AUX Fed Sub. Should be an easy one

[sants]

I know all the benefits and have done it before with an active sub when I patched into an active house system.

 

My normal rig consists of both mains and subs being crossed over and each receiving the entire mix.

 

My question is for guys that run subs aux fed, do you crossover the mains or run full range?

[Bufalo]

I still put a high-pass filter on the main speakers while feeding a sub signal from a separate Aux mix.

[dboomer]

You should know that nothing has an easy answer in audio. Traditionally it is done by high passing the mains and band passing the subs ... but ... depending on what outcome you are looking for it could be done differently

[monthlymixcd]

My question is for guys that run subs aux fed' date=' do you crossover the mains or run full range? [/quote']

 

Since you put it THAT way, it sounds like you're asking if it's better to run the aux fed subs as an additive effect to full-range mains... or using the typical crossover method (as Don described most accurately) and just feed only the channels you want into the signal chain for the sub(s) using an aux send.

 

And the answer, "It depends." lol

 

I can really only tell you how I do it, and that might not help you at all:

 

We use active mains and subs (that all have internal processing that protects them and only lets them reproduce what they're made to reproduce). We also use a Soundcraft GB4 32ch. board that lets you assign channels to a "C" mains output as well as "L/R" mains outputs. We treat the "C" send as the aux feed for the subs and then it also has a dedicated fader for master sub level that way. Depending on how we array the speakers (active mains over active subs on extension poles or mains on stands and the subs center-clustered) I can choose on the back of the mains (PRX615Ms) to use them in "Mains" mode running full range or in "Monitor" mode HPF'd. The former scenario being where we treat the subs like an additive effect and the latter where it's a traditional crossover-type setup where we're just adjusting the mains vs. subs balance on the fly.

 

 

[agedhorse]

IMO, to obtain the benefits worth of the additional work, I recommend that the tops be high passed with everything in the mix and the subs low passed and fed from a post-fader aux bus adding the sub content proportionally on a channel by channel basis as needed.

[mshifflett]

IMO' date=' to obtain the benefits worth of the additional work, I recommend that the tops be high passed with everything in the mix and the subs low passed and fed from a post-fader aux bus adding the sub content proportionally on a channel by channel basis as needed.[/quote']

 

I agree. This would be the way I would approach it as well. I have done it in the past just as an experiment but never really saw(heard) the big payoff from the effort. I think much of it depends on the individual system you are working with.

[Craig Vecchione]

If you don't have the low-end rumble and noise problems, there's little if anything to gain by aux-fed subs.

[dboomer]

Whether you hear it or not depends on how you run your system. But with conventionally configured aux subs you will gain headroom and lower distortion

 

An easy way to check would be to take a recording of the lead vocal channel from one of your live shows and high pass it with the same filter as you would be using for separating the subs from the tops. All that muddy junk that you hear is coming out of your system leaving you with what you hear from the high bandpass

 

Whether that value is worth the effort depends on your music and how you mix. So if you mix in a more "classical" way that I'm sure Andy does (and probably I do when I can) you won't see as much benefit as you will if your show features a lot of low bass and loud stage levels run through a marginal system that doesn't have tons of headroom.

[agedhorse]

I mix in the style that makes me the most money, generally pretty flat, un hyped response.

[Dogoth]

I'd say yes you should definitely high pass the main boxes & band pass the subs. One of the main reasons for having subs is to take the LF load (and it's inherent IM distortion it can cause) away from your main speakers. This gives the mains amp(s) and speakers the ability to reproduce their given frequency range with far more clarity. Let the subs do the heavy work and leave the mid punch & articulation to the mid/tops.

 

I've worked with both type systems and given a choice, I'll take the aux fed subs. It's a bit more wiring & filters in your rack but once it's done you have the best of both worlds (if you set every post aux feed knob at unity you in effect have a standard system - I've never done this but.....).

 

Strip HPF filters are fine but don't seem to have the slope of most crossovers. If you want zero low end coming from F.I. a vocal or acoustic instrument mic, IMHO aux fed subs are where it's at.

 

Just my .02 worth