Radial Engineering ProD8 Owner's Manual - page 3
Radial Engineering Ltd.
ProD8 Owner’s Manual
True to the Music
1
OVERVIEW
The Radial ProD8 is an 8 channel passive direct box
and does not require any powering whatsoever to make
it work. The high performance Radial transformers are
extremely efficient and will both balance the signal and
convert the high source impedance of your keyboards to
a balanced, mic level low impedance output.
All channels are identical and completely isolated. Each
channel features two inputs that are merged to mono
using a resistive mixer. This means you can use either
input for a mono source. If you have a stereo source
such as a synthesizer or digital piano, connecting the
instrument to the two inputs will yield a mono mix at the
XLR output. Should you wish to connect a high output
device like a CD player to the ProD8, a -15dB PAD will
reduce the input level going to the transformer to avoid
saturation. The ¼” THRU is a direct feed that would be
used for your personal monitoring system.
To further advantage the user, an effects-loop has been provided that allows the two inputs on each chan-
nel to share the same effects processor. Each channel features an internal switch that lets you assign the
THRU output either pre or post the effects-loop depending on how you intend to use the system.
IN-A
IN-B
EFFECT
LOOP
-15dB
PAD
THRU
PRE/POST
EFX LOOP
THRU
OUT
POLARITY
REVERSE
GROUND
LIFT
CHASSIS
GROUND
LIFT
XLR
OUT
PASSIVE
SUMMING
SECTION
*One of eight channels.
BLOCK DIAGRAM
As previously mentioned, the ‘engine’ inside the ProD8 is the Radial transformer. This ‘hi-Z to lo-Z’ device
is designed to convert the impedance and balance the signal so that it matches the level of a typical micro-
phone. This way, the keyboards connected to the ProD8 can be ‘managed’ just like microphones and used
with mic splitters as well as the mic inputs on the mixing console. A polarity reverse switch toggles pins 2
and 3 to allow older pre-AES standard gear to be connected in phase.
Transformers are particularly advantageous with keyboards and other devices that are electrically powered
through the common AC electrical system as they isolate the input from the output to help eliminate hum
and buzz caused by ground loops. A ground-lift switch further helps reduce noise by disconnecting pin-1 on
the XLR thus allowing the system tech to derive the channel ground from either the input or the output.