Mackie 1640 Channel Strips, 3. MIC/HI-ZSwitch (Channels 1 and 2), 2. Low-CutSwitch, Onyx 1640 Features, 1. 48V Phantom Power Switch, [46], Low Cut, to the mixer

Low Cut

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1640	Onyx 1640 Features
	Channel Strips
ONYX
			48V		All sixteen channels on the Onyx 1640
		1
					look alike and function identically with
					the following exception: Channels 1
					and 2 have high-impedance instrument
				75Hz	inputs in addition to the mic and line in-
				18dB/OCT
				MIC	puts so you can connect a guitar directly
				HI-Z
	30				to the mixer.
		20 U40

U 60 -20dB +40dB

GAIN			All the input and output connectors
	INOUT EQ
			(except for the headphone jack) are locat-
	U	HIGH
		12kHz	ed on the rear rotopod. We’ll take a look at
-15	+15	FREQ	them after we explore the front panel.
	2k
400	8k		1. 48V Phantom Power Switch
	U	HIGH
		MID
-15	+15
	400	FREQ	Most professional condenser micro-
100	U	LOW	phones require phantom power, which
	2k
		MID	is a low-current DC voltage delivered to
-15	+15		the microphone on pins 2 and 3 of the
	U	LOW
		80Hz	XLR microphone connector. Push in the
-15	+15		48V button if your microphone needs
		1
			phantom power. An LED lights just
	AUX
			above the button to indicate that phan-
	SEND

We recommend that you use the Low-Cut filter on every microphone application except kick drum, bass guitar, bassy synth patches, or recordings of

earthquakes. 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 filter can help reduce the possibility of feedback in live situations and it helps to conserve amplifier power.

Another way to use the Low Cut filteris in combination with the LOW EQon vocals during live performances.

Many times, bass shelving EQ can really benefit voices. Trouble is, adding LOW EQ also boosts stage rumble, mic

handling clunks, and breath pops. Low Cut removes all those problems so you can add LOW EQ without losing a woofer.

1tom power is active on that channel.

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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

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combination of LOW EQ and Low Cut looks like in terms of frequency curves.

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with older ribbon microphones. 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

[46]is turned down when connecting microphones to the MIC Inputs, espe- cially when phantom power is turned on, to prevent pops from getting through to the speakers.

Low Cut with Low EQ Boosted

3. MIC/HI-Z Switch (Channels 1 and 2)

Channels 1 and 2 have an extra button for switching

between the MIC and HI-Z inputs. When the button is out (MIC), the XLR MIC input is used and the HI-Z input is disconnected. When the button is pushed in (HI-Z), the 1/4" HI-Z input is used and the XLR MIC input is discon- nected. The input stage of the HI-Z inputs is specially designed for the high-impedance pickups on guitars.

2. Low-Cut Switch

The Low-Cut switch, often referred to as a high-passfilter, cuts bass frequencies below 75 Hz at a rate of 18 dB per octave.

10 ONYX 1640

Plugging a guitar into a lower-impedanceline input (like those on channels 3-16)can result in the loss of high frequen-cies, causing an unnatural and dull

sound. Normally, you must use a direct box between a guitar and a mixer’s in- put, which serves to convert the impedance of the guitar

from high to low. The HI-Z inputs on channels 1 and 2 make the need for a direct box unnecessary.