Mesa/Boogie Walk About Bass Amplifier - Manual (Page 9)

PAGE 5
FRONT PANEL CONTROLS:
(Continued)
MID:
This is the only passive style control in the string of rotary tone controls. This scheme was chosen for its inherently musical
blend and for the way the passive style midrange control, with its wide spread and smooth taper, fi lls in the holes. Unlike the BASS,
this control is a boost only, and while it can competently remove this broad
spectrum of midrange from the mix, it cannot provide the extreme attenuation
of an active style control.
You will fi nd, as we did, that this control works amazingly well for shaping the
midrange frequencies with a natural earthiness and character that is a perfect
counterpart to its active neighbors. It is hard to dial wrong with this more forgiving
control, as it seems to give you just enough and no more. This simplicity can be
a welcome respite from the higher tech power of the adjacent tone controls...not
to mention the 3 Band SEMI-PARAMETRIC EQ For radical and specifi c scooping
of the midrange frequencies for modern R&B and Funk styles, there is plenty
of notching power that is infi nitely more accurate to be found in the 3 Band SEMI-PARAMETRIC. Because of this, we opted for the
tried and true passive style midrange control that has been working great in all of our amplifi ers for decades. It’s hard to improve on
a classic.
TREBLE:
The TREBLE is also an active shelving style control like that found in the BASS and again, it was chosen for its ability to
radically shape the upper harmonic region. Like the BASS, it also has a center Q point with harmonics above and below responding
in harmony as it is dialed for either cut or boost.
As the control is increased past 12:00, it produces a 6db per octave rise in gain
starting at 723Hz until +20db is reached. From this point, gain remains constant
at +20db for all frequencies above 723Hz all the way out to 20Khz. This scheme
lends a sweetness of sound while retaining all the necessary cut and focus as-
sociated with a traditional passive
TREBLE control.
As the control is dialed below 12:00, it begins a 6db per octave cut from 3.2Khz
to the shelving point at 723Hz, where it continues to attenuate all frequencies
above 723Hz until - 20db is reached where cut gain remains constant until the
cut gain cut gain
control reaches 7:30 (off). The ability to cut these frequencies more radically
makes it possible to obtain incredibly rich and warm old-school R&B and Jazz sounds that rival any recordings of the day.
This active shelving TREBLE control completes the rotary tone control string to create a powerful and extremely accurate network
to use as your fundamental platform. It’s no wonder many fi rst time WalkAbout players make the comment that just these controls
combined with the GAIN create the best tone they have ever heard!
NOTE: NOTE: NOTE: As with the BASS control, may we remind you that a control of this type with its increased power should be used with fi nesse.
In the
TREBLE’S case, almost more so, because higher frequencies seem louder to the ear and are generally more painful when set TREBLE’S TREBLE’S
to extremes. Another reason to use care is that high frequencies tend to increase the ambient noise fl oor when set too high. This is
then exacerbated if the 3 Band SEMI-PARAMETRIC EQ is combined for added top end boost. Dial with care and music in mind.
ON
POWER
TREBLE DI LEVEL MASTER
INSTRUMENT
INPUTS
PASSIVE
ACTIVE
GAIN BASS MID
FOUR - STAGE VACUUM TUBE PREAMPLIFIER