![4.3.1 ODEP](/images/new-backgrounds/19221/1922141x1.webp)
Studio Reference I & II Professional Studio Amplifiers
and transformer thermal protection. These systems will | The amplifier’s overvoltage protection circuitry will | |
prevent amplifier damage in virtually any situation. | put both channels into standby when excessive AC | |
4.3.1 ODEP | mains voltage is detected. Studio Reference amplifiers | |
should not be operated with an AC mains voltage of | ||
Crown invented ODEP to solve two | more than 10% over the unit’s rated voltage. | |
problems in amplifier design: to prevent amplifier shut- | If dangerous subsonic frequencies or direct current | |
down during demanding operation and to increase the | ||
(DC) is detected in the amplifier’s output, the unit will | ||
efficiency of output circuitry. | ||
activate its DC / | ||
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To do this, Crown established a rigorous program to | and put the affected channels in standby. This protects | |
measure the safe operating area (SOA) of each output | the loads and prevents oscillations. The amplifier re- | |
transistor before installing it in an amplifier. Next, | sumes normal operation as soon as it no longer detects | |
Crown designed intelligent circuitry to simulate the in- | dangerous | |
stantaneous operating conditions of the output transis- | extremely unlikely that you will ever activate the | |
tors. Its name describes what it does: Output Device | amplifier’s DC / | |
Emulation Protection or ODEP. In addition to simulating | proper source materials such as subsonic square | |
the operating conditions of the output transistors, it also | waves or input overloads that result in excessively | |
compares their operation to their known SOA. If ODEP | clipped signals can activate this system. | |
sees that more power is about to be asked of the output | The amplifier’s fault protection system will put an am- | |
transistors than they are capable of delivering under | ||
plifier channel into standby mode in rare situations | ||
the present conditions, ODEP immediately limits the | ||
where heavy | ||
drive level until it falls within the SOA. Limiting is pro- | ||
channel’s output. The amplifier should never output | ||
portional and kept to an absolute | ||
heavy | ||
is required to prevent output transistor damage. | ||
damaged in some way, and putting the channel into | ||
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This level of protection enables Crown to increase out- | standby mode helps to prevent further damage. | |
put efficiency to | The amplifier’s transformer thermal protection cir- | |
greatly increasing amplifier reliability. | ||
cuitry is activated in very unusual circumstances where | ||
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The | the unit’s transformer temperature rises to unsafe lev- | |
els. Under these abnormal conditions, the amplifier will | ||
the amplifier’s ODEP indicators show whether the unit | ||
put both channels into standby mode. The amplifier will | ||
is functioning correctly or if ODEP is limiting output. | ||
return to normal operation after the transformer cools to | ||
Second, ODEP data is fed to the amplifier’s internal | ||
a safe temperature. (For more information on trans- | ||
P.I.P. connector so advanced P.I.P. modules like the | ||
former thermal protection, refer to the section that fol- | ||
lows.) | ||
This is how ODEP keeps the show going with maxi- | ||
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mum power and maximum protection at all times. | 4.3.3 Transformer Thermal Protection | |
4.3.2 Standby Mode | All Studio Reference amplifiers have transformer ther- | |
mal protection which protects the power supplies from | ||
An important part of a Studio Reference amplifier’s pro- | damage under rare conditions where the transformer | |
tection systems is standby mode. Standby protects the | temperature rises too high. A thermal switch embed- | |
amplifier during potentially catastrophic conditions. It | ded in the transformer removes power to the | |
temporarily removes power from the | age power supplies if it detects excessive heat. The | |
plies to protect the amplifier and its loads. Standby | switch automatically resets itself as soon as the trans- | |
mode can be identified using the table in Figure 4.2. | former cools to a safe temperature. | |
Standby mode is activated in five situations. First, when | If your amplifier is operated within rated conditions, it is | |
you turn on the enable switch, standby mode is acti- | extremely unlikely that you will ever see it activate | |
vated to provide | transformer thermal protection. One reason is that | |
lay lets other system components settle before any | ODEP keeps the amplifier working under very severe | |
signals are amplified and it provides some | conditions. Even so, higher than rated output levels, | |
“randomness” for multiple units so the system’s | excessively | |
current demands are better distributed over time. | high input signals can generate more heat in the trans- |
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