Forums › Forums › Qu Forums › Qu general discussions › Feeding subs via Mix 5-6 using LPF, as a substitute crossover › Reply To: Feeding subs via Mix 5-6 using LPF, as a substitute crossover
In theory it could work, kind of. An improvement on point 5 would be to instead of taking out <105Hz on every channel without useful bass content (I think you mean the HPF here, not LPF) in LR to instead just take out <105Hz on the LR bus as a whole using LR’s own peq\geq, kind of as you described in point4 for mix5-6, but backwards (create a hpf instead of a lpf.) This may knock all the bass out of your recordings if you’re using LR for recordings though.
However, I am against using the desk as a quasi-XO. Firstly, the eq filters on the peq\geq are nowhere near as steep (nor do they have as many options: eg Bessel, Buttersworth, Linkwitz-Riley) as they are on a proper XO, so although using the Qu as an XO could produce a semi-acceptable result, the result you’d get with a proper XO will almost certainly be better. Nextly, a board reset or botched scene\show recall without the appropriate safes could nix the settings entirely, and end up sending a full range signal to places that shouldn’t get it, which could be bad for your speakers and bad for peoples’ ears. The chance of this happening increases dramatically as you get over-helpful volunteers and\or people controlling things with ipads. Finally, if something happens to your Qu and it needs servicing, (unless you’ve got your scene backed up and you replace it with another Qu in the interim,) you’re going to need another XO anyway.
I’m all for running aux-fed subs (and I’d be setting mix5\6 as post fader with send levels at unity, essentially making it a subgroup.) I’m also all for using the outputs’ peq\geq to try to deal with room resonances or shape the mix in general etc (if it goes badly you might get some feedback or it might just sound bad, but it won’t destroy your speakers the same way that introducing a full range signal to drivers that can’t handle it will.) Tying the aux+LR levels together through a DCA will make things easier. I just don’t think it’s a good idea to use the mixer as a speaker processor, if it can be avoided.