Power Rating

TC Electronic bass amp power rating & Active Power
Management
About this document
This abstract outlines the power rating used on TC Electronics bass amps as well as background
and basics of our Active Power Management™ first introduced on the RH450 Bass amp.
What watt?
When rating an amps power handling there are number of factors that need to be included, i.e.
voltage, time, crest factor of the source signal and a number of other technical parameters.
However to most bass amp users how it is heard and experiencedx is more important than how it
measures in other words, it all comes down to sound and loudness.
In bass amps specifically, there are very obvious differences in the perceived power handling of
the two most classic categories: Tube- and solid state- (transistor) amps. In order to understand
why this is, we need to take a quick look at the dynamics of a typical bass signal as well as how
our ears respond to sound.
Bass signals and Dynamics
The average signal of a bass has a very wide dynamics span that ranges from a short and very
high peak at the stroke of the string and quickly dropping to a significantly lower level at the
sustain of the note played. This is known as the ‘crest factor’ and describes the ratio between the
highest peak and the average energy (ratio between peak and RMS (root-mean-square) of the
signal. Typically bass signals have a high crest factor of 10-15dB depending on playing style (fig.
1).
For reference, a 3dB change equals double output power and vice versa in other words a 6dB
difference between highest peak and sustained notes translates into quarter power in difference.
Figure 1: Bass signal sample
Human ear response
The human ear, being fairly slow in response, pick up on the average level of sound rather than
short term peaks. In other words the level, or loudness, that we experience rarely has to do with
the peaks, but is tied closely to the average level, or energy, of a certain signal.
In the case of bass signals, this means that it is not the actual stroke of the string, but the
sustained note that we determine the perceived loudness by (fig 2).
Using a 12dB crest factor bass example, this means that the peak will be sixteen times as the
average (RMS) signal, or opposite, the loudness perceived by our ears is sixteen times lower
than the maximum peaks of the signal.

Summary of content (7 pages)