24 vs 6 dB, are there different dB in Live?

Discuss music production with Ableton Live.
black.onyx
Posts: 7
Joined: Fri Nov 29, 2024 12:47 am

Re: 24 vs 6 dB, are there different dB in Live?

Post by black.onyx » Tue Dec 03, 2024 10:56 am

@x3000:

Indeed, your spectrum shows a declining slope of ~ 24 dB/octave. (-51, -74 between 5 k and 10 k). That's what I would expect. My spectrum gives me ~ 16 dB/octave both for the autofilter and the VCF of the Juno 6. That's at least acceptable.

Now, send the same input to the spectrum of EQ Eight. For me the result is fully different, maybe 8 dB/octave.

Hence, I still think this could be a different scale.

x3000
Posts: 52
Joined: Wed Oct 04, 2023 2:47 pm

Re: 24 vs 6 dB, are there different dB in Live?

Post by x3000 » Tue Dec 03, 2024 8:37 pm

Yes, indeed. The display in the EQ8 does not appear to be technically correct. The reference does not describe the spectrum display exactly.
It could be that the frequency response in EQ8 is displayed in dB(A) and in Spectrum in dB(C). But that would not explain the big difference.

I would guess that Ableton hasn't reinvented the wheel every time, but has integrated standard libraries or algorithms for various cases.

Maybe they forgot to square the values:
log(1/16) = -12dB
log(1²/16²) = - 24.1dB

I wouldn't bother with that. The display of the spectrum in EQ8 is only a rough guide. In the end, you have to adjust by ear.

However, you can see that the stand-alone spectrum analyzer in Live (Spectrum) appears to output consistent values.

benmuetsch
Posts: 76
Joined: Wed Sep 28, 2011 8:45 pm

Re: 24 vs 6 dB, are there different dB in Live?

Post by benmuetsch » Wed Dec 04, 2024 8:48 am

I really don't see the point here. These Ableton filter implementations are mathematical textbook variable Q filters and they work exactly as they should.

There is a VST plugin to check frequency response and phase, maybe try that, it'll prove everything.

https://www.bertomaudio.com/eq-curve-analyzer.html

x3000
Posts: 52
Joined: Wed Oct 04, 2023 2:47 pm

Re: 24 vs 6 dB, are there different dB in Live?

Post by x3000 » Wed Dec 04, 2024 9:23 am

@benmuetsch:

The point is not the filter, but the display of the frequency band in EQ8, which you can easily check with Spectrum.

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