Mesa/Boogie M-PULSE Owner'S Manual Download Page 9

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FRONT PANEL CONTROLS:

(Continued)

BASS:

This control is responsible for the basic mix of low frequencies in the tube pre-amp. As mentioned earlier in the Helpful

Hints section, the

BASS

control is an active shelving type control as opposed to a passive style control. This means that a center Q

point has been chosen and this control allows you to either boost or cut that frequency. This control differs from the low bands of the

Parametric in that it has a broader Q point with a more gentle ramp as opposed to the Parametrics’
narrow Q that is used with a separate GAIN control.

The

BASS

control is actually a gain and frequency control all rolled into one with the Q center at 55Hz

and harmonics in both low and high directions are affected because of its broader band nature. As the
control is increased past 12:00 there is a 6db per octave rise in gain with the frequency topping out at
321Hz. With 12:00 straight-up representing “flat” (a no boost/no cut setting). As the

BASS

control is

dialed below 12:00, 55Hz and all associated harmonics are reduced and eventually notched completely
out of the signal. Conversely, there is a 6db per octave cut beginning at 55Hz going down to 20Hz
where the shelving ends with a

cut gain

of -20db as the control approaches 7:30 (off).

This type of broad band, active rotary control makes it possible to achieve bass characteristics far
beyond that of a conventional passive type control. It can increase the low end to an almost absurd level

and with a flick of the wrist, dip it to near transitor radio skinniness. Needless to say, with any control this powerful a certain amount
of finesse must be applied to achieve musical results. Be especially mindful of this when using the 5 Band Parametric in conjunction
with the

BASS

control.

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,

fills 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 find, as we did, that this control works amazingly well for shaping the midrange fre-
quencies with a natural earthiness and character that is a perfect counterpart to its 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 5 Band Parametric. For radical and specific scooping of the
midrange frequencies for modern R&B and Funk styles, there is plenty of notching power that
is infinitely more accurate to be found in the 5 Band Parametric. Because of this, we opted
for the tried and true passive style midrange control that has been working great in all of our
amplifiers 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

PAGE 5

INSTRUMENT

INPUTS

PASSIVE

ACTIVE

GAIN

BASS

FOUR - STAGE VACUMM

INSTRUMENT

INPUTS

PASSIVE

ACTIVE