Ampeg Bass heads enclosure V4BH User Manual

							Owner’s Guide
for the
V4BH
Bass Amplifier
Made in the U.S.A.by 
						

							V4BH Bass Amplifier
2
Table of Contents
Important Safeguards and Precautions  . . . . . . . . . . . . . .2
Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Features  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
System Block Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . .3
The Front Panel Controls and Their Use  . . . . . . . . . . . . .4
The Rear Panel  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Some Suggested Settings  . . . . . . . . . . . . . . . . . . . . . . . .6
Changing the Tubes  . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Troubleshooting  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Technical Specifications  . . . . . . . . . . . . . . . . . .back cove
r
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 prob-
lems. Abiding by the following rules can help prevent damage to your amplifier, yourself and others. 
•The amplifier is equipped with a three-prong AC power cord. To reduce the risk of electrical shock, NEVERremove or otherwise attempt to
defeat the ground pin of the power cord.
•Connect the amplifier ONLYto a properly grounded AC outlet of the proper voltage for your  amp. If no grounded outlet is available, use only
an approved method of adapting to a two-prong AC source.
•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.)
•NEVERset the amplifier on a support that might give out under its weight.
•Always keep the total impedance at or above the rated load.
•Unplug the amplifier before cleaning it. NEVER spray liquid cleaners onto the unit. Wipe the unit 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 is advised and ear protection recommended when playing at
extremely loud levels.
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.
SOUND LEVEL dBA DURATION PER DAY
SLOW RESPONSE IN HOURS
90 8
92 6
95 4
97 3
100 2SOUND LEVEL dBA DURATION PER DAY
SLOW RESPONSE IN HOURS
102 1-1/2
105 1
110 1/2
115 1/4 or less
IMPORTANT SAFETY INSTRUCTIONS•READ, FOLLOW, HEED, AND KEEP ALL INSTRUCTIONS AND WARNINGS.•DO NOT OPERATE NEAR ANY HEAT SOURCE AND DO NOT BLOCK ANY VENTILATION OPENINGS ON THIS APPARATUS. FOR PROPER OPERATION, THIS UNIT REQUIRES 3”
(75CM) OF WELL VENTILATED SPACE AROUND HEATSINKS AND OTHER AIR FLOW PROVISIONS IN THE CABINET.
•DO NOT USE THIS APPARATUS NEAR SPLASHING, FALLING, SPRAYING, OR STANDING LIQUIDS.•CLEAN ONLY WITH LINT-FREE DAMP CLOTH AND DO NOT USE CLEANING AGENTS.•ONLY CONNECT POWER CORD TO A POLARIZED, SAFETY GROUNDED OUTLET WIRED TO CURRENT ELECTRICAL CODES AND COMPATIBLE WITH VOLTAGE, POWER, AND
FREQUENCY REQUIREMENTS STATED ON THE REAR PANEL OF THE APPARATUS.
•PROTECT THE POWER CORD FROM DAMAGE DUE TO BEING WALKED ON, PINCHED, OR STRAINED.•UNPLUG THE APPARATUS DURING LIGHTNING STORMS OR WHEN UNUSED FOR LONG PERIODS OF TIME.•ONLY USE ATTACHMENTS, ACCESSORIES, STANDS, OR BRACKETS SPECIFIED BY THE MANUFACTURER FOR SAFE OPERATION AND TO AVOID INJURY.•WARNING: TO REDUCE THE RISK OF ELECTRIC SHOCK OR FIRE, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE.•SERVICE MUST BE PERFORMED BY QUALIFIED PERSONNEL.•OUR AMPLIFIERS ARE CAPABLE OF PRODUCING HIGH SOUND PRESSURE LEVELS. CONTINUED EXPOSURE TO HIGH SOUND PRESSURE LEVELS CAN CAUSE PERMA-
NENT HEARING IMPAIRMENT OR LOSS. USER CAUTION IS ADVISED AND EAR PROTECTION IS RECOMMENDED IF UNIT IS OPERATED AT HIGH VOLUME.
• WARNING: THIS UNIT REQUIRES A SAFETY GROUNDED OUTLET WIRED TO CURRENT ELECTRIC CODES HAVING THE LINE SUPPLY VOLTAGE, POWER, AND FREQUENCY
IDENTIFIED ON THE REAR OF THE UNIT. THE OUTLET MUST REMAIN ACCESSIBLE TO DISCONNECT THE UNIT IF A FAULT SHOULD ARISE WHILE IN USE. THIS UNIT SHOULD
BE UNPLUGGED WHEN NOT IN USE.
CAUTIONRISK OF ELECTRIC SHOCK
DO NOT OPEN
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE
THIS APPARATUS TO RAIN OR MOISTURE. TO REDUCE THE RISK OF ELECTRIC
SHOCK, DO NOT REMOVE COVER. NO USER-SERVICEABLE PARTS INSIDE. REFER
SERVICING TO QUALIFIED SERVICE PERSONNEL.
PRECAUCIONRIESGO DE CORRIENTAZO
NO ABRA
PRECAUCION: PARA REDUCIR EL RIESGO DE INCENDIOS O DESCARGAS ELECTRICAS, NO PER-
MITA QUE ESTE APARATO QUEDE EXPUESTO A LA LLUVIA O LA HUMEDAD. PARA DISMINUOIR EL
RIESGO DE CORRIENTAZO. NO ABRA LA CUBIERTA. NO HAY PIEZAS ADENTRO QUE EL USARIO
PUEDO REPARAR DEJE TODO MANTENIMIENTO A LOS TECHNICOS CALIFICADOS.
ATTENTIONRISQUE DELECTROCUTION
NE PAS OUVRIR
ATTENTION: PROTÉGEZ CET APPAREIL DE LA PLUIE ET DE LHUMIDITÉ AFIN DÉVITER TOUT
RISQUE DINCENDIE OU DÉLECTROCUTION. POUR REDUIRE DELECTROCUTION NE PAS ENLEVER
LE COUVERCLE. AUCUNE PIECE INTERNE NEST REPRABLE PAR LUTILISATEUR. POUR TOUTE
REPARATION, SADRESSER A UN TECHNICIEN QUALIFIE.
IT IS NECESSARY FOR THE USER TO REFER TO THE INSTRUCTION MANUAL
“ES NECESARIO QUE EL USUARIO SE REFIERA AL MANUAL DE INSTRUCCIONES.”
REFERREZ-VOUS AU MANUAL DUTILISATIONEXPLANATION OF GRAPHICAL SYMBOLS:
EXPLICACION DE SIMBOLOS GRAFICOS:
EXPLICATION DES SYMBÔLES GRAPHIQUES:DANGEROUS VOLTAGE
“VOLTAJE PELIGROSO”
DANGER HAUTE TENSION== 
						

							V4BH Bass Amplifier
3 An Introduction to your new Ampeg V4BH Bass Amplifier
The harmonically rich sound and legendary performance of the classic AMPEG SVT are redefined in the V4BH.
This dynamically powerful bass amp delivers a thunderous 100 watts of unsurpassed quality, reliability and tonal
flexibility. It also provides the classic vibrance of tubes as well as contemporary features. The features and controls
of your V4BH are covered in detail within the pages of this owner’s guide. We recommend going over them before
you use the amplifier.
Features
I
n true Ampeg tradition, your new V4BH offers you more power, performance and flexibility than any other bass ampli-
fier in its class. Below are some of the outstanding features of your new amplifier – features which set it apart from the
competition! Additional information on these features can be found on the pages indicated.
•-15dB INPUT:This feature is perfect for “active” basses (page 4)
•ULTRA LO AND ULTRA HI SWITCHES:These enable you to tailor your sound in many different ways at
the touch of a button (page 4)
•5-POSITION FREQUENCY SELECTOR:Take your pick from the five center frequency points to get just the
right midrange voice (page 4)
•SLAVE OUT:Use for powering another amp from the V4BH’s preamp (page 5)
System Block Diagram
0dB INPUT
GAIN
ULTRA
LO
MID
FREQUENCY
MASTERBUFFERPREAMP 
OUT PWR AMP
INPUTSLAVE
OUTBAL
OUT
SPEAKER
OUT
EXT.
SPEAKER
OUT
POWER
AMP
PWR/STDBY LED
ULTRA
HI
-15dB INPUTBASS TREBLE
4 OHMS 8 OHMS
IMPEDANCE
SPEAKON*
JACK1+
2+ 1- 2-
*Speakon is a registered trademark of Neutrik U.S.A. 
						

							4
The Front Panel Controls and Their Use
V4BH Bass Amplifier
Gain Bass Midrange Frequency Treble Master Standby Power
HiHi
LoLoUltra Hi / LoUltra Hi / Lo–15dB15dB0dB0dB
0105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 6
5 4 3
12
0105
4
3
2
1
98 7 6
12345678910121113
 Standby/ Standby/ Power Power
1. 0dB INPUT:The signal output from an
instrument (active or passive – typically
passive) or a line level signal may be con-
nected here by means of a shielded instru-
ment cable. The signal at this jack is sent
into the preamp at full strength.
2. -15dB INPUT:The signal output from
an instrument (active or passive – typically
active) or a line level signal may be con-
nected here by means of a shielded instru-
ment cable. The signal at this jack is
padded 15dB before it is sent into the pre-
amp.
3. GAIN:This control adjusts the basic
level of signal in the preamp.
4. ULTRA HI:This switch boosts high
frequencies.
5. ULTRA LO:This switch, when
depressed, provides emphasis to the
low frequencies by boosting the low
frequencies and selectively cutting the
mid frequencies.
6. BASS:This is the primary low fre-
quency control. It allows for 12dB of
cut or boost at 40Hz.7. MIDRANGE:This is the primary
midrange control. It allows for 20dB of
cut or 10dB of boost at the center fre-
quency selected by the Frequency
control (8).
8. FREQUENCY:Allows you to select
the center frequency for the Midrange
control (7), giving you a choice of five
“voices” for the Midrange. The numbers
correspond to the following center fre-
quencies as indicated: 1=220Hz,
2=450Hz, 3=800Hz, 4=1.6kHz, 5=3kHz.
9. TREBLE:This is the primary high
frequency control. It allows for 20dB of
cut or 15dB of boost at 4kHz.
10. MASTER:This controls the signal
level to the power amp and therefore the
overall listening level. It also controls the
level to the Preamp Out jack (20).
11. STANDBY/POWER LED:This is a
dual-function LED. In Standby Mode, it
glows red. In the On mode (when high
voltage is applied to the tubes) it glows
green. If it does not turn green in the
On mode, there is no high voltage
present and the unit needs servicing.12. STANDBY:The Standby mode
allows the tubes to warm up or remain
warm without high voltage being
applied to them. This extends tube life.
This switch should be OFF when first
turning the amplifier on. Allow the unit
to warm up for 20 seconds before
switching to the ON position. During
short periods of non-use, the amp
should be put into Standby mode.
13. POWER:This supplies AC power
to the unit. Turn this switch on before
turning on the Standby switch (12), as
explained above. 
						

							5
The Rear Panel
V4BH Bass Amplifier
1418171619202221 15
14. FUSE:This protects the unit from
damage due to overload conditions or
power line surges. If the fuse blows,
replace it only with the same size and
type.
15. AC LINE IN:Firmly insert the sup-
plied AC power cord into this socket
until it is fully seated. Plug the male
end of the cord into a grounded AC
outlet. DO NOT DEFEAT THE
GROUND PRONG OF THE AC
PLUG!
16. PREAMP OUT:This jack carries
the post-Master (10) signal. Using this
jack does not break the path to the
power amp. This signal can be used to
feed an external power amplifier, mix-
ing console or house PA system.
17. POWER AMP IN:This jack
accepts a signal to be sent to the
power amp and the Slave Out jack
(18). Using this jack breaks the path
from the signal that was present at the
Preamp Out jack (16). This can be
used as a post-Master (10) patch
point.18. SLAVE OUT:This jack receives
the same signal that is being sent to
the power amp. It is useful for power-
ing another amp (slave) from this unit’s
preamp. It can also be used as an
“unbalanced” version of the Balanced
Out (19) signal. 
19. BALANCED OUT:This XLR jack is
the preamp output. Thus, it will include
any processing done in the Preamp
Out/Power Amp loop (16,17). This sig-
nal can be used to feed an external
power amplifier, mixing console or
house PA system.
20. PRESENCE SWITCH: When this
switch is depressed a high fequency
boost is added to the output signal.
This helps compensate for a speaker
cabinet with no high frequency driver,
adding a glassy top end to the sound.
21. SPEAKER OUT:Two 1/4” phone
jacks are provided for connecting
speakers to the unit. These jacks are
wired in parallel. Use the jack on the
right (“Main”) first. The jack on the left
should only be used to connect a sec-
ond speaker cabinet.NOTE: In some areas 1/4” speaker jacks are
not acceptable for use on amplifiers with
high output power levels. For this reason the
1/4” jacks on your amplifier may be sealed. If
this is the case, use the Speakon
®jack to
connect the amplifier to your speaker cabi-
net. Use a heavy duty speaker cable termi-
nated with the proper connectors.
22. IMPEDANCE SELECTOR:Use
this switch to match the output imped-
ance of the amp to the speaker(s)
being used (4 or 8 ohms). For help in
deciding the total impedance of your
system, consult the chart below.
Cabinet Number of Total
ImpedanceCabinetsImpedance
4 ohms 1 4 ohms
8 ohms 1 8 ohms
8 ohms 2 4 ohms
16 ohms 2 8 ohms
16 ohms 4 4 ohms
Speakon®is a registered trademark of
Neutrik U.S.A. 
						

							V4BH Bass Amplifier
Gain Bass Midrange Frequency Treble Master
Hi
Lo
Ultra Hi / Lo
0105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 6
5 4 3
12
0105
4
3
2
1
98 7 6
Gain Bass Midrange Frequency Treble Master
Hi
Lo
Ultra Hi / Lo
0105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 6
5 4 3
12
0105
4
3
2
1
98 7 6
Gain Bass Midrange Frequency Treble Master
Hi
Lo
Ultra Hi / Lo
0105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 6
5 4 3
12
0105
4
3
2
1
98 7 6
Gain Bass Midrange Frequency Treble Master
Hi
Lo
Ultra Hi / Lo
0105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 60105
4
3
2
1
98 7 6
5 4 3
12
0105
4
3
2
1
98 7 6
IN
IN
IN
IN
6Some Suggested Settings
FUNK: JAZZ:
ROCK: 
COUNTRY:
The setting of the
Gain control
depends on your
particular instrument.
The Master should
be set to produce
the appropriate
output volume level.  
						

							V4BH Bass Amplifier
Changing the Tubes
The performance characteristics of tubes are degraded in direct proportion to how often and under what conditions
the amplifier is used. Power tubes should be checked at least once a year - more frequently if you use the amplifier
nearly every day. When power tubes wear out, the amplifier will begin to grow weak, lack punch, fade up and down,
or lose highs and lows. Power tubes work together in a push/pull configuration and should all be replaced at the same
time with matched or balanced tubes. Your dealer can recommend the best replacement tubes for your amplifier.
Preamp tubes typically last longer than power tubes. When a preamp tube wears out, the amplifier may squeal, get
noisy, lose gain and sensitivity, or just quit working. A service center can determine which tube(s) may need replacing.
To gain access to the power tubes in the V4BH, the rear panel must be removed. Tube replacement should only
be performed by a qualified service person.
•Turn the amp off, unplug it and let it cool for at least 5 minutes.
•Remove the screws which hold the panel to the rear of the cabinet.
•Set the panel aside.
•Gently pull the tube retainer away from the base of the tube.
•Grasp the tube at its top and gently work it out of its socket by rocking it slightly back and forth as you pull on it.
•When inserting new output tubes, align the tab in the tube’s plastic base with the slot in the socket and press
the tube gently but firmly into place by pushing down on its top. (Preamp tubes have a “missing pin” which cor-
respondes with the “missing hole” in the socket – line up the missing pin and hole before pressing the tube into
its socket.)
• Make sure that each tube retainer firmly grips the base ot the tube.  
•Replace the rear panel and tighten its screws.
•Power up the amplifier and let it sit for at least 20 minutes. Bias the amplifier per the schematic (qualified tech-
nicians only!).
7
In the event that your V4BH should stop working properly, or just stop working, take a few minutes to troubleshoot it
before you call for service. You can save yourself time and money doing it yourself, and often the problem is something
quite simple. Please refer to the Troubleshoointg Diagram below for guidelines. Symptoms of tube failure are defined
above.
If the problem isn’t covered above, or if the steps lead you here, then contact your Ampeg dealer for service information. Also, you
should refer your amp to an authorized service center for servicing if it gets dropped, has liquid spilled into it, or sustains damage to
its power cord.
Troubleshooting
NO SOUND
LEDs LIGHT
POOR SOUND
Check bass, cables
Check speaker(s)
Replace speaker(s)
POOR SOUND
LEDs DONT LIGHT
Check AC outlet
NO SOUND
NO HUMHUM
Listen for hum
NO CHANGE
SOUND OK
SOUND OK
POOR SOUNDSOUND OK
SOUND OK
Check amp controls, check
for signal from bass
Check power cord,
fuse, power switchCheck house fusebox
or circuit breakerSPEAKER(S) OK,
POOR SOUNDSPEAKER(S)
DEFECTIVE
Check speaker Unplug bass,
touch tip of cable
Speaker OK
Replace cable
NO CHANGE
SEE BELOWSEE BELOW
NO POWEROUTLET OK
OK
Troubleshooting Diagram: 
						

							Ampeg reserves the right to change specifications without notice.
Ampeg is proudly Made in America. ©1999 SLM Electronics, 1400 Ferguson Avenue, St. Louis, MO 63133 U.S.A.
P/N 47-509-42 • 092805
V4BH Bass Amplifier
www.ampeg.com
Technical Specifications
OUTPUT POWER RATING100 watts RMS minimum continuous @