from mesa boogie webpage
July 28, 2004
ADVISORY NOTICE concerning MESA WalkAbout and WalkAbout Scout (Combo) Bass Amplifiers – Effecting Serial Numbers, 000011 through 002001, and Serial Numbers, 002084, 002087, 002088, 002089, 002090, 002091.
Attention Owners, Retailers, Distributors & Authorized MESA Warranty Service Centers;
We have discovered that certain extreme settings can cause a high frequency oscillation (whistling sound) that can damage the horn and L-pad in our Scout Combo and Extension Cabinets - as well as other MESA and potentially non-Mesa Bass Cabinetry, if allowed to continue.
While less than one-tenth-of-one percent of units have shown damage to the Horn and L-Pad, we at Mesa/Boogie want to inform you of this possibility and recommend that you have it cured under our Warranty as soon as convenient. This modification will improve reliability and ensure uninterrupted performance from your Walkabout. You may continue to use your amplifier in the mean time, but please avoid the settings listed below.
Settings To Avoid;
High settings of the Treble control (above 2-3 o’clock) combined with boosted settings of high frequencies with the Parametric EQ, plus high Master settings (above 1 o’clock) can induce the audible high frequency oscillation. This is not a musical setting anyone is likely to use and reducing any one of these control settings will prevent the possibility of the damaging oscillation. Also, since the oscillation is audible as a high-pitch squeal, it is not likely that anyone would allow it to continue, anymore than they would leave a microphone feedback into a PA.
However if the oscillation is allowed to continue for a few minutes or more, it can and probably will damage the L-pad and/or high-frequency horn. Momentary oscillation will not cause damage.
It is likely that you would never discover this setting and therefore would never encounter the associated problem. However, we suggest you arrange with your nearest Authorized Mesa/Boogie Service Center to have the modification made under Warranty. It will not cause any alteration in the sound or response of your WalkAbout. We hope it can be done with the least possible inconvenience to you.
Your Authorized Service Center has the info and parts to do the work in only a few minutes. (If you play a Scout combo, why not help them out by removing the chassis yourself and leaving the cabinet at home.)
We work hard to maintain our reputation for outstanding quality and great customer service and it is in this spirit that we issue this Advisory Notice.
Special Note To Subsequent WalkAbout Owners: If you possess a WalkAbout Bass Amplifier within the serial number range listed above and are not certain that this improvement update has been completed by the previous owner or retailer, please contact our Customer Service Department as soon as possible at 707-778-6565. Please have your serial number available when you call; we will be able to advise you whether or not your amp has been updated. If it hasn’t, we will be happy to put you in contact with your nearest Authorized Mesa/Boogie Service Center to have the update completed under Warranty.
