Dod AC 260 User Manual

Introduction

Congratulations, and thank you for your purchase of
the DOD direct box. The AC 260,265,275, and 285 all

solve distortion problems normally associated with
using high impedance sources with low impedance
inputs. The product line begins with the AC 260 which
is a basic easy to use direct box and progresses into
the AC 285 with a cabinet emulator. The features,
operation, and specifications literature have been indi­vidualized for each box. Determine which box you
have and consult the following text until you reach the
section that is specific to your box.

AC 260 Direct Box
Features of the AC 260

• Allows a hi 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.

XLR

12

3

600Ω CT 50KΩ

1/4"

Hi Z

Block Diagram AC260

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- 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 imped-

ance.

• Ground lift switch to fix ground-loop hum problems.

• Allows a hi impedance unbalanced source to directly
feed a low impedance balanced input.

• Low distortion

• Low noise

• Adjustable attenuation pad, makes this different 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 with the least
amount of hum or noise.

47K

50K

4.7K

470Ω

WHT GRN

BLUORG

XLR

GND LIFT

YEL

Block Diagram AC265

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 -1/4 inch 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 hi 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

600Ω

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 pad switch to INSTRUMENT for line level input
sources or to SPEAKER for speaker level input
sources. Set power selector switch to ON for battery
power or to OFF for phantom power.

NOTE: To preserve battery life, set power selector switch
to OFF when AC275 is not in use.

Unbalanced

Hi-Z Input

-12dB (INST)

-40dB (SPKR)

PAD

Battery

Phantom Power

+

Unbalanced

Output

Left
Ground

Block Diagram AC275

Specifications of the AC 275

Balanced

+

-

Low-Z
Output

1

3

2

Frequency Response: 20Hz-20kHz, ±0.5dB

Gain:

Inst: -12dBu
Spkr: -40dBu

Input Impedance: Instrument 1.3MΩ

Output Impedance: 200Ω
Power Requirements: 9V battery or 15-48V phan-

Distortion(1kHz, Inst @-10dBV input): <0.02%
Signal-to-Noise Ratio (Inst @-10dBV input):

Maximum Input:

Instrument Position: +7dBu (9V battery)

Supply Current: 4mA (9V battery)

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

Speaker 10kΩ

tom power

Better than 86dB

+5dBu (15V phantom)
+20dBu (48V phantom)

4mA (15V phantom)
8mA (48V phantom)

AC 285

Features of the AC 285

• Allows a hi 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 pad switch to INSTRUMENT for line level input
sources or to SPEAKER for speaker level input
sources. Set power selector switch to ON for battery
power or to OFF for phantom power.

• Set speaker settings to FLAT if you want the direct­to-microphone sound. If you are seeking the guitar­to-board sound, the 4x12 or COMBO settings are
great.

Unbalanced

Hi-Z Input

Unbalanced

Output

Left
Ground

-12dB (INST)

-40dB (SPKR)

FLAT 4x12
COMBO

PAD

Phantom Power

Battery

+

Balanced

+

-

Low-Z
Output

123

Specifications of the AC 285

Block Diagram AC285

Frequency Response: 20-18 kHz ±1dB

10-30 kHz ±3dB

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)

DOD Electronics Corporation

8760 South Sandy Parkway

Sandy, Utah 84070

Telephone [phone]

FAX [phone]

International Distribution

3 Overland Drive, Unit 4

Amherst, New Hampshire 03031

U.S.A.

FAX [phone]

Copyright © 1994 DOD Electronics Corporation

Printed in U.S.A. 12/94

Manufactured in the U.S.A.

AC260,270,275,&285 18-0054-B

AC

260
265
275
285

Instruction Manual