Genelec HT324AC Owner's Manual

HT324AC

Operating Manual

Genelec HT324AC
Three-Way Active Loudspeaker

System

The GENELEC HT324AC active loudspeaker

is designed for neutral sound reproduction

at high SPLs in large Home Theater rooms.

Its cabinet has been designed for optimum

placement in the limited space above or

below a video screen, but it can also be

installed in vertical configuration. Acousti-

cally the HT324AC is identical to Genelec

HT324A. The system consists of a 160 litre

loudspeaker cabinet and a 19” 7U rack mount

amplifier unit.

The cabinet contains two 305 mm (12”)

bass drivers, a 130 mm (5”) midrange, and

a 25 mm (1”) treble driver. The midrange

and treble drivers are mounted in a Genelec

Directivity Control Waveguide™ (DCW™)

which can be rotated through ±90° for either

horizontal or vertical mounting. The cabinet

low frequency -3 dB point is at 32 Hz and the

bass response extends down to 27 Hz. The

high frequency response extends up to 22 kHz

(-3 dB).

Each amplifier unit contains a three-chan-

nel active crossover, driver overload protec-

tion circuits, and four separate power ampli-

fiers producing 2 x 400 W, 350 W and 120 W

of short term power in the bass, midrange,

and treble channels respectively. The crosso-

ver filter incorporates tone controls to enable

the user to accurately match the speaker to

the local acoustic environment.

Unpacking

The Genelec HT324AC is shipped in a single

box, containing a cabinet, an amplifier unit, a

mains connecting cable, a LED connecting

cable, a loudspeaker connecting cable and

one Allen key. (See Fig 1)

Before installing the system, check all

items for damage and omissions. If there are

any damaged products, contact directly the

distributor and insurance agent. If there are

any missing components, contact your local

dealer or Genelec.

Installing the amplifier

The Genelec HT324AC amplifier electron-

ics is encased in an standard 19” 7U rack

chassis. The unit should be well ventilated to

prevent overheating, there must be a supply

of air to the front and sufficient ventilation to

dissipate the generated heat from the space

behind the amplifier unit. The maximum per-

missible ambient temperature is 35° C (95°

F) If the system overheats it will stop operat-

ing until a safe temperature is reached.

Each amplifier unit has been calibrated

at the factory with the loudspeaker cabinet

it is packed with. They also share the same

ID number. Make sure that each amplifier is

connected to the cabinet bearing the same

ID number when installing multiple loud-

speakers.

Make sure that the amplifier is positioned

so that the loudspeaker connecting cables

wil l reach. Longer cable lengths can be

ordered from the manufacturer upon special

request. A space 120 mm deep should be left

behind the rear panel of the amplifier unit to

allow for the cable connectors.

Check that the amplifier unit is wired to the

correct mains voltage for your power supply.

The correct mains voltage for the amplifier

unit is shown at the bottom of the sticker on

the rear panel of the amplifier unit.

The amplifier power can be switch ed

between ON and standby modes by a remote

con trol unit connected to the respective

inputs on the amplifier. Two pairs of connec-

tors are provided, 1 and 2 for a 12 V DC type

remote control, and 3 and 4 for an external

switch or relay type control. Do not connect

two remote controls to the loudspeaker at the

same time. Activate the function by turning

the "REMOTE CONTROL" dip switch on the

amplifier panel to "ON".

Loudspeaker positioning

The HT324AC is desig ned to be flush

mounted in either the vertical or horizontal

configuration. The DCW™ should be rotated

so that the treble and midrange drivers align

vertically. This ensures that optimum symme-

try is obtained.

Note that the DCW™ plate is heavy, care

must therefore be taken when removing and

replacing the DCW™. To rotate the DCW™

plate, proceed as follows:

• Place the loudspeaker in its intended

listening orientation.

• Unscrew the eight M5 fixing screws on

the edges of the plate using the 4 mm

Allen key provided with the system.

• Carefully pull the plate a small distance

away from the cabinet.

• Rotate the DCW™ so that the midrange

and treble drivers are aligned vertically

(treble driver on top) and remount the

DCW™ plate reversing the procedure

above.

Flush mounting of the

loudspeaker

Although the HT324AC may be used suc-

cessfully as a free standing loudspeaker,

flush mounting is strongly recommended for

acoustical reasons. Flush mounting improves

the bass response and efficiency and also

enhances the midrange transient and fre-

quency response.

The loudspeaker has its acoustical axis

midway between the midrange and treble

drivers. This axis should be used as the lis-

tening and measuring axis of the system.

(See Fig 1)

The listening position should be between

2 ... 3.5 m (6½ ... 11½’) from the loudspeak-

ers. The loudspeaker should be aimed so

that the acoustical axis of the two loudspeak-

ers meet at ear height at the center of the

listening area. The loudspeakers should not

be mounted too high as this increases the

required vertical tilt of the loudspeaker and

reduces the optimum listening area.

The ceiling, side walls and especially the

rear wall should be acoustically absorbent at

low frequencies. The loudspeaker mounting

wall should be acoustically hard and there-

fore reflective. The mounting wall should be

angled so that the loudspeakers are correctly

aimed. Great care should be taken over how

the loudspeaker is mounted into the wall.

Note the following:

• A space 50…100mm (2..4”) wide can be

left around the loudspeaker.

• Cover the space around the

loudspeaker with a facing panel, this

should be fixed to the wall. Leave a gap

of about 5..10 mm (¼..½”) between the

loudspeaker and the panel. Fill this gap

with a soft rubber gasket to allow for

possible cabinet movement.

• Ensure that the loudspeaker cables can

reach the rear of the loudspeakers.

• If a light (e.g. wooden) wall is used,

the loudspeaker cabinet should be

mounted on vibration isolators, with a

resonant frequency of around 2…8 Hz,

to prevent vibrations from being

transmitted to the wall and impairing

the low frequency performance. The

space around the cabinet should be

filled with absorbent mineral wool or

foam plastic. The walls must be well

braced.

• For a solid wall (e.g. concrete), the

loudspeaker may be directly mounted to

the wall without vibration isolators. The

space around the cabinet should be

filled with mineral wool or sand bags.

Discontinuities in the mounting wall will cause

diffraction, which leads to inferior frequency

response and stereo imagery, so:

• Ensure that the cabinet is flush with the

surface of the wall.

• If a decorative cloth frame is used to

cover the wall, make sure that the edges

adjacent to the speaker are less than

20 mm (3/4”) deep. The cloth must be

very thin Tricot or acoustically

transparent material, otherwise the high

frequency response of the system will

be adversely affected. Genelec

approved cloth grilles are available).

Recess for loudspeaker

connectors

A space at least 120 mm (4 3/4”) deep

must exist to allow for the cable connectors

behind the loudspeaker. The dimensions of

the recess should be at least 100 x 140 x 75

mm (4” x 51/2” x 3”), as shown in Fig. 6. Note

that the connectors are positioned off-center.

Therefore, if the loudspeaker is rotated for a

left and right channel, the recess will be at dif-

ferent heights on the left and right side. This

occurs when the loudspeakers are mounted

in the horizontal configuration.

Connecting cable

The two connecting cables have different

types of connectors at each end, a loud-

speaker connector and an LED connector.

The loudspeaker connector is larger than the

LED connector. Insert the connectors into the

appropriate sockets found on the rear panel

of the amplifier unit and the rear of the loud-

speaker.

To insert the connectors proceed as follows:

• Insert the connectors into the sockets

and turn the connectors clockwise. The

connectors lock automatically.

• The electrical connections are only

made when the connectors are fully

inserted.

To remove the connectors pull the release

lever on the connector and turn the connector

counterclockwise simultaneously. The con-

nector can now be removed from the socket.

Speaker mounting
envir onment

Flat anech oic
response ( factor y
setting)

Free s tanding in
a heavily damped
room

Free s tanding in a
reverberant room

Flush moun ted in a
hard wall

In a corner -4 dB ON -6 dB ON -2 dB ON All OFF All OFF

Table 1.Suggest ed startin g positions for tone con trols.

Bass Roll- Off Bass Tilt Bass Level Mid Level Treble Level

All OFF All OFF All OFF All OFF All OFF

All OFF -2 dB ON All OFF All OFF All OFF

All OFF -2 dB ON -1 dB ON All OFF All OFF

All OFF -4 dB ON -1 dB ON All OFF All OFF

Acoustical Setup

Control

range and treble controls should be left in

their free field positions, since these frequen-

Input sensitivity adjustment

The input sensitivity of the HT324AC can be

adjusted to match the output signal level of

the signal source. This is done by turning the

‘Input sensitivity’ trimmer, which is accessed

cies are controlled by the speaker more than

the room. Acoustical measurements, and

precise listening tests should be completed

by qualified personnel, to determine the opti-

mum tuning in each case.

through the front panel of the amplifier unit.

However, an accurate left/right balance is

obtained when the trimmer is set to the fully

clockwise ‘cal’ position. Leaving the input

sensitivity trimmer in the ‘cal’ position is

therefore recommended.

To obtain the maximum sound pressure

level of 123 dB SPL, with the input sensitiv-

ity set to -6 dBu, a signal level of +20 dBu is

required.

Tone control adjustment

The frequency response of the system

should be adjusted to match the listening

room’s acoustic environment. This adjust-

men t is made using th e tone controls,

‘BASS TILT’, ‘BASS ROLL-OFF’, ‘BASS

LEVEL’, ‘MIDRANGE LEVEL’, and ‘TREBLE

LEVEL’. These co ntrol s a re accessed

through the amplifier unit’s front panel. The

default setting of these controls is in the

‘OFF’ position, which yields a flat frequency

response when the speaker is operated in

Measuring the frequency response

The ove rall sound balance experienced

at the listening position can, to a cer tain

extent, be measured with steady state sig-

nals (e.g. pink noise, warble sine etc.) and

a corresponding frequency analyser. How-

ever, the results obtained are very sensitive

to the measuring methods and the equip-

ment used

.

Recommended Measuring Equipment

1. Microphone

• Always use a laboratory grade

measurement microphone.

• B&K 4134 (or similar) for far field, 4133

or 4165 (or similar) for near field below

8kHz.

• B&K 4004 and 4007 (or similar) up to

8kHz.

Do not use a microphone having a polar pattern

other than omnidirectional, or one not having

an accurately known frequency response.

an anechoic environment. Note that only

one switch in each control group should be

in the ‘ON’ position.

The room normally boosts the low frequen-

cies compared with free field conditions. To

get a flat room response, adjustments to

the bass tone control switches are usually

required. See table 1 for suggested starting

positions of the tone controls in four different

2. Signal Source

Use a signal source which is suitable for the

type of analyser being used. Do not use a

noise generator which is integrated into a

mixing console, since these signal genera-

tors tend to have a very coarse spectrum

content and are not intended to be used for

measurement purposes.

room types. The table shows that the mid-

Fig 1. Location of the acoustic axi s in horizontal and ver tical configurations. Note the alignment
of the DCW.

Fig 2. Amplifier unit connectors.

Fig 3. Speaker mounting.

Fig 6. Recess for l oudspeaker connectors. (Rear view)

Fig 4. Speaker mounting detail s.

Fig 5. Eliminating discontinuities.

Fig 7. Speaker/LED connector

3. Analyser

Any professional quality real time analyser

or tracking plotter can be used. (1/3 or 1/1

octave analysis is usually sufficient for fre-

quency response balancing)

Near field measurement

This measurement gives an indication of the

direct sound radiation of the loudspeaker

below 1 kHz.

• Set the microphone 1 m away from the

loudspeaker on the acoustic axis. (See

Fig 1)

• Measure the frequency response of

the speaker, and adjust the tone controls

to achieve a flat frequency response

below 1kHz.

Make sure that any sound reflecting objects

such as chairs etc. are removed from the

close proximity of the loudspeaker.

Listening position measurement

Once the near field frequency response

measurement has been made, the frequency

response at the listening position can be

determined by the same means. When com-

paring the results, the following items should

be noted.

1. High frequency roll-off

This is due to the following physical factors:

• Increasing room and air absorption with

higher frequencies.

• Increasing loudspeaker and microphone

directivity with increasing frequency.

2. Low frequency irregularities.

These are caused by:

• Insufficient standing wave absorption in

the control room.

• Reflections from nearby boundaries

(Floor, ceiling, walls) interfering with

direct sound.

Incorrect ver tical speaker alignment can

cause interference dips at the upper crosso-

ver frequency (around 3.2 kHz). Hence care

should be taken aiming the speaker correctly

towards the listening position. (See Fig 3.)

Overload indicators

Each loudspeaker is pr ovid ed with two

LED’s marked ‘CLIP PROTECT (FAULT)’

and ‘READY’. The green ‘READY’ LED

indicates that the amplifier system power is

switched on, and that the speaker is ready

for use. The red ‘CLIP PROTECT (FAULT)’

LED indicates that the amplifier system

is overloaded or that the driver protection

circuit is activated. If the red LED lights,

reduce the signal level so that the LED stops

blinking. If this LED stays lit constantly, the

amplifier thermal protection circuitry has

activated. Let the amplifier cool down, and

ensure that the amplifier is adequately ven-

tilated.

Maintenance

There are no user serviceable parts within

the amplifier unit. Any maintenance of the

unit should only be undertaken by qualified

service personnel. Ensure that only fuses

of the appropriate voltage and current rat-

ings are used if a fuse has to be replaced.

REMEMBER to disconnect the power supply

by removal of the mains cable before chang-

ing a fuse. Clean the amplifier unit’s air filter

every six months, or more frequently in dusty

environments. The air filter is located behind

the grille, found to the left of the front panel.

The air filter can be cleaned with a vacuum

cleaner without removing the grille.

Safety considerations

Although the HT324AC has been designed

in accordance with international safety stand-

ards, to ensure safe operation and to main-

tain the instrument under safe operating con-

ditions, the following warnings and cautions

should be observed:

• Servicing and adjustment must only

be performed by qualified service

personnel. The loudspeaker or the

amplifier must not be opened.

• The amplifier must only be connected

to mains socket outlet with a protective

earthing connection.

• Do not use the amplifier with

an unearthed mains cable as this may

compromise electrical safety.

• Do not expose the loudspeaker or the

amplifier to water or moisture. Do not

place any objects filled with liquid, such

as vases, on the loudspeaker or near it.

• Do not place naked flame sources like

lighted candles on or near the

loudspeaker or the amplifier.

• This loudspeaker is capable of

producing sound pressure levels

in excess of 85 dB, which may cause

permanent hearing damage.

• Proper ventilation of the amplifier is

necessary to maintain sufficient cooling.

Ensure that air flows freely into the

openings on the amplifier front panel

and that the space behind the amplifier

is sufficiently ventilated to dissipate the

generated heat.

• Note that the amplifier is not completely

disconnected from the AC mains service

unless the mains power cord is removed

from the amplifier or the mains outlet.

Guarantee

This product is guaranteed for a period of one

year against faults in materials or workman-

ship. Refer to supplier for full sales and guar-

antee terms.

EC Declaration of Conformity

This is to certify that Genelec HT324AC

loudspeaker conforms to the following stand-

ards:

Safety:

EN 60065 / IEC 60065:1998 7th Edition

EMC:

EN 55013: (2001)

EN 55020: (1994), A11: (1996), A12: (1999),

A13: (1999), A14: (1999)

EN 61000-3-2 (2000)

EN 61000-3-3 (1995)

The product herewith complies with the

requirements of The Low Voltage Directive

73/23/EEC, EMC Directive 89/336/EEC and

93/68/EEC

Signed:

Ilpo Martikainen

Position: Chairman of Board

Date: 16-January-2006

HT324AC Operating Manual

Fig 8: The above cur ves illustrate the effect of the 'bass til t', 'bass roll-off'
and 'bass' ,' mid' and 'treble' level controls o n the free field response,
measured a t 2 m

SYSTEM SPECIFICATIONS

Lower cut-off frequency, -3 dB: ≤32 Hz
Upper cut-off frequency, -3 dB:
Free field frequency response of system:
33 Hz - 20 kHz (± 2.5 dB)

Maximum short term sine wave acoustic output on
axis in half space, averaged from 100 Hz to 3 kHz
@ 1 m
Maximum long term RMS acoustic output in same
conditions with IEC-weighted noise (limited by
driver unit protection circuit)@ 1 m:
≤118 dB SPL
Maximum peak acoustic output per pair @ 2 m from
the engineer with music material:
≤125 dB

Self generated noise level in free field @ 2 m on
axis:
Harmonic distortion at 100 dB SPL @ 1m on axis:
Freq: 50...200 Hz <1%

200...10kHz <0.5%
Drivers:
Bass 2 x 305 mm (15") cone
Mid 1 x 130 mm (5") cone
Treble 1 x 25 mm (1") metal dome

Weight: Speaker 84 kg (185 lb)
Amplifier 30 kg (66 lb)

≤20 kHz

≤123 dB SPL

≤15 dB(A)

CROSSOVER SECTION

Bass amplifier output power with an 8≤ load:
Short term 2 x 400 W
Mid amplifier output power with a 8≤ load:
Short term 350 W
Treble amplifier output power with an 8≤ load:
Short term 120 W
Long term output power is limited by driver unit
protection circuitry.

Slew rate: 80 V/µs
Amplifier system distortion at nominal output:
THD
SMPTE-IM
CCIF-IM
DIM 100

Signal to Noise ratio, referred to full output:
Bass
Mid
Treble

Mains voltage: 100/200 or 115/230V
Voltage operating range at
230V setting: 207 - 244 V (-10/+6 %)
115V setting: 104 - 122 V (-10/+6 %)
Power consumption:
Idle 70 W
Full output 1000 W

Speaker dimensions (Horizontal mounting):
Height 489 mm (19 1/4”)
Width 1210 mm (47 5/8”)
Depth 412 mm (16 1/8”)
*Amplifier dimensions:
Height 310 mm (12
Width 483 mm (19")
Depth 250 mm (9

13

3

/16")

/16")*

Fig 9: The upper curve group sh ows the horizontal directivit y
characteristics of the HT32 4AC in its horizontal co nfiguration measured
at 29m. The lower curve is a 1/6 octave power response measurement,
derived from 144 directivity measuremen ts..

AMPLIFIER SECTION

Input connector: XLR female pin 1 gnd
pin 2 +
pin 3 -

≤0.05%
≤0.05%
≤0.05%
≤0.05%

≤100 dB
≤100 dB
≤100 dB

Input impedance: 10 kOhm≤ balanced

Input level for 100 dB SPL output @ 1m:
variable from +6 to -6 dBu

Input level for maximum short term output of 126 dB
SPL @ 1m: variable from +32 to +20 dBu

Subsonic filter below 25 Hz : 18 dB/octave
Ultrasonic filter above 22 kHz: 12 dB/octave

Crossover frequencies:
Bass/Mid 400 Hz
Mid/Treble 3.2 kHz

Crossover acoustical slopes: >24 dB/octave

Level control operating range in 1 dB steps:
Bass from 0 to -6 dB & MUTE
Mid from 0 to -6 dB & MUTE
Treble from 0 to -6 dB & MUTE

Bass roll-off control in 2 dB steps:
from 0 to -8 dB @ 32 Hz

Bass tilt control operating range in 2 dB steps:
from 0 to -8 dB @ 50 Hz

The 'CAL' position is with all tone controls set to 'off'
and input sensitivity control to maximum and cor­responds to a maximally flat free field response.

Genelec Docu ment D0071R001 Copyrig ht Genelec Oy 2.2006. All data subject to change without prior notic e

Inter national e nquiries:

Genele c, Olvitie 5

FIN-74 100, Iisal mi, Finlan d

Phone [phone]

Fax [phone]

Email genele [e-mail]

In the U.S. please c ontact:

Genele c, Inc., 7 Tech C ircle

Natick, MA 01760 , USA

Phone [phone]

Fax [phone]

Email genele [e-mail]

www.genelec.com

In Chi na please contact:

Genele c China Re presentati ve Office

Soho N ew Town, 88 Jiangu o Road

D-1504 , Chaoyang D istrict

Beijin g 100022, China

Phone [phone] Fax [phone]

Email [e-mail]