Crate Amplifiers owner manual BT-350ThunderBass Amplifier Front Panel con’t, Biamp section

BT-350ThunderBass 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. The BT-350 has a special APM (Automatic Power Maximizer) limit- ing circuit which helps minimize this problem by monitoring the power amp’s output signal, keeping it below clipping. This feature insures you that even as you push your amplifier to its full 350-watt output, the sound will remain clean and pure. To activate the limiter circuit, press the Limiter switch in until it locks in place. The limit LED (#11) lights up when the APM circuit is actually limiting the signal.

NOTE: The limiter may be defeated, which allows higher power output, but there may be more distortion than the

.2% shown in the specifications chart.

BIAMP section:

13.FREQUENCY: This sets the crossover point when using the BT-350 in the biamp mode (using two power amplifiers, one for the low frequencies, one for the highs). Please see the section entitled “Using the Biamp Capabilities” on pages 8 and 9 for more details about biamping.

14.BALANCE: This adjusts the relative level between the low frequency and the high frequency biamp output signals. Please see the section entitled “Using the Biamp Capabilities” for more details

15.LINE OUT LEVEL: This adjusts the output level for the Line Outputs jacks on the rear panel (#31, 32), separately and independently from the amplifier’s Master level control (#10). The line out feature can be used to send a low-level (pre-amplified) signal to a mixing board, recorder or external power amp. The Line Out signal will have the same tone and Chorus information as the Master Level (speaker output) signal. Turning

the Line Out Level control to the right increases the output level; to the left decreases it.

NOTE: The Line Level signal is pre- Effects Loop and therefore will not be affected by any external signal proces- sors connected to the Loop (see #33 and 34).

16.POWER: This heavy-duty rocker- type switch is used to turn the amp on in the “up” position, off when “down.” The switch lights up when the power is on.

17.FOOTSWITCH: A two-button footswitch (such as Crate’s CFP-2) can be plugged in here to give you remote on/off control of the graphic eq and the chorus. When connected, the footswitch overrides the front panel on/off switches for these features.

NOTE: This is a stereo 1/4” jack: “ring” controls the chorus, “tip” controls the eq, and the “sleeve” is ground. Use only a footswitch equipped with a stereo plug (such as Crate’s CFP-2).

EQUALIZATION section:

The graphic equalizer can be used in two different ways: 1: To fine-tune your sound, make small adjustments at the desired frequencies and leave the EQ on for the entire performance;

2:For a completely different sound, make larger adjustments and only switch the EQ on when you want the radical change (such as during bass solos).

18.LEVEL: This serves as the overall volume control for the BT-350’s on- board 7-band graphic equalizer, and only affects the signal when the EQ is on (see #20). Use this control to adjust the volume of the equalized signal: pulling the Level control down from the center position reduces the volume, pushing it up from center increases it. The center detent is “flat” (no increase or decrease in level).

19.40Hz – 10kHz: These slide controls allow you to vary the output at the fre- quencies shown under each control by ±12dB. The center position of each con- trol is “flat” (no boost or cut): pushing a

control up from center boosts the output at its given frequency; pulling it down reduces that frequency. The 40Hz and 100Hz controls affect the lower notes of your bass, changing how much bass is felt. 250Hz through 1.6kHz affect the upper notes, modifying the amount of “punch” that comes across. 4kHz and 10kHz affect the upper harmonic over- tones of your bass, such as the sounds of your fingers in the strings or the strings striking the fretboard.

20.ON: When this switch is in, the EQ is active, and the settings of the controls affect the sound of your bass.

21.ENABLED LED: This LED will only light when the EQ is activated, showing you that the signal will be affected by the settings of the EQ controls.

CHORUS section:

22.ON: When pushed in, the on-board Chorus is activated and the signal pro- duced by your bass will have the Chorus effect applied to it.

23.ENABLED LED: This LED will light when the Chorus is activated, giving you a visual sign that the Chorus is function- ing.

24.SPECTRUM: (or “crossover:”) This unique feature allows you to adjust which frequencies – either the entire range or only the upper bass tones – are enhanced by the Chorus effect. In the fully counter-clockwise position the entire range (or “spectrum”) will have the chorus effect. As you rotate the con- trol clockwise you change the roll-off fre- quency for the Chorus, which allows the lowest tones to come through “dry” (without chorus applied). This is extremely useful for maintaining full low- end impact and definition during live performances.

25.DEPTH: Adjust the overall amount of the Chorus effect with this control: to the left for a little, to the right for a lot.

26.RATE: Adjust the speed of the cho- rus effect with this control: to the left for slow, smooth “phasing” sounds, to the right for faster, “vibrato” sounds.

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