BSS Audio AR-133 User manual

Active Direct Box
AR-133
Why do I need
a DI Box?
Signals from electronic instru-
ments such as guitars, keyboards
and similar sound sources gener-
ally have a low level, high im-
pedance output, which will not
interface with the low impedance
balanced input found on
professional sound mixing con-
soles. Furthermore these signals
cannot be driven up long cable
lengths without serious loss of
level and degradation.
The DI box converts this signal to
a more suitable form without
interfering with or modifying the
signal at the instrument source,
and should provide freedom from
ground and power line related
problems.
Passive DI boxes have limited
applications as they will inevita-
bly affect the signal source for
guitar type applications, and can
also have an insertion loss of
around 20dB.
The only safe and predictable
way to provide direct feeds from
instruments or other sources is by
using an Active DI box utilising
an input amplifier driving an
output transformer.
The AR-133 fulfills all the
requirements of an active DI and
more.
• Switchable input
attenuation
0dB for guitar-type
pickups
-20dB for line level
signals
-40dB for speaker
feeds
• Matches the level and imped-
ance with unity gain without
loading the source
• Can drive signals up long cable
lengths
• Powered from console
phantom power or internal
battery
• Automatic switchover to bat-
tery if phantom power fails
• Parallel Link Jack output to feed
amplifiers directly
• Parallel XLR input for
converting unbalanced out-
puts to balanced lines
The audio signal path of the
AR-133 is an enhanced design
based upon the long established
BSS AR-116, now regarded by
many as a reference unit.
The sound quality, particularly
on acoustic guitar and bass
guitar pick-ups, is recognised as
outstanding.
The uses, however, are not
limited to guitars or keyboards.
The AR-133 is suitable for use
whenever it is critical to match
levels and impedances, sources
need isolation or long cables are
used.

BSS Audio,A Division of Harman International Industries Ltd,
Cranborne House, Cranborne Road, Potters Bar,
Herts EN6 3JN, England
Tel [phone] Fax [phone]
email: [email protected], online http://www.bss.co.uk
BSS Audio USA
1449 Donelson Pike, Nashville TN 37217
Tel [phone] Fax [phone]
email: [email protected]
The provision of both jack and
XLR connectors on the input
further extends the use of the
AR-133 with a multitude of
source devices.
Powered from the console or
battery
The AR-133 takes its power
either from the standard micro-
phone phantom powering
available from the desk, or from
an internal 9V battery. When
phantom is used, the power led
on the AR-133 is lit continu-
ously. If the phantom fails, the
battery immediately takes over,
with a flashing led showing
battery use.
Earth lift for solving grounding
problems
The earth lift switch enables the
input signal’s earth to be sepa-
rated from the output ground, a
quick and easy way to prevent
ground-loop problems.
Typical Applications
Guitar pick-up feed
Suggested Attenuation Setting 0dB
The low level, high
impedance signal from the guitar
pick-up is translated by the AR-
133 into the high-level, low
impedance balanced signal
required by the front-of-house
console.
Keyboards - line level feed
Suggested Attenuation Setting -
20dB (line level) or -40dB (amp
level)
The line level output of the
keyboard is balanced and
matched by the AR-133.
In multiple keyboard setups
where a mixer-amp is used for
monitors, the AR-133 can be
used to save on DI boxes by
taking the output of the amplifier
as the interface to the console,
rather than using separate DI’s for
each keyboard. In this case,
either a line output or the speaker
output can be used, depending
on the mixer/amp.
Speaker feed
Suggested Attenuation Setting -40dB
Taking a feed from the amplifier
output allows the post-amplifier,
post EQ/effects signal to be fed to
the console, meaning that a
particular effect/amp sound can
be sent to the mix.
Input Section
Input 1M Ohm (pad at 0dB)
Impedance 47k Ohm (pad at -20dB)
47k Ohm (pad at -40dB)
Max Input +9dBu (pad at 0dB)
Level +29dBu (pad at -20dB)
+49dBu (pad at -40dB)
Connectors Two Parallel 1/4" jack
connectors and a parallel
XLR connector (unbalanced)
Jack: Tip Hot (+ve)
Sleeve Ground
XLR: Pin 2 Hot (+ve)
Pin1 & 3 Ground
Output Section
Output Transformer Balanced
Max. Output +8dBu into 600 Ohms or
Level greater
Connector XLR3-32 or equivalent
System Performance
Distortion (THD) < 0.005% at 1kHz, 0dBu
output
Noise <-105dBunweighted,
22Hz-22kHz, rms*
Frequency 30Hz to 20kHz, +0dB/-1dB
Response
General
Main/Standby 9 volt PP3 type, battery
preferably alkaline.
Current drain :on phantom, less than 7.5mA
:on battery, less than 2mA.
Phantom +20 volts DC to +48 volts DC
Power
Weight 650 gms, excluding batteries.
Overall 59 mm x 124 mm x 143 mm
Dimensions (2.3“ x 4.9“ x 5.6“)
* Noise measured relative to maximum output.
In keeping with our policy of continued improvement, BSS
Audio,reserves the right to alter specifications without further
notice.This product was designed developed and
produced by BSS Audio, Hertfordshire, England.
AR-133 Active DI Box