description, there are many details omitted, but the basic operational function is accurate. There is a lot of engineering that goes into
making a high performance, robust, safe and reliable design.)
QUESTION: Why does this amp use 12AT7/12AU7 type tubes/valves and not 12AX7 type tubes/valves?
ANSWER: This amp uses these tubes along with additional circuitry and techniques to accurately model some specific response and
feel elements without the negative artifacts that are more common to many 12AX7 approaches. In fact, using a 12AT7 in the legacy
bass amp models was a fairly common user modification. This type of circuitry was first adopted in the WD-800 and received such
positive player feedback that its use has been expanded to this new model.
TROUBLESHOOTING:
In the event that your amplifier appears not to work correctly, often enough the problem is not with
the amp, but a related piece of equipment, so it’s necessary to take a deliberate, systematic approach to troubleshooting in order to
effectively identify and correct the problem. Yes, believe it or not, we have seen all of these things many times.
SYMPTOM: No audio output:
Is the power LED lit and do the tally LEDs over the function switches work?
NO: Possible causes to check in this order are
1. Verify the power source, verify that the IEC power cable is not damaged and is fully inserted into its socket,
2. Verify that nobody unplugged your amp or turned off your power strip when you weren’t looking (if so, blame the guitar player,
turn on and play.).
3. If these do not solve your problem, it’s possible that your amplifier has failed so call our customer service department and we
will help you get this resolved.
YES: Possible causes to check in this order are:
1. Defective speaker cable or cabinet (test known good speaker cable and cabinet)
2. Defective bass or cable (test with known good bass and instrument cable)
3. Defective pedals/effects/pedalboard (plug bass directly into amplifier input, bypassing all devices in front of the amp)
4. Mute switch engaged or mute footswitch turned on (turn mute function off)
5. Problem with effects loop (for models with effects loop, a cable plugged into the effects return will interrupt signal, there is a
problem with an effects device or patch cable, there is an intermittent connection due to dust or debris inside the effects return
jack. Try bypassing effects loop with short shielded patch cable.
6. Gain or Master controls turned down (turn the controls up)
7. On 2 channel amps, be sure the amp is switched to the channel you are using and that you are adjusting that channel’s controls.
8. Will the amp play with a signal fed into the AUX INPUT or EFFECTS RETURN jacks? If so, the problem is with the preamp.
It’s possible that the tube/valve has failed. (substitute a known good 12AT7 or 12AU7 into the V1, V2 or V3, position, one at
a time and see if this restores audio)
9. There is indeed a problem with the amp, call our customer service department and we will help you get this resolved.
SYMPTOM: Distorted audio output:
1. Defective battery in active bass causing instrument’s onboard preamp to distort (replace battery)
2. With very hot 18V basses, it may be possible to overdrive the amp’s first stage preamp when in high gain mode (switch to
low gain mode)
3. Gain structure problem if using pedal based effects in the effects loop. The amp’s effects loops operate at line level, while
most pedals operate at instrument level, so it’s quite possible to overdrive effects pedals designed exclusively for instrument
PAGE 14
To Next Page
Loading...
Need help?
General
