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#2927144 - 05/15/18 09:31 AM OT - PA Question
midinut Offline
Platinum Member

Registered: 08/18/03
Posts: 1463
Loc: North Carolina
We are trying to set up in-ear monitors for our tribute band. So far, we have a Presonus StudioLive 32R Digital Mixer with all those aux outs to be used for monitor mixes. Coming out of the aux outs into a Behringer PwerPlay DA8000 V2 8-Channel Headphone amp and then everybody has either a wireless in-ear system or wired headphones. We have 4 QSC K12.2 speakers in our practice room for mains. The main out of the 32R is feeding two of them now. The other two I've been using 2 aux channels to feed them. If we were to daisy chain off the two main K12.2s would the drop in impedence be substantial or bearable. One of the K12.2s is also feeding an 18" subwoofer as well. Just trying to gauge whether the drop in impedence would be feasible or are we better off feeding them with aux outputs? Just throwing it out there for the group. As always, thanks in advance.

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#2927149 - 05/15/18 09:55 AM Re: OT - PA Question [Re: midinut]
timwat Offline
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Registered: 11/21/01
Posts: 5552
Loc: Concord,CA,UNITED STATES
I think you're mixing up electronic principles.

Impedance halving occurs when a passive load is set across power. In other words when you daisy-chain two passive speakers across a power amp's output.

What you're doing is something entirely different. You're using active, self-powered speakers and looking to daisy-chain the mixer's line-level output across multiple line-level inputs.

I believe the k12.2 should have (like most other active pa speakers these days) a "thru" XLR male jack for exactly this purpose.

edit: Also, perhaps the ideal way to set up your rig is to run mixer to subwoofer (presuming your sub has built-in high-pass crossover), subwoofer high-passed stereo outs to k12.2, thru jack of k12.2 from 1st cab to second (on each side, left and right). But if for some reason distance, cabling etc makes that impractical, and you're not running drastic Left/Right panning on anything, the subwoofer chained from the k12.2 should provide the low octave thump you're craving.

Although I gotta say, if you're using four (4!) k12.2s, I'm curious if you really need an 18" subwoofer in the equation.


Edited by timwat (05/15/18 09:59 AM)
Edit Reason: add'l thought
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#2927224 - 05/15/18 06:49 PM Re: OT - PA Question [Re: timwat]
hardware Offline
Platinum Member

Registered: 03/04/14
Posts: 1258
Loc: Macau
Definitely take the K12 feeds from the Sub.
Much better roll off for the 12s.
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#2927234 - 05/15/18 08:00 PM Re: OT - PA Question [Re: hardware]
WesG Offline
MP Hall of Fame Member

Registered: 02/16/13
Posts: 3361
Loc: Inverary, ON, Canada
Quote:
We have 4 QSC K12.2 speakers in our practice room for mains.


Wow, you practice LOUD!

You also don't need to worry about input/output impedances with the active gear. The input impedance of your speakers will be at least 10,000 ohms. The output impedance of your board will be no more than 600 ohms. This means you can run at least 16 speakers off each output.

Wes
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#2927391 - 05/16/18 04:27 PM Re: OT - PA Question [Re: WesG]
midinut Offline
Platinum Member

Registered: 08/18/03
Posts: 1463
Loc: North Carolina
Thanks guys. Yeah, I had forgotten that the impedence drop only happened with passive speakers. Duh. I'm frustrated because I recommended this setup (for the in-ears anyway) and we can't get it to work. I just need to spend some time on the phone with a tech from Sweetwater or Presonus and I'm sure we'll get it figured out. Thanks for the help!

Yeah Wes, we practice LOUD. Hence the effort to try to save mine and everyone else's hearing. I'm sure you understand!

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