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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.
