BACK OF UNIT FRONT OF UNIT
DB1
DIRECT BOX
FEATURES:
» Floating Transformer-Balanced XLR Output for
Maximum Isolation
» SPKR Mode Handles Ampliers Up to 600W RMS*
» HI CUT Filter Reduces High Frequency Hiss
» GND/LIFT Switch Eliminates Hum and Buzz
» Rugged “Uni-box™” Construction for Superior
Protection and Shielding
» Flush-mounted Switches and Connectors Resist
Damage
» Passive Design Requires No Batteries or Phantom
Power.
DESCRIPTION:
The Pro Co Model DB1 is a simple passive direct box that
oers clean, reliable performance. It can be used for
nearly any instrument or signal source, from electric bass,
keyboards and drum machines to sub-mixers and external
speaker outputs*.
The DB1 preserves the “punch” and clarity of the sound
that is often lost when mic’ ing a speaker, while eliminating
the leakage, distortion and coloration. The signal delivered
to the P.A. or studio mixer is crisp and clean - a vital
element in retaining the full depth and brilliant sound of
digital instruments such as synthesizers and digital drum
machines.
The DB1 may be inserted into the signal path at virtually
any stage required. For instance, a bass guitar signal can be
“taken direct” from the instrument for a clean, natural tone,
from a preamp or line output for a punchier or “equalized”
sound, or from the speaker output of the amp if a dirtier
“edge” is desired. For stereo or multi-channel applications
such as Keyboards or digital drums we recomend the DB2 or
DB4A. The four-channel, rack-mountable DB4A Quad Direct
Box is highly recommended for multi-channel applications.
Built for the road, but equally at home in the recording
studio, the DB1’s rugged 16-gauge steel and aluminum “Unibox” enclosure is nished in a durable black texture powder
coat nish with black anodized aluminum side channels.
The uniquely slotted side channels allow for stacking on top
or strapping side-to-side of virtually any number of Pro Co
TradeTools devices using the Uni-box construction. Easy to
read control graphics are incorporated into the Lexan® top
panel overlay.
*properly loaded speaker output
Pro Co Sound
225 Parsons Street | Kalamazoo, MI 49007
800-253-7360
» www.procosound.com
ENGINEERING SPECIFICATIONS:
The signal splitting/impedance matching unit shall be suitable for interfacing one (1) unbalanced
high- or low-impedance source to one (1) balanced or oating low-impedance (1.0 kohm nominal)
microphone preamplier input. There shall be two (2) 1/4” (6.3mm) 2-conductor phone jacks wired
in parallel to provide input and loop-through output for the source. There shall be a switchable 20
dB attenuator to accommodate line- or speaker-level sources*, with a switchable lter to further
attenuate high frequencies by 6 dB per octave above 4.0 kHz. There shall be a transformer-isolated
low-impedance output from a 3-pin male XLR-type connector. The transformer shall be a Pro Co DBT-1
Direct Box Transformer. The primary electrostatic shield shall be connected to the source input ground
and the enclosure. There shall be a ground-lift switch to allow the shields to be connected together or
isolated as required. The XLR output connector shall be wired with pin 2 “hot” or “in phase” and pin 3
“cold” or anti-phase” with respect to the input.
The enclosure shall be constructed in the Pro Co “Uni-box” design with 16-gauge steel black zinc nish
top and bottom plates, 16-gauge black texture powder coated steel end plates and black anodized
aluminum side channels. Control functions shall be identied by a printed Lexan® top panel overlay.
Switches shall be of the miniature “rocker” type and shall be ush-mounted. The enclosure shall be
TYPICAL PERFORMANCE:
NOTES: All measurements made with a 20 kohm source feeding IN/OUT and 1.0 kohm load on LO-Z
OUTPUT to simulate typical “real world”instrument puck-up and mic preamp. 0 dBv ref. = .775 volt.
FREQUENCY RESPONSE: 20 Hz-20 kHz, +/- .5 dB @ -15 dBv output.
-3 dB @ approximately 85 kHz.
FILTER mode introduces 6 dB/octave attenuation above 4.0 kHz.
TOTAL HARMONIC DISTORTION: < .03% 20 Hz-20 kHz @ -30 dBv output.
< .1% 30 Hz-20 kHz @ -15 dBv output.
< .25% 20 Hz-20 kHz @ -15 dBv output.
PHASE RESPONSE: < -18 degrees @ 20 kHz (ref. 1.0 kHz).
RISE TIME: < 4.5 microseconds (2.0 kHz square wave, 10%-90%).
VOLTAGE STEPDOWN: < 22 dB @ 1.0 kHz (INST mode).
SPKR mode attenuate signal by 20 dB.
provided with two (2) miniature handles at each end (front and back) and four (4) non-conductive
feet. The dimensions of the unit shall be 4.875” D x 4.375” W x 1.75” H (123.8mm D x 111.1mm W x
44.4mm H).
The signal splitting/impedance matching unit shall be a Pro Co TradeTools DB1 Direct Box.
The DBT-1 is a carefully designed, custom-built impedance-matching transformer whose characteristics
are optimized for use with high-impedance sources such as electric bass guitars and other unbalanced
sources such as keyboard instruments. Special winding techniques and a high-permeability (80%
nickel) core lamination preserve full frequency response while minimizing signal losses and other
“loading” eects. Mu metal can and separate electrostatic shields for primary (input) and secondary
(output) windings reduce capacitive coupling of ground-borne electrical noise between stage amps
and PA or recording mixers, eliminating EM/RF and ground noise. The source impedance of the DBT-1
is very similar to that of a low-impedance microphone to ensure proper matching to the input circuitry
of the mixer. The result is clean transient response (minimal overshoot or ringing) and low distortion
even at low frequencies and high input levels.
INPUT IMPEDANCE: > 130 kohm @ 1.0 kHz (INST mode).
> 105 kohm @ 10 kHz (INST mode).
Nominal source impedance is 20 kohm.
Approximately 8.2 kohm (SPKR mode).
Nominal source impedance is 0 ohm.
OUTPUT IMPEDANCE: < 200 ohm @ 1.0 kHz.
< 215 ohm @ 10 kHz.
Nominal load impedance is 1.0 kohm.
MAXIMUM INPUT LEVEL @ 50 HZ FOR 1% THD:
+16 dBv (INST mode), +34 dBv (SPKR mode ) @ 20 Hz.
+21 dBv (INST mode), +41 dBv (SPKR mode ) @ 30 Hz.
+26 dBv (INST mode), +46 dBv (SPKR mode ) @ 50 Hz.
CONTROLS:
INPUT: 1/4” (6.3mm) phone jack accepts signals from instrument or other
source. Input impedance-greater than 100 kohm; SPKR-approx.
8 kohm. Handles signals of up to 69V RMS (approx. 600 watts across
an 8 ohm load).
OUTPUT: 1/4” (6.3mm) phone jack provides “loop-through” parallel
connection from input jack. Used when inserting DB1 between
instrument and amplier.
HI CUT/FLAT: Switch is only functional when SPKR/ INST switch is set to SPKR. HI
CUT position inserts a low-pass lter (-3 dB @ 4 kHz, 6 dB. Octave) to
simulate frequency response of a typical loudspeaker. Used when
source is guitar or bass amplier speaker output. FLAT position
bypasses lter. (HI CUT aects LO-Z OUTPUT response only>.)
PRO CO MODEL: DB1 DIMENSIONS ........4.88” D x 4.38” W x 1.75” H
......... 123.8mm D x 111.1mm W x 44.4mm H
WEIGHT.................................... 1.00 lb/0.46 kg
SHIPPING WEIGHT .................. 2.00 lb/0.92 kg
DBT-1 TRANSFORMER
YEL
ORN
BLK
WHT
(CAN)
INPUT
OUTPUT
SPKR
T
T
7.5k
INST
SPKR
INST
HI CUT
FLAT
0.047uf
100v
1.0k
20k
LO-Z OUTPUT: Male 3-pin XLR-type connector provides balanced oating low-
impedance output (pin 2 hot). Connect to mixing board microphone
channel input. Recommended load impedance: >1.0 kohm.
SPKR/INST: SPKR position inserts 20 dB pad between INPUT and DBT-1
transformer for increased level handling capability (used for speaker or line-level sources). INST position bypasses pad. (SPKR/INST switch
aects LO-Z OUTPUT level only.)
GND/LIFT: GND position connects INPUT and LO-Z OUTPUT grounds together.
LIFT position “oats” LO-Z OUTPUT. Used to reduce hum and buzz by
eliminating ground loops and providing proper grounding for
various conditions.
LO-Z OUTPUT
GRY
RED
BRN
LIFT
GROUND
S (PIN 1)
H+ (PIN 2)
C- (PIN 3)
TOP VIEW
SIDE VIEW
FRONT VIEW
Pro Co Sound
225 Parsons Street | Kalamazoo, MI 49007
800-253-7360
» www.procosound.com
DB1-01 Rev. 10/10
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