User manual FENDER RUMBLE-BASS

[. . . ] A straight forward Treble-Bass-Mid Tone control section allows for adjustments in tonal balance at frequencies musically relevant to the bass guitar. An effects loop with a mix control to infinitely adjust the amount of external effects is standard, and is switchable, on or off, in both channels. [. . . ] When the control is rotated fully counter-clockwise the signal sent to the speaker jacks is completely "dry". When the control is fully clockwise the signal sent to the speaker jacks is completely "wet". PILOT LIGHT - When this lamp is illuminated the amplifier is receiving power. Should the lamp burn out, turn off the amplifier and unplug it from its power source, unscrew the red jewel, and replace the lamp with type T47 light bulb. CAUTION: WARNING: CHASSIS SURFACE HOT TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE AVIS: RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR SUPERFICIE DE CHASSIS CHAUDE SERIAL NUMBER ATTENTION: RUMBLE BIAS AND BALANCE ADJUSTMENT WARNING: Bias and balance are pre-set at the factory. If you are unsure about setting the bias and balance, take your Rumble Bass to the nearest authorized Fender service center. Turn on the amplifier and let it warm up for at least three minutes with the STANDBY switch in the ON position. Remove the front grill to gain access to the bias and balance controls. With a digital voltmeter set to its most sensitive DC voltage scale, insert the Common Probe into the test point BALANCE. Remove the Common Probe from the BALANCE test point and insert it into the BIAS1 test point. It is advised to recheck BIAS2 to confirm that 90 mVDC is still present. With a speaker (or equivalent) load connected to the MAIN SPEAKER jack, run a 1 kHz sine wave through the amplifier. Connect an oscilloscope to the positive lead of a 1/4" phone plug so that you can view the output waveform. Adjust the BALANCE control so that the viewed waveform clips evenly on both the positive and negative peaks. For optimum performance, set the bias to 90 mVDC, then set the balance. [. . . ] The jack can also be used to send signal to a mixing console for recording or sound reinforcement. TUBES The Fender Amp Custom Shop Rumble Bass consists of six 6550WA's, four 12AX7's, three 12AT7's and two 12BH7's. [. . . ]