Ampeg 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 ONLY to a properly grounded AC outlet of the proper voltage for your amp.
• Avoid sudden temperature extremes, rain and moisture. Also, avoid sudden and intense impact. (If the unit
has been subjected to any of the preceding abuses, have it looked at by an authorized service center.)
• NEVER set the amplifier on a support that might give out under its weight.
• Whenever using tall or stacked speaker cabinets, use them ONLY on a level surface. NEVER set tall or stacked
cabinets on a surface with more than a five degree incline since tipping or falling could occur, possibly causing serious injuries.
• Always keep the total speaker impedance at or above the rated load.
• Unplug the amplifier before cleaning it. NEVER spray liquid cleaners onto the amplifier. Wipe it with a slightly
dampened, lint-free cloth to remove dirt and film.
• Don’t use the amplifier if it has sustained damage to the chassis, controls, or power cord. Refer the unit to an
authorized service center for inspection.
• Amplifiers capable of producing high volume levels are also capable of inflicting permanent hearing loss or
damage, if the exposure to such levels is prolonged. Such damage is progressive and irreversible!
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,
DO NOT REMOVE COVER.
NO USER-SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
ATTENTION
RISQUE D'ELECTROCUTION
NE PAS OUVRIR
ATTENTION: POUR REDUIRE D'ELECTROCUTION NE PAS
ENLEVER LE COUVERCLE. AUCUNE PIECE INTERNE N'EST REPRABLE
PAR L'UTILISATEUR. POUR TOUTE REPARATION, S'ADRESSER A UN
TECHNICIEN QUALIFIE.
VORSICHT
ELEKTRISCHE SCHLAGGEFAHR
NICHT OFFENEN
VORSICHT: ZUR MINIMIERUNG ELEKTRISCHER SCHLAGGEFAHR NICHT
DEN DECKEL ABENHMEN. INTERNE TEILE KONNEN NICHT VOM
BENUTZER GEWARTET WERDEN. DIE WARTUNG IS QUALIFIZIERTEM
WARTUNGSPERSONAL ZU UBERLASSEN.
THIS EQUIPMENT HAS BEEN DESIGNED AND ENGINEERED TO PROVIDE SAFE AND RELIABLE OPERATION. IN ORDER TO PROLONG THE LIFE OF THE UNIT AND PREVENT ACCIDENTALDAMAGES OR INJURY, PLEASE FOLLOW THESE PRECAUTIONARYGUIDELINES:
WARNING: TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOTOPEN CHASSIS; DO NOTDEFEAT OR REMOVE THE GROUND PIN OF THE POWER CORD; CONNECT ONLYTO APROPERLY GROUNDED AC POWER OUTLET.
CAUTION: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.
CAUTION: NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
CAUTION: OUR AMPLIFIERS ARE CAPABLE OF PRODUCING HIGH SOUND PRESSURE LEVELS. CONTINUED EXPOSURE TO HIGH SOUND PRESSURE LEVELS CAN CAUSE PERMANENT
HEARING IMPAIRMENT OR LOSS. USER CAUTION IS ADVISED AND EAR PROTECTION IS RECOMMENDED IF UNIT IS OPERATED ATHIGH VOLUME. The chart below shows the U.S.
Government Occupational Safety and Health Administration (OSHA) regulations which were in effect at the time of this publication for permissible noise exposure, per 29CRF1910, Table G-16.
According to OSHA, any exposure in excess of those listed above could result in some hearing loss.
"IT IS NECESSARY FOR THE USER TO REFER TO THE INSTRUCTION MANUAL"
"REFERREZ-VOUS AU MANUAL D'UTILISATION"
"UNBEDINGT IN DER BEDIENUNGSANLEITUNG NACHSCHLAGEN"
EXPLANATION OF
GRAPHICAL SYMBOLS:
"DANGEROUS VOLTAGE"
"DANGER HAUTE TENSION"
"GEFAHLICHE SPANNUNG"
=
=
SOUND LEVEL dBA DURATION PER DAY
SLOW RESPONSE IN HOURS
90 8
92 6
95 4
97 3
100 2
SOUND LEVEL dBA DURATION PER DAY
SLOW RESPONSE IN HOURS
102 1-1/2
105 1
110 1/2
115 1/4 or less
TABLE OF CONTENTS
Important Safeguards and Precautions . . . . . . . . . . . . . . .2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
The Front Panel Controls and Their Use . . . . . . . . . . . . .4,5
The Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6,7
Connections: Mono Bridged . . . . . . . . . . . . . . . . . . . . . .8
Dual Mono . . . . . . . . . . . . . . . . . . . . . . . . .8
Biamp, Full Range and Lows . . . . . . . . . . .8
Biamp, Highs and Lows . . . . . . . . . . . . . . .9
Biamp With Second Amplifier . . . . . . . . . . .9
Some Suggested Settings . . . . . . . . . . . . . . . . . . . . . . . .10
Rack Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . .11
Technical Specifications . . . . . . . . . . . . . . . . . . .back cover
B4R Bass Amplifier
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 amplifier.
Features
In the world of high performance bass amps, Ampeg amplifiers stand alone. In true Ampeg tradition, the
B4R offers you more power, performance and flexibility than any other bass amplifier in its class. The outstanding features of your new amplifier, features which set it apart from the competition, are listed below.
• DUAL SEPARATE POWER AMPLIFIERS: Operate in true stereo or mono bridged
mode for even greater output power (page 6,8,9).
• BIAMP CAPABLE: Adjustable crossover frequency control. Low-to-high frequency
balance control (page 5,8,9).
• 5-POSITION STYLE CONTROL: Take your pick from five different tone variations to
best suit your playing style (page 4).
• TEXTURE CONTROL: Changes your tone for a more aggressive sound (page 4).
• 9-BAND GRAPHIC EQ: Switchable at front panel or with a footswitch, you can use
this as a “second channel” for bass solos, or to shape your sound to your own exacting standards. An independent level control lets you adjust the Graphic EQ volume.
(page 5).
• EFFECTS MIX: Varies the amount of external effects mixed into the signal (page 4,5).
• TUNER OUT JACK: Allows connection to an electronic tuner and provides an “always
live” monitor feed even when the output is muted (page 7).
• HEAVY-DUTY SPEAKER JACKS: For more reliable connections at higher outputs
and for mono bridged connections: dual binding posts (domestic units) or Speakon
®
jacks (export units) (page 6,7).
• BALANCED AND UNBALANCED LINE OUTPUTS: Independent level control.
Balanced XLR and unbalanced 1/4” output jacks. Switchable pre or post EQ (page 7).
• EFFECTS LOOP: Connect your effects here for increased intensity and quieter oper-
ation (page 7).
• POWER AMP IN/PREAMP OUT : Two separate loops, one for each channel: a sepa-
rate preamp may be connected to the Power Amp In jack, and the Preamp Out jack
may be connected to a slave amp (page 6,7).
• FOOTSWITCH CONTROL: Use a footswitch to activate the Graphic EQ and the Mute
feature (page 6,7).
• CIRCUIT BREAKER PROTECTION: A heavy duty resettable circuit breaker provides
protection against fault conditions (page 6).
Speakon®is a registered trademark of Neutrik AG.
B4R Bass Amplifier
4
The Front Panel Controls and Their Use
-15dB0dB
GAIN
INPUT
BASS
STYLE
ULTRA MID
TEXTURE
MUTE
PEAK
33Hz 80Hz 150Hz 300Hz 600Hz 900Hz
0
+12dB
-12dB
1 2 6 75 8 93 4
18
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 signal may
be connected here by means of a shielded instrument cable.
The signal at this jack is padded 15dB before it is sent into
the preamp.
3. MUTE: This switch, when depressed, mutes all outputs
except the Tuner Out (#41). A footswitch can also control
muting if the Mute switch on the front panel is left in the “out”
position. (The front panel switch is still active with a
footswitch connected.) This is excellent for tuning your bass
with an electronic tuner without having to adjust any levels or
turn down your house volume.
4. TEXTURE: This switch adds a “tube emulation” stage
which changes the tone for a more aggressive sound. Using
the Texture switch, you can overdrive the amplifier without
typical (and harsh-sounding) solid state clipping.
5. GAIN: This control sets the level of the signal entering the
preamp stage. Adjust this control until the Peak LED (#6)
flashes on strong signal peaks (but is not illuminated constantly while playing). To obtain the best signal to noise ratio,
set the Gain control as described above and adjust the
Master (#14) to obtain the desired volume level.
6. PEAK LED: This LED will illuminate when the signal
entering the preamp stage is near the clipping level. Adjust
the Gain control (#5) until a strong signal from your instrument causes this LED to flicker.
7. STYLE: This five-position switch allows you to vary the
tone of the amplifier. The following table lists each of the different settings – experiment with the Style and other EQ controls (#8,9,10,18,19) for the results which suit you best.
POSITION 1: Fully “scooped” mids (mid cut)
POSITION 2: Traditional passive tone setting
POSITION 3: Basically flat
POSITION 4: Boosted high end
POSITION 5: Basically flat with low end roll off – for
loud playing without “muddiness”
8. BASS: This is the primary low frequency control which
allows 12dB of cut or boost at 50Hz. The low frequency output is flat at the center position.
9. ULTRA MID: This is the primary midrange control which
allows 7dB of cut at 400Hz or boost at 800Hz. The midrange
output is flat at the center position.
10. TREBLE: This is the primary high frequency control
which allows 18dB of cut or boost at 5kHz. The high frequency output is flat at the center position.
11. EFFECTS MIX: This control varies the mix between the
direct (dry) signal and the effects (wet) when the effects loop
(#39,40) is used. Full counterclockwise results in all direct
signal (no effect) and full clockwise gives all effect and no
direct signal. The clockwise position is equivalent to a series
effects loop and should be used with such devices as limiters
and equalizers.
B4R Bass Amplifier
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