AMPEG J-20 Owner's Manual
J-20 JET
All-Tube Guitar Amplifier
with Tremolo Effect
Owner’s Manual
J-20 Jet All-Tube Guitar Amplifier with Tremolo
TABLE OF CONTENTS
Introduction ..........................................................................3
The Front Panel ....................................................................4
The Rear Panel .....................................................................5
Important Information About Tubes and Tube Products ............6
A Brief History of Tubes ..................................................6
Tube Types and Usage ....................................................6
The Nature of Tubes: Why (and When) to Replace Them ....7
The Importance of Proper Biasing ....................................8
Survival Tips for Tube Amplifiers ......................................9
System Block Diagram ........................................................10
Service Information .............................................................11
Technical Specifications .......................................................12
CAUTION
RISK OF ELECTRIC SHOCK
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.
DO NOT OPEN
PRECAUCION: PARA REDUCIR EL RIESGO DE INCENDIOS O DESCARGAS
ELECTRICAS, NO PERMITA 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.
PRECAUCION
RIESGO DE CORRIENTAZO
NO ABRA
ATTENTION
RISQUE D'ELECTROCUTION
NE PAS OUVRIR
ATTENTION: PROTÉGEZ CET APPAREIL DE LA PLUIE ET DE L'HUMIDITÉ
AFIN D'ÉVITER TOUT RISQUE D'INCENDIE OU D'ÉLECTROCUTION. 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.
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” (75mm) 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 PERMANENT 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.
EXPLANATION OF GRAPHICAL SYMBOLS:
EXPLICACION DE SIMBOLOS GRAFICOS:
EXPLICATION DES SYMBÔLES GRAPHIQUES:
"DANGEROUS VOLTAGE"
=
“VOLTAJE PELIGROSO”
"DANGER HAUTE TENSION"
"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 D'UTILISATION"
2
Introduction
J-20 Jet All-Tube Guitar Amplifier with Tremolo
Congratulations!
This no-compromise combo amplifier packs 20 watts of vintage tube sound with a classic
tremolo effect into its retro-style cabinet, providing you with an amp that is portable and easy
to operate, yet still produces incredible sounds!
Part of the Diamond Blue Lead Series, the J-20’s preamp section boasts not one, but three
12AX7 tubes that drive a pair of 6V6 power tubes into a 12-inch alnico speaker, with point-topoint wiring throughout to insure solid and reliable connections.
The J-20 Jet features a Volume and Tone control, a Speed and Intensity control for the tremolo
section, and a footswitch for turning the tremolo on and off.
Like all Ampeg products, your J-20 Jet amplifier is designed by musicians and built using only
the best components. Each amplifier is tested to confirm that it meets our specifications, and
we believe that this amplifier is the absolute best that it can be.
In order to get the most out of your new amplifier, please read this manual before you begin
playing.
Here are some of the features packed into your new J-20 Jet Combo Amplifier:
• Two 6V6 power vacuum tubes for smooth overdrive sound
You are now the proud owner of an Ampeg J-20 Jet all-tube guitar amplifier.
And thank you for choosing Ampeg.
• 20 watts rms power output
• 1 x 12" alnico speaker
• Extension speaker output for adding additional speakers (8 ohm minimum)
• Two inputs, Bright and Normal
• Volume control
• Tone control
• Tremolo Speed and Intensity controls
• Footswitch option for turning tremolo effect on and off
3
The Front Panel
1 2 3 4 5 6 7 8 9
J-20 Jet All-Tube Guitar Amplifier with Tremolo
1. NORMAL: Use this jack to connect
your guitar to the amplifier using a
shielded instrument cable.
2. BRIGHT: Using this jack to connect
your guitar provides a high-frequency
boost compared to the Normal input,
for a brighter, punchier sound.
3. VOLUME: Use this to adjust the output
level of the amplifier.
4. TONE: This adjusts the overall tone of
the sound. Turning the control clockwise
(toward the “T”) increases the higher
frequencies for a brighter, crisper
sound. Turning the control counterclockwise (toward the “B”) reduces the higher
frequencies for a darker sound.
5. LAMP: This illuminates when the amplifier is turned on.
6. SPEED: Use this to adjust the rate at
which the tremolo effect “vibrates.”
Turn the control counterclockwise to
slow down the tremolo effect, and turn
it clockwise to speed up the tremolo
effect.
Note: The Tremolo Intensity control (7)
must be turned up partway to hear the
effect of the Speed control.
7. INTENSITY: This controls the depth of
the tremolo effect. Turn the control counterclockwise to lessen the intensity, and
turn it clockwise to increase the intensity
For a slow, smooth tremolo effect try
setting the Intensity control at about 6
and the Speed control at 1. For a really
wild tremolo, crank the Intensity up to 8
and increase the Speed control to 6 or 7
(or more).
8. ON/STANDBY Switch: Use this switch
to activate the amplifier after the On/Off
switch (9) is turned on.
Always turn this switch OFF first, and
ON last! Turn the On/Off switch (9) on at
least 30 seconds before turning on the
standby switch.
During short breaks, you should turn
this switch off, and leave the On/Off
switch on. This will help prolong the life
of the amplifier tubes.
9. ON/OFF SWITCH: Use this switch to
turn the amplifier on and off.
Always turn this switch ON first and OFF
last! Turn the Standby switch (8) on at
least 30 seconds after turning on the
On/Off switch.
.
4
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