Mackie M800 Bedienungsanleitung PDF herunterladen (Seite 15)

15

CONSTANT DIRECTIVITY SWITCH

If you don’t have constant directivity horns,

you can leave this switch

OFF

.

Compression drivers mounted on constant-

directivity horns require compensation in the

form of a high-frequency boost, with its “knee”

set somewhere between 2kHz and 6kHz. Until

now, you’d have to resort to external crossovers

or worse yet, graphic EQ modules. Both of

these are fraught with limitations, not to men-

tion adding cost, rack space requirements, and

complexity to your system.

The M•800 power amplifier eliminates the

need for any of these external devices — it has

the compensation circuitry already built in,

and using it is a breeze.

CD FREQUENCY

Your compression drivers’ spec sheet should

have a suggested frequency for compensation

boost. If so, just turn the

CONSTANT DIREC-

TIVITY

switch

ON

and set its knob to match

that frequency. If your spec sheet doesn’t have

that information, you can simply adjust the

frequency knob by ear, preferably using the

same music as the actual performance (3.5kHz

is a good place to start).

100

Hz

1k

Hz

20

Hz

10k

Hz

20k

Hz

–5

dB

0

dB

5

dB

15

dB

10

dB

Even if you don’t have CD horns, you can

use the

CONSTANT DIRECTIVITY

feature to

enhance your EQ curve. By setting the fre-

quency knob fully clockwise, you introduce a

very high-frequency boost to the signal (above

6kHz). And in Mackie-land, this gentle boost

has a name:

AIR

, as seen on our SR series of

consoles. By boosting these high frequencies,

AIR

will breathe life into your mix, making

cymbals brighter and vocals silkier.

Speaking of Mackie SR consoles: If you use

the

AIR

feature on an SR console as well as the

AIR

feature just described on the M•800, you

may be overdoing it. You won’t hyper-ventilate

or anything, but it might cause your audience

to experience ear fatigue from too much high-

frequency content. Too much of a good thing,

perhaps.

Constant Directivity EQ

OFF ON

CONSTANT DIRECTIVITY

HORN EQ /AIR EQ

4.5k Hz

6k Hz

2k Hz

AIR EQ

TYPICAL

More on Constant

Directivity Horns

All high-frequency compres-

sion drivers have an inherent

roll-off of about 6 dB per oc-

tave above about 3kHz. The

exact frequency at which the roll-off occurs

(called the mass breakpoint) depends on the ma-

terials used, the mass of the moving parts

(diaphragm and voice coil) and the strength of

the magnet. The

CONSTANT DIRECTIVITY

HORN EQ

control on the M•800 compensates for

this natural roll-off in the power response of the

compression driver coupled to a CD horn, with

the end result of flat-frequency response (con-

stant) over a wide coverage angle (directivity).

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