# Higher voltage preouts = more dynamic range



## oca123 (Aug 16, 2010)

I know that higher voltage pre-outs have the benefit of increasing signal to noise ratio. They also can, at times, make amplifier gain setting easy (if you have 8V preouts and your amp's minimum gain/maximum sensitivity setting is 8V )

I keep reading that higher voltage pre-outs provide increased dynamic range.
This seems to make sense at first.

But then I thought about it for a couple of minutes. In a head-unit, processor with digital inputs, etc. the digital to analog conversion is done via a DAC chips and I don't know of a DAC chip that puts out 8V.

So, does 8V pre-outs means that the DSP chip is putting out 2V for example, and then the signal is amplified to 8V?
Comparing this 8V signal to the 2V signal coming out of the DSP chip, isn't the dynamic range exactly the same?


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## Maylar (Dec 6, 2012)

Yes, it's the same. The ratio of loudest to softest doesn't change with amplification.


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## oca123 (Aug 16, 2010)

That was my point... higher voltage preouts do nothing for dynamic range, and the benefit of increased snr can also be achieved by using balanced connections.


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## t3sn4f2 (Jan 3, 2007)

Does nothing for s/n ratio either since the component noise entering the preamp stage after the dac gets amplified by the same amount. And the extra stage is not perfect so it itself will add a little noise onto the original signal. So you could say it reduces noise performance. 

Where more output voltage could help is to increase the signal level further away from an induced noise on the cable run. Or to use that extra gain instead of the following devices noises input stage, if it has one (ie hissy amp gain). But none of those two should be part of a quality setup to begin with. So its pointless to have more voltage than what you will ever use.


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## oca123 (Aug 16, 2010)

> Where more output voltage could help is to increase the signal level further away from an induced noise on the cable run.


if the signal level increases, and the induced noise on the cable run stays constant, does that not equal in a greater signal to noise ratio at the amplifier?


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## t3sn4f2 (Jan 3, 2007)

oca123 said:


> if the signal level increases, and the induced noise on the cable run stays constant, does that not equal in a greater signal to noise ratio at the amplifier?


Yes, but there should not be an induced noise in a properly implemented wire run. So using a higher than needed source output to make up for that is a wastefully poor band-aid at best.


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## oca123 (Aug 16, 2010)

agreed


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