Quartz Q16/Q32 System Manual
18 May 2004
Issue 5.00
Page 32
The 1U Q16 frame is shown in schematic form below
Inputs 1-16,
outputs 1-16, and
processor
(PC-225 / PC-215)
PS-0008
The 2U Q32 frame is shown in schematic form below:
Inputs 1-32,
outputs 1-32,
and processor
(PC-225 / PC-215)
Inputs 1-32,
outputs 1-32,
and processor
(PC-225 / PC-215)
PS-0008
Main PSU
PS-0008
Backup PSU
Not fitted in mono units
Inputs
The inputs are electronically balanced. This provides a very high common mode rejection ratio
over a wide frequency range. Also, the balance is maintained even if the source is floating. Some
designs of electronically balanced inputs cause the input lines to become unbalanced which can
cause an increase in crosstalk if the input cables are un-screened and run together over long
distances.
The input and output connectors are D50 multi-way types.
The signals are filtered to reduce out-of-band high frequency signals and re-balanced for internal use.
The use of balanced circuitry throughout is of immense value to the overall quality of performance. It
improves virtually every measured parameter by at least a factor of 2 compared to a similar
unbalanced design.
Matrix
The matrix uses 16x8 crosspoint chips. These exhibit excellent signal path performance together with
minimal crosstalk and switch click noise.
Outputs
The outputs are balanced. Normally the outputs are balanced about earth. This is the preferred
arrangement as it is offers lower common mode impedance to ground than a floating output and thus
is more immune to such interference. However sometimes a signal may need to be connected to an
unbalanced load. In this case one of the outputs of a driver will be connected to earth. As well as
losing half the signal there may be an increase in distortions etc. as the amplifier struggles to drive
into a short circuit!
There is only one adjustment in the audio path to allow the gain to be adjusted up slightly if the
outputs are terminated in 600
Ω
. As this is now an unusual practice, the insertion gain is factory set
for unity into a load of 10k
Ω
.
Soft Crossover
A soft crossover option is available if the router has been purchased as one of the following and is
being used in dual channel (stereo) mode:
Q16-AA-3208-M used as 16x4 stereo
Q16-AA-3216-M used as 16x8 stereo
Q16-AA-3232-M used as 16x16 stereo
This is achieved by using otherwise unused crosspoint circuitry that is built on to the module.
