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Author Topic: Bass Management - Crossover slopes  (Read 2726 times)

ppataki

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Bass Management - Crossover slopes
« on: April 19, 2017, 06:54:15 am »

Hello,
I would like to ask a question about the recommended crossover slopes in Bass Management
In the first row ("Crossover") - I suspect this is the high pass part of the crossover - the recommended setting is 12dB/octave while in the second row ("Routing") it is 48dB/octave - I suspect this is the low pass part

But regardless of the above, the 48dB/octave setting is fine as in that case the phase shift introduced by the slope will be 360° but in case of the 12dB/octave slope the phase shift will be 180°
So I would guess that instead of using 12dB/octave, the 24dB/octave could be a better solution as the latter has again a 360° phase shift - so the phase shifts will be 360° for both slopes
(I am having an assumption that JRiver filters are non linear phase filters - which would be great to be changed to linear phase IMHO)

Can you please clarify?
Thank you
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mwillems

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Re: Bass Management - Crossover slopes
« Reply #1 on: April 19, 2017, 06:09:17 pm »

They're minimum phase butterworth slopes so if they're phase aligned they'll be a 3dB bump. You're correct that with the default they'll be 180 degrees out of phase, but you can just invert one of the channels to resolve that (it may be that it's already inverted by default, I haven't checked recently). 

If you're concerned about getting the crossover to sum cleanly, I'd recommend that you set them up in the parametric equalizer by setting two 12dB low passes at the same frequency and two 12dB high passes also at the same frequency.  Stacking to 12dB butterworths will make a 24dB linkwitz-riley, which will sum flat at the crossover point.
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ppataki

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Re: Bass Management - Crossover slopes
« Reply #2 on: April 20, 2017, 04:46:59 am »

Thank you mwillems!

Also what I could probably do is to set it up like 24dB/octave and 48dB/octave (or both 24dB/octave) in Bass Management (screenshot attached) - in that case there shall be no phase issue as both of them have a shift of 360° - is that a correct assumption?

Do you think it is likely that once JRiver will have a checkbox to change filter behaviour to be linear phase? So we could toggle between linear and minimum phase then

Thank you
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mwillems

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Re: Bass Management - Crossover slopes
« Reply #3 on: April 20, 2017, 05:42:50 pm »

Thank you mwillems!

Also what I could probably do is to set it up like 24dB/octave and 48dB/octave (or both 24dB/octave) in Bass Management (screenshot attached) - in that case there shall be no phase issue as both of them have a shift of 360° - is that a correct assumption?

There will be no phase problem, but you'll have the "butterworth bump" and the lack of symmetry will introduce a ripple.

Quote
Do you think it is likely that once JRiver will have a checkbox to change filter behaviour to be linear phase? So we could toggle between linear and minimum phase then

Linear phase filtering requires convolution, which requires both some amount of delay and significantly more CPU processing power.  JRiver already allows for convolution and linear phase filtering via the convolution module. 
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ppataki

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Re: Bass Management - Crossover slopes
« Reply #4 on: April 21, 2017, 01:29:17 am »

OK, I see, thank you for the clarification
In this case I will go for a symmetric setting!
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