*Racks* : Sweepable Crossover

[ra78]

thanks, a lot for sharing, Gentlemen.
Best regards from Kiev/Ukraine,
feel free to give me a shout,
if anybody will come over - will share my advice over local specifics gladly.


my skype is arj1978

[Khazul]

Tip:

If you want a totally flat frequency response, do this:

Take a lowpass filter, like one band of EQ-8, with a Q of 0.7.
The output of this one is your Low Out. Now take the output and subtract it from the original signal by adding it with inverted phase to the original. To invert the phase use the Utility device. This gives you the High Out. By cascading more of these you can create a 3 or 4 band crossover with moderate seperation but perfect flat frequency response and almost no coloration of the signal at the crossover points.
If i find the time I will post a Rack doing this...

Robert

I dont beleive this will be transparent, otherwise the overall matrix is right.

Try Q=0.5, otherwise you end up with a non-transparent crossover. Anything above 0.5 ends up with insufficiently damped filters which means they start to resonate a tiny bit, coloring the sound around the cross over - like EQ3 suffers from (which I beleive also has Q=0.7.

[ethios4]

It's been awhile so I should test it again, but I do believe when I originally made this rack I did some phase cancellation tests with white noise samples and the filter was perfectly transparent. I'll try to test again and see how it fares.

[Khazul]

The sum is transparent as so will cancel wth the original sound, however when Q>0.5 the individual hi and low are not and will have slight coloration (which gets cancelled in the sum due to inversion) which might matter when applying separate procesing (for eg a different compressors in the resulting hi and low bands), or even if driving different speaker systems for eg.

Im assuming here that the Q values are in fact real DSP filter Q values - maybe google for 'damped filter' or similar might exlain this.

[ethios4]

Ahh, I think I get what you are saying. I'll try a Q of 0.5 and see how that goes.

[Septr]

Cool beans. I was rackin' my brain on how to do this. Glad to have that terrible phasing behind me. I took the liberty of making some higher order versions of this for everyone to enjoy. Adding bands isn't as simple as it might look at first glance.

Downloads:
3-Band Sweepable Crossover
4-Band Sweepable Crossover
4.5-Band Sweepable Crossover
5-Band Sweepable Crossover

On the 5-Band, I've made it possible to completely close both LoMid and HiMid bands by setting the crossover freqencies to their extremes. On the 4-Band it is only possible to close the HiMid band in this way. The 4.5 Band is actually just a 5-Band with the two mid crossovers tied together. This makes the center mid band non-adjustable, only sweepable. You can close either the LoMid or the HiMid bands in the way previously mentioned. I don't know how useful this version will be, but I made it anyways.

I want to encourage you guys to play with the min-max ranges to fit your specific needs. Though, I did my best to make them as versatile as possible, trying to give each band the widest ranges I could.
Also, there is a chain I left in there, but is turned off, called 'Inverted Clean'. That is just a clean signal with inverted phase. I used it to make sure I was building everything correctly. You can use it to check how transparent this crossover is. When turned on, things should turn silent. This can also be used to monitor side channel content if you build a Multiband Stereo Imager or something like that.

By the way, I've made these racks in Live 7 incase there are some folks, like me, on older versions. I'm sure newer versions can open them just fine. It's the other way around that is impossible if I remember correctly.

[ze2be]

Nice!

[ethios4]

Awesome, thanks Septr!

[Warmonger]

Thanks to Septr I was able to create transparent 8-band DJ mixer just out of stock Ableton plugins. Thanks!

[Tumby]

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