In the digital world measurement criteria differ. Instead of using a reference level that relates to a
particular power or voltage (like 0dBm) the 0dBf reference is the maximum signal that the analogue to
digital converter can accept before the onset of clipping.
The 0dBf level is usually somewhere in the region of +18dBu to +24dBu in the analogue world…. It is
NOT
the same as 0VU (+4dBu) on an analogue VU meter.
It’s very important to use an A to D input level that maximizes the headroom and minimizes the noise
in the analogue world.
E.G
. If an attempt was made to drive the console or preamplifier high enough to hit the 0dBf
(+24dBu) reference level on the A to D, the amplifier would be running at over 20dB greater than
it’s normal operating level. This raises the noise floor by 20dB (ten times louder) and reduces the
analogue headroom to around 2dB. A microphone normally needing 40dB gain would need 60dB
gain and any peaks would drive both the pre-amplifier and the A to D into clipping. Not good!
Depending on the reference level recommendations of the A to D manufacturer, the analogue levels on
its input should be typically around –18dBf. This will optimize both the signal to noise ratio and the
headroom of the analogue signal. A degree of variance, say –16dBf, is acceptable but higher levels will
begin to degrade the analogue performance with no improvement to the quality of the sound.
When using condenser microphones req48v, be sure to turn the volume control down before
pressing the 48v switch as applying this voltage may involve a switch on thump, especially if set to
high gains. The complex relay switching for the alternate mid frequencies involves a similar small click
and the volume should be turned down before either function is switched.
Specifications:
Input impedances :
XLR Input = 300 ohms or 1200 ohms, switch selectable on the rear panel.
Transformer balanced and floating
D.I Input =
10Mohm into a “super-transistor” class A amplifier.
Unbalanced mono jack socket input disables the rear XLR input.
Frequency response:
20Hz to 50KHz + 1dB
Total Harmonic Distortion
:
< 0.075% @ 1KHz @ +20dBu
Equivalent input noise:
Mic input, +80dB gain < -125dB (20Hz to 20KHz)
Warranty:
ONE YEAR PARTS AND LABOR LIMITED WARRANTY
Aurora Audio International warrants this GTQ2 unit against defects in workmanship for a period of one
year and parts for a period of one year from receipt by the original end user. This warranty shall not
apply to damage resulting from misuse including water damage, in-transit damage, fire damage,
improper maintenance, dropping the unit and operation or storage outside the environmental
specification for the product.
Do not try to repair this GTQ2. Only qualified Aurora Audio International technicians are authorized to
repair this unit. WARRANTY VOID IF CASE IS OPENED