Owner’s Manual for the BT-350 Bass Amplifier
BT-350 ThunderBass Amplifier Congratulations! You are now the proud owner of one of the most advanced bass guitar amplifiers available, the Crate BT-350 ThunderBass amp. This flexible and compact unit combines a tube preamp, 7-band graphic equalizer, chorus, biamp capabilities and 350 watts of power in a rugged and attractive package that can be rack-mounted in only three spaces.
BT-350 ThunderBass Amplifier Introduction: The Crate BT-350 ThunderBass amp is a high-quality bass guitar amplification system that combines extremely high power with very desirable features. Each feature and control is discussed in detail in the sections entitled “The Front Panel,” “The Rear Panel” and “Using the Biamp Capabilities.
BT-350 ThunderBass Amplifier The Front Panel: INPUTS: 1. 0dB INPUT: Connect your bass here using a shielded instrument cable. The output signal of your bass will run full-strength into the amplifier, which is fine for most basses having passive electronics and/or low-output pickups. If your bass has active on-board electronics and/or active pickups, use the -15dB input jack (#2) to avoid overloading the amp’s input stage. 2.
BT-350 ThunderBass Amplifier The Front Panel (con’t): 11. LIMIT LED: The BT-350 offers a special limiting circuit which helps to keep the output of the amplifier “clean” when played at extreme volume levels. When the Limiter is engaged, the Limit LED will come on as the power amp is being driven to full output. 12. LIMITER: When a power amplifier reaches maximum output levels, it may begin to “clip” its output signal, which generates potentially speaker-damaging distortion.
BT-350 ThunderBass Amplifier The Rear Panel: 27. SPEAKER OUTPUT jacks: Using a 1/4” mono phone plug, connect the output of the BT-350 to your speaker cabinet(s) via these jacks. Be sure to use heavy gauge speaker cable – not instrument patch cords – for these connections. These jacks are wired in parallel: when connecting your speakers, keep the total impedance at or above 4 ohms. The chart below can help you determine the total impedance load when connecting various combinations of speakers in parallel.
BT-350 ThunderBass Amplifier System Block Diagram: 7
BT-350 ThunderBass Amplifier Using the Biamp Capabilities: Your BT-350 can be used along with an additional power amplifier, to “biamp” your system: that is, using two amplifier/speaker combinations to share the task of reproducing the full range of your bass. Due to increased efficiencies, the combined output may sound cleaner and more powerful than that of a single-amped system, especially during high-volume, live performances.
BT-350 ThunderBass Amplifier Using the Biamp Capabilities (con’t): Using the BT-350 as the high-frequency power amplifier: In the biamp configuration shown below, the BT-350 serves as the system preamp, biamp crossover, and high-frequency power amplifier. A second power amp of 200 to 500 watts may be used to amplify the low frequencies. The crossover frequency (that point where one amplifier ends and the other amp takes over) is set by adjusting the BT-350’s Biamp Frequency control (#13).
BT-350 ThunderBass Amplifier Some Suggested Settings: ROCK: Biamp and Chorus controls optional. You can crank the Tube Drive even more for distortion; if you do, back off the EQ level. JAZZ: This will produce a very smooth sound with a minimum of percussive tones.
BT-350 ThunderBass Amplifier Some Suggested Settings: COUNTRY: Increasing the EQ Level produces more clean volume. Set the Master Level to taste. FUNK “POPPING”: Chorus is a great effect with this setting.
BT-350 ThunderBass Amplifier Technical Specifications: Output Power Rating 350 watts @ 0.2% THD, 4 ohm load – 120VAC 200 watts @ 0.2% THD, 8 ohm load – 120VAC Gain @ 1kHz 61dB, tones at “5” Tone Control Range Low Boost Low Mid High High Boost +8dB @ 20Hz ±13dB @ 40Hz ±11dB @ 260Hz ±15dB @ 5kHz +10dB @ 10kHz Graphic EQ Level +8dB, -10dB Graphic EQ Range ±12dB @ 40Hz, 100Hz, 250Hz, 625Hz, 1.
