PRE SHAPE
Next to the INPUT GAIN control is the switch for selecting PRE SHAPE 1 or 2. The selected PRE SHAPE sound is switched in and out
with the footswitch below this marked PRE SHAPE.
The PRE SHAPE facility is like a preset graphic equaliser built into the SM7EQ that you can switch in or out to modify the sound of
the bass.
PRE SHAPE 1 is the classic TRACE ELLIOT EQ as found on Series 6 units the SMX and the SM range of amplifiers, it adds a boost at
both the low end (50Hz) and the high end (2 to 5kHz) of the frequency spectrum as well as a cut at mid frequencies (400Hz).
PRE SHAPE 2 is more rock orientated equalisation providing a wider bandwidth boost at low frequencies, less of a mid cut and a
slight boost at higher frequencies. This is a less extreme EQ than PRE SHAPE 1.
Both these pre shaped sounds will add extra punch to your sound and may be used with or without the GRAPHIC EQUALISATION
section being switched in.
GRAPHIC EQUALISER
A carefully designed GRAPHIC EQUALISER is a very flexible way of varying the sound of a bass guitar and if properly used will
provide an extremely powerful method of tone shaping for your instrument.
The SM7EQ has a 7 band GRAPHIC EQUALISER that can be switched IN or OUT of the signal path from the right hand foot switch.
Because of the flexibility and massive BOOST and CUT potential of the GRAPHIC it is important to know how to get the best from it.
It is equally important to know how to avoid the problems that can be associated with its incorrect use, so firstly here is a list of
things not to do, and why:-
1.
Do not
fully boost just one frequency band as this will tend to emphasise a small range of notes on the bass producing a PEAKY
and not very useful sound
2.
Do not
boost or cut all frequencies as this will have the same effect as increasing or decreasing the overall volume level without
affecting the tonal characteristics of the sound.
3.
Do not
use excessive bottom (50Hz) boost on the graphic unless your speakers can handle it (very few speakers are capable of
handling frequencies as low as this with any degree of efficiency).
4.
Do not
use excessive top boost; this will tend to add a lot of HISS to the sound (especially with active instruments).
The 7 sliders have been provided to give you full control at a number of frequencies providing a flexible and comprehensive bass EQ
system for the discerning user.
USEFUL OBSERVATIONS
The fundamental frequency range of a bass guitar is from 41.2Hz (bottom E string) to around 392Hz (two octaves up on the G string)
not a very wide range. Obviously a lot of harmonics are produced when playing and these can extend up to 5kHz or more.
Other frequencies are also produced by the attack portion of the note when the string is first struck. This attack can be emphasised
by boosting the top end.
However because of the fairly small range of frequencies from a bass by top end we mean between 2kHz and 5kHz. You will find by
boosting at 5kHz the ATTACK will be emphasised whereas by boosting at 1kHz and 2kHz you will bring out the harmonics in the note.
Use the 50Hz slider sparingly unless you have a stack of speakers available, and the power amps to drive them. You will find that
rolling off the bottom end by using this slider to give a degree of cut will alow you to play at a far greater volume level without the
speakers complaining. You will find that boosting at 100Hz will give greater perceived increase in bottom end than boosting at 50Hz.
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