I know this has been talked about before, I just do not remember where and when. From what I have seen, brands have their wattage based on 14.4 volts. I believe someone stated that a boat will never run at 14.4 volts, but rather closer to 12 volts, thus causing a lower wattage than expected. Was/is this true. If so, what brands have their wattage based on 12 volts?
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04-20-2013, 07:19 PM #1
Amplifier Specs With Respect To VoltageJoe
2010 Outback V
Rockford Fosgate P500-4 Amp
Aerial 2 Speaker 3 Light Combo with Kicker KM6200 Speakers
Replaced Gravity I with Gravity III
Soon - Add IBS
04-20-2013, 08:13 PM #2
Re: Amplifier Specs With Respect To Voltage
Most brands post both ratings. I've noticed alot of jl stuff had the same ratings across the board.
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04-20-2013, 08:13 PM #3Senior Member
- Join Date
- Feb 2009
- Wausau, WI
Not a big audio guy here, but I put JL Audio amps in my boat. They list their amp specs at 14.4 volt and 12.5 volt. Most charging systems operate at 14 volt, when the engine is running (to spin the alternator). 12 volt is the battery at rest (no loads, engine off).Matt
2003 Outback, Assault EFI, (6) Polk Audio DB651s, JL Audio M6600 amp, JL Audio M1700 amp, JL Audio 10w6v2 subwoofer
04-21-2013, 11:40 AM #4
Most of the legit specs use the CEA2006 standard which is an extremely easy standard in hopes of seeing some consistency throughout the industry. But just because they are stated doesn't make them so. Power is taken at 1 kHz at 1% total noise/distortion at a 14.4 volt supply. That doesn't reveal much about an amplifier but at least it is a 'standard'.
Your boat alternator will deliver around 14 volts with good rpms in parallel with a 12.7 volt battery. Far less at idle or low rpms. You have perhaps 13.7 volts of supply with only a moderate load. As the current load increases the supply voltage will drop.
When at rest you will begin with a fully charged flooded battery at 12.7 volts (12.8 on an AGM). The battery should not be allowed to be discharged below a 50% charge, which is 12.0 volts, at least with any regularity in order to get good battery longevity. The 'at rest' supply voltage also sags when under considerable load.
The unregulated amplifier 14.4 volt supply specs will decline by an average of 25 percent with a 12.6 volt supply. So 100 watts becomes 75 watts. The power output continues to fall as the voltage continues to drop.
A strictly regulated amplifier, like a JL Audio HD series for example. will hold it's 14.4 volt power down to an 11 volt supply. Why? Because the power supply draws more current to offset the supply voltage drop to keep a consistent supply to the audio section. The first thought is more power, which is a secondary benefit. The primary benefit is sound quality. How do you expect an amplifer to perform when the solid state parts in it's audio section must contend with a supply voltage from 11 to 14 volts?
Another interesting point about unqualified power specs is that you have no idea how the amplifier is performing at 50 Hz or 15 kHz at full rated power and with various reactive loads.
An amplifier manufacturer with bogus amplifier specs has to create equally bogus thermal speaker ratings in order to match up components. This can take a bit of reading between the lines when matching products from different brands.