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Author Topic: Recorder showed levels even across channels , files were drastically different  (Read 906 times)

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Offline ycoop

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When I run 4 channels I set my levels to peak evenly. Despite doing this last night, ch1+2 are around 10 dB louder than ch3+4. While this isn't the biggest issue since I amplify them to a similar level, I'm wondering what might cause this.
Mics: Avantone CK-1s, CA-14 omnis
Pres: CA9100
Recorders: Marantz PMD-706, DR-60d mkII, DR-22wl

Offline DSatz

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Without seeing the actual waveforms, we can only guess, but: Some signals have a lot of internal variation in their moment-to-moment levels; others, not as much. It all depends on the nature of the original sound plus any processing that's been applied.

If the variation in levels within a signal is considerable, that signal's average levels will be considerably lower than its peak levels. If the variation is less, then average levels won't be as far below the peak levels. For example, if any compression and/or limiting are applied to a signal, its peak levels will then become more similar to its average levels (the overall variation is reduced). But naturally-occurring (not electronically generated) sound, recorded without compression or limiting, often has peak levels that are much higher than its average levels.

Some people describe this as the "peak-to-average ratio" of the signal. A piano or a drum set can have 20+ dB difference between peak and average levels, while the 'cello section of an orchestra might have only 4 or 5 dB depending on the music and the miking.

The point is, if you have both types of signal on hand and you set their peak levels to be equal, then their average levels will differ considerably--the tracks with greater internal variation (contrast) will have lower average levels. And the perception of loudness depends much more on the average levels than on the peaks.

--best regards
« Last Edit: January 21, 2019, 01:24:28 PM by DSatz »
music > microphones > a recorder of some sort

Offline Fatah Ruark (aka MIKE B)

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Does this happen every time or was it a one time issue. Can it be replicated?
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Offline Gutbucket

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Is one set of mics omnis and the other a directional pair, say cardioids or super/hypercards?

If so, even if you set approximately equal levels across all channels at the start you are apt to find significantly higher levels in the omni pair once the show gets rolling and significant low frequency content kicks in. 

[edit- ..because low frequency content is dominant in terms of SPL combined with directional microphones being inherently less sensitive to the bottom few octaves]
« Last Edit: January 21, 2019, 04:36:26 PM by Gutbucket »
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Offline ycoop

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Does this happen every time or was it a one time issue. Can it be replicated?

I’ll check the next time out.
Is one set of mics omnis and the other a directional pair, say cardioids or super/hypercards?

If so, even if you set approximately equal levels across all channels at the start you are apt to find significantly higher levels in the omni pair once the show gets rolling and significant low frequency content kicks in. 

[edit- ..because low frequency content is dominant in terms of SPL combined with directional microphones being inherently less sensitive to the bottom few octaves]

One set was hypers and the other omnis. The set that ultimately showed lower levels was the Omni pair.
Mics: Avantone CK-1s, CA-14 omnis
Pres: CA9100
Recorders: Marantz PMD-706, DR-60d mkII, DR-22wl

 

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