Additional Load Protection; Ac Mains Power Requirements; Loudspeaker Fuse Nomograph; Ac Mains Cords And Plugs - Crown Micro-Tech 600 Reference Manual

3.3.6 Additional Load Protection

Micro-Tech amplifiers can deliver very high power lev-
els, so it's a good idea to add some protection if its not
already built into your loudspeakers. Loudpseakers are
subject to thermal damage from sustained overpower-
ing and mechanical damage from large transient volt-
ages. In both cases, fuses may be used to protect your
loudspeakers.
Thermal protection and voltage protection require dif-
ferent types of fuses. Slow-blow fuses are used to pre-
vent thermal damage because they respond to thermal
conditions like a loudspeaker. High-speed instrument
fuses like the Littlefuse 361000 series are used to pro-
tect loudspeakers from transient voltages. The nomo-
graph in Figure 3.15 can be used to select the correct
fuse for thermal or voltage protection.
There are two common ways to install the fuses. One
approach is to put a single fuse in series with each
output. This is easy because there is only one fuse per
channel to install. But if the fuse blows, power is re-
moved from all of the connected loads.
1.0
1.2
1.4
1.6
2
2.5
3
4
5
6
Example:
Impedance = 8 ohms.
7
Peak Power = 75 W
8
Answer: Fuse = 1.5 A
9
10
12
14
16
20
25
30
40
Fig. 3.15 Loudspeaker Fuse Nomograph
Page 18
20
3000
15
2000
10
1500
8
1000
800
6
600
5
4 400
300
3
200
150
2
100
80
1.5
60
1
40
.8
30
.6
20
.5
15
.4
10
8
.3
6
4
.2
3
.15
2
.1 1.5
1
.08
Micro-Tech 600/1200/2400 Power Amplifiers
A better approach is to fuse each driver independently.
This allows you to apply the most appropriate protec-
tion for the type of driver being used. In general, low-
frequency drivers (woofers) are the most susceptible
to thermal damage and high-frequency drivers (tweet-
ers) are usually damaged by large transient voltages.
This means that your loudspeakers will tend to have
better protection when the woofers are protected by
slow-blow fuses and high-frequency drivers are pro-
tected by high-speed instrument fuses.

3.4 AC Mains Power Requirements

All Micro-Tech amplifiers are shipped with an appropri-
ate line cord and plug. The standard cord and plug for
each model are listed by country (or region) in Fig-
ure 3.16. When possible, use a power receptacle on a
dedicated circuit, and always make sure it will provide
the right voltage with sufficient current. We do not rec-
ommend operating your amplifier with voltages greater
than 10% above or below the unit's rated voltage. For
example, an amplifier rated for 120 VAC operaton
should not exceed 132 VAC. See Section 7 for power
requirements under a variety of conditions.
Micro-Tech
600
Country or Region
Cord
2
Australia, New Zealand 1.5 mm
Argentina, Austria, China, 2
1.5 mm
Denmark, Finland, France,
Germany, Greece, Holland,
Indonesia, Italy, Korea,
Malaysia, Portugal, Spain,
Sweden, Switzerland,
Turkey
Brazil, Guam, Hong Kong, 14/3 SJT
Jamaica, Japan, Peru,
Phillipines, Singapore,
Tahiti, Taiwan, Thailand,
Venezuela
Central America,
14/3 SJT
North America
2
India, South Africa 1.5 mm
Ireland, Norway, 2
1.5 mm
United Kingdom,
United Arab Emirates
Fig. 3.16 AC Mains Cords and Plugs
All specifications in this manual were measured using
120 VAC, 60 Hz power mains unless otherwise noted.
Specifications are derived using a mains voltage that
is accurate to within 0.5% with THD less than 1.0%
under all testing conditions. Performance variations
can occur at other AC mains voltages and line frequen-
cies. In addition, line regulation problems will directly
affect the output power available from the amplifier.
Micro-Tech Micro-Tech
1200 2400
Plug Cord Plug Cord
2 2
AS 3112 1.5 mm AS 3112 1.5 mm AS 3112
10 A 10 A
2 2
CEE 7/7 1.5 mm CEE 7/7 1.5 mm CEE 7/7
NEMA 14/3 SJT NEMA 12/3 SO
5-15P 5-15P
NEMA 14/3 SJT NEMA 12/3 SO
5-15P 5-15P
2 2
BS 546 1.5 mm BS 546 1.5 mm BS 546
2 2
BS 1363 1.5 mm BS 1363 1.5 mm BS 1363
Plug
15 A
NEMA
5-15P
NEMA
5-20P