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DE1730-01 Limpet Data Sheet


    Limpet       is a signal processing and networked control                           Two independent channels
    and monitoring module intended for installation in an
    active loudspeaker, making an ideal companion for Linea’s                           High quality 96kHz audio processing
    MiniPod amplifiers. Processing includes crossover filtering,                        Separate OEM and User settings
    equalisation, delay and limiting, in addition to
    comprehensive monitoring features. Exceptional sonic                                Temperature monitoring
    quality is assured by careful selection of critical                                 Driver impedance monitoring
    components, minimum signal path and expert DSP
    algorithm design. Limpet’s small dimensions allow it to be                          Abuse logging
    tucked away in a restricted space.                                                  BvNET networking
                                                                                                The number of channels shown in PodWare
Introduction / Key Features                    Branding                                         is determined by the firmware model
                                                                                                issued by Linea Research.
Primarily targeted at active loudspeakers,     Each device is branded for the OEM
Limpet is an ideal companion for Linea         customer so that PodWare reports the model
Research’s analog pod amplifiers, adding       name of your choice, with your colour            Voices
Digital Signal Processing and BvNET            scheme etc.
networked setup, monitoring and control.                                                        Limpet allows four complete sets          of
                                                                                                parameters to be stored. Each set is
Housed in a compact, rugged steel case,        Crossover shapes
Limpet provides generous amounts of                                                             called a Voice. Voices may be used, for
                                               Limpet is capable of crossovers up to 8th        example, to select an alternative tuning as
signal processing capability, with access to   order (48dB/Octave). In addition to the
a wide variety of crossover shapes.                                                             may be required if a speaker is used with
                                               usual Butterworth, Linkwitz-Riley and Bessel     or without a separate sub-bass unit. Voice
                                               filter shapes, Limpet provides access to         settings are stored permanently inside
A simple user-interface may consist of         Hardman crossover filtering, a technique we
some essential indicators and a switch                                                          Limpet and so will always be available even
                                               are proud to have introduced to the industry.
arrangement which allows the user to                                                            if Limpet is not being used with PodWare.
                                               Hardman filters produce much steeper cut-
select from a number of Voicings which         off slopes for a given order than
you provide.                                                                                    The voice selected depends on the
                                               conventional crossover alignments, without       condition of two ‘switch’ lines. Normally two
                                               any additional group delay. This allows a        latching switches would be used to
A multi-km network of devices may be           lower order filter to be used without
monitored and controlled by the PodWare                                                         determine which voice is selected. If no
                                               sacrificing cut-off characteristics, but with    connections are made to either of the two
Windows application. Protection of your        smoother group delay and less severe phase
settings is assured in an uncomplicated                                                         voice select terminals, voice 1 will always
                                               penalties, giving a more natural sound.          be activated at power-on.
fashion by cleanly separating your OEM         Hardman filters also provide identical phase
settings from those which the user has         characteristics between adjacent bands (like
access to.                                     Linkwitz-Riley), so the polar performance is     Indicators and Switches
                                               rock steady
                                                                                                Up to two LED indicators and up to two
                                               We also employ phase matching on our             Switches may be used on your loudspeaker
                                               Bessel filters, so adjacent bands are in-phase   and wired into Limpet. The LEDs can be
                                               throughout the crossover region.                 configured to show a range of things such
                                                                                                as Signal Presence and Limiter action. The
                                               Our white-paper “Crossover Filter Shape          switches would normally be used to select
                                               Comparisons” provides more detail on this        Factory/User Voice and Factory A/Factory B
                                               subject.                                         Voice.

                                               High-Pass Filtering                              Temperature Sensing
                                               To avoid unnecessary inter-band phase            Limpet contains a temperature sensor
Sonic Purity                                   shifts common in many competing products,        internally, which is always shown on the
                                               we provide high-pass filtering on the inputs     PodWare panel.
Limpet uses 96kHz sampling rate, Burr-                                                          Up to two further external temperature
                                               rather than forcing you to apply ‘system’
Brown analogue-to-digital converter, the                                                        sensors may be attached. Your OEM
                                               high-pass filtering on the low crossover
renowned Wolfson multi-bit digital-to-                                                          settings will determine whether each of
analogue converter, and a powerful 3rd                                                          these sensors is enabled. If any external
generation Sharc Digital signal Processor                                                       sensor is enabled, a temperature bargraph
                                               Our white-paper “High-Pass Filtering in Two-
(DSP) running audio processing algorithms                                                       and a temperature log will be displayed for
                                               Way Systems” explains why this is
borne of years of experience in high                                                            that sensor in PodWare.
quality professional digital audio. All this
adds up to deliver the ultimate in sonic
transparency and a stunning open natural       Configuration                                    Impedance Monitoring
sound quality, fully living up to the very     Limpet may be configured to provide              Up to two external current transformers
high sonic standards set in our amplifier      processing for up to 2 audio inputs and up to    may be attached which can monitor the
products.                                      two audio outputs.                               impedance of the connected driver(s).

    Limpet                                                                              Page 1 of 3
PodWare is then able to check that the           However, the OEM can optionally hide the
driver impedance is within the limits            input High-Pass filters from the user in
determined by your OEM settings.                 situations where these are required by the
                                                 OEM for integrating the loudspeaker with a           Parameter              OEM        User
                                                 separate Sub-woofer.
PodWare’s MonIcon                                User settings
                                                                                                 Input gain

The PodWare application uses a small             The user cannot access your driver (output)     Input High-Pass filter
panel called a MonIcon to display all the        settings since these are only accessible in     Input Low-Pass filter
                  important           status     OEM mode, which is password protected.
                  information         about      The user can however apply input                8 band Input
                  Limpet at a glance.            processing, which will effectively overlay      2-band Input shelving
                  From this small panel it       your OEM settings.
                  is possible to see input                                                       Input Delay
                  signal activity, limiter       In normal User mode, the full Limpet control    Output Gain
                  activity, temperatures,        panel in PodWare looks like this:
                                                                                                 Output High-Pass
                  amplifier       protection
                  status, driver impedance                                                       Output Low-Pass Filter
                  status and amplifier clip
                                                                                                 6 band Output
                  indication, as well as
                  being able to change                                                           2 band Output
the gain and mute the loudspeaker. The
                                                                                                 Output Delay
full control panel is only one click away
from the MonIcon. You can also update                                                            Output Limiter
the firmware in the unit via PodWare –                                                           Input level meter
even via the network.
                                                                                                 Limiter meters

OEM Settings                                                                                     Amplifier protect
                                                 Abuse Monitoring
                                                                                                 Temperature meter(s)
As the OEM, you have complete freedom            Limpet continuously records logs against
to edit the crossover, driver equalisation       time for all the temperature readings, and      Driver imp.indicator(s)
and driver delay parameters. You can also        the state of amplifier protection for up to 3   Amplifier clip indicator
apply a model name for the loudspeaker.          days into the past. These may be easily
Once a complete tuning has been                  viewed at any time. The data from them can      Abuse logging
completed, PodWare allows you to save a          even be exported to a spreadsheet for           Power cycle count
Factory file which contains all these            further analysis.
parameters. This file can then be used to
load settings in production.                                                                     Obcom
Should you wish to change the OEM
settings in the field, modified Factory files                                                    An all-new, clean messaging system
can be distributed and loaded by the user                                                        developed by Linea Research, called
without disturbing the user-settings, and                                                        Obcom is at the heart of our software.
without the user being able to access the                                                        Obcom is used throughout our application
OEM settings.                                                                                    software, and across all communications
In OEM mode, the full Limpet control                                                             media (such as BvNET). It is a thoroughly
panel in PodWare looks like this:                                                                uniform standard that allows easy
                                                                                                 communication       between      different
                                                                                                 applications and different devices that
                                                                                                 support the Obcom standard. Obcom now
                                                                                                 has a large user base and is supported by
                                                                                                 many Pro Audio manufacturers.

                                                                                                 There are eight multi-way connectors on
                                                                                                 Limpet, suitable for connection to:
                                                                                                 •   The Channel A amplifier (audio output
                                                                                                 •   The Channel B amplifier.
                                                                                                 •   The ‘interface panel’ (audio input A
                                                                                                     and indicators, switches etc).
                                                                                                 •   The channel B audio Input
                                                                                                 •   External temperature sensor A
                                                                                                 •   External temperature sensor B
                                                                                                 •   External current sensor A
                                                                                                 •   External current sensor B
By having a clean split between OEM and          Availability of Features                        Linea Research can supply ‘standard’ wiring
User processing, security is very simple:        Depending on whether PodWare is in OEM          looms     and    interface   circuit board
The user cannot access any of the                mode or User mode, the ‘parameters’ which       assemblies. We would also be pleased to
parameters which are considered to be the        may be viewed (and if appropriate, edited)      assist with the design of any custom wiring
responsibility of the OEM. Only with the         are as follows:                                 looms, and would be pleased to offer a
OEM password (agreed with Linea                                                                  quotation to supply such looms or
Research) can PodWare be unlocked to                                                             completely wired panels
gain access to the OEM parameters.

Limpet                                                                                  Page 2 of 3
                                                                                       with these directives implies conformity
Technical Specifications                Environmental
                                                                                       with the following European standards:
                                          Temperature:    0 to +55°C
                                          Humidity:       0 to 80% RH                  •    EN55103-1        Electromagnetic
Input impedance: 5.5k Ohm unbalanced
                 11k balanced                             (non-condensing)                  Interference (Emission)
                                        Dimensions                                     •    EN55103-2        Electromagnetic
Output Imp:       <50R Gnd balanced                                                         Susceptibility (Immunity)
                                          Height:         24mm
Max Input level: +10dBu                   Width:          83mm
Max Output level: +5.5dBu                 Depth:          138mm                        It also meets the requirements of part 15B
                                          Weight:         300g                         (EMC).
Sample rate:     96kHz
Frequency Resp: 20Hz - 20kHz+/-0.5dB                                                   This product is intended for operation in
                10Hz - 40kHz +/- 1dB    Regulatory compliance                          the E2 (commercial & light industrial) and
Dynamic range : 110dB A                                                                E3 (urban outdoors) Electromagnetic
                                        This product complies with the EMC Directive
                (20Hz - 20kHz)                                                         Environments.
                                        (89/336/EEC) as issued by the Commission
THD (20Hz–20kHz): <0.01%                                                               E&OE
                                        of the European Community. Compliance
Power consumption: 4W max.

   Signal Processing Block Diagram

   Dimensional Drawing

Limpet                                                                     Page 3 of 3

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