Ampeg Bass heads enclosure SVTCL User Manual

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

							SVT CLASSIC
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 Controls and Their Use  . . . . . . . . . . . . .5
Some Suggested Settings  . . . . . . . . . . . . . . . . . . . . . . . .6
Changing the Tubes  . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Troubleshooting  . . . . . . . . . . . . . . . . . . . . . . . .back cover
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
CAUTIONRISK 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.
ATTENTIONRISQUE DELECTROCUTION
NE PAS OUVRIR
ATTENTION: POUR REDUIRE DELECTROCUTION NE PAS
ENLEVER LE COUVERCLE. AUCUNE PIECE INTERNE NEST REPRABLE
PAR LUTILISATEUR. POUR TOUTE REPARATION, SADRESSER A UN
TECHNICIEN QUALIFIE.
VORSICHTELEKTRISCHE 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 ACCIDENTAL DAMAGES OR INJURY, PLEASE FOLLOW THESE PRECAUTIONARY GUIDELINES:
CAUTION:TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT OPEN CHASSIS; DO NOT DEFEAT OR REMOVE THE GROUND PIN OF THE
POWER CORD; CONNECT ONLY TO A PROPERLY GROUNDED AC POWER OUTLET.
WARNING: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 REC-
OMMENDED IF UNIT IS OPERATED AT HIGH VOLUME.
IT IS NECESSARY FOR THE USER TO REFER TO THE INSTRUCTION MANUAL
REFERREZ-VOUS AU  MANUAL DUTILISATION
UNBEDINGT IN DER BEDIENUNGSANLEITUNG NACHSCHLAGEN EXPLANATION OF
GRAPHICAL SYMBOLS:DANGEROUS VOLTAGE
DANGER HAUTE TENSION
GEFAHLICHE SPANNUNG=
= 
						

							SVT CLASSIC
3 An Introduction to your new Ampeg SVT CLASSIC Bass Amplifier
The harmonically rich sound and legendary performance of the classic AMPEG SVT are redefined in the SVT
CLASSIC. This dynamically powerful bass amp delivers a thunderous 300 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 SVT CLASSIC 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 the world of high performance bass amps, SVT amplifiers stand alone. In true Ampeg tradition, the SVT CLASSIC
offers you more power, performance and flexibility than any other amplifier in its class. Listed below are some of the
outstanding features of your new amp: 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)
•BIAS ADJUSTMENT CONTROLS:These controls allow you to adjust the tube bias for proper operation
(pages 5 & 7)
•SLAVE OUT:Use for powering another amp from the SVT CLASSIC’s preamp (page 5)
System Block Diagram
BIAS
ADJUST
SPEAKER
OUTS
0dB INPUT
GAIN
ULTRA
LO
MID
FREQUENCY
MASTERBUFFERPREAMP 
OUT PWR AMP
INPUTSLAVE
OUTBAL
OUT
1/4 JACK
1/4 JACK
POWER
AMP
STANDBY/ 
POWER/
FAULTBIAS
INDICATORS
ULTRA
HI
-15dB INPUTBASS TREBLE
4 OHMS
2 OHMS IMPEDANCE
POWER AMP 
PROTECTION
SPEAKON ®JACK
1+
2+ 1- 2- 
						

							4
The Front Panel Controls and Their Use
SVT CLASSIC
Gain Bass Midrange Frequency Treble Master Standby Power
Hi Hi
Lo Lo
Ultra Hi / Lo Ultra Hi / Lo
–15dB
15dB 0dB
0dB Standby/
 Standby/ Power/
 Power/Fault
Fault0105
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
CLASSIC0105
4
3
2
1
98 7 6
12345678910121113
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/FAULT INDI-
CATOR LED:This is a multi-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. If the ampdetects a fault in the power tube circuit,
the high voltage is turned off and the
LED flashes between red and green.
This usually indicates a bad power
tube. The amp will remain in this con-
dition until the unit is turned off.
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. This switch must be
turned off to reset the amp after a Fault
condition. 
						

							5
The Rear Panel
SVT CLASSIC
1423171819212220 15 16
14. 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!
15. 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.
16. POLARITY:Place this switch in
the position that provides the least
electrical buzz from the unit.
17. BIAS SECTION:These two con-
trols and sets of LEDs allow the user to
properly bias the power amp. See
“Setting Tube Bias” on page 7 for a
complete description of how to use this
section.  
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. 19. BALANCED OUT:This XLR jack is
the preamp output. Thus, it will include
any processing done in the Preamp
Out/Power Amp loop (20, 21). This sig-
nal can be used to feed an external
power amplifier, mixing console or
house PA system.
20. 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.
21. 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 (20). This can be
used as a post-Master (10) patch
point. 22. IMPEDANCE SELECTOR:Use
this switch to match the output imped-
ance of the amp to the speaker(s)
being used (2 or 4 ohms). For help in
deciding the total impedance of your
system, consult the chart below.
23. SPEAKER OUT:Two 1/4” phone
jacks and one Speakon
®jack are pro-
vided for connecting speakers to the
unit. These jacks are wired in parallel.
When operating at or near full power,
the  Speakon
®jack is recommended
for use over the 1/4” jacks due to its
higher current handling capability.
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 not be accessable – use the
Speakon
®jack.
Cabinet Number of Total
ImpedanceCabinetsImpedance
2 ohms 1 2 ohms
4 ohms 1 4 ohms
4 ohms 2 2 ohms
8 ohms 2 4 ohms
8 ohms 4 2 ohms 
						

							SVT CLASSIC
Gain Bass Midrange Frequency Treble Master
Hi Hi
Lo Lo
Ultra 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 Hi
Lo Lo
Ultra 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 Hi
Lo Lo
Ultra 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 Hi
Lo Lo
Ultra 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.  
						

							SVT CLASSIC
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 SVT CLASSIC, the rear screen must be removed and the tube retainer(s)
must be moved out of the way. 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 perforated metal screen to the rear of the cabinet.
•Set the perforated metal screen aside.
•Remove the tube retainer(s) by lifting them off the tube(s) and moving them to one side.
•Grasp the tube at its top and gently work it out of its socket by rocking it slightly back and forth as you lift up 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.
•Replace the tube retainers.  
•Replace the perforated metal screen and tighten its screws.
•Power up the amplifier and let it sit for at least 20 minutes. Bias the amplifier as directed in the section below.
Setting Tube Bias
Allow the unit to warm up at the proper AC line voltage for at least 20 minutes. With no input signal present, adjust
each control so that only the associated green LED is illuminated. The controls may be slightly interactive. If neither
LED is illuminated, the amp is over biased.This will result in some distortion in the power amp and a generally thin
sound. If the green and red LED are illuminated, the amp is under biased and too much current is flowing to the power
tubes. This will give a big, full sound but will also reduce the life of the power tubes. Once set, the controls should not
have to be changed except as needed for tube replacement, or to compensate for tube aging. Note that the AC line
voltage may vary from place to place causing the LEDs to react slightly different. There is no need to readjust the bias
as these slightly different conditions occur. Note that it is normal for the red LEDs to illuminate when there is a signal
present. Bias 1 Control adjusts the three left (as seen from the rear) power tubes. Bias 2 Control adjusts the three right
power tubes. By observing the LEDs as the Bias Controls are slowly rotated clockwise, a number of tube problems can
be diagnosed by the user:
ConditionProblemSolution
Green illuminates, then red No problem The longer the green LED is illuminated before the
red LED illuminates – the better matched the
tubes are.
Red illuminates, then green Tubes not properly matched Set to just before the green LED is illuminated. 
Obtain matched tubes whenever possible.
Red illuminates, no green One or more tubes are non-functioning Check to make sure tubes are all seated
properly. If so, find and replace the bad tube(s).
None illuminated Possibly no high voltage or badHave unit checked by a qualified service technician.
Bias Control or bad tube(s)
Both illuminated all the time Possible bad Bias Control or bad tubesHave unit checked by a qualified service technician.
If tube wear is bad enough to cause damage to the unit, the Fault Indicator (#11, Front Panel) will flash between red
and green and the unit will shut down.
7 
						

							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 47-509-23 • 06/99
SVT CLASSIC
www.ampeg.com
Technical Specifications
OUTPUT POWER RATING300 watts RMS minimum continuous @