Behringer Eurodesk SX4882 User Manual

EURODESK SX4882

Gain optimization

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!

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

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

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

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).

Gain optimization

10.

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,