U.S. Amps Bass Mekanik Owner's Manual And Installation Manual - page 22
A basic rule of thumb of audio amplifier design dictates that the
is
than the audible range. This bare minimum is necessary to keep transistor “switching noise”
out of the audible signal.
To adequately reproduce the audible range, (20Hz to 20KHz) the “Class D” PWM would have to switch at a
of 200KHz, which represents the upper range (and cost) of PWM capability.
As a result,
“Class D” is generally used only in low frequency or low fidelity applications where the performance level of
PWM is acceptable.
Large speakers - such as woofers, or inaccurate speakers like the full-range single cone drivers used in
General Motors'
systems - help to hide the audible high frequency noise of “Class D” by
virtue of their mechanical inability to reproduce high frequencies.
“Class D” is load-specific. Both “Class D” and
amplifiers require
to eliminate
spurious digital “switching noise” from the output signal. The slow switching speed of “Class D”
necessitates a large, built-in, high-value output filter that acts as a passive crossover and is dependent
upon the correct speaker impedance.
Additionally, “Class D” operates at a relatively low voltage, much like a high current amplifier, and must be
used into low impedances to make power with current. This emphasis on current requires a larger output
filter that is more critical to impedance load matching.
This is why “Class D” amplifiers are specific “1 Ohm” or “1/2 Ohm”, etc. Failure to observe the exact
recommended speaker load is akin to connecting an improper speaker load to a passive crossover
network, and will result in degradation of the already limited “Class D” frequency response.
To be sure, “Class D” is (was) a step in the right direction. It does work, and works rather well in certain
instances. It is, however, a crude and incomplete technology when compared to T-Class™ and DPP. The
underlying technology of U.S. Amps T-Class™ does not use PWM and is not pure analog. T-Class™
incorporates cutting-edge
™ (DPP*), a product of Tripath Technologies. DPP
combines the benefits of
with a completely new approach.
U.S. Amps' T-Class™ amplifiers are among the first to apply this breakthrough technology.
DPP utilizes ultra-high speed digital switching that
with the amplitude of the incoming signal. At rest,
with no signal input, DPP switches at an
(Wow!)
As the signal amplitude increases, the switching frequency of DPP decreases correspondingly, but never
enough to degrade sound quality. DPP maintains an average switching frequency of 600 to 800KHz while
sampling and switching audible frequencies.
This incredible sampling and switching speed gives U.S. Amps T-Class™ amplifiers their full-range
characteristics, and requires a smaller and less restrictive output filter.
minimum circuit switching frequency 10
times greater
minimum
Delco-Bose™***
T-Class™
digital and analog
varies
incredible 1.5 MEGAHERTZ
output filters
U.S. Amps T-Class™:
Digital Power Processing
!
T-CLASS EXPLAINED - PART 2
TM
22