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.
G 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
G Before connecting/disconnecting cables or turning the unit on/off, be
sure to set the VOLUME control on the F-20B to 0.
G Keep the F-20B away from neon signs or fluorescent lighting to
prevent noise pickup.
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
q INPUT :
Connect your bass guitar to this jack.
w PASSIVE/ACTIVE (Input Level Select Switch) :
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.
e VOLUME :
Controls the volume level.
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.
r TREBLE :
Controls the level of the amplifier's high frequencies.
t HIGH MID :
Controls the level of the amplifier's upper middle fre-
y LOW MID :
Controls the level of the amplifier's lower middle fre-
u BASS :
Controls the level of the amplifier's low frequencies.
G Handle the unit carefully — never apply excessive force to the
controls and avoid dropping the unit.
G For safety, always remove the power plug from the AC wall outlet if
there is any danger of lightning striking in your area.
G To prevent damage and possibly electrical shock, never open the
case and tamper with the internal circuitry.
G Never use solvents such as benzene or thinner to clean the F-20B.
Wipe clean with a soft, dry cloth.
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)
* Specifications and external appearance are subject to change without notice.
i Power Indicator :
The lamp will light when the F-20B's power
switch is ON.
o AUX 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
* 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