the bass part directly
into your audio software. A pre-amp can add that much-needed warmth to your
bass sound.
Once you've recorded your bass part, use an amp modeller
to round the tone out. A DI'd sound can sometimes sound too "stringy," so
an amp modeller can really help you round out your tone.
Recording the amplifier
It's a little trickier to record a bass amp. Especially if you're in a home
studio. You want the cleanest sound possible, and if you're in a sub par room
you need to isolate your amp.
Throwing thick blankets over the amp and microphone can work to deaden some
of the reflections. Putting the amp in a padded closet is also a way to keep
the reflections out.
Finding the Sweet Spot
The quick and dirty way to record a guitar cabinet is to throw a dynamic mic
up to the grill and hit record. You'll get a close and full range sound from
your guitar, but miking up the bass cabinet is a bit different.
A Little bit of Physics
Here is a short physics lesson. Let's say we want to capture the thickness
of the bass around 80 Hz.
Sound travels at 1130ft/344m per second. Lower frequencies travel slower,
and take longer to finish one period of their wavelength. If we know this,
we can actually calculate where we should put the mic.
Wavelength = Speed of sound(1130ft or 344m) / Frequency
We want the thickness of the 80 Hz.
Plugging 80 Hz into the formula we see that:
1130(OR 344M)/80HZ = 14.125 Ft. or 4.3 Meters
Now we know the full wavelength of 80 Hz, or how long it takes 80 Hz to travel
one cycle, as shown in the image above.
But we don't want to capture the energy of 8 Hz at the end of its cycle. You
can see that the most amount of energy coming from the wave is around 1/4 of
its cycle. This is where the sine wave peaks. By dividing the waveform by 4
we see where the most amount of 80 Hz is located.
14.125/4 = 3.53 ft, or approx. 1 meter.
Now we know where we should put the microphone in front of the bass cabinet
if we really wanted to accent the 80 Hz. Placing your microphone like this
doesn't mean you're not capturing any other frequency. It means that in that
position, that particular wavelength is very strong and prominent.
Recording Well to Start With
If you record the cabinet as well as a DI'd signal you get best of both worlds.
Later, you can combine both signals to get the most ideal sound you are looking
for. You'll have both to choose from, giving you a nice palette of bass sounds
to choose from.
As always, if you're recording a cabinet, make sure your bass is sounding
good in the room. Fix everything at the source and make sure that the bass
sound you are hearing before you record is the bass sound you want recorded.
You don't want to record a lackluster bass track that's impossible to fix in
the mix. Record it well at the source and you'll save yourself a lot of heartache
during mixing.
Bjorgvin Benediktsson is an audio engineer and writer. He is an Alumni from
the SAE Institute and has been working in the audio industry since 2006. He
has written about audio and music for blogs and magazines since 2006 and has
published books on audio recording and mixing. He writes about music production
on his blog.
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