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 ....................
J-20 Jet All-Tube Guitar Amplifier with Tremolo Introduction Congratulations! You are now the proud owner of an Ampeg J-20 Jet all-tube guitar amplifier.
J-20 Jet All-Tube Guitar Amplifier with Tremolo The Front Panel 1 2 3 4 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.
J-20 Jet All-Tube Guitar Amplifier with Tremolo The Rear Panel 100-120VAC 220-240VAC 10 T 1A T .5A 11 10. AC LINE CORD: The grounded power cord should only be plugged into a grounded power outlet that meets all applicable electrical codes, and is compatible with the voltage, power, and frequency requirements stated on the J-20 Jet rear panel. Do not attempt to defeat the safety ground connection. 11. FUSE: This protects the unit from damage due to overload conditions or power line surges.
J-20 Jet All-Tube Guitar Amplifier with Tremolo Important Information about Tubes and Tube Products: A Brief History Of The Tube: In 1883, Edison discovered that electrons would flow from a suspended filament when enclosed in an evacuated lamp. Years later, in 1905, Fleming expanded on Edison’s discovery and created the “Fleming Valve.” Then, in 1907, Dr. Lee de Forest added a third component – the grid – to the “Fleming Valve” and the vacuum tube was a fact of life.
J-20 Jet All-Tube Guitar Amplifier with Tremolo Important Information About Tubes and Tube Products (continued): The power tubes are the largest tubes used in an amplifier. These tubes convert the low-level, conditioned signal from the preamplifier into a level that is sufficient to drive the speakers. There are several types of power tubes available, each of which offers a different performance/sound characteristic. For example, the EL34 power tube produces a great classic rock sound.
J-20 Jet All-Tube Guitar Amplifier with Tremolo Important Information About Tubes and Tube Products (continued): Whenever you replace the power tube(s): • Always have the amplifier’s bias voltage checked by a qualified service center. Improper bias voltage will cause degradation in performance and possibly damage the tubes and/or the amplifier. (See “The Importance of Proper Biasing”, below for more information). • We highly recommend that you replace the driver tube(s) as well.
J-20 Jet All-Tube Guitar Amplifier with Tremolo Important Information About Tubes and Tube Products (continued): Survival Tips For Tube Amplifiers: To prolong tube life, observe these tips and recommendations: • Match the impedance of your speaker cabinet(s) to your amplifier. Improper impedance matching will contribute to early tube degradation and may cause premature tube failure. • Make sure the speaker(s) are properly connected prior to turning on the amplifier.
J-20 Jet All-Tube Guitar Amplifier with Tremolo System Block Diagram NORMAL INPUT 12AX7A PHASE SPLITTER V3A 12AX7A V1A 6V6 V4 8 OHM INTERNAL SPEAKER 12AX7A V2A BRIGHT INPUT VOLUME TONE 12AX7A PHASE SPLITTER V3B 12AX7A V1B 12AX7A TREMOLO OSCILLATOR V2B 10 SPEED INTENSITY 6V6 V5 8 OHM EXTENSION SPEAKER
J-20 Jet All-Tube Guitar Amplifier with Tremolo Service Information If you are having a problem with your J-20 Jet, you can go to our website (www.ampeg.com) and click on Support for service information, or call 1-800-898-3211 during business hours (7 am to 5 pm PST, Monday-Friday). If you are outside of the U.S., contact your local distributor for technical support and service. Declaration Of Conformity Manufacturer: LOUD Technologies Inc. 16220 Wood-Red Rd.
J-20 Jet All-Tube Guitar Amplifier with Tremolo J-20 JET TECHNICAL SPECIFICATIONS Output Power Rating 20 W rms @ 5% THD, 8 ohm load, 120 VAC Noise < 60 mV (Volume and Tone @ 0) < 90 mV (Volume and Tone @ 10) Gain Bright1: Normal: 70 dB (±6 dB), all controls @ 10 64 dB (±6 dB), all controls @ 10 Maximum Input Signal 600 mV rms @ 1 kHz Tone ±30 dB @ 10 kHz Speaker Specs 12", 20 W, 8 ohm, 1.
