Do volts matter?

[dragonrage 10+ year member]

That can equate to slightly better signal to noise ratio... But usually/probably not.

 

[Immacomputer 10+ year member]

Pre-out voltage really only reduces possible noise from the amps. If you have decent amps, anything above 2v should NOT make a noticeable difference. If you're upgrading to a much better deck, the change in sound may appear to be from the pre-out voltage but it's really not.

I have had multiple decks with all different pre-out voltages and I cannot say that it has even made the slightest difference in sound when the gains are properly set. I went from 1.8 to 2.2 to 5 and to 8. The 1.8v deck sounded better than the 2.2v and the 5v decks and they were all equally as loud. The 8v deck sounds the best but it's mainly in the EQs and other features of the deck that make it better, not the pre-out voltage.

 

[helotaxi 5,000+ posts]

That can equate to slightly better signal to noise ratio... But usually/probably not.

Higher preout voltage will, by definition, increase the s/n ratio of the RCAs, but if it's already way beyond audible at 2V, there is nothing to be gained by insisting on higher preout voltage.

 

[mlstrass 5,000+ posts]

My only real world experience is as follows:

Had a 15" Tempest sealed getting 500watts, sounded good in my car off a Excelon HU 4.5v pre-outs. Put it in the GF's car with a Pioneer with 2v pre outs. Same amp/sub, but very little output. Played around with EQ settings for a few days. Finally ended up using the Loud button and the sound came back.

Not saying it was a scientific "study" but there "might" be something to 2v vs higher pre-outs. What exactly does the loudness button do/increase?

 

[helotaxi 5,000+ posts]

The Loudness button is nothing more than an EQ with a boost on the high end and a boost on the low end. It could very well be that your GF's HU only put out 2V with the loudness enabled. It also could be that the 2V is a max figure rather than a RMS one. The final explanation is that the amp needed more input voltage than it should have to make power and/or the gains were set wrong.

 

[chartman18 10+ year member]

So all in all, would it be worse to have the amplifier below or above the Head Unit's pre-out voltage?

Hmm?

 

[Immacomputer 10+ year member]

I drew this ghetto image to help explain why there could be a difference in output:

If you're using a 5v headunit, you don't need to turn the gain much to get the max output. If you swap it with a headunit that only has a 2v output, you need to increase the gain to get to the same max output level. If you did a direct swap, you needed to reset the gains.

 

[T3mpest 10+ year member]

My only real world experience is as follows:
Had a 15" Tempest sealed getting 500watts, sounded good in my car off a Excelon HU 4.5v pre-outs. Put it in the GF's car with a Pioneer with 2v pre outs. Same amp/sub, but very little output. Played around with EQ settings for a few days. Finally ended up using the Loud button and the sound came back.

Not saying it was a scientific "study" but there "might" be something to 2v vs higher pre-outs. What exactly does the loudness button do/increase?

First things first. If the amp's lowest highest setting was lower than the hu preout voltage, then it's all gravy. Ex, if your amps min gains setting is 2volts, and your hu can output 2volts, then you CAN draw max power from the amp. If your amp only accepts 3volts and higher, you couldn't get full power without clipping the hu. All gain does is set the ratio of imput voltage to wattage coming from the amp.

Secondly, the BIGGEST thing your missing in your experiment is that it was in a totally different car. Every car has a different transfer function, what makes CRX's so popular?

 

[squeak9798 5,000+ posts]

Secondly, the BIGGEST thing your missing in your experiment is that it was in a totally different car. Every car has a different transfer function, what makes CRX's so popular?

I tried to explain the huge fallacies in his comparison in another thread a couple months ago.

 

[squeak9798 5,000+ posts]

So all in all, would it be worse to have the amplifier below or above the Head Unit's pre-out voltage?
Hmm?

I have no idea what you are trying to ask.

Are you referring to the gain setting itself?

Or the input sensitivity range ?

 

[chartman18 10+ year member]

Im referring to the head units pre-amp voltage to the amplifiers voltage settings.

 

[Immacomputer 10+ year member]

Im referring to the head units pre-amp voltage to the amplifiers voltage settings.

Most amps will accept inputs from like a couple hundred millivolts to about 8v or sometimes higher. As long as your headunit falls within this range, it doesn't really matter. With a headunit that has a higher pre-out voltage (5v-8v), you will need to set your gain lower. This can help reduce noise from the amp but like already stated, most decent amps will not give noise with a 2v input signal gain level.