4•Bus

Onyx 4•Bus Features

ONYX

Mono Channel Strips

The Onyx 24•4 has 20 mono channel strips and two stereo channels, and the Onyx 32•4 has 28 mono channel strips and two stereo channels. Each mono channel has a mic and line input connector and an insert jack for connecting an external signal processor.

1. PAD Switch

In most cases, you will leave the PAD switch out. How- ever, you may have a microphone that produces a higher output signal than usual, which may require you to turn the GAIN control way down. If that is the case, push in the PAD switch to insert a 20 dB pad at the input to the mic preamp, to prevent overloading the microphone pre- amp and provide better gain control.

2. Low-Cut Switch

The Low-Cut switch, often referred to as a high-pass filter, cuts bass frequencies below 100 Hz at a rate of 18 dB per octave.

We recommend that you use the Low-Cut switch on every microphone application except kick drum, bass guitar, bassy synth patches, or recordings of earth- quakes. These aside, there isn’t much down there that you want to hear, and filtering it out makes the low stuff you do want much more crisp and tasty. Not only that, but the Low-Cut switch can help reduce the possibility of feedback in live situations and it helps to conserve amplifier power.

Another way to use the Low-Cut switch

is in combination with the LOW EQ on

vocals during live performances. Many

times, bass shelving EQ can really ben-

efit voices. Trouble is, adding LOW EQ also boosts stage rumble, mic handling clunks, and breath pops. Low Cut removes all those prob-

lems so you can add LOW EQ without losing a woofer.

Here’s what the combination of LOW EQ and Low Cut looks like in terms of frequency curves.

+15

+10

+5

0

–5

3. 48V Phantom Power Switch

Most professional condenser microphones require phantom power, which is a low-current DC voltage delivered to the microphone on pins 2 and 3 of the XLR microphone connector. Push in the 48V switch if your microphone needs phantom power. An LED lights just above the switch to indicate that phantom power is active on that channel.

Dynamic microphones, like Shure’s SM57 and SM58, do not require phantom power. However, phantom power will not harm most dynamic microphones should you accidentally plug one in while the phantom power is turned on. Be careful with older ribbon micro- phones. Check the manual for your microphone to find out for sure whether or not phantom power can damage it.

Note: Be sure the MAIN MIX fader

[72]is turned down when connect- ing microphones to the MIC Inputs, especially when phantom power is turned on, to prevent pops from get- ting through to the speakers.

4. GAIN Control

If you haven’t already, please read “Set the Levels” on page 5.

The GAIN control adjusts the input sensitivity of the mic and line inputs. This allows the signal from the outside world to be adjusted to optimal internal operating levels.

If the signal is plugged into the XLR jack, there is 0 dB of gain (unity gain) with the knob turned all the way down, ramping up to 60 dB of gain fully up (–20 dB to +40 dB with the PAD switch pushed in).

1

PAD

48V

30

20 U 40

U 60

-20dB +40dB

GAIN

UEQ

HIGH

12kHz

-15 +15

2k

FREQ

400 8k

U

HIGH

MID

-15 +15

400

FREQ

1002k

U

LOW

MID

-15 +15

U

LOW

80Hz

-15 +15

EQ OUT

IN

AUX

1

OO

MAX

2

OO

MAX

3

OO

MAX

4

OO

MAX

5

OO

MAX

6

OO

MAX

–10

 

 

 

–15

 

 

 

20Hz

100Hz

1kHz

10kHz 20kHz

Low Cut with Low EQ Boosted

When connected to the 1/4" jack, there is 20 dB of attenuation all the way down, and 40 dB of gain fully up, with a “U” (unity gain) mark at about 10:00.

10

ONYX 4•Bus