8/22/2017
SUBLIME ACOUSTIC MODEL K231
2
K231 Stereo 3-Way Active Crossover Overview
The K231 Stereo 3-Way Active Crossover
significantly improves the audio quality of sound systems by separating the low, mid and high
frequency sounds using ultra low noise, high precision active filter circuits. This allows the use of a separate power amplifier dedicated to
each speaker driver. These functions result in greatly improved clarity and lower distortion of the sound that is produced.
The block diagram below shows the primary functional blocks of the K231. The line-level audio signals, either balanced or unbalanced,
enter from the left and are received and buffered by the ‘Balanced/Unbalanced Input Stage’ circuits. Note that the balanced and
unbalanced inputs are both always active. Whether your inputs are balanced or unbalanced is selected simply by which jacks you plug in
to. The balanced inputs are ¼” TRS jacks, and the unbalanced inputs are RCA jacks. Since this is a shared circuit between balanced and
unbalanced input jacks, only one or the other can be connected at any given time.
After the input stages, the signal is processed by the ‘Baffle Step Compensation’ circuit, or BSC. This is simply a configurable stereo low
pass shelf filter with adjustable gain that compensates for the ‘Baffle Step’ effect. See below for a more detailed description.
Next in the signal path is the Subwoofer crossover. This is a 2-way crossover that splits the subwoofer frequencies from the mid and high
frequencies. Any frequencies below the ‘Sub’ XO module setting are sent to the Sub output. The low output can optionally be mixed into
a mono subwoofer signal via a small slide switch that is accessible through an access panel on the bottom of the chassis. The high output
of this crossover gets passed on to the mid/high crossover.
The mid/high crossover, as the name implies, splits the mid frequencies from the high frequencies. Any frequencies above the ‘Mid/High’
XO module setting goes to the high output. Note that since the Sub crossover has already removed the subwoofer frequencies from the
mid/high signal, this makes the mid filter into band pass filter, whose frequency is bounded on the low end by the Sub XO module setting
and on the high end by the Mid/High XO module setting.
All of the crossover circuit outputs then go to six identical ‘Balanced/Unbalanced Output Stages’. Again, both the balanced and
unbalanced outputs are active at all times. But, again, this is a shared circuit between balanced and unbalanced outputs and only one set
or the other should ever be connected at any given time.
Figure 1.
K231 Block Diagram
