Overview; Pro48 Block Diagram - Radial Engineering Pro48 User Manual

CONGRATULATIONS on your purchase of the Radial Pro48 active direct
box. As with all Radial products the Pro48 is easy to use. This short manual
contains all the information you need to start using the Pro48 right away. For
more information on the Pro48 and other Radial products, visit our website at
www.radialeng.com.

OVERVIEW

The Pro48 is a great sounding active direct box. It has been optimized to
produce maximum headroom and dynamics while working within the limited
current available from 48V phantom power.
The Pro48 employs a unique switching power supply that steps up the current
from phantom power to produce higher internal rail voltage than typical
active DI's. This makes the Pro48 capable of peak input transients to 9 volts
without any noticeable distortion, making it perfect for both active and passive
instruments. The Pro48 is equipped with an input PAD to help prevent overload
from hot signals and a ground lift to reduce noise caused by ground loops. The
balanced XLR output can drive very long cables without appreciable signal
loss. The Pro48 is constructed for heavy use in the studio and on stage.

Pro48 BLOCK DIAGRAM

To fully understand the Pro48 follow the block diagram from the inputs on the
left to the outputs on the right.
After the paralleled input and thru jacks the signal passes through a switchable
15dB PAD which allows the Pro48 to handle virtually any audio device from
passive pickups to high output instruments without overloading.
Next comes the active drive circuit that converts the signal to balanced low
impedance mic-level for transmission over long cables without noise or signal
loss. The switching PSU steps up the current from phantom power and the
drive circuit uses the higher rail voltage to increase headroom and dynamic
range.
The switching PSU uses a transformer in the DC path to block noise caused
by ground loops. The ground LIFT switch interrupts the ground path around the
transformer to help suppress noise from bleeding through into the audio path.
Radial Engineering Ltd. Pro48 User Guide
™