Ampeg BT-15 Solid State 50 Watts Portaflex Amplifier Instruction Manual

Ampeg BT-15 Solid State 50 Watts Portaflex Amplifier

Take a few minutes to read the following instructions and fully acquaint yourself with our recommended procedures. You will be rewarded with many years of trouble-free performance.

HOW TO USE

1. Release the cabinet clamps and withdraw the shock-mounted amplifier. Invert and reclamp the lid. The control panel may face in either direction.
2. Connect the speaker cable to the receptacle on the side of the cabinet, making certain pins line up properly. Do not force this connection, let the keyway be your guide.
3. With all amplifier controls at zero, and the power switch off, plug the line cord into any 105-125 volt, 50-60 cycle AC power source.
   • IMPORTANT: Any other line voltage will severely damage the amplifier.
4. INPUTS: Plug the instrument cable into the appropriate input on the panel.
   • NOTE: Your solid-state PORTAFLEX Bassamp is a two-channel amplifier. Each channel has its own volume and tone controls. Two instruments can be played on each channel, or a total of four on both channels. Let us consider here its use with a single instrument.
   • Although the BT-15 is designed primarily for bass, other instruments requiring greater depth of sound also use this model with exceptional results.
   • Accordionists, for example, enjoy its strong bass response, especially on the left hay, where a mellow, a note sound is desis cute is also appreciated (See #10)
5. To turn on the amplifier, flip the toggle switch marked “Power” upward. The pilot bulb will light and the luminescent control panel will glow.
6. The polarity switch will eliminate the 60-cycle hum that is present in all AC power lines. Simply plug your cable into any input on either channel (do not connect the instrument). Slowly turn up the volume for that channel when a hum is audible, and flip the polarity switch to the position of least hum.
   • IMPORTANT: Reduce the volume setting to zero before plugging the free end of the cable into your musical instrument.
7. Turn the volume and tone controls of your musical instrument up. Always keep them at, or very near maximum while making preliminary adjustments.
8. Control Adjustments: Separate bass and treble controls enable you to obtain the most critical balance of tone. The Treble Control, when turned to the extreme right, provides full “normal” treble. The Bass Control, when turned to the extreme right, provides the ultimate bass response. When playing the AMPEG Fretted Bass, or AMPEG upright bass, we recommend that you turn the bass control to near maximum, the treble control may remain at a minimum.
9. Ultra-High Switches: For guitarists desiring a strong treble, the BT-15 also has an “ultra-high” switch built into the treble control on both channels. Simply move the control to “full-on,” then pull outward on the control knob. However, the ultra-high switch may be pulled at any degree of the treble setting. thus providing unlimited combinations of tone color.
10. Volume Controls: For the bass, raise the volume control of the amplifier. while at the same time testing on the lowest string (the open E). Pick the open E-string, using your strongest plectrum attack, (for the accordion, depress the lowest bass note while using your strongest bellows attack), and gradually bring the volume to its ultimate level just before distortion occurs. Always keep your controls below this overload point. If you hear a slapping sound, you are inviting a blown speaker! TURN DOWN THE VOLUME IMMEDIATELY! Once these settings have been determined, turn down the controls of the instrument itself to achieve your normal working level. Should it be desirable to raise your volume for solo performance, you will still be operating in a safe range. The importance of this procedure cannot be overemphasized, it will prevent you from inadvertently raising your instrument controls beyond the overload point of the speaker.
    • Bear in mind that an increase in treble or bass settings will also increase your volume! Thus, if you are operating at full output (before distortion), a higher setting of any controls (at the amplifier) may carry you beyond the overload point. lower the volume control (at the amplifier)
    • If you feel you need more treble or bass, lower the volume control (at the amplifier) correspondingly, thus keeping volume and tone controls in balance.
11. Voice Microphone: It is advisable to use your voice microphone on one channel, (preferably on the bass input) and your musical instrument on the other. If you are using only one channel, leave the controls of the unused channel on zero.
12. Recording: Another outstanding feature of your BT-15 is its advantage in recording. The “ext. amp” jack has an output impedance of 500/600 ohms which is standard in most professional recording studios. The engineer can feed your pure signal directly into his console, eliminating balance problems common when a microphone is set up in front of the speaker enclosure. Just tell the engineer that the output voltage from your “ext. amp” jack is 1-volt R.M.S. at 500/600 ohms.
13. Extension Speaker Information: To double your power output, you may obtain an extension speaker with matched impedance for your BT-15. The Ampeg extension speaker (BT-15X) is specifically designed to convert your BT-15 to 100 watts of R.M.S. power. The right-hand input on the rear side of the chassis (when viewed from behind) is for the extension speaker.
14. Extension Amplifier Operation: Another method of increasing power and sound distribution is to plug one end of an extra cable into the rear jack marked “ext. amp,” then plug the other end into the input (on the front panel) of any auxiliary amplifier. Before playing, adjust the volume on the auxiliary amplifier to zero, then adjust the volume on your BI-15 to an approximate level, then adjust the controls on the auxiliary to the desired level.
    • If you have two Ampeg BT-15s, you may connect the extension amplifier inputs (with a standard cable), this will enable you to double your power and give you the added advantage of having only one control panel to adjust.

CARE AND MAINTENANCE

• A dampened, soapy sponge will quickly clean the tough, durable vinyl covering of your PORTAFLEX.
• The grill cloth should be brushed occasionally with a soft bristle brush, especially if the unit is used in a dusty location.

TROUBLESHOOTING

• A common trouble in instrument amplification is caused by faulty external connections.
• Standard phone-jack cables receive considerable abuse during performances and loss of power (or gain) or an uneven tone quality can often be traced to a damaged cable.
• Your pickup leads should be shielded thoroughly. Included with the instruction literature is a complete list of Certified Ampeg Service Centers.
• Should you encounter any difficulty with your equipment, please contact the Ampeg service center in your area for a complete continuity check.
• A complete wiring diagram (schematic) is attached to the underside of the chassis cover of your BT-15 •
• Feel free to contact us with any questions you may have, and include the serial number of your equipment in any correspondence.
• *U. S. Patent No. 3183305
• -110966-
• CO. INC., 330 DALZIEL ROAD • LINDEN, N. J.

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