Operating Instructions
HM-1S
Self-Powered
Studio Monitor
Patents Pending
Copyright © 1998
Meyer Sound Laboratories, Inc.
All rights reserved
Part # 05.059.004.01 Rev A2
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Introduction
Power Requirements
The Meyer HM-1S Studio Monitor is a compact, full-
range, self-powered reference monitor that employs a
concentric tweeter mounting structure to achieve true
point-source performance. Sophisticated phase-correc-
tion circuitry provides superb imaging without the off-axis
cancellation effects, back-wave interference, and IM dis-
tortion commonly exhibited by dual-concentric speakers.
The HM-1S requires a 48 VDC external power supply,
which provides these benefits:
•
•
•
Low voltage wiring simplifies installation.
Utilizes telecom 48 V supply and bus standard.
Eliminates 50/60 Hz AC noise coupling in wiring.
The power supply input uses a male 2-pin EN3 connector.
The HM-1S can be powered by the Meyer PS-1 AC
adapter or a supply that conforms to the 48 VDC specifi-
cations detailed in this section.
The HM-1S Studio Monitor is a two-way system comprising a
7-inch graphite cone low-frequency driver, and a concen-
trically-mounted, 1-inch soft-dome high-frequencydriver.
A constant-directivity, high-frequency horn affords a sym-
metric 100° beam width. The HM-1S employs optimized
electronics, drivers, and cabinet venting (tuned to40Hz)
to achieve low frequency response far exceeding that of
mostsmallspeakers.Thedriversaremagneticallyshielded
and the magnets employ field-cancelling techniques
to minimize magnetic leakage, allowing speaker place-
ment within one foot of color video monitors.
MeyerPS-1ACAdapter
Using the Meyer PS-1AC adapter is the simplest way to
power a pair of HM-1Ss, or a single HM-1S with a sub-
woofer. TheAC adapter can be purchased through Meyer
Sound and comes with two 10 ft power cables. The AC
adapter has two output connectors that are wired together
inside the supply, allowing either one connector to
drive two speakers at the end of a single cable, or one
connector and cable per speaker.
The HM-1S can be used with the Meyer HM-1S Studio
Subwoofer, extending the free-field LF (low frequency)
response down to 42 Hz. The passive subwoofer is
poweredfromtheSuboutputontherearpaneloftheHM-
1S. Although each HM-1S Studio Monitor can power a
subwoofer, ample LF energy may be obtained by driving
one subwoofer from two HM-1S Studio Monitors, result-
inginacorrectly-summedmonosignal. Subwooferusage
depends on the loading conditions, the LF gain desired,
and whether a stereo LF signal is required. Placing the
HM-1S next to a wall or ceiling (half-space loading) also
extends the LF response down to 42 Hz.
Do not connect the outputs of multiple PS-1 AC
adapters together!
For installations up to 10 HM-1Ss, using multiple PS-1
AC adapters is often the simplest and most cost-effective
solution. Since the limited output power for each supply
acts as circuit protection for light gauge cables, it is not
necessary to install circuit breaker distribution panels.
Using the PS-1 does, however, limit each 48 V line to two
speakers. The dimensions of theAC adapter are 10” x 5” x 3”.
Contact Meyer Sound for further information on the PS-
1 AC Adapter.
The HM-1S Studio Monitor and Subwoofer cabinets are
constructed from medium density fiberboard and fin-
ished with an attractive, durable oak veneer (natural
wood or black). Although external heatsinks on the rear
of the cabinet provide adequate convection cooling, a
variable-speedcoolingfanassembly(part#40.039.016.01,
driven from a rear-panel output and mounted on the rear
of the speaker) is available if the HM-1S will be operated
in hot temperatures or in an unventilated, enclosed area.
Theenclosurecontainsa400Wstereoamplifier, anactive
crossover, frequency and phase alignment circuitry, and
driver protection voltage limiters. Front-panel LEDs indicate
power, signal limit, and thermal overload, and a rear-
panel circuit breaker provides overall DC power protection.
!
Do not use a ground-lifting adapter or cut the AC
cable ground pin.
The HM-1S accepts a unipolar 48 VDC power source,
which may be supplied by the Meyer PS-1 AC Adapter.
Using a DC supply enables long power cable runs with
minimal induced noise or hum, which is particularly im-
portant for recording studios and other noise sensitive
environments.
3
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Power Supplies for Larger Systems
If an installation includes more than 10 speakers, or
requires several speakers to operate from a single 48 V
line, a single, high-output power supply should be
considered. The following sections provide current and
voltagespecificationsfortheHM-1S’spowerrequirements.
Current Ratings
Thewidedynamicrangeofaudiosignalsnormallycauses
a high peak-to-RMS ratio in an amplifier’s DC supply
currents. The HM-1S has internal storage circuits to
minimize the peak-to-average ratio, which
•
reduces the peak power rating required by the
supply;
•
allows efficient use of switched-mode power sup- An HM-1S with subwoofer draws 0.4 ADC, 20 W in a
plies which have similar peak and continuous rat- quiescent state.
ings.
Voltage Ratings
The following table lists the current and power draw for a
single HM-1S at light, moderate, and maximum operating
levels.
The voltage operating range for the HM-1S is 48 VDC
nominal, 52 VDC absolute maximum, and 35 VDC
minimum without shutoff.
Allowing operation down to 35 VDC provides two ben-
efits. First, a moderate voltage drop (up to 8 V) for long
DC power cables has a minimal impact on audio perfor-
mance, enabling the use of light-gauge cables for most
installations.
Second, since some switched-mode power supplies
slowly foldback the voltage if they experience current-
limit, power supplies with lower power (current) ratings
can be used efficiently. Since supplies with lower power
ratings typically experience current-limit when the HM-
1S is at continuous limiting, some voltage drop and loss
of headroom is acceptable provided the voltage does
not drop below 35 VDC. At 35 V, the maximum current
draw is 25% lower than the values stated in the preceding
tables.
Each HM-1S draws 0.4 ADC, 20 W in a quiescent state.
The RMS current is measured over a 500 ms integration
time. The peak current is measured over a 10 ms integration
time.
Each HM-1S can drive a slaved Meyer subwoofer from a
connection on the amplifier panel. Adding the subwoofer
increases the amplifier’s output current, which increases
the power supply current. The current and power ratings
for an HM-1S and a subwoofer are listed in the following
table at light, moderate, and maximum operating levels.
NOTE: If the HM-1S will not be driven at continuous limiting,
a power supply that satisfies the moderate specifications
for voltage and current can be used safely without risk of
sonic degradation or interruption.
It is important to understand how the selected power
supply responds to current-limit, particularly for switched-
mode supplies. Some supplies trip off and must be reset
manually, while others remain off for a period of time and
reset automatically. In both cases, the HM-1S suffers
4
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audio interruption. In the third, and preferable case, Asingle HM-1S attached to a 100 ft 18AWG cable (1.27
supplies that feature voltage foldback allow brief periods Ω total) produces a 6.4 VDC loss at the speaker (41.6 V)
of current-limit without audio interruption; for this reason, during maximum audio bursts (5A, 0.5 s). This results in
we recommend using such supplies.
a small loss in peak SPL.
The HM-1S does not require tight voltage regulation and
operates down to 35 V although peak SPL values are
reduced. This operating voltage flexibility allows for wir-
ing loss and voltage foldback without interruption or
degradation of the audio signal.
Audio Input
TheHM-1Shasaninputimpedanceof10kΩandreceives
its audio input signal at a female XLR connector. Pins 2
and 3 carry the input as a differential signal; pin 1 and the
case are connected to the chassis. The power and audio
cables can be jacketed in the same sheath without induc-
ing noise to the input signal.
Many high power industrial supplies (1–5 kWatt) are
available for 19” EIA racks that are suitable for large
installations with equipment rooms. Distribution panels
with branch circuits can be used economically with up to
8 HM-1Ss on a branch. Contact Meyer Sound for in-
formation on tested and approved supplies.
For best EMI immunity, it is desirable to use a twisted pair
shielded cable with the twisted pair connected to pins 2
and 3, and the shield to pin 1. However, an unshielded
twisted pair cable can be used effectively, even if it is
jacketed with the power cable.
Power Cable Requirements
Each HM-1S draws a maximum of 3 Arms and 5 Apk The input is RF and ESD protected, capacitive coupled,
from a 48 V power supply at peak SPL. The cabling ±50Vcommon modetoground, +4dBunominal, +21dBu
between the 48 V supply and the speaker adds resis- max. Clippingoccursattheinputat12Vpk. TheCommon
tance to the circuit and produces a voltage drop at the Mode Rejection Ratio (CMRR) is greater than 80 dB.
speaker. Decreasing the voltage at the speaker com-
promises the peak SPL so cable resistance should be
minimized.
The HM-1S Subwoofer
For best sonic performance, avoid voltage drops greater
than 8 V at the speaker. Voltage drops greater than 15
V may cause the speaker to mute or distort. The maxi-
ThelowfrequencyresponseofanHM-1Scanbeextended
mum round-trip resistance for a cable attached to a
downto42HzifusedwiththeHM-1SSubwooferorplaced
single HM-1S should be no higher than 1.6 Ω, which
keeps the voltage drop below 8 V during the maximum
current draw of 5 Apk.
next to a wall or ceiling (half-space loading). Each HM-1S
can power a subwoofer from the male 3-pin EN3 Sub
outputconnectorontherearpanel.However,dependingon
the loading conditions, ample low frequency energy may
be obtained by driving a single subwoofer from two HM-
1Ss, resultinginacorrectly-summedmonosignal. Cables
forconnectingoneHM-1Stoasubwoofer andtwoHM-1s
to a single subwoofer are shipped with each HM-1S
Subwoofer.
The following table helps select cable gauges for various
cable lengths.
The addition of one subwoofer increases the maximum
SPLof a single HM-1S by 4 dB (without sub: 116 dB SPL;
with sub: 120 dB SPL). The HM-1S Subwoofer has the
following specifications:
Transducer
10” low frequency cone driver
Enclosure/Finish
Medium Density Fiberboard (MDF) /
Oak Veneer (natural or black)
Weight
33 lb (11.0 kg)
Dimensions
Height: 17.5”; Width: 12.3”; Depth: 9.3
5
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HM-1S Speaker Cable
The following drawings and procedures are provided as
an aid in the event that the speaker cable used to connect
theHM-1StotheHM-1SSubwooferneeds toberepaired
or extended. In cases where the original speaker cable
has been modified, be sure to complete the Subwoofer
Performance Verification section on page 10 of this
manual. Misalignment of the polarity between the HM-1S
and the HM-1S Subwoofer will result in a serious degra-
dation of performance.
(Single HM-1S to HM-1S) Stereo Subwoofer Cable
M.S.P.N. 28.062.007.01
(2 HM-1S to 1 HM-1S) Mono Subwoofer Cable
M.S.P.N. 28.062.009.01
Connections:
Gray wire to pin 1,
pin 2 no connection,
pin 3 no connection.
GRAY
-
Connections:
Gray wire to pin 1,
pin 2 no connection,
White wire to pin 3.
Connections:
pin 1 no connection,
pin 2 no connection.
White wire to pin 3.
WHITE
+
6
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HM-1S to HM-1S Subwoofer Cable
Connector Assembly Procedure
Boot
Coupling Ring
Cord Connector
Cable
Cable Clamp Housing
Contact Pins
Step 1:
Feed the end of the cable through the boot, cable clamp housing,
and coupling ring in the order and position shown.
Cord Connector
Dot pin 1
Cable
Solder
9/32"
3/8" Max.
indicator
3
1
1
3
7/32"
2
Contact Pins
Step 2:
FOR STEREO CABLES: Strip cable as shown and begin soldering conductors to pins starting
with the Gray wire to pin 1, pin 2 no connection, and the White wire to pin 3.
FOR MONO CABLES: See wiring instructions on page 6.
Cord Connector
Cord Connector
Tab
Tab
Coupling Ring
Side notch
Step 3:
Align coupling ring's tabs with cord connector's side notches and push
the coupling ring onto cord connector.
Clamp
Clamp
Lock
Step 4:
Push the cable clamp housing foward until it locks into the connector body
and snap the two clamps into their compartments.
Step 5:
Push the boot all the way foward to seat tightly onto the cable clamp housing.
7
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Subwoofer Performance Verification
There are two methods of verifying that the phase relationship between the HM-1S and its subwoofer. One method is
free field, the other is a ground plane measurement in half space.
Free Field:
Place the HM-1S directly above and coplanar to the subwoofer as pictured below:
Place a calibrated measurement microphone 1 meter, on axis to the tweeter of the HM-1S as pictured below:
Using the noise or other broadband test signal, perform a transfer function of the HM-1S. Start with the subwoofer
disconnected.
8
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HM-1S on axis at 1 meter, free field.
This represents a typical response of the HM-1S in free-field environment, on axis at 1 meter. This measurement
was performed in the large anechoic chamber at MSLI.
Connect the subwoofer and measure the combined response of the system.
9
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HM-1S with in-phase subwoofer on axis at 1 meter, free field.
This represents a typical response of the HM-1S and subwoofer, in phase, in a free field environment on axis at 1
meter. This measurement was performed in the large anechoic chamber at MSLI. This response indicates a
complementaryphaserelationshipbetweentheHM-1Sandsubwoofer.
10
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If the subwoofer is out of phase, the combined response will have a significant loss of energy compared to the
overall response at around 82 Hz as illustrated below:
HM-1S with out-of-phase subwoofer on axis at 1 meter, free field.
11
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This represents a typical response of the HM-1S and subwoofer out-of-phase phase, in a free field environment on-
axis at 1 meter. This measurement was performed in the large anechoic chamber at MSLI.
If your system response indicates a phase reversal please contact Meyer Sound Technical Support for assistance.
Half Space:
To verify the system performance in half space you must perform a ground-plane measurement. This type of
measurement is not desirable for system calibration and should only be used to verify the performance of the
subwoofer. Place the HM-1S next to the subwoofer on the flat ground and position the calibrated measurement
microphone one meter on axis from the tweeter of the HM-1S as pictured below:
Using noise or other broadband test signal, perform a transfer function of the HM-1S. Start with the subwoofer
disconnected.
12
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HM-1S on axis at 1 meter, ground plane.
This represents a typical ground-plane response of the HM-1S, on-axis at 1 meter. Keep in mind that any surface
close to the test space can create reflections which will change the response of the speaker.
Connect the subwoofer to the HM-1S and measure the combined response of the system.
13
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HM-1S with in-phase Subwoofer on axis at 1 meter, ground plane.
This represents a typical ground-plane response of the HM-1S and subwoofer, in phase, at 1 meter. This response
indicates a complementary phase relationship between the HM-1S and subwoofer.
14
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If the subwoofer is out of phase the combined response will have a significant loss of energy compared to the
overall response at around 82 Hz as illustrated below:
HM-1S with out-of-phase Subwoofer on axis at 1 meter, ground plane.
This represents a typical ground plane response of the HM-1S and subwoofer out-of-phase, in a ground plane
environment on axis at 1 meter. If your system response indicates a phase reversal please contact Meyer Sound
Technical Support for assistance.
15
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The fans attach easily to the two bottom rear corners of
the HM-1S. Use a 5/32” Allen wrench to remove the bottom
screws and install the left and right fans according to the
diagram below. The fans are shipped with a terminal plug
keyed for insertion into the 2-pin fan output connector in
the proper orientation only.
Cooling and Fan Installation
The HM-1S depends on natural convection to cool the
heatsinks that absorb heat from the amplifiers and radiate
the heat into the surrounding air space. Natural convection
requires free air in back of, and underneath the HM-1S to
allowairtoflowupovertheheatsinks. TheHM-1Sreaches
an equilibrium temperature in approximately 15 minutes
at a steady operating level.
The fan speed is temperature controlled. At a heatsink
temperature of 25°C, the fans turn on at half speed and
increase speed linearly until reaching full speed at
75°C.
In free air, at a typical room temperature of 25°C, the HM-
1S reaches an equilibrium temperature of
Protection and Limiting
•
•
40°C in a quiescent state (no audio signal);
60°C at a moderate operating level (occasional
limiting);
ThefrontoftheHM-1ShastwoLEDsthatindicatepowerand
limiter activity. The right LED is green when power is ap-
plied. This LED turns red if thermal limiting occurs (de-
scribedinthesectionCoolingandFanInstallation)untilthe
temperature decreases to 75°C.
•
75°C at the maximum operating level (continuous
limiting), or at a moderate level with a subwoofer.
If the temperature reaches 85°C, the thermal limiters
activate (see Protection and Limiting) to prevent high
source levels from further increasing the temperature
and damaging the drivers and electronics. The thermal
limiters provide 30 dB of muting until the temperature
decreases to 75°C.
The left LED indicates driver limiter activity with a vari-
able intensity red color; full illumination occurs at thermal
limiting.
The HM-1S can be cooled by two fans, available as an
accessory kit. The fans should be used if:
Rigging
•
•
•
the HM-1S is enclosed in a soffit or ceiling mount
without adequate space for natural convection;
the HM-1S is used in hot ambient temperatures or
direct sunlight;
!
Do not drill into the HM-1S Cabinet.
theuserwishestoavoidaccidentalcontactwiththe
heatsinks if the rear of the HM-1S is exposed.
The HM-1S is not designed for use with rigging systems.
For rigging needs, Use the Standard Contractors version
HM-1cabinetswhichcanbeeasilyfittedforomni-mounts,
and other rigging options.
Installed fans blow air over the heatsink
16
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!
Safety Summary
English
Français
• To reduce the risk of electric shock, disconnect the loud-
speakerfromtheACadapterbeforeinstallingaudiocable.
Reconnect the adapter only after making all signal con-
nections.
• Pourréduirelerisqued’électrocution, débranchezlaprise
principale de l’haut-parleur, avant d’installer le câble
d’interface allant à l’audio. Ne rebranchez le bloc
d’alimentation qu’après avoir effectué toutes les connections.
• Connect the AC adapter to a two-pole, three wire grounding
mains receptacle. The receptacle must be connected to a
fuse or circuit breaker. Connection to any other type of
receptacle poses a shock hazard and may violate local
electrical codes.
• Branchez l’haut-parleur dans une prise de courant à 3
dérivations (deux pôles et la terre). Cette prise doit être
munie d’une protection adéquate (fusible ou coupe-circuit).
Le branchement dans tout autre genre de prise pourrait
entraîner un risque d’électrocution et peut constituer une
infractionàlaréglementationlocaleconcernantlesinstal-
lations électriques.
• Do not install the loudspeaker in wet or humid locations.
• Do not allow water or any foreign object to get inside the
loudspeaker. Do not put objects containing liquid on, or
near, the unit.
• Ne pas installer l’haut-parleur dans un endroit où il y a de
l’eau ou une humidité excessive.
• Ne pas laisser de l’eau ou tout objet pénétrer dans l’haut-
parleur. Ne pas placer de r´cipients contenant un liquide
sur cet appareil, ni à proximité de celui-ci.
• To reduce the risk of overheating the loudspeaker, avoid
exposing it to direct sunlight. Do not install the unit near
heat emitting appliances, such as a room heater or stove.
• Pour éviter une surchauffe de l’haut-parleur, conservez-la
à l’abri du soleil. Ne pas installer à proximité d’appareils
dégageant de la chaleur tels que radiateurs ou appareils
de chauffage.
• Thisloudspeakercontainspotentiallyhazardousvoltages.
Do not attempt to disassemble the unit. The unit contains
no user serviceable parts. Repairs should be performed
only by factory trained service personnel.
• Ce haut-parleur contient des circuits haute tension
présentant un danger. Ne jamais essayer de le démonter.
Il n’y a aucun composant qui puisse être réparé par
l’utilisateur.Touteslesréparationsdoiventêtreeffectuées
par du personnel qualifié et agréé par le constructeur.
Deutsch
Español
• UmdieGefahreineselektrischenSchlagesaufeinMinimum
zu reduzieren, den Lautsprecher vom Stromnetz trennen,
bevor ggf. ein Audio-Schnittstellensignalkabel
angeschlossenwird. DasNetzkabelerstnachHerstellung
aller Signalverbindungen wieder einstecken.
• Para reducir el riesgo de descarga eléctrica, desconecte
de la red el altoparlante antes de instalar el cable de
señalización de interfaz de la segnale. Vuelva a conectar
el conductor flexible de alimentación solamente una vez
efectuadas todas las interconexiones de señalizatción.
• DerLautsprecheraneinegeerdetezweipoligeDreiphasen-
Netzsteckdoseanschließen. DieSteckdosemußmiteinem
geeigneten Abzweigschutz (Sicherung oder
Leistungsschalter) verbunden sein. Der Anschluß der
unterbrechungsfreienStromversorgunganeinenanderen
Steckdosentyp kann zu Stromschlägen führen und gegen
die örtlichen Vorschriften verstoßen.
• Conecteelaltoparlanteauntomacorrientebipolarytrifilar
con neutro de puesta a tierra. El tomacorriente debe estar
conectado a la protección de derivación apropiada (ya
sea un fusible o un disyuntor). La conexión a cualquier
otro tipo de tomacorriente puede constituir peligro de
descarga eléctrica y violar los códigos eléctricos locales.
• No instale el altoparlante en lugares donde haya agua o
humedad excesiva.
• Der Lautsprecher nicht an einem Ort aufstellen, an dem
sie mit Wasser oder übermäßig hoher Luftfeuchtigkeit in
Berührung kommen könnte.
• No deje que en el altoparlante entre agua ni ningún objeto
extraño. No ponga objetos con líquidos encima de la
unidad ni cerca de ella.
• Darauf achten, daß weder Wasser noch Fremdkörper in
das Innere den Lautsprecher eindringen. Keine Objekte,
die Flüssigkeit enthalten, auf oder neben die
unterbrechungsfreie Stromversorgung stellen.
• Parareducirelriesgodesobrecalentamiento, noexponga
la unidad a los rayos directos del sol ni la instale cerca de
artefactos que emiten calor, como estufas o cocinas.
• Um ein Überhitzen dem Lautsprecher zu verhindern, das
GerätvordirekterSonneneinstrahlungfernhaltenundnicht
in der Nähe von wärmeabstrahlenden Haushaltsgeräten
(z.B. Heizgerät oder Herd) aufstellen.
• Este altoparlante contiene niveles de voltaje peligrosos
en potencia. No intente desarmar la unidad, pues no
contiene piezas que puedan ser repardas por el usuario.
Lasreparacionesdebenefectuarseúnicamenteporparte
del personal de mantenimiento capacitado en la fábrica.
• Im Inneren diesem Lautsprecher herrschen potentiell
gefährliche Spannungen. Nicht versuchen, das Gerät zu
öffnen. EsenthältkeinevomBenutzerreparierbarenTeile.
Reparaturen dürfen nur von ausgebildetem
Kundenienstpersonal durchgeführt werden.
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Rear Panel Connectors
AudioInputSignal
(femaleXLR)
6 A
FanOutput
(2-pinterminalplug)
CircuitBreaker
Dimensions
All units in inches
HM-1SFront
HM-1SSide
HM-1STop
HM-1SSubFront
HM-1SSubSide
HM-1S weighs 11.0 lb (5.0 kg);
HM-1S Subwoofer weighs 33 lb (15 kg)
MeyerSoundGermanyGmbH
Carl Zeiss Strasse 13
D-56751 Polch
Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, California 94702
Telephone: 510 - 486 - 1166
Germany
Telephone: 26 54 96 00 58
FAX:
510 - 486 - 8356
FAX:
26 54 96 00 59
E-mail: [email protected]
E-Mail: [email protected]
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