Manual
page 12
page 13
LS1s - Subwoofer
LS1s - the optional Low Frequency Extension
With some kinds of music at higher playback levels, sufcient acoustic power in the low
frequency range is required for high delity playback. In many cases the standard 2-way
conguration will be able to deliver the full range at a sufciently high level, because of
the generally limited amount of ultra-low frequency sound in most music.
The software control settings in the ’LS1‘ tab of the preferences allows the user to set a
’Low-cut frequency‘. If that is set to 40-45Hz the LS1 can produce impressive levels, even
as a 2-way system. If you set the low-cut frequency down to 35Hz or even 28Hz the LS1
will still stay completely linear, only the maximum achievable sound level becomes lower.
With large church organs or modern music with non-acoustic electronic instruments the
content at frequencies below 40 Hz can, however, become signicant and a little help
from a big ’woofer‘ would be required to play at higher sound levels. So we developed the
’LS1s‘ low frequency extension.
Normally the reproduction of very low frequencies demands for a large driver, because
for physics reasons more air has to be moved for the same amount of sound as at high
frequencies. Unfortunately a large driver needs a large cabinet in order to not limit the
lowest frequency, when no other means are available to correct this. We wanted the
LS1s - Subwoofer
additional woofer to be both acoustically and visually integrated, which did not allow for a
large cabinet. So the challenge was to reach a high SPL level at low frequencies, while at
the same time retaining a perfectly at frequency, time and phase response down to very
low frequencies, without a large cabinet.
Fortunately, the same DSP controller that ensures the awless combination of the tweeter
and woofer with perfect timing and frequency behaviour can also be used to overcome
the issues that arise when adding an additional ’sub‘-woofer for the ultra-low frequencies.
By selecting a moderately large high performance driver with a very long linear excursion,
sufcient air can be moved and the DSP in combination with a powerful 400W amplier
compensates the frequency limitation due to the mounting in a small cabinet.
The LS1´s have a dedicated subwoofer output, which can be controlled from within the
remote software. It is possible to connect any subwoofer to this output, using a standard
setting without phase compensation because standard subwoofers are designed to act
as standalone units. The optional LS1s low frequency extension adds something more
and provides full integration with the LS1 itself. With the LS1s added, the LS1 effectively
becomes a 3-way speaker system with perfect time and frequency alignment.
Switching to the ’Grimm Sub‘ setting in the preferences sets a dedicated crossover, time
and phase correction preset in the DSP, so the system becomes a perfectly matched
3-way speaker and not only a 2-way with an added subwoofer. It completely retains and
even stretches its phase and time coherence as well as a linearized frequency response
over the full frequency range down to 20Hz. The woofer of the LS1 becomes a mid-only
unit that is crossed over to the subwoofer at ca. 70Hz, and is now able to handle higher
levels of sound.
The result is that the LS1 sounds nearly identical, both as a 2-way or a 3-way system.
The main difference is the higher possible sound pressure level and a powerful low
frequency extension down to 20 Hz. Also, distortion in the low frequency range has
dropped a bit.
LS1s - Subwoofer