Arrakis Systems X-mixer-14-22 Operations Instructions download pdf (Page 66)

dB=20[log(V1/V2)]

SPECIFICATIONS & TESTING

Arrakis Systems, inc. --- 6604 Powell st., Loveland, CO 80538 --- 970-461-0730 --- www.arrakis-systems.com

5-1)

5.1

FREQUENCY RESPONSE (continued)

5-1c) CONSOLE PERFORMANCE

All Arrakis consoles feature “Active Balanced” (electronic balanced) inputs and outputs.

That is , there are no transformers or inductors in the signal path. Accordingly, there is

no midband ripple at all. The frequency response is flat across the product’s entire

bandwidth (between the upper and lower roll off frequencies). The product’s bandwidth

is strictly controlled by internal RC time constants.

5-2a) DEFINITION

The purpose of this test is to measure the noise floor of the console and compare it to

the nominal signal level. This will tell us the console’s signal to noise ratio (SNR). The

maximum signal level can be also be measured then compared to the console’s noise

floor thereby quantifying the console’s dynamic range.

5-2b) TEST

This is extremely difficult to perform due to differences in test procedures, setup and

equipment. Many times consistent results are elusive. Careful attention to test p

arameters is essential to obtaining meaningful results. The equipment needed for this

test is an audio frequency signal generator and an audio millivoltmeter.

The signal is applie to a console input, either mic or line, at a known level and

impedance. the AC millivoltmeter is connected to a console output, Program Left for

example. The levels are set up such that the VU meters read “0VU” with all the slide

faders at their nominal setting (the thick line or ‘in hand setting’). The output level is

recorded. This is the ‘signal’ part of the SNR measurement. Th input signal is them

emoved from the console and the noise level is measured using the AC millivoltmeter.

The RATIO between the SIGNAL out of the console and residual NOISE measured by

the millivoltmeter is the SNR. The formula for the SNR is :

SNR=20[Log(Vsignal/Vnoise)]

where V2 is the reference level (some arbitrary voltage usually measured at 1kHz) and

V1 is the voltage level in question.

5-12

SIGNAL TO NOISE RATIO

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Arrakis Systems X-mixer-14-22 Operations Instructions Page 66