I/O Connection Considerations - Aphex COMPELLOR 300 Operating Manual

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Fig. 3-2. COMPELLOR Model 300 back panel. Models 301 and 303 have
only one pair of XLR connectors.
3.5 I/O Connection Considerations
Prior to installing the COMPELLOR into your system, take note of the
following considerations for I/O impedance matching and system wiring.
3.5.1 Impedances
The COMPELLOR features a high input impedance (50 kû balanced, 25 ki
-
2
unbalanced), allowing it to be easily driven by any other piece of audio
equipment, including consumer gear. However, a piece of equipment
designed to work into a 600 SI load may show unusually low output meter
readings, even though the unit is driving the COMPELLOR properly. Or the
unit may considerably overdrive the COMPELLOR 's input while still
indicating 0 VU.
In either case, you will observe a large disparity between indicated drive
levels, with the COMPELLOR 's meter reading a much higher level than the
output meter of the driving unit. If this occurs, install a 60012 resistor across
pins 2 and 3 on each COMPELLOR input, to lower input impedance to 600 Û.
The output impedance of the COMPELLOR is very low (20 û balanced, 10 û
unbalanced), allowing it to easily drive almost any load. However, there are
some types of inputs, especially transformer types, that are designed to see a
600 i) source impedance. An indication of this mismatch would be a non-
linear frequency response, emphasizing the low frequencies.
In this case, install two 300 0, 1/4 watt, 1% resistors ( at each output) in a
series bridge with pins 2 and 3 to create a 600 i«
.
2 source impedance, as shown
Fig. 3-3.
Fig. 3-3. Circuit for creating COMPELLOR
a 600f2 source impedance OUTPUT
at a COMPELLOR's output XLR
(one channel shown).
I 303 OHM. 1%
3 sp
-
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-
1)
3
300 OHM. 1%
2 Q-We-<> 2
1
ONLY ONE CHANNEL SHOWN
SOURCE
INPUT
XLR
Installation 3-3