The Graphic EQ.
This is a 15 band EQ that covers the full spectrum of a bass and beyond. This is used to
fine-tune your bass tone to perfection. Often playing in different venues will cause your
bass to sound different. This is partially due to the acoustics of the hall influencing the low
frequency waves that are coming from your speaker. Bass waves are large and room
dimensions heavily influence them when the walls reflect the sound waves, causing them to
collide by adding together or canceling each other out. This causes some fundamental notes
(the ones you feel more than hear) to ring out louder than others and some note not to be
heard at all.
Here is an indication of where fundamental bass frequencies are, showing open string’s
approximate frequencies and acoustic wavelength.
F# string 24Hz 46 feet
B string 31Hz 36 feet
E string 41Hz 27 feet
A string 55Hz 20 feet
D string 73Hz 15 feet
G string 98Hz 11 feet
C string 130Hz 9 feet
This may give you some indication of the offending notes (frequencies) that may be
booming or resonating louder or quieter than others. For example if your speakers are 5 feet
from a wall, the open A string may sound lack of weight. That could be because the path
length of the reflected sound off the wall from your speaker is exactly corresponding to half a
wavelength on the open A string causing at that particular note a cancellation.
Note that the position of where you place your speakers will ultimately affect your tone.
Placing a speaker with the back close to a wall will help to reinforce the lower notes.
Placing the speaker in a room corner will further enhance the low notes.
Unfortunately for bass players, low frequencies are always very difficult to control with
room acoustics. The reproduced wavelengths of the notes you are playing often correspond
to the room dimensions, in which case the reflected sound off the walls interferes with the
sound from the speaker. So the graphic EQ is by far your best weapon of choice in killing
standing waves that develop in the room. From about 250Hz upwards, the graphic EQ is just
controlling your overtones on the strings bearing in mind that even the 60Hz control will alter
the second harmonic on an open B string.
The amount of control per frequency band is up to 36dB (+/-18dB). You should try to
avoid using excessive boosting of EQ on the lower frequency ranges (25, 40, 63 and 100Hz
bands) as this will reduce amplifier headroom and possibly damage your speakers, since the
amplifier may force them to move beyond their physical capability. If you hear large
amounts of distortion coming from your speakers when you boost the lower bands, you
should immediately back off on the EQ. If you cannot get enough low-end weight for your taste,
maybe you need more speakers.
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