Introduction
Congratulations on your purchase of a DOD direct box. The AC 260, 265, 275, and 285 models are designed to solve distortion problems commonly associated with connecting high impedance sources to low impedance inputs. The product line starts with the AC 260, a basic and easy-to-use direct box, and progresses to the AC 285, which includes a cabinet emulator. The features, operation, and specifications are individualized for each box. Please identify your specific model and consult the relevant section below.
AC 260 Direct Box
Features of the AC 260
- Allows a high impedance unbalanced source to directly feed a low impedance balanced input.
- Low distortion
- Low noise
- Rugged metal chassis
Operation of the AC 260
- Connect the output of the high impedance source to the input of the AC260.
- Connect the low impedance output of the AC260 to a mixing console or other low impedance input.
- Connect the unbalanced 1/4" tip-sleeve output to a high impedance input.
Block Diagram Description (AC260)
The AC260 features an XLR connector for its balanced 600-ohm low impedance input/output and two 1/4" mono phone jacks for its unbalanced 50K-ohm high impedance input/output. The diagram illustrates a transformer and a ground lift switch.
Specifications of the AC 260
- Low Impedance In/Output: 600 ohms center tapped (balanced)
- Low Impedance Connector: XLR type jack
- High Impedance In/Outputs: 50KΩ
- High Impedance Connectors: 2 x 1/4" mono phone jacks
AC 265 Direct Box
Features of the AC 265
- Connects high impedance (50K ohms) to low impedance (600 ohms), or low impedance to high impedance.
- Ground lift switch to fix ground-loop hum problems.
- Allows a high impedance unbalanced source to directly feed a low impedance balanced input.
- Low distortion
- Low noise
- Adjustable attenuation pad, differentiating it from the AC 260.
Operation of the AC 265
- Connect the output of the high impedance source to the input of the AC 265.
- Connect the low impedance output of the AC 265 to a mixing console or other low impedance input.
- Connect the unbalanced 1/4" tip-sleeve output to a high impedance input (if desired).
- Set the ground lift switch to the position that yields the least amount of hum or noise.
Block Diagram Description (AC265)
The AC265 block diagram shows an XLR connector for balanced 600-ohm low impedance and two 1/4" mono phone jacks for unbalanced 50K-ohm high impedance. It includes a transformer, a ground lift switch, and an adjustable attenuation pad switch with settings for 0, 12, and 40 dB.
Specifications of the AC 265
- Low Impedance In/Output: 600 ohms center tapped (balanced)
- Low Impedance Connector: XLR type jack
- High Impedance In/Outputs: 50K ohms (unbalanced)
- High Impedance Connectors: 2 x 1/4" mono phone jacks
- Attenuation Range Switch: 0, 12, 40 dB attenuation
- Frequency Response: 60 to 15 kHz, ±3 dB
AC 275 Active Direct Box
Features of the AC 275
- Allows a high impedance unbalanced source to directly feed a low impedance balanced input.
- Connects guitar pickups, microphones, or electric instruments to a recording or P.A. console without audio quality loss.
- Input signal isolation using FET input operational amplifiers that reduce loading effects normally found on passive direct boxes.
- Flat frequency response.
- Operates with battery or phantom power.
- Ground isolation switch.
- Internal pad for speaker level input.
Operation of the AC 275
- Connect the output of the high impedance source to the input of the AC275.
- Connect the low impedance output of the AC275 to a mixing console or other low impedance input.
- Connect the unbalanced 1/4" tip-sleeve output to a high impedance input (if desired). This output is hard-wired to the input.
- Set the ground lift switch to the position with the least amount of hum or noise.
- Set the pad switch to INSTRUMENT for line level input sources or to SPEAKER for speaker level input sources.
- Set the power selector switch to ON for battery power or to OFF for phantom power.
NOTE: To preserve battery life, set the power selector switch to OFF when the AC275 is not in use.
Block Diagram Description (AC275)
The AC275 block diagram shows a 1/4" Hi-Z Input, a PAD switch with INSTRUMENT (-12dB) and SPEAKER (-40dB) settings, a Ground Lift switch, a Power selector for Battery (+) or Phantom Power, a 1/4" Unbalanced Output, and an XLR Balanced Low-Z Output (Pin 1: Ground, Pin 2: Left/Hot, Pin 3: Right/Cold). It indicates the use of FET operational amplifiers.
Specifications of the AC 275
- Frequency Response: 20Hz-20kHz, ±0.5dB
- Gain: Inst: -12dBu, Spkr: -40dBu
- Input Impedance: Instrument: 1.3MΩ, Speaker: 10KΩ
- Output Impedance: 200Ω
- Power Requirements: 9V battery or 15-48V phantom power
- Distortion (1kHz, Inst @ -10dBV input): <0.02%
- Signal-to-Noise Ratio (Inst @ -10dBV input): Better than 86dB
- Maximum Input (Instrument Position): +7dBu (9V battery), +5dBu (15V phantom), +20dBu (48V phantom)
- Supply Current: 4mA (9V battery), 4mA (15V phantom), 8mA (48V phantom)
- Input Connector: 1/4" tip-sleeve
- Output Connector: XLR, 1/4" tip-sleeve
- Dimensions: 2.5"x4.5"x1.5"
- Weight: 15oz (422g)
- Note: 0dBV=1.0 Vrms; 0dBu=0.775 Vrms
AC 285 Direct Box
Features of the AC 285
- Allows a high impedance unbalanced source to directly feed a low impedance balanced input.
- Connects guitar pickups, microphones, or electric instruments to a recording or P.A. console without audio quality loss.
- Input signal isolation using FET input operational amplifiers that reduce loading effects.
- Flat frequency response.
- Operates with battery or phantom power.
- Ground isolation switch.
- Internal pad for speaker level input.
- 4x12 emulator cabinet that gives a more enhanced low end.
- Twin open-back combo that provides a brighter sound with less low end.
Operation of the AC 285
- Connect the output of the high impedance source to the input of the AC 285.
- Connect the low impedance output of the AC 285 to a mixing console or other low impedance input.
- Connect the unbalanced 1/4" tip-sleeve output to a high impedance input (if desired).
- Set the ground lift switch to the position with the least amount of hum or noise.
- Set the pad switch to INSTRUMENT for line level input sources or to SPEAKER for speaker level input sources.
- Set the power selector switch to ON for battery power or to OFF for phantom power.
- Set speaker settings to FLAT if you want the direct-to-microphone sound. For a guitar-to-board sound, the 4x12 or COMBO settings are recommended.
Block Diagram Description (AC285)
The AC285 block diagram shows a 1/4" Hi-Z Input, a PAD switch (INST/SPKR), Speaker Emulation settings (FLAT, 4x12, COMBO), a Ground Lift switch, a Power selector for Battery or Phantom Power, a 1/4" Unbalanced Output, and an XLR Balanced Low-Z Output. It also indicates the input impedance settings for Instrument (>1 megΩ) and Speaker (>200 kΩ).
Specifications of the AC 285
- Frequency Response: 20-18 kHz ±1dB (Balanced), 10-30 kHz ±3dB (Unbalanced)
- Gain: Instr: -12dB, Spkr: -40dB
- Input Impedance: Inst: > 1 megΩ, Spkr: >200 kΩ
- Output Impedance: 200Ω
- Power Requirements: 9V Battery, 15-48V Phantom, 9V AC Adapter (DOD PS3)
- THD (1kHz, Inst @ 0dBu, 9V batt): <0.08%
- Signal to Noise Ratio (Inst @ -10dBu, 9V): Flat: >86dB, Spkr Emulation: >80dB
- Maximum Input Level (Inst): 7dBu (9V battery or adapter), 5dBu (15V Phantom), 20dBu (48V Phantom)
- Supply Current: 8 mA (9V battery), 16 mA (48V Phantom)
Manufacturer Information
DOD Electronics Corporation
8760 South Sandy Parkway
Sandy, Utah 84070
Telephone: (801) 566-8800
FAX: (801) 566-7005
International Distribution
3 Overland Drive, Unit 4
Amherst, New Hampshire 03031
U.S.A.
FAX: (603) 672-4246
Copyright © 1994 DOD Electronics Corporation
Printed in U.S.A. 12/94
Manufactured in the U.S.A.
Model Numbers: AC260, AC265, AC275, AC285
Document Number: 18-0054-B
