Thump

[FretLessSince68]

Thump
What is thump? The word, for our purposes, seems to originate in the Upright Bass community. Thump is the percussive sound you hear as the bass players right hand finger releases a string pluck. This thump quickly dissipates and is replaced by a musical note the instrument makes.

On the electric bass thump is not created in exactly the same way as Upright bass because of differences in instrument construction and sound production characteristics. In my playing, I wish to emulate the URB thump so consider it a positive attribute.

In synthesized sound, the wave form is often described using the acronym ADSR - Attack, Decay, Sustain, Release. Thump is analogous to the Attack phase where the note takes a small amount of time to "rise" in amplitude, sometimes called rise time.

When you pluck a note, there is a very short period of string instability (milliseconds) before the oscillation stabilizes into a regular wave. You can hear this clearly on very large cables such as telephone pole guy wires. If you strike a guy wire you can hear the strike impulse wave travel up the string to its' end, and then back down to where you are. This impulse wave will travel several times in a guy wire before it starts to oscillate at its' fundamental. The same thing happens in your bass strings but in a much shortened time scale due to the shorter scale length and lower tension.

The period of instability in the string after you pluck it does make a sound, we usually hear it approximately as 1/2 wave of a 10 Hz note lasting about 4 to 5 milliseconds. Sometimes this sound is described as "finger noise". The lower the note, the more pronounced the "thump". This also happens to be a fair description of the rise time of a bass drum note. In the electric bass this sound never reaches the amplitude of a bass drum hit but has similar attributes.

Low tension strings take longer to establish fundamental oscillation. The period of instability is longer (in milliseconds), thus the apparent Thump is greater.

Having said that, I use high tension strings and left hand muting to accentuate Thump when desired. I also use my URB Simulator to mimic the sound and air of the Upright Bass body which contributes to Thump.

James Jamerson used high tension strings, yet his sound was very "thumpy", in fact he practically defined electric bass thump. Thump comes from the fingers as well as the type (and condition) of the strings ones uses. I do admit that low tension electric bass strings have greater "thump" mainly due to less sustain.

Old worn strings have less sustain (and tone) and more Thump.

In the URB thump is a very low frequency sound so the electric bass player should have an amp that can move adequate air.