Equalization; Gain Optimization - Behringer EURODESK SX4882 User Manual

EURODESK SX4882
Rather you should be looking at disconnecting the signal screen
somewhere.
You could do worse than ensure that all screens are commoned
at the patchbay in which case all unearthed equipment would pick
up earth from this point via a single screen (more than 1 route
= an earth loop), while mains-earthed equipment would have all
screens cut at the equipment end.
Some quality equipment has an independent signal and
+
mains earth. In this case, at least one and possibly all
screens should carry earth to the equipment. Sometimes
the only way to find out is "suck and see".
Take care to ensure that using the patchbay does not disturb the
studio's earth architecture. Always use short as possible patch
leads with the screen connected at both ends.
If you're really serious about hum levels, you could run balanced
lines wherever appropriate. The earth wiring scheme would be the
same as before. By shorting the ring to the barrel for all balanced
jack sockets connected to unbalanced equipment, you could use
balanced patch leads throughout. (There is no percentage in wiring
a balanced output to a balanced input with a mono patch cord!)
(See section 12 "(Un)balanced lines".)
Having designed mains hum out of the system, make up your cable
looms from the patchbays outwards, and use cable ties, flexible
sheaths, multicores etc. to keep the back of your racks tidy. It's
going to get very busy in there, and loose cables will inevitably
mean lost signals. Possibly even lost equipment!
9.

Equalization

The variable parameters of the channel A and B equalizers on the
EURODESK SX4882 are described in sections 3.4 and 3.7.
Few people buying the EURODESK will need to be told how an
equalizer works. But how to get the best out of it? Well, that's
another story.
In the beginning EQ was an instrument for removing unwanted
frequencies, or compensating for imperfect microphone response
curves, or bumps in a studio's acoustic. It was a corrective device.
Tamla Motown turned that notion upside down in the sixties with the
novel idea that you try to find for each instrument a characteristic
frequency not shared by the other instruments in the mix. Then you
whack up its gain. This makes individual voices punch through a
mix in a slightly unnatural but exciting way. In general, corrective
EQ usually involves broadband (slope) contouring, together with
narrowband notching of unwanted resonances. The narrower the
notch or "Q", the less the total signal will be affected.
Finding bad resonances is made easier by first fre-
+
quency sweeping in boost mode.
"Motown" EQ is achieved by applying boost in a fairly broad-
band way. The broader the band, the more musical but less
instrument-specific the effect. Applying boost over a narrow
bandwidth will sound "Honky". The two semi-parametric bands
of the EURODESK EQ have had their Q fixed at 1, a typical and
sensible value. For sounds which require drastic corrective EQ
(remember no MIDI instrument should need it), it is advisable to
have a couple of channels of fully comprehensive equalization
in your rack. (You can always bounce tracks though the out-
board EQ, freeing up the unit for the next task). Check out our
BEHRINGER ULTRACURVE PRO DEQ2496, which promises to
be another price/performance buster.
The EURODESK EQ might be applied to a signal as follows:
First, trim the LF and HF shelves to achieve the required slope or
"LOUDNESS". (These controls mirror the tone controls of a typi-
cal HiFi amp.) Now use one parametric band to boost the nicest
frequency, and another to cut the nastiest. Over all channels in
the mix, if too many of the nicest frequencies coincide, then you
might have to settle for second best in some cases! Often you
might want to boost two nice frequencies. Really nasty frequencies
will need notching. Time to go outboard.
Why does the upper mid bell frequency go up to 20 kHz? A more
pertinent question might be, why has it taken so long to get there?
After all, even 16 bit (the lowest acceptable quality) digital audio
16
sports a 20k bandwidth: surely if 20k is important then so is
controlling it. OK. You and I will never hear a pure 20k sine tone.
However, Rupert Neve, the audiophile Guru, would argue that
when it comes to real instruments, what happens even above
20k may have a perceptible effect on the listener. It seems that
one reason why high- quality (1/2" at 30 IPS) analog tape sounds
better than DAT to many discerning ears is because, although its
frequency response begins to roll off at 12 dB/octave somewhere
around 15 to 20 kHz, it is not abruptly cut off at 20!
We have heard, or "detected", a 20+ kHz low pass filter being
switched in and out when monitoring an analog master tape
through a speaker system that included piezo-electric tweeter
elements capable of reproducing up to 40 kHz. Perhaps less
controversially it can be shown that if cut/boost is applied at 20
kHz, a significant portion of the resulting EQ curve for all but the
tightest of Q's actually occurs in the audible spectrum, below 16
to 18 kHz. For example if the BEHRINGER EQ is boosted by +15
dB at 20 kHz, the amount of boost at 10 kHz will be 3 dB. The
resulting EQ curve will bear no relation to one where 3 dB of boost
is applied at 10 kHz.
A good vocal signal can be enhanced by applying a
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significant boost in the 15 k region or higher, above the
nasty sibilance region. Especially effective if you've got
a de-esser post EQ.
Use the LF cut to tighten up channels in a mix: maybe
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remove it only for the bass, kick drum, toms, tablas,
didgeridu and other deliberate subsonics. (When record-
ing classical music ignore this advice).
With an LF cut at 100 Hz and a low shelf boost at 80 to
+
160 Hz, you have pretty much got a peak response rather
than shelving at the bottom.
+ Look at the extraordinary width of the frequency sweep
of the upper mid EQ -300 Hz all the way up. Set to maxi-
mum boost and play about with the frequency in real
time. We bet you'll get some stunning filter sweeps. Try
it on drumloops – great for dance music!
+ You can cascade channel EQs by connecting the DIRECT
OUT (see section 7 "Connections") of one channel into
the LINE or TAPE INPUT of another. The first channel
should first be un-routed to all buses, including L/R
and aux sends. The second channel then becomes the
"control" channel, routing to the buses. You now have a
23- channel mixer, but one channel has a 4-band (semi)-
parametric plus 30 dB of shelving swing!
Remember EQ contouring can be done with CUT as
+
well as BOOST. E.g.: cutting away the top and bottom,
then pushing up the gain is equivalent to MID-RANGE
BOOST! EQ is NOT a 1-way street!
+ Always re-set a channel's input gain after altering the
amount of EQ cut or boost applied (see 3.3).
10.

Gain optimization

PFL (Pre-Fader-Listening) is the way to set a desk level. Setting
up the channel input gain is discussed in the essential section 13.
Optimum master aux send levels will be dependent on the sen-
sitivity of the FX device being driven, but unity gain is a useful
starting point. As the mix progresses, more and more channels
are likely to be sending to effects via the aux buses, and it's best
to PFL all sends (aux, subgroup, MIX-B) just before setting up
for the final mix.
Outboard reverbs etc. should all be made to work hard. There's no
point in having an 85 dB dynamic range if the input meter of your
reverb is barely flickering. On the other hand, digital distortion is
not one of the nicer noises around. Fortunately you can SOLO the
FX returns. Here you'll have to rely on your ears to detect digital
distortion, since different outboard processors calibrate their me-
ters differently, and their dynamic range is not sufficient to allow,
Gain optimization