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Author Topic: Why not Aux Controlled Subs?  (Read 31575 times)

Samuel Rees

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Why not Aux Controlled Subs?
« Reply #10 on: January 12, 2014, 11:02:21 pm »

Why is this bad?

Mac

Perhaps I should stay out of the science of it, because I'm really no qualified. I stepped out on the ledge for a moment because I believed that was a one sentence summary of the issue. What I can say is that I heard some people at AES talk about it, so I gave it a go in my workflow, and I feel like I get better behavior around the crossover frequencies of the rigs I'm using than I used to using aux-fed with various send levels. I find this to be especially true on rigs that have been professional processed, but not so much on rigs that are just thrown together. I can share that experience, but I'd like if someone else would explain the science. I believed that was a one sentence summary of the phenomenon I believe I've experienced - please, correct me if I'm wrong. Mac, you were there at the Rational Acoustics discussion I'm referring, perhaps you can share your insight on aux-fed vs group-fed and system tuning.
« Last Edit: January 12, 2014, 11:07:26 pm by Samuel Rees »
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Corey Scogin

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Re: Why not Aux Controlled Subs?
« Reply #11 on: January 12, 2014, 11:24:23 pm »

Sorry for being thick, but I don't get it.  Isn't the point of using Aux/group fed subs so that you can tweak the thump when you need it?  It is messing with the crossover point for the channels feeding the group, but isn't that the objective?

If you just leave a sub group set at unity, what benefit does it give over just routing to LR and letting your crossover do its thing?

My reason for using a dedicated sub bus is not to "tweak the thump" but to keep instruments/vocals out of the subs that don't need to be there.  It helps clean up the bottom end without needing to EQ or high pass those instruments.
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David Sturzenbecher

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Re: Why not Aux Controlled Subs?
« Reply #12 on: January 12, 2014, 11:33:22 pm »

When running subs from a bus (I like to use the mono bus, especially if there is a handle for it) it gives you one less point to mess up the drive levels (no aux knob, just a bus assignment) .  Yes, you can still push the bus output harder, just like you could have turned the aux master up more.  My reason for this to keep the acoustical crossover point consistant, as my stereo and mono fader would always track. Of course there is value in having your mains and subs phase aligned above and below crossover but sometimes there is only so much time. Plus don't you hate it when you bring your stereo fader down and the subs are still on because the aux doesn't have a easy handle?...DCA/VCAs can help you out here.   I try to avoid using the bus driven method as an easy way to push the low end harder when desired and keep those decisions on the channel strip, where adjustments won't effect crossover points.

I will also admit that I spend more time as a system engineer then mix engineer, so do whatever sounds best to you.
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Ted Christensen

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Re: Why not Aux Controlled Subs?
« Reply #13 on: January 12, 2014, 11:38:14 pm »

I would like to hear from you if what ever reason you are Not using Aux Controlled Subs. What is it you are doing that lets you mix the subs with the tops, and not getting too much being sent to the subs, that should not be there. Thank You!!

I see people saying it helps them not HPF the channel they need to...BUT IF you have a correctly set up PA with HPF on every channel up to say 400HZ why would you need to use an aux sub?? makes sense to me.

For me just using a HPF at the right place is all i need. I will use aux on occasion but only if i don't have a hpf.
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Tim McCulloch

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Re: Why not Aux Controlled Subs?
« Reply #14 on: January 13, 2014, 12:01:13 am »

I would like to hear from you if what ever reason you are Not using Aux Controlled Subs. What is it you are doing that lets you mix the subs with the tops, and not getting too much being sent to the subs, that should not be there. Thank You!!

I'm in the business of supplying systems set up the way the client wants.  I'm "sub agnostic".  8)

That said, most often the requests for a full-range setup come from jazz and classical gigs or where there is neither need nor desire for a "haystack" subwoofer response.
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Tim Padrick

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Re: Why not Aux Controlled Subs?
« Reply #15 on: January 13, 2014, 01:49:22 am »

Cranking the sub may give you a bump because of a "change in the acoustic crossover", but it gives a better result than the boosting of most shelving LF channel EQs, which have a very soft slope - thus boosting at much higher frequencies than you want. 
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Tim Perry

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Re: Why not Aux Controlled Subs?
« Reply #16 on: January 13, 2014, 02:44:23 am »

I'm in the business of supplying systems set up the way the client wants.  I'm "sub agnostic".  8)

That said, most often the requests for a full-range setup come from jazz and classical gigs or where there is neither need nor desire for a "haystack" subwoofer response.

Many guest "engineers" are befuddled by anything other then full range L/R.

Any DJ/EDM gig I don't even consider it.
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Nicolas Poisson

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Re: Why not Aux Controlled Subs?
« Reply #17 on: January 13, 2014, 03:39:08 am »

Cranking the sub may give you a bump because of a "change in the acoustic crossover", but it gives a better result than the boosting of most shelving LF channel EQs, which have a very soft slope - thus boosting at much higher frequencies than you want.

Funny, when I compared two ways of setting up my system for heavy low end:
- boost the low output of the processor (after filtering)
- boost the low end at the console (before filtering)
I found that the second solution was better.

Also, when using sub on aux (which I never tried), why is there a change in the acoustic crossover? Isn't the sub aux filtered ? Aren't you supposed to use a three inputs crossover in such cases ?
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Bob Leonard

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Re: Why not Aux Controlled Subs?
« Reply #18 on: January 13, 2014, 07:45:08 am »

I use a dbx Driverack 4800 for a DSP. The crossover is set correctly, and my subs and upper cabinets respond correctly. If I need more low end I use the board to increase levels or tailor response for the instruments needing help.
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Jeff Bankston

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Re: Why not Aux Controlled Subs?
« Reply #19 on: January 13, 2014, 08:02:13 am »

first of all i never use subs. i have always run a woofer that could go to at least 50 cps. there are 15" that can go flat to 40. i roll everything off at 40. i have a main pa with 18-12-2 horn. i cross at 130 and 1200 with an ashly xr4001 and i use the low section to roll the bottom end off at 40. the sound is awsome. everthing is nice and clear. long ago midrange soeakers couldnt handle much power and had a short xmax. the turbosound tms3 used a mid 10" that had an xmax of less than 2mm. you couldnt cross them low cause they would over excursion and blow up or freeze, etc. todays good speakers have 10" and 12" mids that handle 400-500 rms watts of power and have an xmax of 8mm-8.5mm and can be run down to 130 real easy or be used a a woofer even though they wont be much good below 100. try setting you lower crossover at 130 and try it. instead of having subwoofers i suggest you buy a 3 way system with 15" woofers that are flat to 40. or use an 18-10(12)-2. besides if you use your aux sends for subs what do you use for monitors ? i use my aux sends for stage monitors.
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ProSoundWeb Community

Re: Why not Aux Controlled Subs?
« Reply #19 on: January 13, 2014, 08:02:13 am »


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