User manual

5.2. Analog Outputs
5.3. RCA – Single-ended outputs
The RCA outputs are designed to drive a preamp, amplifier or high-impedance
headphones. These are AC-coupled, so there is a delay in the power output from them
on power-on in order that the DC voltage settle-out. The line output level from these is
2.3VRMS in high-gain mode and 1.0VRMS in low-gain mode. The volume control
reduces this. On power-down, the outputs disconnect from the output drivers and short
to ground. When there is no valid signal, the outputs are disconnected from the output
drivers and shorted to ground. When active, the outputs can withstand short to ground
without damage to the Overdrive.
5.3.1. Headphone adapter
A headphone adapter is provided. The red plug on the adapter goes into the left
channel RCA output. Never use standard Headphones and the balanced
outputs to speaker system at the same time without selecting the RCA out
Buffer - this may cause system or speaker damage. Also avoid high static
charge on the headphone cable when plugging it in. Ground yourself and
the cable contacts first.
5.4. XLR – Balanced outputs
The balanced outputs are designed to drive a preamp, amplifier or high-impedance
balanced headphones. These are AC-coupled, so there is a delay in the power output
from them on power-on in order that the DC voltage settle-out. The line output level
from these is 4.6VRMS in high-gain mode and 2.0VRMS in low-gain mode. The volume
control reduces this. On power-down, the outputs disconnect from the output drivers and
short to ground. When there is no valid signal, the outputs are disconnected from the
output drivers and shorted to ground. When active, the outputs can withstand short to
ground without damage to the Overdrive.
5.5. Using both RCA and XLR outputs simultaneously
For best performance, this is best avoided, however this is sometimes necessary in
order to drive a subwoofer or other ancillary electronics. Each of the 4 output drivers is
shared between the balanced XLR and single-ended RCA outputs. However, there is
some isolation with small resistance between the XLR and RCA outputs. If one uses all
outputs simultaneously to a system, it is recommended that either the XLR cables or the
RCA cables be short and low-capacitance and drive a high impedance buffer or preamp.
If this is not possible, then switch the recessed “Normal/Bypass” switch to the Bypass
position. This causes the RCA outs to be driven from a separate Op-amp, isolating them
from the XLR outputs.
5.6. DC Power Connector
The DC power connector is a professional 5-pin high-current locking connector. The power
inputs are:
•
+12VDC Digital Power
•
Digital Ground/Return
•
-18VDC Analog Power
•
Analog Ground/Return
•
+18VDC Analog Power