QuestionQUESTION: I want to install a stereo for my large pool area. The stereo will be enclosed but I want an outdoor rated system. I want to buy the Sony Marine CDX H905iP receiver (http://www.crutchfield.com/App/Product/Item/Main.aspx?i=158H905IP&tp=1721)and a Poly-planar ME400 Marine grade Amp:(http://www.crutchfield.com/App/Product/Item/Main.aspx?search=poly%2Dplanar&i=693) to power four 150-200W, 8 ohm outdoor speakers. My question is about the power supply. I want to run this system from a regular 120v AC power outlet. How do I get the AC converted to 12v DC required to power this system? I want to make sure I buy a converter that can handle the load and I am interested in how the wiring would work. Can you help? Thanks
ANSWER: You will need a 13.8 volt DC 50 ampere bench-top power supply. It will run you $150 - http://www.nextag.com/582432920p/prices-html
With an 8 ohm load per channel, the amp will put out half the power as it would 4 ohm, so that would be 50 watts RMS per speaker, not 100 watts RMS as spec'ed.
Look for 4 ohm marine speakers rated for 100 watts RMS.
The power supply will have to be housed indoors and the power wires ran through conduit out to the pool to power the audio system. Use 8 AWG power wire.
A custom made weather proof shelter for the audio equipment is a must.
Good luck.
---------- FOLLOW-UP ----------
QUESTION: Thank you. I have three short follow up questions.
1) Would a SE-600-12 work? http://www.trcelectronics.com/Meanwell/pdf/se600.pdf
2) I have a fully enclosed waterproof outdoor counter/bbq. When you said to mount inside, were you concerned about rain/direct mositure or humidity?
3) You did not mention anything about watts on the power supply. Is that relevant? The planar does havce 2x20 Amp fuses and the Sony has 1x10 Amp so the 50 Amp is spot on. I wondered if you needed enough wattage to handle the load of the 400 Watt device. Thanks
Answer1) Yes that will work just fine.
2) Just remember any voltage accessory like that must pass inspection for safety. I would have a qualified electrician make the final call. Yes, I was concerned with moisture. Electronic equipment such as a power supply is extremely vulnerable to any moisture as corrosion is so easy to occur. Once oxidation starts on a circuit board, it doesn't stop as long as power is supplied.
3) Mathmatically the volts, watts and amperes are all intertwined. It's know as Ohm's Law. Most power supplies aren't specified in watts as amperes is the driving force. The actual wattage power isn't a constant 400 watts as an audio signal isn't a constant signal. Having a power supply that capable of the full power is overhead.
