Thank you for purchasing a Yamaha F-20B Bass Amplifier.
To get the best results and longest life out of your F-20B, we recommend that you
carefully read this manual, and keep it in a safe place for future reference.
To avoid possible damage do not expose the unit to:
direct sunlight
very high or low temperature/humidity
sand or excessive dust
* Especially inside a vehicle, the temperature may rise
excessively — do not leave the F-20B in your parked car on a
sunny day!
Before connecting/disconnecting cables or turning the unit on/off, be
sure to set the VOLUME control on the F-20B to 0.
Keep the F-20B away from neon signs or fluorescent lighting to
prevent noise pickup.
Precautions
Rated Output Power : 20 W
Speaker : 25 cm x 1
Controls : VOLUME, TREBLE, HIGH MID, LOW MID, BASS, Input
Level Select Switch (PASSIVE/ACTIVE)
Input/Output Terminals : INPUT, AUX IN, PHONES
Control PanelSpecificationsqINPUT : Connect your bass guitar to this jack.
wPASSIVE/ACTIVE (Input Level Select Switch) : Select the
setting that best matches the type of bass guitar you are using. Set
the switch to its PASSIVE position (raise the switch ?) when using a
passive type bass guitar (one without a built-in pre-amplifier). Set the
switch to its ACTIVE position (depress the switch >) when using an
active type bass guitar (one with a built-in pre-amplifier), or when the
sound of a passive instrument has a lot of distortion.
eVOLUME : Controls the volume level.
Active Equalizer
The center position (0) of each knob is “flat”, having no effect. Rotating
the knob to the right (+) boosts the frequency while rotating the knob to
the left (–) cuts the frequency.
rTREBLE : Controls the level of the amplifier’s high frequencies.
tHIGH MID : Controls the level of the amplifier’s upper middle fre-
quencies.
yLOW MID : Controls the level of the amplifier’s lower middle fre-
quencies.
uBASS : Controls the level of the amplifier’s low frequencies.
Handle the unit carefully — never apply excessive force to the
controls and avoid dropping the unit.
For safety, always remove the power plug from the AC wall outlet if
there is any danger of lightning striking in your area.
To prevent damage and possibly electrical shock, never open the
case and tamper with the internal circuitry.
Never use solvents such as benzene or thinner to clean the F-20B.
Wipe clean with a soft, dry cloth.
iPower Indicator : The lamp will light when the F-20B’s power
switch is ON.
oAUX IN : Connecting the output of an external audio device, such
as a CD, MD, cassette deck, etc., to this jack allows you to listen to
the audio playback of the device while playing along on your bass
guitar.
* Use the volume control on the audio device to control its volume level.
!0 PHONES : Connect a pair of headphones to this jack.
* The speaker will produce no sound when a pair of headphones is con-
nected to this jack.
!1 POWER : This is the amplifier’s power switch. When the switch is
ON, the power indicator i will light.
Power Requirements : U.S. and Canadian models : 120V, 60Hz
General model : 230V, 50Hz
Dimensions (W x H x D) : 357 x 453 x 242 mm (14.1" x 17.8" x 9.5")
Weight : 10.5 kg (23 lbs 2 oz)

BASS AMPLIFIER

Owner’s Manual

* Specifications and external appearance are subject to change without notice.

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