Grimm Audio LS1, User Manual, Page: 7 / 62

The electronics
With an acoustically optimised response as a starting point, we applied DSP equalisation
to flatten the response of woofer and tweeter. Thanks to the cabinet design only a few
minimum phase IIR corrections with low Q were necessary to linearize amplitude- and
phase response. Correction and cross-over were adjusted by hand, based on a multitude
of measurements in an anechoic environment. Driver errors need to be treated differently
from cabinet diffractions and automatic algorithms are unable to distinguish between the
two kinds. Finally, the acoustic sum was phase corrected to minimum phase which avoids
the pre-echos introduced by more common linear phase corrections. Measurements of the
step response confirm the effectivity of this strategy.
When adding the LS1s an LS1 turns into a true three-way system. The DSP again takes
care of all filtering, including the cross-over and its phase correction which has dramatic
impact at low frequencies. A three-way system has never sounded so even as this. Just
like with the two-way system our DSP correction offers a freely configurable low cut
frequency. Usually the two-way is cut off at 40 Hz and the three way at 20 Hz.
Digital input signals are re-clocked by a state of the art ASRC circuit which is based on the
same oscillator as the legendary Grimm CC1 clock. Analog inputs are first converted to
digital with a high performance A/D converter. The signal then enters the DSP, which has
a data path of 48 bits wide with a 76-bit accumulator. Each driver then has its own high
quality D/A-converter. The output of the D/A converters is directly fed into 120 W Hypex
Ncore power amplifiers. The optional LS1s have an additional 400 W amp each. Hypex
Ncore power amplifiers have the lowest harmonic distortion on the market and are the
perfect choice for the LS1 due to their linearity and excellent transient response.
Throughout the whole circuit, careful attention has been paid to component selection like
capacitors and resistors. Critical parts such as power supply regulators are of our own
discrete design. Once our circuits measure well, we start listening to tweak the last parts
by ear.
And this explains why the LS1 is not only neutral and precise but also a joy to listen to
and musically pleasing. We started with smart concepts and measurements but we did
not stop there. We listened. And doing so we developed a loudspeaker system that is
equally at home in a studio as well as in a living room. The LS1 is a true step forward into
the 21st century.
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