FRONT OF HOUSE
[ UNDERSTANDING DIRECT BOXES | Kent Morris ]
After microphones, direct boxes are the most 3. GOOD DIRECT BOXES ARE WORTH THEIR COST. available. High end passive DIs can run
common audio input devices on stage. Though While a $25 DI will function, it will not transfer hundreds of dollars and often boast Jensen
seemingly simple, direct boxes are vital to the the true character of a $4000 guitar. Think of brand transformers. Active DIs start around
clean transfer of audio from source to system. a direct box like a tire on a car. A Ferrari 488 $100 for decent units and go up from there.
Originally termed DI (Direct Injection), direct will simply not perform as designed on $59 Some high-end versions include pass filters
boxes usually accept an unbalanced hi-Z signal and tonal compensation. Finally, tube-based
from a bass guitar, acoustic pick-up, keyboard, DIs, such as the REDDI, are popular in studios
or laptop and convert it to a low impedance
balanced signal suitable for a console or stage
box. Understanding how they work and when
to use each type is a handy skill to possess, so
and have some application in live environments,
Audio from
if given proper care.
laptops and other
here are some steps toward that goal: media players
1. DIs ARE TYPICALLY USED TO INTERFACE STAGE is notoriously
INSTRUMENTS WITH THE SOUND SYSTEM.
A standard unbalanced ¼” TS (Tip Sleeve)
instrument output will not transmit more than
about fifteen feet without succumbing to noise
and interference, making the DI a perfect
solution since it converts the output into a
balanced mic signal able to travel 100’ or more
to the console without interference, thanks to
unstable. The tiny
with that of the instrument. While passive DIs
worked with most instruments, the sound of
Rhodes electric pianos and single coil basses
were altered, leading to the introduction of
active DIs with additional circuitry. As its name
implies, an active direct box contains electronics
to gain and shape the signal, and those circuits
and makes it possible to send short-range
signals (HDMI, guitar) over distance without
on stage while the amp is in the back room.
behind it always the stage volume of a cranked tube amp to
hum as part of
matching the impedance the mixer requires
cable. A balun is a balanced/unbalanced device
cheap sound card 2. INITIALLY DIRECT BOXES WERE PASSIVE,
A transformer inside the DI is responsible for
to create what is essentially a really long guitar
issue. The SGI uses a transmit (TX) and receive
have noise and
OPERATE.
The Radial SGI (Studio Guitar Interface) is used
3.5mm jack and common mode rejection.
MEANING THEY REQUIRE NO EXTERNAL POWER TO
4. CONSIDER REMOTE AND RE-AMPING SITUATIONS.
their output. A
solid DI designed
for stereo line
level signals will
(RX) module to allow the remote use of a guitar
The primary worship application is to remove
an unpopulated area. Re-amping is running a
signal through an alternative signal chain and
can be helpful when trying to recreate Gateway,
Bethel, and Hillsong tonality with limited gear.
5. USE A STEREO DIRECT BOX TO FIX MEDIA
AUDIO PROBLEMS.
Audio from laptops and other media players
is notoriously unstable. The tiny 3.5mm jack
and cheap sound card behind it always have
noise and hum as part of their output. A solid
eliminate almost DI designed for stereo line level signals will
every issue. to have one on the stage plus one in the tech
eliminate almost every issue. It is a good idea
booth.
need power to operate. While battery power
Direct boxes can transfer clean audio from
was an option, most current active DIs use 48V
phantom power coming down the XLR cable Pep Boys tires. For passive direct boxes, the stage to console and do so with little cost
from the console to provide the energy needed. low-cost standard is the Whirlwind IMP2. It has relative to the system. Keep several on hand
A general rule of thumb is to use passive DIs a decent transformer to prevent saturation on and remember to use active DIs on passive
on active instruments such as keyboards and most instruments and is built tough enough signals and passive DIs on active signals.
active DIs on passive instruments such as to survive years on the road. The Radial PRO a P-Bass. series is the most common step-up model
with both mono (D1) and stereo (D2) versions
28
March 2018
Kent Morris
35 year veteran of the worship technology arena
with a passion for excellence balanced by the
knowledge digital is a temporary state.
WorshipMusician.com