Ampeg Bass Combo B4R User Manual

Owner’s Guide
for the
B4R
Bass Amplifier
Made in the U.S.A.by 

2
Important Safeguards and Precautions:
All Ampeg products are designed for continuous safe operation, as long as common sense is used and steps are taken to
help avoid certain problems. Abiding by the following rules can help prevent damage to your amplifier, yourself and others.
•The amplifier is equipped with a three-pronged AC power cord. To reduce the risk of electrical shock, NEVER
remove or otherwise attempt to defeat the ground pin of the power cord.
•Connect the amplifier ONLYto a properly...

3
An Introduction to your new Ampeg B4R Bass Amplifier
Thank you for making one of the best choices you will ever make for your musical career – choosing one
of the finest bass amps available, the Ampeg B4R. This versatile and powerful bass amplifier delivers up
to 1350 watts of unsurpassed musical power, and offers several outstanding features.
All of the features and controls of your B4R are covered in detail within the pages of this owner’s guide.
We recommend going over them before you use the...

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The Front Panel Controls and Their Use
-15dB 0dB
GAIN INPUTBASSSTYLEULTRA MID
TEXTURE MUTEPEAK
33Hz 80Hz 150Hz 300Hz 600Hz 900Hz
0 +12dB
-12dB
126758934
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1. 0dB INPUT:The signal output from an instrument (active
or passive – typically passive) or a line level signal may be
connected here by means of a shielded instrument cable. The
signal at this jack is sent into the preamp at full amplitude.
2. -15dB INPUT: The signal output from an instrument
(active or passive – typically active) or a line level...

5
The Front Panel Controls and Their Use – Con’t.
12. GRAPHIC EQ:This switch activates the graphic equaliz-
er. When a footswitch is used, this switch is disabled.
13. LIMIT DEFEAT: The B4R employs internal limiter circuits
to help keep the power amplifier’s output clean at extreme
volume levels. (All amplifiers may begin to clip their output
signals as they approach maximum output levels, resulting in
potentially speaker-damaging distortion.) These circuits may
be disabled by depressing this switch....

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The Rear Panel
BI-AMP
SPEAKER
OUTPUTS
HIGH
OUTPUTLOW
OUTPUT
CHANNEL
BCHANNEL
A CHANNEL
BCHANNEL
A
350 WATTS/CH. @ 4 OHMS, STEREO
500 WATTS/CH. @ 2 OHMS, STEREO
2 OHM MINIMUM LOAD
1000 WATTS @ 4 OHMS, MONO BRIDGE
4 OHM MINIMUM LOAD
MONO
BRIDGE+ –*MONO BRIDGE: 1+ HOT, 2+ RETURN
BIAMP: 1+ LOW HOT, 1– LOW RETURN
2+ HIGH HOT, 2– HIGH RETURN
232425
33
23. CIRCUIT BREAKER:The B4R employs an AC line circuit
breaker to help protect against damage due to excessive cur-
rent demands. If the amplifier stops...

7
The Rear Panel – Con’t.
32. FOOTSWITCH: Connect a two button footswitch to this
jack for remote Mute and EQ On/Off control. On the stereo
1/4” plug, the tip controls Mute and the ring controls EQ
On/Off. When a footswitch is connected, the Mute switch
(#3) can still be used; however, the EQ switch (#12) is dis-
abled.
33. BIAMP HIGH/LOW OUTPUTS: When using the amplifi-
er in the biamp mode, the Biamp High Out jack carries the
high frequency signal and the Biamp Low Out jack carries
the low frequency...

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Connections:
In the example shown below, the B4R’s two internal power amplifiers are bridged together to produce maximum output power. 
Set the Stereo/Mono Bridge switch to the IN (Mono Bridged) position and connect the system as follows:
1: Connect a heavy duty speaker cable terminated with a Speakon
®connector or dual banana plugs from the B4R’s Mono Bridge / Biamp Output jack
to the input jack of a speaker cabinet capable of handling the extremely high output power. (Speakon®: pin 1 +, 2 +; Banana:...

In the example shown below, the B4R’s two internal power amplifiers will power both a high frequency cabinet and a low frequency cabinet. The crossover
point is determined by the Frequency control (#16). 
Set the Stereo/Mono Bridge switch to the OUT (Stereo) position and connect the system as follows:
1: Set the Full Range/Biamp switch to the IN (Biamp) position.
2: Connect a speaker cable from the B4R’s Power Amp A Speaker Output jack to the input jack of the low frequency cabinet(s).  
3: Connect a...

GAINBASSSTYLEULTRA MID
TEXTURE MUTE
TREBLE
PEAK
GAINBASSSTYLEULTRA MID
TEXTURE MUTE
TREBLE
PEAK
GAINBASSSTYLEULTRA MID
TEXTURE MUTE
TREBLE
PEAK
GAINBASSSTYLEULTRA MID
TEXTURE MUTE
TREBLE
PEAK
IN
GAINBASSSTYLEULTRA MID
TEXTURE MUTE
TREBLE
PEAK
OUT
IN
IN
IN
OUT
OUT
OUT
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Some Suggested Settings
ROCK:
JAZZ:
COUNTRY:
BRIGHT:
FUNK “POPPING:”
Since so many variables
affect the actual sound of any
system, the following settings are
offered as starting points to help
you find the exact sounds your
playing...