WARNING: The headphone amps are

designed to drive any standard head-

phones to a very loud level. We’re not

kidding! They can cause permanent hearing damage. Even intermediate

levels may be painfully loud with some headphones. BE CAREFUL! Always start with the PHONES level turned all the way down before connecting headphones to the PHONES jack. Keep it down until you’ve put on the headphones. Then turn it up slowly. Why? Always remember: “Engineers who fry their ears, find themselves with short careers.”

8. 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 button if your microphone needs phantom power. An LED lights next to the button to indicate that phantom power is active.

This is a global phantom power switch and applies 48V to the XLR input connectors on channels 1-4.

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 microphones. Check the manual for your microphone to find out for sure whether or not phantom power can damage it.

9. Channel GAIN

The GAIN controls adjust the input sensitivity of the mic and line inputs on channels 1-4. This allows the signal from the outside world to be adjusted to optimal internal operating levels.

If a mic-level signal is plugged into the XLR combo 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.

When using the balanced line input of the combo jack (1/4" TRS connector), 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. Signal Level Indicators

These LEDs indicate the channel’s signal level after the GAIN control and the INSERT jack.

If you’ve followed the “Set the Levels” procedure on page 6, the –20 and –10 LEDs should light frequently, and the OL (Overload) LED should not light at all. If the OL LED is blinking frequently, the signal is probably distorted from overdriving the input. Either turn down the GAIN control or turn down the signal at its source.

11. Instrument Switch

Channels 1 and 2 have an extra button for switching between the MIC/LINE and Instrument inputs. When the button is out (MIC/LINE), the XLR MIC input or the 1/4" LINE input is used, and the Instrument input [12] on the front panel is disconnected. When the button is pushed in (Instrument), the 1/4" Instrument input is used and the XLR MIC and 1/4" LINE inputs are discon- nected. The input stage of the Instrument inputs is specially designed for the high-impedance pickups on electric guitars, basses, acoustic guitar pickups, etc.

Plugging a guitar straight into a typical

line input can result in the loss of high

frequencies, causing an unnatural and

dull sound. Normally, you must use

a direct box between a guitar and a mixer’s or preamplifier’s input, which serves to convert the impedance of the guitar from high to low. The Instrument inputs on channels 1 and 2 make the need for a direct box unnecessary.

HOWEVER: The Instrument inputs are unbalanced, so if you are running a long cord between the instrument and the Onyx 400F (say over 25 or 30 feet), it is best to use a direct box with a balanced output to avoid picking up noise over the length of the cord.

12. Instrument Input

This is a 1/4" TS connector that accepts an unbalanced instrument-level input signal from a high-impedance instrument like a guitar.

Manual Owner’s

 

ONYX MIC PRE

 

1 ONYX MIC PRE

 

2 ONYX MIC PRE

 

3 ONYX MIC PRE

4

 

OL

20 U

30

OL

20 U

30

OL

20 U

30

 

OL

20 U

30

 

-10

40

-10

40

-10

 

40

-10

40

48V

-20

U

60

-20

U

60

-20

U

 

60

-20

U

60

 

 

 

 

 

 

-40

-20dB

+40dB

-40

-20dB

+40dB

-40

-20dB

+40dB -40

-20dB

+40dB

 

 

GAIN

 

GAIN

 

GAIN

 

 

GAIN

 

 

Owner’s Manual

13