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(click thumbnail)The Mackie Onyx 1640 is a versatile 16 channel/4-bus analog small-format mixer at the top of the Onyx line. An accessory FireWire card allows for connecting the mixer up to various Mac and Windows programs for computer control and mixing in software.

In setting the channel gains with the gain trim pots, it was difficult to get repeatable consistent gain at the maximum setting. Further, the gains were a bit difficult to set to some desired value for the knob positions of half rotation to maximum rotation.

Frequency response of a typical channel feeding the mic input at minimum and maximum gain is shown plotted in Fig. 1. The measurement was taken at the main outputs.

Distortion of the Onyx 1640 was generally very low with circuitry just shy of clipping. Fig. 2 is a plot of THD+N vs. frequency for the conditions of 6.72V or 6.72 mV input into mic input of channel 1 with channel gains set for min and max. This just caused the channel red LEDs to come on. Master fader set to unity with channel faders set for +4 dBu main output. Measurement bandwidth was 80 kHz here and the distortion is mostly out of band noise. Another distortion condition is shown in Fig. 3. In this case, channel and main faders are full up, input voltage is set to produce main output voltage of +20 dBu, and channel gain is set for min and max. Measurement bandwidth is 22 kHz. This test is more indicative of the performance of the mic preamps

The equalizer section of the 1640 is quite flexible. Fig. 4 shows the range of equalization for the low and high shelving along with the two parametric controls with frequencies set for mid rotation.

Channel separation varied somewhat for different channels and conditions. A typical result is plotted in Fig. 5 for the two testing directions for Channels 1 and 2

The unit under test was equipped with the accessory FireWire card. After testing the 1640 itself, I installed the included software on my lab computer that I use to control my Audio Precision System Two Cascade measurement system. The software consists of an Onyx control panel where sample rate and latency are selected and a full version of Tracktion, Mackie's multitrack recording and sequencing software for the PC and Mac. I got this all going and briefly experimented with recording and playing back some signal test files. I must say that it is pretty impressive how the FireWire card and the Onyx 1640 work together as a mixer/recording system.

— Bascom H. King

Mackie Onyx 1640 Analog Mixing Console

INPUT SENSITIVITIES

For output level of +4 dBu at main outputs, Input & output faders set to maximum

Mic inputs

Gain trims at maximum 118.3 uV, -76.3 dBu

Gain trims at minimum 122.4 mV, -16.0 dBu

Line inputs

Gain trims at maximum1.23 mV, -56.0 dBu

Gain trims at minimum1.23 V, +4.0 dBu

Insert inputs151.0 mV, -14.2 dBu

Aux Return inputs123.4 mV, -16.0 dBu

Main Insert inputs199.0 mV, -11.8 dBu

GAINS

Mic inputs

Gain trims at maximum80.3 dB

Gain trims at minimum20.0 dB

Line inputs

Gain trims at maximum60.0 dB

Gain trims at minimum0 dB

Insert inputs18.2 dB

Aux Return inputs20 dB

Main Insert inputs15.8 dB

INPUT OVERLOAD

Mic inputs

Gain trims at maximum9.14 mV, -38.6 dBu

Gain trims at minimum4.94 V, 16.1 dBu

Line inputs, Ch 3 – 16

Gain trims at maximum93.9 mV, -18.3 dBu

Gain trims at minimum> 25 V, 30.2 dBu

Instrument inputs, ch 1 & 2

Gain trims at maximum91.6 mV, -18.3 dBu

Gain trims at minimum8.4 V, 20.7 dBu

OUTPUT LEVEL

At main out, onset

of clipping @ 1% THD+N9.7 V, 22.0 dBu

INPUT/OUTPUT POLARITY

Input to main outputs

Mic input non-inverting

Line inputnon-inverting

Channel insert inverting

Aux returns non-inverting

Main insert inverting

INPUT IMPEDANCE

Mic inputs2.5 K

Line inputs28.0 K

Instrument inputs Ch 1 & 2> 300 K

Insert inputs1.3 K

Aux returns19.8 K

OUTPUT IMPEDANCE

Main stereo outputs152 ohm

Tape outputs2.15 K

Aux send outputs300 ohm

Headphone outputs27 ohm

HEADPHONE OUTPUT

Power at onset of Clipping, 1% THD+N

600 ohm 145 mW

50 ohm 144 mW

FREQUENCY RESPONSE

Mic input to main output

Min gain

+0,-1 dB < 10 Hz – 78 kHz

+0,-3 dB < 10 Hz – 144 kHz

Max gain

+0,-1 dB 25 Hz – 40 kHz

+0,-3 dB 12 Hz – 74 kHz

TOTAL HARMONIC DISTORTION

Input level at 6.7V, gain trim at minimum, main mix fader at "unity setting, Channel red LED lights just on, channel gains set for output of +4 dBu at main outputs

< 0.015% 20Hz – 20 kHz

Input level at 6.7mV, gain trim at maximum, main mix fader at "unity setting, Channel red LED lights just on, channel gains set for output of +4 dBu at main outputs

< 0.015% 20Hz – 20 kHz

SIGNAL TO NOISE RATIO

Mic inputs

Signal to noise ratio with +4 dBu input to mic channels,

channel fader and main mix faders at unity setting, gains

set for +4 dBu output

22 – 22 kHz bandwidth86 dBu

Equivalent input noise, channel gain, channel fader and main mix fader at maximum, 150 ohm source impedance, 22 Hz – 22 kHz bandwidth–129 dBu

CHANNEL SEPARATION

Adjacent channel

Mic inputs

Gain trims at minimum

> 70 dB 20 Hz – 700 Hz

> 42 dB @ 20 kHz

Gain trims at maximum

> 70 dB 20 Hz - 3 kHz

60 dB @ 20 kHz

Line Inputs

Gain trims at minimum

> 70 dB 20 Hz - 2 kHz

> 58 dB @ 20 kHz

Gain trims at maximum

> 70 dB 20 Hz - 300 Hz

> 40 dB @ 20 kHz

Notes: All measurements with balanced I/O unless otherwise Noted.