BT25/BT50
BASS AMPLIFIER
USER’S GUIDE
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BT25/BT50 Bass Amplifier
Congratulations!
You are now the proud owner of the compact but powerful Crate
BT25/BT50 Bass Amplifier. The BT25/BT50 features two different chan-
nels: a distortion channel, featuring Crate’s exclusive Shape control for
quick and easy access to the tone you need, and a clean channel with
a four-band rotary EQ. Another unique and valuable feature of this
amplifier is the Octave control. This feature electronically creates a sec-
ond signal that is one octave lower than the original signal. An active
electronic tuner, conveniently located on top of the amplifier, allows you
to get in tune and stay in tune “on the fly.” Front panel jacks are provid-
ed for connecting a CD player and a pair of headphones, thereby opti-
mizing your practice time.
Like all Crate products, your BT25/BT50 is designed by musicians
and built using only the best components. Extensive testing at the hands
(and ears) of skilled technicians and musicians insures you that this
amplifier is the absolute best it can be.
In order to get the most out of your new bass amp, we urge you to
check out the information in this manual before you begin playing.
And thank you for choosing Crate.
Declaration Of Conformity
#28, Effective 01-01-2001
Manufacturer’s Name:
SLM Electronics
Production Facility:
Production Facility:
Shipping Facility:
Office Facility:
1901 Congressional Drive, St. Louis, MO 63146, USA
700 Hwy 202 W, Yellville, AR 72687, USA
1400 Ferguson Ave., St. Louis, MO 63133, USA
1400 Ferguson Ave., St. Louis, MO 63133, USA
Product Type:
Audio Amplifier
Complies with the following Standards:
Safety:
EMC:
EN60065, E60065, C22.2, UL6500 and/or UL813
Directive 89/336/EEC, EN55103, EN55013, EN61000,
and/or FCC 47CFR 15B clA
Supplementary information provided by:
SLM Electronics - R & D Engineering
1901 Congressional Drive, St Louis, MO 63146, USA
Tel.: 314-569-0141, Fax: 314-569-0175
3
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BT25/BT50 Bass Amplifier
The Front Panel:
1
2
3
4
5
6
7
8
1. INPUT: Use this 1/4” jack to connect your bass to the amplifier by means of a shielded instrument cable.
2. GAIN: Use this control to adjust the amount of distortion for the Distortion channel. As you rotate the control
clockwise the amount of distortion increases.
3. SHAPE: Use this control to adjust the tone of the Distortion channel, from a studio “V”-shaped tone to a
more “live,” more present sound.
4. LEVEL: Use this control to adjust the output level of the Distortion channel.
5. CHANNEL SWITCH: Use this switch to select either channel. With the switch in the out position, the Clean
channel is selected. When the switch is depressed, the Distortion channel is selected. The adjacent LED illu-
minates when the Distortion channel is selected. NOTE: When using a footswitch: when this switch is
depressed, the footswitch switches between the Distortion channel and the Clean channel; when this button
is in the out position, the Clean channel is always active, and the footswitch turns the Distortion channel on
and off, allowing you a blend of both channels.
6. LEVEL: Use this control to adjust the output level of the Clean channel, and as part of the Octave level con-
trol (see #11).
NOTE: The BT25/BT50 employs an internal noise gate to keep residual noise to a minimum. Regardless of
which channel is selected, the Clean channel’s Level control (#6) must be turned up above “0” in order for the
noise gate to trigger.
7. LOW: Use this control to adjust the low frequency output of the Clean channel.
8. LOW MID: Use this control to adjust the lower-midrange frequency output of the Clean channel.
9. HIGH MID: Use this control to adjust the upper-midrange frequency output of the Clean channel.
10. HIGH: Use this control to adjust the high frequency output of the Clean channel.
11. OCTAVE: The BT25/BT50 features internal circuitry which creates a second signal which is one octave
lower than the input signal. Use this control in conjunction with the Clean channel’s Level control (#6) to adjust
the level of the octave signal.
12. MASTER: Use this control to adjust the overall output level of the amplifier.
4
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BT25/BT50 Bass Amplifier
9
10
11
12
13
14
15
13. CD INPUT: Use these RCA jacks to connect the line level (or headphones) output of a CD player, tape
deck or rhythm machine to the amplifier. The signal level from these jacks is adjusted by the Master control
(#12). If the signal from the source connected to these jacks is too strong, use the output level control on the
source to adjust the signal to obtain the proper level for a good mix.
14. HEADPHONES: Use this jack to listen to the amplifier through a pair of stereo headphones. The internal
speaker is disconnected when the headphones jack is used.
CAUTION: To avoid possible damage to your hearing, do not use head-
phones for extended periods of time at extremely loud listening levels.
15. POWER: Use this switch to turn the amplifier on and off. The adjacent LED illuminates when the amplifi-
er is turned on.
16. ELECTRONIC TUNER (top panel): This active
electronic tuner is on whenever the amplifier is turned
on, allowing you constant, “real-time” tuning. The tuner
is fully chromatic – use the flat and sharp indicators
until the LED between them illuminates, indicating
proper tuning.
The Rear Panel (not shown):
17. 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 rear panel. Do not attempt to defeat the safety ground connection.
18. FOOTSWITCH: Connect a two-button footswitch (such as the Crate CFP-2) here for remote control of the
channel selection/“blend” (see #5) and octave on/off. (When the Channel Switch [#5] is depressed, the
footswitch switches between the Clean channel and the Distortion channel; when the switch is in the out posi-
tion, the Clean channel is always active, and the footswitch turns the Distortion channel on and off, allowing
you a blend of both channels.)
19. EXTERNAL SPEAKER: Use this jack to connect the amplifier to an external speaker cabinet (BT25 = 4
ohms minimum, BT50 = 8 ohms minimum). The internal speaker is disconnected when the external speaker
jack is used.
5
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BT25/BT50 Bass Amplifier
Suggested Starting Settings:
Rock:
OUT
OUT
OUT
OUT
IN
* *
* *
* *
* *
* *
*
Jazz:
Country:
Funk:
Solo Fuzz:
Super Fat Fuzz:
IN
6
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BT25/BT50 Bass Amplifier
System Block Diagram:
OCTAVE
LEVEL
TUNER
FOOT
SWITCH
A BC D EF G
BUFFER
EQ
INPUT
CHANNEL
SWITCH
LEVEL
LOW LOW HIGH HIGH
MID MID
NOISE
GATE
SHAPE
DISTORTION
LEVEL
GAIN
POWER
AMP
EXTERNAL
SPEAKER
MASTER
SPEAKER
CD
INPUT
ATTENUATOR
HEAD
PHONES
7
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BT25/BT50 Bass Amplifier
BT25/BT50 Technical Specifications:
BT25
BT50
Output Power Rating
25W RMS 2% THD, 4Ω, 120 VAC 50W RMS 2% THD, 4Ω, 120 VAC
Gain
Distortion Channel 100dB
Clean Channel 60dB
CD Inputs 33dB
Low 21dB @ 50Hz
104dB
63dB
37dB
Tone Range
21dB @ 50Hz
23dB @ 150Hz
18dB @ 1kHz
34dB @ 10kHz
Lo Mid 23dB @ 150Hz
Hi Mid 18dB @ 1kHz
High 34dB @ 10kHz
Signal to Noise Ratio
Input Impedance
75dB
75dB
220k ohms
220k ohms
Maximum Signal Accepted
Input Power Requirements
15 volts peak-to-peak
15 volts peak-to-peak
120 VAC, 60Hz, 45VA
120 VAC, 60Hz, 85VA
100/115VAC, 50/60Hz, 45VA
230VAC, 50/60Hz, 45VA
100/115VAC, 50/60Hz, 85VA
230VAC, 50/60Hz, 85VA
Internal Speaker
Size 10”
Type Crate Custom
12”
Crate Custom
30 oz.
Magnet 30 oz.
Voice Coil 1”
1.5”
RMS Rating 30 watts
Impedance 4 ohms
50 watts
8 ohms
Size
18” H x 18” W x 12-1/2” D
37 lbs
21” H x 18” W x 14” D
46 lbs
Weight
Specifications subject to change without notice
©2003 ST. LOUIS MUSIC, 1400 FERGUSON, ST. LOUIS, MO. 63133
47-376-01 • 012904
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