Air sound...

[sTaLa 10+ year member]

I went to the cine-parc yesterday to see how my sound system sounded. It was really good. Except that when there was no action and the only sounds were voices, I had this continuous sound of air. The one you hear when you turn up the volume of an amplifier even if nothing is playing.

Do you know anyway to remove it? A filter, better wires. Is it caused by the head unit or the amplifers?

Here's my setup:

Pionneer DEH-P7600MP Head Unit

2 Infinity Kapas 5¼ in front

2 Infinity Reference 6½ at rear

1 Old school Alpine Amplifier for those 4 speakers

1 Infinity Reference 12" subwoofer

1 MTX 3002 Amplifier for the sub

Thanks!

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[sTaLa 10+ year member]

No one?

 

[sTaLa 10+ year member]

If nobody on this forum knows the answer I don't know where I'll get it...

 

[azbass 5,000+ posts]

ah floor noise.

 

[sTaLa 10+ year member]

I don't really think so... it does the same thing on my home system. If you don't have anything playing and you turn up the volume, you will hear a sound, a kind of sssshhhhhhhhhhh...

I just wondered if there was any way to remove it.

Thanks

 

[helotaxi 5,000+ posts]

It's the noise floor as azbass said. It's present in most systems. You can minimize it by turning down all the gains. The only way to really get rid of it is with a noise gate. This basically mutes the input to the amp if the signal isn't of a certain level.

 

[azbass 5,000+ posts]

^^^ see

 

[sTaLa 10+ year member]

Ah, I didn't know the term "floor noise". But, when I listen to a movie for example, the noise gate will mute the input only when there's no signal at all if I understant well. So there is no point in having a noise gate because I will hear the floor noise all the same when the characters will talk...

Correct me if I'm wrong.

And just by curiosity... will the best system ever have the floor noise? Cause when I go to the theater I don't hear it.

 

[helotaxi 5,000+ posts]

When there is an audio signal and the gain structure is set right, you will not notice the noise floor. It's still there, it's just far enough below the level of the audio signal that you don't hear it.

Testing for system noise used to be (not sure if it still is or not) a staple of all SQ comps. They would play a zero data track at really high volume and turn on and off electrical accessories in the car and listen for any noise.

Noise in a system, just like distortion, is additive. A good Class A/B amp will usually test in the mid 70dB range for noise. Most Class D and a lot of the newer budget Class A/B amps only advertise s/n in the mid 50s. This should still be inaubible and on its own it probably is, but add in a series of other budget components and all that noise adds up to a level of audibility. Like I said before, you can minimize the noise by keeping the gains as low as possible. The input stage of the amp is one of the places that the current budget manufacturers cut corners on design, construction and materials. This leads to an input section that is noisier the harder that you ask it to work. This is one of the few places that a line driver (a quality quiet one, anyway) will actually help by allowing you to minimze gain settings on an amp with a sub par input stage. The onboard crossovers on a lot of lower end amps have the same problem and it is worth the trouble to go with an external crossover in the cases where the noise is noticable. The other solution is to buy quality components from the begining so you don't have to spend the money that you thought you saved by going with the cheaper gear covering up the flaws of the "good deal."

You don't hear it at the theater because of a combination of noise gates and really quiet gear.