Dm420ds M420 Dm420 Ds Scr[3114]
User Manual: M420
Open the PDF directly: View PDF 
.
Page Count: 2
Background
In-wall loudspeakers are not a new invention. Indeed they have been employed for
many years by installers who wish to provide an unobtrusive audio solution to customers
who have been unwilling or unable to install conventional free-standing loudspeakers.
However, the design restraints generally imposed on an in-wall design – limited space
and thus limited enclosure volume, physical limitations on materials and other restric-
tions – have meant that in-walls have traditionally offered a level of quality and per-
formance that has lagged some distance behind their free-standing counterparts.
Meridian’s DSP420 breaks that mould with an in-wall loudspeaker that is a cut above
the rest. Inside each unit, Meridian’s unique high technology digital signal processing is
used to free the sound from the walls: the result is clear and open with a wide response,
very much in line with the performance of Meridian’s smaller free-standing DSP-based
loudspeaker models, and with a similar character, enabling in-wall and free-standing
speakers to be combined in a single system as required.
As a result, the DSP420 has become one of Meridian’s most popular loudspeakers.
Following its success, and in response to customer demand, an active analogue variant,
the M420, is now available, with the same bass drivers and power amplifiers as the DSP
version. In addition, the back-box available for both units has been redesigned to permit
easier and quicker installation, including BNC connectors on the digital version and XLRs
on the analogue.
Truly Active In-Walls
The DSP420 and M420 are truly active in-wall speakers with separate internal amplifica-
tion for high and low frequency bands. Rated at 65 and 85 Watts respectively and using
carefully selected bipolar output devices, the idealised low feedback designs are based
on those used in other Meridian loudspeakers to deliver exceptionally fast bass response
and high resolution. These amplifiers are coupled directly to the drive units for the most
efficient delivery of power and the best possible control over driver excursion. Both ana-
logue and digital variants exhibit extremely low levels of noise and distortion, aided by
careful star earthing, while the power supply includes a substantial toroidal transformer
and audiophile-grade capacitors.
Meridian DSP
The DSP420 accepts digital input signals up to 96kHz/24bit, including Meridian High
Resolution (MHR) streams from Meridian Surround Controllers, Processors and DVD
Players.
DSP420
Digital Signal Processing
In-Wall Loudspeaker System
M420
Analogue Active In-Wall
Loudspeaker System
The world’s first DSP In-wall
based on technology used in
Meridian’s famous DSP speakers
New analogue active version
also available
Easy-install sealed pre-
construction enclosure with
redesigned, simplified back-box
Double sealed and damped
acoustic enclosure
Separate, on-board,
85W bass and 65W treble
power amplifiers
2 way active speaker with
DSP (DSP420) or analogue
line-level (M420) crossover
Custom paintable grille/frame
The DSP420 accepts up to 96kHz/
24-bit inputs including Meridian
MHR Smart Link. The M420 accepts
line-level balanced analogue inputs.
Unit is designed to comply fully with
international building regulations
Meridian America Inc
8055 Troon Circle, Suite C
Austell, Atlanta GA 30168-7849
USA
T +1 (404) 344 7111
F +1 (404) 346 7111
Meridian Audio Limited
Latham Road
Huntingdon
Cambridgeshire PE29 6YE
United Kingdom
T +44 (0) 1480 445678
F +44 (0) 1480 445686
www.meridian-audio.com
Enclosed in a fully shielded housing, Meridian’s unique DSP processing is performed
on a specially-designed six-layer PCB using a powerful 100 MIPS Motorola DSP engine.
Thanks to this sophisticated audio computer, the DSP420 embodies identical high-tech-
nology features to those found throughout the Meridian DSP Loudspeaker family. These
include:
• Position control to compensate for speaker location
• FIFO memory buffer at the input for the lowest possible jitter
• Linear-phase crossover for precision drive unit integration
• Tweeter delay for perfect driver alignment
• 48-bit resolution volume control
• Minimal frequency equalisation, delivering a frequency response free from drive unit
or electronic colouration
• Transparent tone controls
• Absolute phase control
• Phase-corrected balance control
Active Bass Extension
A further DSP-enabled enhancement to the audio performance of the DSP420 is
Meridian’s active bass extension. This deepens the response of the system without exces-
sive woofer excursion and in turn produces a convincingly ‘big box’ sound from an in-
wall unit. At moderate volumes, a psychoacoustically-correct filter significantly extends
the bass response, while at high volumes dynamic DSP bass protection is used to prevent
the woofers from bottoming.
Analogue or Digital – Your Choice
Following the success of the original DSP420, the loudspeaker is now also available in
an analogue active version, the M420. The M420 features a balanced line-level audio
input (which may be unbalanced), with an XLR link from back-box to speaker unit (the
digital unit is connected to the back-box via a 15-pin DSUB cable) and analogue crosso-
ver. The amplifiers, bass drivers and enclosure are identical in both variants. In addi-
tion, a redesigned back-box is available, common to both units, that features several
design improvements based on installer feedback from the original design. Audio and
power interfacing are built into fire-retardant boxes. The available redesigned back-box
kit includes both analogue and digital input boards, allowing the correct board to be
installed as appropriate. While the original screw terminals are retained, digital audio
and Meridian Comms connections also employ BNC connectors, while analogue audio is
on XLR. Power is hard-wired into the back-box and supplied to the speaker assembly via
an IEC connector, thus helping to maximise the speed and efficiency of installation.
Acoustics
The DSP420/M420 front baffle and acoustic back box are made from aluminium. This
offers very low resonance at low frequencies and is further damped by the incorpora-
tion of stiffening into the back-box. Additional high frequency damping means that
the whole system suffers exceptionally low cabinet colouration and delivers excellent
mid-range transparency. All damping materials have been fully tested and in all cases
comfortably meet or exceed building regulations for in-wall design.
The bass drive units are two parallel 5in woofers with cast alloy chassis, carbon fibre
cones and very large shielded magnets that provide excellent drive and control.
The tweeter (aluminium-domed in the DSP420, silk-domed in the M420) has a
Neodymium magnet and a protective grille, while an acoustically transparent grille pro-
tects the front baffle and drive units from harm when installed. Its powder finish means
the grille can be easily painted, helping the unit to blend in with its surroundings.
DSP420
Digital Signal Processing
In-Wall Loudspeaker System
M420
Analogue Active In-Wall
Loudspeaker System
The DSP420 uses the same design
principles as the famous Meridian
DSP8000 and is perfect for use in a
Meridian Digital Theatre® where a
discreet appearance is required
DM420DS v3.6 20050623 RE
Outline Specifications
Inputs: DSP420—1 x 75Ω coaxial digital input, IEC958 (S/PDIF), 44.1kHz – 96kHz.
FIFO locks at 44.1, 48, 88.2, & 96kHz ±150 PPM, PCM & MHR.
M420—1 x 300Ω balanced line-level input on XLR connector
Enclosure: Aluminium front baffle with sealed, mechanically damped and insulated
acoustic enclosure. Baffle finished in textured black enamel.
Grille finished in easy-to-paint white powder coat, backed by acoustically-
transparent scrim. White moulded custom paintable frame.
Acoustics: 2-way Infinite Baffle enclosure.
2 x 127mm high-efficiency long-throw custom bass drivers,
1 x Meridian 25mm tweeter with aluminium (DSP420) or silk (M420) dome.
Response: 55Hz – 20kHz ±3dB.
Amplification: Internal 85W woofer, 65W tweeter. 6VA (quiescent) – 200VA (full output).
DSP (DSP420): 100MHz Motorola 56364, Linear Phase Crossover, 96kHz, 24-bit DAC.
Controls & Indicators: Front baffle controls for power and channel selection.
LED indicators for power, lock (DSP version) and thermal warning.
Approx. Dimensions: Frame 450mm (17.72in) square, depth 102mm (4.02in) Hole cutout 357 x 388mm (14.10 x
15.28in) Note: dimensions are approximate. See installation drawings for detailed informa-
tion. The DSP420 and M420 are designed to fit standard 16in stud centres.
Approx. Weight: 8.5 kg (18.7 lb) main unit without frame, grille or connection boxes.
Mounting: Easy-install frame with fire-retardant power and audio connection boxes. Templates pro-
vided for both new construction and installation into existing walls/ceilings.
