Meyer Sound HD-1 User Manual

HD-1

The HD-1 High Definition
Audio Monitor* is a self-contained,
precision loudspeaker for near­field sound reproduction.

Aligned to closely approximate
a true point source radiator, the
HD-1 features exceptionally broad
directivity characteristics. Its time
delay response is tightly controlled,
with minimal deviation from linear
phase across the full frequency
range of its operation. Each unit is
individually factory-calibrated to
ensure unprecedented consistency
of performance. The HD-1 is
suitable for critical applications
ranging from professional record­ing to psychoacoustical research.

The HD-1 is a two-way system
comprising an 8-inch cone low­frequency driver and dome tweeter
housed in a vented cabinet. The
low-frequency driver features an
exceptionally large magnet struc­ture and a 2-inch voice coil for
greatest efficiency and heat dissipa­tion. The tweeter employs a
specially-developed impregnated
silk dome to minimize breakup and
colorization.

Both drivers are of a proprietary
design, and are individually
selected for maximum linearity.
Their magnet structures employ
sophisticated field-cancelling
design techniques to minimize
magnetic field leakage, and the
cabinets may safely be placed

High Definition
Audio Monitor

within 2 feet of sensitive color
video monitors. For applications
requiring closer proximity to
monitors, an optional steel­shielded model is available.

The HD-1 incorporates line-level
control electronics mounted within
a rear-panel chassis, including:

• an active balanced input circuit

with switchable sensitivity

(+4 dBu or -10 dBV);

• an active crossover utilizing

optimized pole-zero filter

combinations to achieve acousti-

cal transparency and linear

phase;

• independent protection circuits

for each loudspeaker driver;

• dual power amplifiers for

biamplification.

The driver protection circuits
employ thermo-predictive limiters
and soft peak clamps to guard

Operating Instructions

against damage from excessive
amplifier power and ensure
graceful overload characteristics.

Independent power biamplifiers
maximize system headroom,
efficiency and damping while
minimizing distortion. The low
frequency amplifier delivers 150
watts output power, while the high
frequency amplifier provides 75
watts. Both employ complementary
power MOSFET output stages
operating class A at low-to-moder­ate listening levels (<90 dB SPL),
and class AB at high levels.

The HD-1’s free-field frequency
response is flat within ±1 dB from
40 Hz to 20 kHz (-3 dB at 32 Hz
and 22 kHz). It delivers high peak
SPL with >100 dB dynamic range
and extremely low distortion.
Covers are included for use during
transport.

* patents pending

Meyer Sound Laboratories, Inc.
2832 San Pablo Avenue
Berkeley, California 94702

Setup & Operation

High
Definition
Audio

HD-1

Monitor

Locations of HD-1 Loudspeaker Components, Connectors and Controls

Dome tweeter

Cone low fre­quency driver

Indicator LED

IEC mains connector

and power switch

Voltage selector

switch

Calibration port

(factory use

only)

Voltage selection and

40
2

0
2
2

0
2

1

0

0
1

PUSH

fuse rating chart

Input connector

Input sensitivity
switch

Impact indicator

Power

• Set the voltage selector switch
before you connect and operate
the unit.

The HD-1 accepts AC voltages

from 90 to 260 VAC, at 50 or 60 Hz,
in four ranges. Select the range that
is closest to the local mains AC
voltage.

Do not switch among AC voltage
ranges with the power cable
connected to an outlet.

Fuse

The HD-1 is protected by a fast-

acting fuse in the voltage selector
switch.

• If the fuse blows, check the line

voltage and the voltage selector
setting.

• Always replace the fuse
with a component of
the same type and
rating.

Power Cable

• Connect the HD-1 to a
three-prong outlet.

Earth ground

Chassis ground

The HD-1 requires a grounded
outlet. Use a grounding adapter
when connecting to ungrounded

outlets.

Blue =
Neutral

Yellow/Green =
Earth Ground (Chassis)

Brown =
Hot

AC cable color code for wiring

international or special-purpose

power connectors

Placement

The HD-1 is designed for “near
field” operation. The best listening
distance is between 3 and 9 feet
from the speaker face.

The HD-1 is aligned for flat
frequency response in free field (no
adjacent boundary surfaces).
Placing it next to a wall or on the
floor will cause the low frequencies
to be exaggerated.

Nearby surfaces (such as a
mixing console control surface)
should be angled to minimize
reflections toward the listener.

For stereo playback systems,
speaker stands are highly recom­mended. Place them at least 3 feet
from any wall. In recording studios
the speakers may be placed on the
meter bridge.

When handling the
HD-1, avoid touching or
pressing on the dome
tweeter. If the dome
becomes dented, the
unit should be returned
for testing and
calibration

dome pops back into
position.

even if the

If the power cable appears frayed
or broken, replace it immediately
before operating the unit.

2

Never use ground-lifting
adapters. Do not cut the
AC cable ground pin.

• Always allow at least 6 inches

clearance behind the speaker for

cooling airflow.

Input Connection

The HD-1 presents a 10 kohm
input impedance at a three-pin
XLR-type receptacle wired as
follows:

Pin 1 Audio common
Pin 2 Signal low (-)
Pin 3 Signal high (+)
Case Earth (AC) ground

Shorting any input connector pin

to the case may form a ground

loop and cause hum.

Standard audio cables with
XLR-type connectors may be used
for balanced signal sources. Unbal­anced sources will require an in­line adapter.

Troubleshooting

Sensitivity Switch

• For professional balanced
equipment, use the +4 dBu
setting.

• For semiprofessional and
consumer unbalanced equip­ment, use the -10 dBV setting.

Note that the -10 dBV setting is

more sensitive (designed for lower
signal levels) than the +4 dBu
setting:

• +4 dBu position:

1.23 VRMS = 114 dB SPL RMS

• -10 dBV position:

0.316 VRMS = 114 dB SPL RMS

Driving the HD-1 from a +4 dBu
source with the switch set to -10
dBV will result in increased noise.

Operation

In normal operation, the front-

panel LED will glow green.

At high listening levels, the LED
may flash red on program peaks.
This indicates the onset of over­load, where the loudspeaker
protection limiters are activated.

If the LED is continuously red
for an extended period (8 hrs.),
thermal damage may result.

Calibration Port

The calibration port is for factory
use only. Do not apply external
voltages to any of the connector
pins.

Problem Symptom Possible Cause Action

No sound

not lit

Power switch on and lit, LED
out

Power switch on and lit, LED
lit

Distorted sound with hum

Selector switch setting correct

Low sound levels Insufficient drive from signal

Hiss Input sensitivity incorrectly set

Sensitivity setting correct

Program material OK

Bad AC connectionPower switch on but switch

Blown fuse

Signal source disconnected

AC voltage selector incor­rectly set

Power brownout

source

Input sensitivity incorrectly set

Program material

Source equipment malfunc­tion

Check AC outlet and power
cord.

Replace fuse. Check voltage
selector and AC line.

Check input cables, connec­tots and signal source.

Turn off HD-1. Check AC
outlet voltage and selector
switch setting.

Turn off HD-1. Check AC
outlet voltage; if low, contact
power company.

Increase source equipment
output level.

Set input sensitivity switch to

-10 dBV

Check sensitivity switch and
source equipment output.

Stop playback. If hiss
disappears, check program.

Unplug input connector. If
hiss disappears, check
source equipment.

Distorted or intermittent
sound

Input cables OK

Bad input connection

Defect in signal source
equipment

Check input cables

Substitute known good signal
source. If problem stops,
replace signal source
equipment.

3

Obtaining Service

The HD-1 Monitor is protected
by Meyer Sound’s Limited One­Year Warranty. For complete
information regarding terms and
conditions, refer to the printed
warranty statement that is packed
with the system.

To extend coverage to two full
years, and assure notification of
product improvements or literature
updates, complete and mail the
enclosed Warranty Registration
Card.

Specifications

Acoustical - HD-1 System

Frequency Response

Free Field

Maximum SPL

Signal-to-Noise Ratio

Coverage Angle (-6 dB)

Audio Input

Type

Connector

Nominal Input Level

1

32 Hz to 22 kHz

-3 dB at 32 Hz and 22 kHz

±1 dB from 40 Hz to 20 kHz

125 dB SPL peak capability (120 dB @ 1 meter)

> 100 dB (noise floor 20 dBA @ 1 meter)

60 degrees horizontal and vertical

Electronically balanced, 10k ohms impedance

XLR (A-3) female

Accepts either +4 dBu or -10 dBV, switchable

To obtain service:

1) Contact your dealer or call
Meyer Sound.

2) If you are calling Meyer Sound,
have the serial number(s) of the
unit(s) at hand for reference. Ask
for Customer Service, and be
prepared to describe the prob­lem clearly and completely.

3) If the problem cannot be re­solved over the phone, you must
return the unit for service.

2

4) You will be given an RA (Return
Authorization) number for job
tracking. Refer to this number
on shipping materials and in all
correspondence concerning the
repair. Shipping charges are the
responsibility of the purchaser.

Any attempt to modify or replace
components of the HD-1 will
invalidate your warranty. Service

must

be performed by a Meyer

Sound service center.

Notes:

1. Subject to room loading. Specified for
8 feet actual distance between HD-1
cabinet and a single boundary
surface.

2. One-third octave resolution.

Unless otherwise specified, all acoustic
and magnetic measurements are
performed at one-half meter from front
baffle on tweeter axis.

Amplifiers

Type

Power Output

Low Frequency

High Frequency

THD, IM, TIM

Crossover

Transducers

Low Frequency

High Frequency

AC Power

Physical

Dimensions

Weight

Stray magnetic field

Complementary power MOSFET output stages

150 watts burst capability

75 watts burst capability

< .02 %

Optimized pole-zero filter combinations to

complement transducer response and to achieve

acoustical transparency and flat phase

8" diameter cone (2" voice coil)

1" dome tweeter (1" voice coil)

3-pin IEC male receptacle. Voltage selector switch

for 100/120/220/240 VAC, 50 or 60 Hz (accepts

voltages from 90 to 260 VAC)

16" H x 12" W x 14" D (+ 2" additional depth for

amplifier chassis and HF dome clearance)

51 lbs. (23 kg.)

<1 Gauss in all directions from cabinet

Physical Dimensions

12.00"

16.53"

15.65"

16.00"

14.00"

05.550.026.01 A2

Copyright © 1994, Meyer Sound Labora­tories, Inc. All rights reserved.

9.20"

1.40"

13.20"5.00"

3.85"

1.40"

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