Grimm Audio LS1 Manuale utente
DRIVEN TO IMPROVE
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Congratulations on your purchase of the Grimm Audio LS1 playback system.
In this manual we like to assist you in setting up the LS1 playback system. You will learn
how to connect various sources and how to control the electronics, the LS1r Controller
and the LS1 remote software for Mac and PC. Furthermore we like to explain what makes
the LS1 playback system so different from all other hi speakers, why they look, function
and most important sound the way they do. If you are about to unpack and assemble
your LS1 set, please move forward to ’Assembly and Install‘ on page 14 of this manual.
Grimm Audio‘s LS1 was designed to show that one speaker can be both analytically
precise and musically pleasing at the same time. When we developed the LS1, we had
the professional user in mind. In a studio you need a speaker that is as linear as possible.
’Voicing‘, as the practice of tuning a loudspeakers' response by ear is called, only masks
abberations from linearity. The better way is to carefully measure the response with the
best test gear available and use that as a guide. We tested the LS1 in a large anechoic
room using a measurement microphone that we calibrated ourselves with a spark
gap reference. In fact we perform part of these measurements as a standard routine
during production, so the response of your LS1 loudspeakers has also been individually
measured and corrected.
By integrating top quality digital signal processing, converters and ampliers in one of
the speakers' legs, we were able to apply technical strategies no one had used before.
As a consequence, the LS1 is not just a loudspeaker, but a complete audio system that
only needs an analog or digital line source to perform. CD players, phono stages, music
servers or computers all connect straight to the speaker.
The correction of the measured response is done digitally in DSP (’Digital Signal
Processing‘). Digital processing offers a much higher degree of correction then possible in
the analog domain, and without the distortion associated with analog components. Digital
sources are fed directly into the DSP, in case you like to listen to an analog source we
included a very high quality AD converter in the system. The DSP in the LS1 takes care of
three important tasks: response correction of the drivers, cross-over between the drivers
and phase correction of the cross-over. Let's look at the response correction rst. And
remarkably this means we rst need to step back into the analog domain of acoustics.
The spatial radiation behavior of a loudspeaker cannot be corrected electrically so it
should be taken care of rst.
GRIMM AUDIO LS1
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The Electronics
With an acoustically optimised response as a starting point, we applied DSP equalisation
to atten 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 conrm the effectivity of this strategy.
When adding the LS1s subwoofer an LS1 turns into a true three-way system. The DSP
again takes care of all ltering, 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 congurable
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 rst 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 ampliers. The optional LS1s subs have an additional 400 W amp each.
Hypex Ncore power ampliers 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.
The Acoustics
The theory behind the LS1's acoustical design originates back to the 1930s and '40s.
Cabinets in those days were at but wide, which moved the so called ’bafe-step‘
frequency to lower than 250 Hz. Below the bafe step frequency, sound is radiated
equally in all directions. Above the bafe step the sound becomes more forward directed,
thereby attenuating reections against the wall behind the speaker and the side walls.
These reections normally cause phase errors in the perceived sound. Psycho acoustics
says that the ear is sensitive to phase errors down to approximately 250 Hz. The wide
bafe helps to attenuate interfering reections throughout this whole range.
Progress since the 40's has learned that edge diffraction of the cabinet deteriorates the
stereo image, hence the sides of the LS1 cabinet are strongly rounded by the legs. As
a bonus, the shallow cabinet moves the resonance along the depth axis inside the box
signicantly above the cross-over frequency of the low frequency driver. This helps to
avoid boxiness.
Next step in the design phase was the driver selection. We settled on an outstanding pair
of Seas units. The tweeter’s exceptionally low distortion in the mid range allows a fairly
low cross-over frequency that benets vertical dispersion. Its small constant directivity
horn ensures an even spread of high frequency sound.
Even dispersion is also helped by the lack of cone breakup effects in the magnesium
woofer below the crossover frequency. The woofer's long excursion permits generous
sound pressure capability down to 40Hz for the two way conguration. Adding the LS1s
subwoofer takes performance up a notch by extending the response down to 20 Hz and
further increasing attainable loudness.
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sound in all directions and sound travelling backwards and sideways reects against the
walls and adds up to the direct sound. Although the ear is less sensitive to the resulting
phase errors at these low frequencies, the impact on the low frequency energy itself
can be dramatic since at certain frequencies the reected sound can cancel the direct
sound. A real solution is to apply low frequency absorption behind the loudspeaker so
the reection is attenuated. Those who cannot afford such measures are invited to spend
some time shifting the speakers back and forth untill the optimal compromise is found.
In this respect the LS1 is not different from any other loudspeaker. A special feature of
the LS1 however is that the LS1s subwoofer can be taken off the foot plate of the main
system so both can be positioned independently. If your room acoustics are particularly
difcult, feel free to experiment with placing the sub closer to the wall than the main
speaker. You can use the parameters in the subwoofer preference pane (Gain and Delay)
to compensate resulting alignment errors. Please read the chapter ‚Software Control
Settings‘ for more information.
An annoying asset of most rooms is that they resonate at low frequencies (below 200
Hz). Tones bouncing back and forth between walls interfere, and at certain frequencies
they form node and anti node patterns which means that certain tones sound silent in
one place in the room but are very loud at other spots. These resonances are called room
modes and since they are dependent on the dimensions and the weight of the walls, they
vary from room to room. Some rooms therefore sound ‚better‘ than others. Whether a
certain room mode is triggered or not is dependent on the position of the source and of
the listener. So again, it makes sense to spend some time positioning the LS1‘s carefully
to nd the optimal compromise. Consult a specialized acoustician if you have a real strong
room mode problem in your room.
Some companies apply DSP for ’room correction‘. We rather not use DSP in the LS1 for
this since the effects are inuenced by the position of the listener. If we again look at
the three acoustic factors: 1. First reections are strongly dependent on the listeners‘
position, so there is no way to correct these with DSP. This is certainly true above 200
Hz where the wavelength is short. 2. The low frequency coupling effect can partly be
compensated by DSP (please use the LS1 EQ for that). However in the region around
100 Hz where often energy is lowered due to the reection being out of phase, DSP will
not help since a louder tone will still be canceled by its reection. 3. Finally, room modes
are also strongly dependent on the position of the listener. Theoretically it should be
advantageous to attenuate peaks in the room response that reside in the whole listening
area, but all DSP solutions for this we tried so far challenged the LS1's performance too
much.
Positioning
Positioning
Room Acoustics
Keep in mind that one always hears the loudspeaker plus its acoustic environment.
Although the LS1 has superior acoustical characteristics, positioning it correctly in your
room remains of great importance. Let‘s rst have a brief look at room acoustics and then
see how positioning the LS1 inuences them.
Roughly speaking there are three factors in acoustics that inuence the audible
performance of a loudspeaker: rst reections, low frequency coupling of nearby walls
and room modes (or room resonances). Lateral rst reections inuence the stereo
image. Since high frequencies are dominant in acoustic imaging, adding fabric acoustic
absorption like curtains at the reection spots on the left and right walls helps a lot.
Since the LS1 has a wide bafe, aiming the loudspeaker away from the reective spot
helps too. Another major type of reection is via the oor and ceiling. These reections
interfere less with the stereo image, but do color the sound. Absorbing the oor bounce
with a carpet helps. A special case is reections against an obstacle in front of the
listener, like a computer screen, bouncing the sound toward the front wall and from there
back to the listener. In those cases, absorbing the reection at either the obstacle or the
wall cures the problem. Due to the wide bafe of the LS1, which focusses the sound,
reections on the wall behind the listener tend to have slightly more impact than with
other loudspeakers. Please consider to add absorption or sound scattering objects like
bookcases against this wall.
First reections also introduce phase distortion in the early sound if the walls are too
close. Psycho acoustics tells us this effect is important down to 250 Hz. One wavelength
of a 250Hz tone lasts 4ms so this is the time span that certainly needs to be ’clean‘.
Sound travels app. 1.4 m in that time. Rules of thumb are therefore that you need to
have at least 80cm distance from the side walls (1.5 m is better) and 60cm from the
back wall (1.2m is better). The wide bafe of the LS1 makes the distance to the wall
behind them less critical, but if you have the chance, please allow for some distance.
An alternative is to choose the other extreme and place each LS1 with the back directly
against a wall. In that case all reections from the back wall integrate completely in phase
with the direct sound, the speaker gets an ’innite bafe‘. Unfortunately the speakers can
not be aimed inwards in this setting to optimize the stereo image, unless the walls have
the right angle of course.
This brings us to low frequency coupling of nearby walls. Below 250 Hz the LS1 radiates
Positioning
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Positioning
Positioning
LS1 Setup
Correct placement of your loudspeakers is essential for achieving the ultimate goal of
reproducing the music as it was intended by the artists. During production in the studio
the producer listened in a so called ’equal triangle‘ setup where the corners of the triangle
between the two loudspeakers and the listener are all 60 degrees. When possible, please
try to reach this arrangement. The distance between the loudspeakers ideally is between
2.5 and 3m.
It is necessary to make sure that both the left and right loudspeaker have a similar
acoustical environment. For example, if one loudspeaker is placed close to a side wall
and the other has free space on its side, the sound of the speaker against the wall will be
enforced by reections and therefore the stereo image shifts to that side. A quick and easy
check is to sit at the listening position and have an assistant talk to you from both speaker
positions. If his voice sounds equal in both positions, you are ne. If he is boomy in one
position and bright in the other, better search further for better postioning. Listen to both
the sound of the direct sound from the assistant and of the ‚room sound‘. In fact, strange
as it may seem, you can hear these effects too when speaking yourself at the loudspeaker
positions. If you cannot nd equal sounding positions for the loudspeakers in your room,
and for instance one speaker has to stand in a corner and the other just a long a wall, you
may use the LS1 EQ to equalize a difference in the low end between both speakers. Please
consult the EQ paragraph of the Software Control Settings chapter in this manual.
The LS1 cabinet is wider than usual, so the effect of turning the loudspeaker around its
vertical axis is larger than you would expect. The off-axis response on the front side of
the LS1 is extremely even (the LS1 sounds just as good slightly off-axis as on-axis), but
it becomes gradually softer when the angle is larger. We can use this to our advantage. In
the classic arrangement the loudspeakers face the listener. The angle of the loudspeakers
relative to the wall behind them is 30 degrees. The superb off-axis performance of the LS1
offers an alternative setup where both loudspeakers are turned slightly further inward, or
’toe in‘. We advice an angle to the wall of 45 degrees. The listener then sits at 15 degrees
off-axis of the loudspeakers. This ’toe in‘ setup has two advantages:
1. For seats left or right of the sweet spot, the stereo image is better preserved. The
reason is that for a left seat the sound of the left loudspeaker will reach the ear more
early. This causes a shift to the left in the stereo image. But at the same time, the listener
is more on-axis of the right speaker and more off-axis of the left speaker. The right loud-
Positioning
speaker therefore becomes slightly louder and the image shifts back to the right again. It
is not perfect, but the net effect is a wider area to enjoy a nice stereo image.
2. The reection of the left loudspeakers‘ sound to the left wall and vice versa becomes
attenuated a bit. Since this reection path is usually relatively short, it needs to be
attenuated to not interfere with the stereo image. An easy trick to check if this reection
is too loud is to listen to a mono sound on one loudspeaker only. Close your eyes and
point in the direction of the sound. Now open your eyes again and look at your nger. If it
is pointing towards the center of the loudspeaker everything is ne. If you point a little bit
off-center in the direction of the wall, the reection is too loud. If turning the LS1's toe-
in does not cure the problem, you will need to apply acoustic absorption at the reective
spots. Mark that by turning the left LS1 like this, its reection on the right wall will become
relatively louder. Usually this is not a problem but rather an advantage because this
reection comes later. Psycho acoustics says it helps the brain to extract the ’ambience‘
information from the recording.
In about 20% of the rooms, the classic setup where the LS1's face the listener still sounds
better. This is usually the case in fairly large rooms or in rooms with acoustics where
left and right reections are very well balanced. Please accept this as an invitation to
experiment and listen in your own environment.
Once you have decided on which of the two setups sounds best, please run the LS1
remote software and set the ’toe in‘ angle in the preferences to your selected 45 degrees
or 30 degrees angle. This applies a small correction to the highest treble, making sure the
frequency response of the direct sound is perfectly linear at the listening position.
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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
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Unpacking And Assembly
Unpacking And Assembly
If you are ready to assemble your pair of LS1‘s, please rst make yourself
familiar with all components in the box.
The open transport package should look somewhat like in the pictures on
the left. First take out the ’accessory box‘, the CAT5 cables, both speaker
cabinets and the extruded aluminium proles, which for simplicity from
here on shall be called ’legs‘.
The next step is to unscrew the footplates from the transport package, but
be careful as those are really heavy.
Unpacking and Assembly
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Take a speaker cabinet and lay it down on the empty and closed shipping
crate or on a big, clean table, with the drivers facing up. Place two of the
legs next to it, one with and one without electronics.
Normally, when setting up in a living room, you´ll prefer the electronics
panel facing to the back side of the speaker in order to look uncluttered. In
this case put the ’active leg‘ on the left side, next to the speaker cabinet on
the table, the other leg to the right side. If for some reason you want the
electronics to face the front side of the speakers, you can simply swap the
legs.
The multipin connector that is used to connect the speaker cabinet to
the electronics contained in the leg can be pulled out of either side of the
bottom aluminium prole attached to the cabinet. So the choice is yours,
where to place the ’active leg‘.
Plug the cable connector into the chassis connector of the leg.
Very Important:
Every speaker is individually measured and tuned during manufacturing,
the unique correction curve for this speaker is then stored in the DSP of the
matching electronics.
Therefore both parts, speaker and electronics, get the same serial number.
Please always make sure you assemble the matching electronics with its
proper speaker.
Unpacking and Assembly
Unpacking And Assembly
Unpacking And Assembly
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Unpacking and Assembly
Unpacking And Assembly
Unpacking And Assembly
Put both legs ush with the cabinet on the table, until the four magnets
have snapped onto the metal sides of the speaker cabinet.
Please be careful, these are very strong magnets. Keep them far from
anything sensitive to magnetic elds.
Please secure the connection of the legs and cabinet by tting the knurled
screws (found in the ’accessory box‘) on the top part of the inside of the
legs.
Screw them in, but don´t tighten them completely yet, so we can still allign
all the edges exactly by hand later on, once the LS1 are in place, because
we also want them to look good...
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