Marine Boat Radio
2009
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My Radio in my boat keeps cutting out and resetting when i turn radio up a little.?
Ok i just bought a Kenwood - 50W x 4 MOSFET head unit and i previously purchased 2 6.5inch boss marine front speakers and 2 6x9inch boss rear speakers. the 6.5s are 200watts max and the 6x9's are 300 watts max. Am i trying to run to much on my head unit with out an amp? because every time that i try to turn it up past 25 on the unit it cuts out and resets?? when i get around 20 i start to see the lighting on the unit and the background start pulsing with the music. I think maybe my problem might be that im trying to pull to much out of this amp so i want to maybe get a Marine amp if i need one. can anyone tell me what amp i will need with the speaker setup that i have and what i should look for.
Thanks
Nick
Looks like the power supply is sagging pretty bad, and the low voltage is causing the unit to go into fail safe, or even just re-set as if the power has been turned off and then on again. Which as far as the circuit is concerned is exactly what has happened - as the voltage drops the output stages have to draw more current to maintain signal level, but this causes the voltage to sag further...... The mosfets will possibly have various protections built in like over temp, low voltage etc. The speakers momentary peak output rating has no bearing on the output of the amp stages (other than being well matched to your amps on the face of it) although the impedance of the speakers is much more critical in calculating SPL for a given circuit, however for a genuine 200 Watt peak (4 x 50W) your system requires serious supply cable sizing to cope with transient supply current spikes. At 12V nominal an output of 200 watts into say 6 ohms requires at least 20 amps constant - any supply cable should be 4 times that if the battery is a few metres away. Note that any low voltage cable rating - such as 10 amp wire - is the rated failure point, NOT the normal capacity. Mosfets are current switching devices, and if the voltage is lower they get hot while trying to follow the input signal. Kenwood circuit design is pretty clean, but you are pushing any domestic unit into distortion if you use high levels of bass and expect output over 70% of potential, sometimes less. Larger amplifiers can give more headroom before you get near clipping, but will also require larger supply lines and more sophisticated circuit breakers and so on.
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