Digital Signal Processing
Digital Signal Processing is
a science all of its own today. In the old days, there was only analog
processing, done by tubes and solid state (transistors) devices. If you
wanted an effect, such as distortion, you would design one amplifier stage to
overdrive another stage to get the desired effect. Reverb was often
accomplished by converting the signal into actual sound wave and transferring it
to a metal plate, and then converting it back to an electrical signal again.
This is how plate reverb is accomplished. The Tom Shultz Bass Rockman
unit, is a completely analog type of processor. It has a stereo chorus,
distortion, preset EQ, compression, and mixer, and head phone out, and line out
jacks. Pretty impressive for analog technology.
Below are some examples of both analog signal processors and digital signal
The top two units are both analog type processing units: Aphex Aural Exiter,
and Numark Stereo Equalizer. The bottom unit is an Alesis Midiverb II,
Today, all effects can be emulated by digital signal processing or DSP for
short. This process takes the analog signal and converts it to digital
bits and bytes. Today, these bits and bytes are 16 bit, 24 bit and 32 bit
numbers. This conversion factor is the resolution of each sample. When the
analog signal is converted to digital, there are often, 44,100 samples taken per
second. (This is the standard audio rate in the industry for Compact Discs.)
This is known as the sampling rate. It needs to be a least twice the rate
of the highest frequency being converted. Once these samples are taken,
they are then processed. The resulting bits and bytes are then converted
back to an analog signal, which is then fed into your
amplifier and speakers. This entire
process occurs very fast, and is usually done by an dedicated computer
processor, or some computer program.
The advantage of this process, while it is complex, is that it is controlled
by software and therefore it can be changed easily. This allows you to
control several parameters for several different effects. The other
benefit is that multiple effects can be processed on the input signal, with the
only limitation being your electronic hardware and processor for the task.
They do have limits. Almost all recording today is done in the digital
domain. For more information about digital recording check out
For example, you could take your bass sound and feed it into your laptop.
With the right software, you could change the sound of your bass in real time,
and feed the output back into your bass amp.
Back to the Sound-Shaping Page
Back to the Home Page