Figure 7: Comparison of different desktop speaker architectures.
In the figure above (Figure 7), Section A shows a typical 2.0 desktop speaker system with single
drivers for each channel, and two power amplifiers. This design will generally compromise low-
and high-frequency response.
Section B shows a desktop 2.1 system with stereo satellite speakers plus a subwoofer. This
type of system will make up the low-end and sound full, but it will lack a flat frequency response
to 20 kHz
Section C shows the design of Squeezebox Boom. Four separate speakers, four separate
amplifiers, and six DACs all digitally controlled with a high powered DSP provide the ultimate in
acoustic signal integrity and can produce great sound through the entire audio spectrum.
Without a subwoofer, the Squeezebox Boom goes from a -3 dB response at 50 Hz (at low
volume settings) to about 85 Hz (at high volume settings), all the way to 20 kHz. With the
addition of a subwoofer, the entire audio band, from 20 Hz to 20 kHz, is covered.
The Squeezebox Boom DSP
The Squeezebox Boom uses a 48-bit-by-24-bit, 135 MIPS (million instructions per second) DSP
core. With such significant DSP horsepower there are many ways to improve the sound quality;
good crossovers are just the beginning.
One may wonder why we need a 48-bit data path, providing 289 dB of dynamic range, when 16-
bits and 24-bits (96 dB to 144 dB) is good enough for most sound systems The answer is that
when performing mathematical operations (e.g., DSP) on a signal, the signal is often multiplied,
divided, and added to many times. With a 16-bit data signal, any 16-bit signal processing will
inevitably result in loss of signal fidelity, either by causing overflow, saturation, or extra
quantization noise. Quantization noise, saturation and overflow are undesirable.
To Next Page
Loading...
Need help?
General
