The way I mic up
drum-kit overheads normally means that there is a slight level
difference between the left and right gain settings. It’s not more than
10dB at peaks, but it is noticeable. I’m using a pair of AKG C414 XLS
microphones that are perfectly matched for any other work I do with
them, so I don’t think they’re at fault, and I’ve also used my tape
measure to check that the overheads are equidistant from the snare and
kick. It’s really odd because, sonically, the overheads sound the same;
neither one is more bassy than the other, which might have suggested a
boundary effect. I’ve not always got both mics pointing at the snare,
though, so this may account for some level difference, and one of the
mics is closer to the wall than the other (about 1m away), which might
also be a factor, although that mic is pointing away from the wall.
This
is the rear side of the AKG C414 XLS microphone, showing two of its
three rocker switches. These are quite easily adjusted inadvertently
when positioning the mic, so it’s worth double-checking the LED settings
before you hit Record.
I’m just trying to ascertain whether my mic
positioning is awry or whether it’s normal to have overheads with
different average levels like this. So when I’m setting up the preamps
for my cardioid drum-overhead mics, should the gain settings be matched
or should the peak level be the same, even if that means I have
different gain settings?
Via SOS web site
SOS
contributor Mike Senior replies:
A level difference of 10dB between
the snare peaks in each overhead mic is quite a lot so, to be honest, I
smell a rat here on the technical side. Without knowing the specifics
of your mic placement, I think it’s unlikely that the low-level mic’s
polar pattern is having that large an effect. You’d only expect a 6dB
attenuation even for sounds 90 degrees off-axis so, unless you’ve got
the arse end of the mic pointing at the snare, I can’t see that being
the culprit. If you do have one mic pointing completely away from the
snare and the other pointing directly at it, I’d instinctively raise an
eyebrow anyway, as the tonal differences this would create between snare
sounds on each channel would probably sound a bit odd in stereo.
However, the proof is in the pudding, and if an unorthodox mic position
such as this produces the goods for you then, by all means, just match
the snare levels by mismatching the gain controls.
The
room might be having some effect but, again, I’d be surprised if it was
an effect of that magnitude, so I can’t truthfully say I’d look there
for answers, especially given that the tone between the mics seems
fairly consistent to you. Perhaps if the room is fairly dead-sounding
and the drummer is blocking the sight-line between the low-level mic and
the snare, you might expect some level loss, and this could conspire
with the mic’s polar pattern to achieve that kind of level difference,
but I’m still suspicious that there’s simply something technical amiss.
First
off, I’d check filter or pad switch settings on the mics or preamps.
Those new AKG mics have a lot of switch settings, and their rocker
design makes them prone to inadvertent adjustment during normal
handling. You also need to look quite carefully at the LED status
indicators to check that the settings are as you expect them to be. My
best guess is that you’ve put your thumb on the pad selector switch and
knocked it down 6dB, at which point an additional 4dB level change is
much more likely to be arising from your microphone positioning.
My
other idea would be that maybe something is awry with a balanced cable
or socket somewhere, because unbalancing a balanced line can lose you
6dB in some instances too. It’s easy enough to check for this, though,
as it’s just standard studio troubleshooting. Try swapping individual
components between the two analogue signal paths and if the level
difference migrates between them, also, you can point the finger of
blame at whatever it is you’ve just swapped over.
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