Mach 1 Acoustics HR-824 Service manual

HR824

Page 3 is interactive

High Resolution
Active Studio Monitor



SERVICE MANUAL

1999 MACKIE DESIGNS, INC.

820-183-00

C AU TIO N

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AVIS

RISK OF ELECTRIC SHOCK

DO NOT OPEN

RISQUE DE CHOC ELECTRIQUE

NE PAS OUVRIR

CAUTION: TO REDU CE THE RISK O F
ELECTRIC SHOCK DO NOT REMOVE

THE COVER (OR BACK)

NO US ER SERVICEAB LE PAR TS INS IDE

R EF E R S ER V IC IN G T O Q U AL IFIE D

PERSONNEL

W ARNING: TO RE DUCE THE RISK OF

FIRE OR E LEC TRIC SH OC K, DO NO T

EXPOSE THIS PROD UCT TO RAIN OR

MOISTURE

TO PREVENT ELECTRIC SHOCK, DO

NOT USE THIS POLARIZED PLUG W ITH

AN EXTENSION CORD, RECEPTACLE OR

OTHER OUTLET UNLESS THE BLADES

CAN BE FULLY INSERTED TO PREVENT

BLADE EXPOSURE.

ATTENTION: POUR EVITER LES

RISQUES DE C HOC ELECTRIQUE, NE

PAS ENLEVER LE COUVERCLE. AUCUN

ENTRETIEN DE PIECES INTERIEURES

PAR L'USAGER. CONFIER L'ENTRETIEN

A U P E R S O N N E L QU A L IF IE .

A VIS :P O U R EV IT ER L ES R IS Q UE S

D'INCENDIE OU D'ELECTROCUTION,

N'EXPOSEZ PAS CET ARTICLE A LA

PLUIE O U A L'HUM IDITE.

POUR PREVENIR LES CHOCS

ELE CTRIQ UES N E PA S UTILISER C ETTE

FICHE POLARISEE AVEC UN

PROLONG ATEUR , UN PRISE DE

COUR ANT OU UNE AUTRE SORTIE DE

COURANT, SAUF SI LES LAMES

PEUVENT ETRE INSEREES A FOND

SANS LAISSER A UCUNE PARTIE A

DECOUVERT.

This apparatus does not exceed the C lass A/Cla ss B (whichever is applicable) lim its for radio
noise emissions from di

ital apparatus as set o ut in the radio interfe rence regulations o f th e

Cana dia n Depa rtm ent of C om m unic atio ns .
ATTENTIO N :Le présent appareil num érique n'ém et pas de bruits radioélec triques dépassant

las lim ites applicables aux appareils num ériques de c lass A /d e class B (selon le cas) prescrites
dans le ré

le m e n t s ur le b ro u illage radioélectrique édicté par les m inistere des com munications

du Ca nada.
This equipm ent has been tested and found to com ply with the lim its for a Class A di

device, pursuant to part 15 of the FCC rules. These limits a re desi
protection a
environm ent. This equipm ent

ainst harm ful interference when the equipm ent is operated in a com mercial

enerates, uses, and can radiate radio energy a nd, if no t

ned to provide reasonable

ital

installed properly a nd used in acco rd ance with the instruction m anual, m ay ca use harm ful
int e rfe re n ce to r ad io c om m u nic a tio ns . O p e ra tio n of th is e q uip m e n t in a r es id e ntia l a r ea is lik ely
to c au s e h a rm f ul in te rf er e nc e i n w hic h c a se th e us e r w ill be r e qu ire d to co r re c t th e inte rf e re nc e
at his own expense.

The lightning flash with arrowhead symbol within an equilateral
triangle is intended to alert the user to the presence of uninsulated
"dangerous voltage" within the product's enclosure, that may be
of sufficient magnitude to constitute a risk of electric shock to persons.

Le symbole éclair avec point de flèche à l'intérieur d'un triangle
équilatéral est utilisé pour alerter l'utilisateur de la présence à
l'intérieur du coffret de "voltage dangereux" non isolé d'ampleur
suffisante pour constituer un risque d'éléctrocution.

2

The exclamation point within an equilateral triangle is intended to
alert the user of the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the appliance.

Le point d'exclamation à l'intérieur d'un triangle équilatéral est
employé pour alerter les utilisateurs de la présence d'instructions
importantes pour le fonctionnement et l'entretien (service) dans le
livret d'instruction accompagnant l'appareil.

CONTENTS

Click on any item to open that page

SHIPPING ............................................................................................3

INTRODUCTION .................................................................................4

TECHNICAL SUPPORT ................................................................... 4

DISCLAIMER................................................................................... 4

OVERVIEW..................................................................................... 5

REAR PANEL ..................................................................................6

FRONT PANEL ................................................................................ 7

SPECIFICATIONS ................................................................................ 8

BLOCK DIAGRAM ............................................................................. 9

WIRING DIAGRAM ..........................................................................10

PACKAGING PARTS ........................................................................11

QUICK PARTS.............................................................................. 11-12

TEST PROCEDURES ..................................................................... 13-19

PARTS LIST ................................................................................... 21-25

IC AND TRANSISTOR CHARTS .................................................. 25-26

FOLD-OUT SECTIONS:

SCHEMATICS .........................................................................A1-A2

PRINTED CIRCUIT BOARDS REV A ......................................A3-A4

PRINTED CIRCUIT BOARDS REV B ......................................A5-A6

FINAL ASSEMBLY ............................................................... A7-A13

SHIPPING

When shipping this speaker, make sure that all the original packaging is used, including
both the inner and outer boxes, and especially the thin, white sheet material. If shipped
in just one box or without the sheet material, the lovely finish can be damaged. Shipping
damage due to improper packaging is not covered under Warranty!
If you do not have the original packaging, it can be ordered from our parts department.
Never use loose-fill foam pieces (peanuts) as these can damage the finish and get inside
the amplifier section.

3

INTRODUCTION

This manual contains service information for the HR824 Powered Studio Monitor. It is
recommended that you also have a copy of the owner’s manual as this contains the
complete operating instructions.

Service on the HR824 must only be

undertaken by experienced

To service the HR824, technicians should be familiar with op-amp based and discrete
amplifier circuitry, speaker repair and speaker performance testing. Presentation of this
manual does not constitute endorsement of qualifications by Mackie Designs.

The HR824 makes extensive use of

surface mount components.

Service technicians should have the

tools, experience and patience to

perform surface mount rework.

WARNING

service technicians.

! SMD!

PROTECT YOUR HEARING

The HR-824 speakers are capable of producing high sound pressure levels. We
recommend the use of hearing protectors to prevent permanent hearing loss.

SERVICE TECHNICAL ASSISTANCE

Mackie Designs, Service Technical Assistance, is available 8AM - 5PM PST, Monday through
Friday for Authorized Mackie Service Centers, at 1-800-258-6883. Feel free to call with any
questions and speak with a carefully-calibrated technician. If one is not available, leave
a detailed message and a qualified Mackoid will return your call asap.

DISCLAIMER

The information contained in this manual is proprietary to Mackie Designs, Inc. The entire
manual is protected under copyright and may not be reproduced by any means without
express written permission from Mackie Designs Inc.

4

HR824 OVERVIEW

• The HR824 Studio Monitors are two-way,
bi-amplified active monitors with a rear­firing passive radiator. One amplifier drives
the woofer and another drives the tweeter.

• The crossover point is designed so that the
high and low frequency drivers are fed only
the frequencies they can best reproduce.

• The amplifiers are designed with protection
circuits to minimize the danger of speaker
damage due to overdriving.

• The amplifiers’ gain and frequency
responses are individually hand-trimmed by
a host of infernal adjustment pots to
compensate for typical manufacturing
tolerances.

• The adjustments produce a smooth
frequency response from 39Hz to 20kHz
(±1.5dB) with minimal phase difference.

THE DRIVERS

• The monitors feature an 8.75-inch die-cast
magnesium frame woofer and a 1-inch
viscous edge-damped aluminum-alloy
dome tweeter on the front, and a 6-inch x
12-inch elliptical flat piston passive radiator
in the back.

• The high-frequency driver is mounted on a
die-cast zinc exponential waveguide
which results in wide, controlled dispersion
of high-frequency sounds. The unique
passive radiator design provides a smooth
response down to 39Hz.

THE CABINET

• The cabinet is made of high-density MDF
wood from specially grown MDF trees. An
internal “H” brace further increases the
strength and rigidity (stiffness) of the box.
An open-cell adiabatic pillow foam
material gently fills the inside of the box to
absorb internal reflections and dampen
any standing waves.

THE AMPLIFIERS

• The Fast Recovery amplifier design uses low
negative feedback, yet allows the
amplifiers to maintain low distortion and
stability even when driven into clipping.

• The low-frequency amplifier produces up
to 150 watts continuous (350 watts peak)
before clipping, while the high-frequency
amplifier produces up to 100 watts
continuous (210 watts peak).

THE PASSIVE RADIATOR

• The HR824 is a bass reflex 6th-order system,
rotating in geo-synchronous orbit. Rather
than use ports, the vent takes the form of
a passive radiator, a mass-loaded flat
piston coupled to the air trapped within
the enclosure. The passive radiator is
located at the rear of the cabinet, behind
the power amplifier assembly.

• One primary advantage over simple porting
is that a passive radiator can reproduce low
frequencies with lower distortion and at a
higher sound pressure level (SPL).

• The unique passive radiator design uses a
diaphragm made with a composite
honeycomb material providing exceptional
stiffness to the radiating surface.

• The elliptical shape of the passive radiator
takes up nearly the entire surface area
available on the rear of the enclosure,
allowing the passive radiator to move
more air than Congress. This moving air
also helps cool the amplifier.

5

REAR PANEL DESCRIPTION

SIGNAL INPUTS

• The XLR female and TRS female connectors
are connected in parallel .

• Both input connectors accept balanced or
unbalanced signals. They are wired as
follows (per the AES/IEC standard):

XLR TRS
Hot (+) Pin 2 Tip
Cold (–) Pin 3 Ring
Shield (Ground) Pin 1 Shield

INPUT SENSITIVITY CONTROL

• The HR824 expects a line-level signal at its
input connectors.

• The reference sensitivity is -7.5 dBu = 100 dB
SPL at one meter (39 inches) with the INPUT
SENSITIVITY control set to its NORMAL
position.

• The HR824 is designed to operate with a
+4 dBu signal when the INPUT SENSITIVITY
control is in the NORMAL position.

ACOUSTIC SPACE SWITCH

This is a three-way switch that adjusts the
low-frequency response of the speakers to
compensate for their placement in the
room.

• If you place the monitors against a wall
(half space ), set the ACOUSTIC SPACE
switch to the “B” position. This activates a
shelving filter to reduce the low-frequency
output by 2dB to compensate for the bass
boost from half-space placement.

• If you place the monitors into the corners
of your room (quarter space ), the low­frequency output approximately doubles
from what it is in half space. Set the
ACOUSTIC SPACE switch to the “A” position
to reduce the low-frequency output by 4dB
to compensate for the bass boost.

• If you use the HR824s free-standing, away
from walls and corners (whole space ), set
the ACOUSTIC SPACE switch to the “C”
position (NORMAL).

LOW FREQ SWITCH

• The LOW FREQ switch inserts a steep low­frequency rolloff into the response curve.

• For most applications, use the 47Hz setting.

• If you want or need the extra low-frequency
capability, use the 37Hz (NORMAL) position.

• You can use the 80Hz position to simulate
a smaller loudspeaker.

HIGH FREQ SWITCH

• The HIGH FREQ switch tailors the overall
high-frequency response by ±2dB at 10kHz.

POWER MODE SWITCH

• In the OFF position, the power amplifiers
are in Standby mode and produce no
sound. Low-level circuitry is still active, but
the power consumption of the circuitry is
minimal (8 watts).

• In the ON position, the power amplifiers
are live and operate normally. (The front
panel ON/OFF switch must also be ON.)

• Since the power supply and low level
circuitry are already active (assuming the
speaker is plugged into a live outlet), this is
an “instant on” function.

• In the AUTO ON position, the amplifiers turn
on and off depending on the presence or
absence of an input signal. An input signal
level of –45dBu (minimum) activates the
auto-on function. A silent period greater
than five minutes activates the auto-off
function. The red PWR LED on the front
panel reflects the state of the amplifiers.

• Normally, use the front panel switch to turn
the monitors on and off.

• If you unplug the power when a signal is
still applied to the input, you may hear
sound from the monitor. This is after about
6 seconds, when the muting circuit
unmutes and the power supply finishes
discharging. This is normal and not harmful
to the monitor.

MAINS INPUT

• Connect the power cord to this IEC
socket, and plug the other end into your
AC outlet.

IMPORTANT: For safety reasons, the AC
source must be a “3-prong” outlet
with hot, neutral, and ground
terminals.
WARNING: Bypassing the plug’s ground
pin can be dangerous. Don’t do it!

6

FRONT PANEL DESCRIPTION

ON/OFF SWITCH

• Use this switch to turn on or off the HR824
from the front. It works with the POWER
MODE switch on the rear panel in the
following way:

• If the rear POWER MODE switch is OFF, the
front panel ON/OFF switch has no effect.
The PWR LED remains off, so there.

• If the rear POWER MODE switch is ON, the
front panel ON/OFF switch turns the HR824
on and off, as indicated by the PWR LED.

• If the rear POWER MODE switch in the AUTO
ON position, the front panel ON/OFF
switch turns the HR824 on and off as long
as there is a signal present.

OL (overload) LED

• This LED blinks when the amplifiers begin to
clip, and lights steadily if the overload
protection circuit has been triggered.

• Occasional blinking of the OL LED
indicates that the loudest transients are
reaching the maximum output capability
of the amplifiers.

• Frequent or continuous blinking of the OL
LED indicates that you have exceeded the
maximum output capability of the
amplifiers and that the amplifiers are
clipping. If you persist, the overload
protection circuit takes over, reducing the
input level. You should reduce the level
from your signal source until the OL LED
blinks occasionally or not at all.

and volume for the monitors. Change the
LOW FREQ switch to 47Hz or 80Hz, if
necessary, to reduce the bass response. This
may allow the HR824s to play louder and
eliminate most amplifier clipping.

THERMAL PROTECTION

• The HR824 is designed to be efficient both
electrically and thermally.

• If the heatsinks get too hot, a thermal
switch activates, placing the HR824 into
Standby mode (indicated when the red
PWR LED turns off).

• Should this happen, make sure that airflow
to the rear of the cabinet is not restricted.

• When the heatsinks cool down to a safe
temperature, the switch resets and normal
operation resumes.

• If your service customer complains that
their HR824s keep thermalling out, make
sure they keep them in the vertical position
for improved ventilation. Also make sure
the bias has been set correctly.

OVERLOAD PROTECTION

• The high and low frequency power
amplifiers have clipping detectors that
light the OL LED when either power
amplifier output clips.

• If frequent clipping occurs, the driver
thermal overload protection activates a
compressor that reduces the input level to
the amplifiers. During this time the OL LED
lights continuously.

• The compressor was designed to protect
the speakers and its action is highly
audible.

• When listening at a very high volume, you
may find that the OL LED lights frequently.
Since the majority of the power
requirements in any monitor are the low
frequencies, selectively reducing the low
end can provide a little more headroom

7

SPECIFICATIONS

Amplifier Section

Low-frequency amplifier:

Rated power output: 150 watts, 4Ω load
Burst power output: 350 watts
Distortion: THD: < 0.035%

SMPTE IMD: < 0.035%

DIM 100: < 0.035%
Slew Rate: > 35V/µs
Signal-to-Noise Ratio: > 102 dB, referenced to
150 watts into a 4Ω load

High-frequency amplifier:

Rated power output: 100 watts, 6Ω load
Burst power output: 210 watts
Distortion: THD: < 0.035%

SMPTE IMD: < 0.035%

DIM 100: < 0.035%
Slew Rate: > 35V/µs
Signal-to-Noise Ratio: > 102 dB, referenced to
100 watts into a 6Ω load

Crossover Section

Crossover Type:

Modified Linkwitz-Riley, 24dB/octave @ 2kHz
Input Impedance:
20kΩ, balanced bridging

Compressor:

Independent high and low frequency overload
detection

Acoustic Space Equalization:

A position: –4 dB @ 100Hz, shelving
B position: –2 dB @ 100Hz, shelving
C position: flat

Low Freq Filter:

–3 dB @ 35Hz
–3 dB @ 47Hz
–3 dB @ 80Hz

High Freq Equalization:

± 2 dB @ 10kHz, shelving

Transducers

Low-frequency driver:

8.75-inch (222mm) die-cast magnesium frame,
mineral-filled polypropylene cone.

High-frequency driver:

1-inch (25.4mm) viscous edge-damped aluminum­alloy dome with ferrofluid-cooled voice coil.

Passive Radiator:

6-inch x 12-inch (152mm x 305mm) mass-loaded
elliptical flat piston.

Acoustic Section:

Free-Field Frequency Response:

±1.5 dB, 39Hz to 20kHz

Lower cutoff frequency: –3 dB @ 37Hz
Upper cutoff frequency: –3 dB @ 22kHz
Sound Pressure Level at 1 meter,
–7.5dBu into balanced input: 100 dB SPL @ 1m
Maximum short term SPL on axis,
half space 80Hz to 2.5kHz: 110 dB SPL @ 1m
Residual noise (maximum gain, 600
20Hz-20kHz bandwidth): < 8 dB SPL @ 1m
Maximum peak SPL per pair: 120 dB SPL @ 1m

Enclosure

Materials and Construction:

3/4- inch (19mm) thick MDF construction with
1-inch (25.4mm) thick MDF front panel.
Proprietary die-cast zinc exponential wave
guide for high-frequency driver.
Open cell adiabatic “foam fill” acoustical
damping material.

General:

Power Consumption:

135 watts with musical program, loud mix
18 watts quiescent (idle)
8 watts in Standby mode

AC Dropout Voltage:

120V AC versions: 80V AC
240V AC versions: 160V AC

Weight: 33 lbs. 10 oz. (15.25 kg)
Dimensions (HxWxD):

15.75" (400mm) x 10.00" (254mm) x 12.20"
(310mm)

Mackie Designs is always striving to improve our
products by incorporating new and improved
materials, components and manufacturing
methods. Therefore, we reserve the right to
change these specifications at any time without
notice.

ΩΩ

Ω source,

ΩΩ

8