Home Crown User Forum Crown Amplifiers


Hello everybody,
I am running (2) 5002 amps on 15" drivers. Ea. ch. is getting 4z load, identical drivers, identical boxes. Amps running stereo/4z load. Both amps are under IQ-II network control and are using IQPIP-USP2 Ultra cards. and I have the 1.010 chipsets on ea. I believe both cards are scaled to +20 setting.
I'm experiencing a 10dB loss in output power on one amp over the other (yes, both channels). ALL cards and networking aside. Using "dumb" cards, I have the same power loss. (input is not one-legged)
Am I about to see this amp fail? What should I look at if anyone has seen this power loss before?


  • Amplifier output is determined (in most cases) by the amp's supply voltage. The 5002 operates in a bi-polar rail supply, each +/- rail acting as a bi-level supply and switching seamlessly between two voltage levels. The lower supply will usually sit at half the full voltage available. At low power levels, the lower rail voltage is in operation and switching to the higher level (full) supply whenever needed. There is a way to keep amp at high levels, but not necessarily recommended, since it will not benefit from the cooling of being at a lower voltage level. Also, if it is a fet failure, the nomimal voltage will still be set to the lower level. (All of this has to do with the switch located inside the dust foam grill.)

    IMHO, since the amp appears to stay at a low power level it is possible that the bi-level switcher may be at fault. A fet switching circuitry carries out the bi-level operation. I've seen shorted fets or associated components keeping the rail low. Some fets fail due to improper thermal cooling of the device. Devices should be removed, evaluated and thermal paste replaced. Also, refurbish the filter caps since you have the cage open.

    Amplifier needs prompt servicing, adequate refurbishment of output devices (yes! there are 24 per side!), cleaning of the fans and ventilation circuits (airflow) and pots and switches.


Sign In or Register to comment.