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I just installed an Eclipse dead head unit that has 8v RCA outputs. Is there any benefit in having the higher voltage preamp outputs other than the ability to set your gains lower?

There is alot I dont understand about this, such as:
If the difference in amp wattage between 12v and 14.4 volts is so great, why doesn't doubling your preamp voltage allow you to make more power?

What's the difference, SQwise, between setting gains low and running the HU at full throttle (assume no clipping), as opposed to running a HU at half volume and setting gains higher to compensate?

Is reduction in noise floor the only benefit of high voltage preouts?


One more thing; Should this be in the dumb questions section, cause I don't see alot of discussion about it?
 

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Higher pre-amp voltage are for noise rejection, nothing more than that.... Balanced pre-outs/ins are mainly for long lenght from 1 point to another(like a concert hall), just that some companies uses this for marketing gimmick....
Amp's pre-in and output power are depending the multiplier(gain), so if say the amp accept max of 4V pre-in, at that voltage, the amp should have the rated output. With your HU, the gain should be in 0.2V to get an uniform volume control.... But my explanations could be wrong on this....
As for the 12V or 14.4V, I will see the power at 12V only, as that is more accurate. Some car can do 14.4V, but my car can't. Under car enviroment, what more important will be the external noise, I'll put more effort on this.....
 

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Discussion Starter #3
Ok well, one more question,

If you can set your gains lower because of a stronger preamp signal, does that mean your amp will run cooler?
 

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One more thing; Should this be in the dumb questions section, cause I don't see alot of discussion about it?
Nah, this is the right place for it I think. I would definitely like more information on the subject as well as I have the 8443. Are you running the 8053?
 

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Running the gains lower will result in a lower noise level at any given volume. How much of a difference it makes, beats me.
Road noise could easily be 70db, so unless you have the world's first completely silent car, my guess is absolutely no difference when the car is moving - or even running for that matter...
 

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It has been said by some competitors (whos views I deeply respect) that some amps sound better when you adjust gains higher than usual "proper" way would be. I have been thinking what the heck could be the reason for that... ??
Something to do with structure or class of amps pre-stage ...?
 

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Your gain is to match the head unit preamp voltage to the amplifiers voltage. 12V is what your battery runs at (aka the voltage your car has when its sitting in the driveway). 14.4V is the Voltage your car should be outputting if the engine/alternator is running. If your car is not running at 14.4 V you may have a problem with the voltage convertor or the alternator itself in your vehicle. Again as other people are saying, especially if you have a car that is older and as the car gets older, panels and materials wear out and more and more NVH (noise, vibration, harshness) is transmitted into the cabin. Unless you're driving a newer luxury vehicle ($40,000+) you wont notice the THD imputed into the system.
 

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Your gain is to match the head unit preamp voltage to the amplifiers voltage. 12V is what your battery runs at (aka the voltage your car has when its sitting in the driveway). 14.4V is the Voltage your car should be outputting if the engine/alternator is running. If your car is not running at 14.4 V you may have a problem with the voltage convertor or the alternator itself in your vehicle. Again as other people are saying, especially if you have a car that is older and as the car gets older, panels and materials wear out and more and more NVH (noise, vibration, harshness) is transmitted into the cabin. Unless you're driving a newer luxury vehicle ($40,000+) you wont notice the THD imputed into the system.
I agree on the noise, but there are a ton of cars that don't put out 14.4 volts. My wifes brand new civic puts out 13.8. My dads brand new Tacoma puts out 14. 14.4 is ideal, bit not having it doesn't really mean somethings wrong.
 

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Here's the deal, you will ALWAYS have noise induced on the line going to the amplifier/preamp/whatever.

So if you have X amount of signal going to the amplifier you are setting the gain structure up for Y amount of voltage gain at the amplifier, this voltage gain amplifies both the intended signal and the noise.

If you increase the output of the source to 4X then you decrease the voltage gain at the receiving end /4 this leaves you with the same amount of voltage at the output for the intended signal but induced noise is reduced by a factor of 4.
 

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I just installed an Eclipse dead head unit that has 8v RCA outputs. Is there any benefit in having the higher voltage preamp outputs other than the ability to set your gains lower?

There is alot I dont understand about this, such as:
If the difference in amp wattage between 12v and 14.4 volts is so great, why doesn't doubling your preamp voltage allow you to make more power?

What's the difference, SQwise, between setting gains low and running the HU at full throttle (assume no clipping), as opposed to running a HU at half volume and setting gains higher to compensate?

Is reduction in noise floor the only benefit of high voltage preouts?


One more thing; Should this be in the dumb questions section, cause I don't see alot of discussion about it?
Your preamp voltage has nothing to do with the output power. Fluctuating the input voltage to the amp, only changes the magnitude in which the amp receives signal. The amp is just a regulated quantification of whats received.
 

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Discussion Starter #17
Thank you everyone for the responses.

One more question. This might seem dumb though...

What does the amplifier do with the extra voltage? I dont really understaffed many EE concepts, but it seems to me that what goes in must come out. So how can you double the input signal voltage and nothing changes in the amp aside from the gain position?
 

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The extra voltage comes out in the form of clipping/distortion if the gains are set too high. Remember, the gain on an amp is just an attentuator.
 

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If the amp can only accept up to, let say 4 volts input and the deck can actually put out 8... usually amps don't have a problem accepting higher voltage... from what I understand they would simply take the 8volt but use it as if it were 4.... essentially the end results is just lke compressing music, making everything the same loudness.
 
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