# Crown I-tech HD amp fan mod not possible



## Maximilian Negro (Oct 2, 2017)

My crown I-tech 4x3500HD amp is installed in a server rack in my living room and its too noisy. 
The fans on this amp run constantly (this is normal on these amps) and spool up and down as needed (no error with their operation)
The amp has two fans, the one that cools the amplifier modules is a 70x70x35mm, 12v 1.1A, Nidec UltraFlo fan (model T70E12BUA5) capable of running up to 10,000 RPM. The other fan cools the power supply and is a San Ace 60, 24v 0.85A fan. Both fans are regular 4pin PWM fans.
Adding a resistor to the fan power does slow the fan but the amp goes into “protect” mode. 
Changing the fan with a slower fan also makes the amp go into “protect” mode.
The amp is too smart, it monitors the fan speed and knows how fast the fans should be running when it detects a lower RPM than it is expecting the amp goes into “protect” mode. 
The crown manual states “variable-speed fans with tachometer feedback. Microprocessor monitors fans, and signals an error via System Architect if fans are not operating”
Does anyone know how to disable or trick the amps protection system?

Max


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, Max!

If the protection is microprocessor based, there’s probably nothing you can do.

Regards, 
Wayne


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