Frequency Response Graph

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tcatzere
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Joined: Sat Sep 11, 2004 10:46 pm
Location: Scottsdale, Arizona

Frequency Response Graph

Post by tcatzere »

How do you interpret the significance of the vertical "dB" scale in the Frequency Response graph view?

Tom
har-bal
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Re: Frequency Response Graph

Post by har-bal »

tcatzere wrote:How do you interpret the significance of the vertical "dB" scale in the Frequency Response graph view?

Tom
Tom

The vertical scale is in dB so if you want to pull down a particular region by 3dB then you can use the scale as a guide. Probably a better
way to read this is to take note of the values printed in the status bar as your drag your spectrum with the mouse. The actual axis values are reported here to make it easier for you to read. As for what the dB value actually corresponds to, the dB reference 100p = 0.0000001 and that is a power reference (ie. signal squared). That corresponds to a reference of 1/100,000th of full scale. I chose that value so that the dB's would all be positive but in hindsight maybe a full scale sinusoid as 0dB would have been more logical. Maybe I'll change it to that to make it more intuitive.

The final point I'd make is that you can't easily correlate the dB you see in the spectrum with the dB you'll see in your VU meters because what you see in the VU meters is the integral sum of the entire spectrum and not just one point. The case that there'll be a one to one correspondence in the displayed values in each would be for the trivial case of a sine wave, but that doesn't make for very interesting music.

Paavo
tcatzere
Posts: 100
Joined: Sat Sep 11, 2004 10:46 pm
Location: Scottsdale, Arizona

Post by tcatzere »

Thanks, Paavo.

One last hypothetical application question . . . if I wanted to pull back 2 dB at 300 hz, how would I best determine that? (especially given the information you just provided).

Tom
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Post by har-bal »

tcatzere wrote:Thanks, Paavo.

One last hypothetical application question . . . if I wanted to pull back 2 dB at 300 hz, how would I best determine that? (especially given the information you just provided).

Tom
Tom

The easiest method would be to move your cursor to the 300hz mark and look at the bottom left hand portion of the screen that shows your cursor location at all times and just drag it down 2 dbs.
It shows both the db's and hz

Earle
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