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So I'm looking at the JL a4300 and it tells me that at 12 volts it puts out 45 watts @ 4ohms. Then at 14.5 volts it puts out 70 watts at 4ohms. I noticed that the drawing of the side of the amp has a switch that has low or high input voltage, but I don't understand. How do you know what voltage your amp is getting? Or is that even what the voltage means? I don't know. Enlighten me please. I may be dumb so go easy on me if the answer is obvious.
 

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The low or high refers to speaker level input or RCA. DO NOT hook up the battery cable there!!!

There will be only one spot for the + connection from the battery!!!!
 

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Most modern vehicles have an electrical system that steadily runs at 14.4 volts. For years the trustworthy amp manufacturers rated their amps at 12 volts. The lesser brands would rate at 14 or even 16 volts. This is one way they "tricked" consumers to buy the product even though the components and engineering were sub-par. Depending on the power supply design that feeds the transistors within the amp, 2.5 volts can change the output of an amp by up to 30%. I always recommend testing the product before you buy or purchase from someone you can trust like a vendor on this site that others have used.
 

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I'd be willing to bet you will. If you want to be sure, you can buy a voltmeter very cheaply and verify the voltage at your battery. Also, many amps come with a certificate verifying the output wattage at a given test voltage. JL Audio is a solid company. I bet you see around 75 watts. A good company generally underrates it's equipment on a spec sheet.
 

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titanteacher said:
So your saying that I'd get the 14.5 volt output if I have the amp installed in the Titan?
Nobody will know exactly what it is without putting a meter on there. That voltage could also drop a little depending on what accessories are running.
 

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Vipzach is right. I'm talking about a pro install with solid grounding and sufficient gauge power cable. Running a ton of accessories can make it hard for the battery/alternator to keep up.
 

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That switch has nothing to do with vehicle voltage it has to do with the voltage of the preamp outputs on your headunit. Most headunits have 2v outputs and you would leave the switch on low for those units. Some units have preamp outputs with more power (4v - 8v) in those cases you will put the switch on high. Other settings are dependant on that switch so read your manual.
 

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debos titan said:
crap i have a 5v preout and my amp is running low.

Huh? 5V is good, it allows you to set the gain (Voltage Sensativity) adjustment lower. This can help to reduce noise if there is any. Even f the amp only goes up to 2V you can still use a 5V pre-out without issues.
 

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Justintoxicated said:
Huh? 5V is good, it allows you to set the gain (Voltage Sensativity) adjustment lower. This can help to reduce noise if there is any. Even f the amp only goes up to 2V you can still use a 5V pre-out without issues.
yes but he has amp set on low. the jl amps do like voltage at 4 volts or higher but really get some problems above 9 volts
 
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