Author Topic: Is white noise output flat across range?  (Read 8099 times)

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confuserated

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Is white noise output flat across range?
« on: April 30, 2012, 02:37:59 PM »
I expected the white noise signal to produce a roughly equal output of all frequencies but it doesn't seem to reproduce much at the lower frequencies, is this to be expected or can this be adjusted?

Thanks in advance, confuserated

FaberAST

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Re: Is white noise output flat across range?
« Reply #1 on: May 03, 2012, 09:00:20 AM »
confuserated,

How are you generating the white noise signal? Have you purchased the signal generator upgrade in SignalScope?

How are you measuring the spectrum of the white noise signal? Which input is the white noise connected to you your iOS device?

Ben

confuserated

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Re: Is white noise output flat across range?
« Reply #2 on: May 03, 2012, 01:43:44 PM »
Hi Ben,

I'm using signalscope pro to generate the white noise and it's that which I am asking about.

The output from my iPhone is going out of the headphone socket into an amp and out to a two wharfedale 9.1 left/right speakers and an sw150 subwoofer.

I feel like the white noise output is not across all frequencies because if I send a similar db level in a single tone out to the speakers and take the frequency down to the sub's level, it generates a lot of movement in the cone which is not replicated in white noise mode at the same db level.

I know it's not very scientific but it just feels wrong.

Thanks for your response,

FaberAST

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Re: Is white noise output flat across range?
« Reply #3 on: May 07, 2012, 09:31:00 AM »
confuserated,

A. You cannot generally expect white noise to be white anymore after it passes through a loudspeaker.
B. The acoustic environment (room) in which the loudspeaker is placed further affects the signal.
C. It is important to understand that white noise with a similar level to a single tone will have it's energy distributed across all frequencies. This means that the level at each frequency is much lower than the level of the single tone.

Ben

confuserated

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Re: Is white noise output flat across range?
« Reply #4 on: May 07, 2012, 02:36:52 PM »
Ok, thanks for the response Ben.

Should I expect the levels to be consistent after I have adjusted the output of the subwoofer to be the same as the left/right channels after calibrating them to be the same with a single tone, when measured with the same mic that I used for the single tone but in white noise output?

Thanks again, confuserated
« Last Edit: May 08, 2012, 08:25:21 AM by confuserated »