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Author Topic: dbx Drive rack 360 Venue  (Read 2457 times)

Rob Spence

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Re: dbx Drive rack 360 Venue
« Reply #20 on: May 24, 2019, 05:13:41 pm »

Distributed systems are a valid approach to system design; when there is no practical point source design (hotel ball rooms/salons) and when a point source system cannot achieve sufficient intelligibility are a couple of good reasons. :D

Regarding your hotel acoustics:  many acoustic "charms" can be heard with simple impulse excitation - hand claps, dropping a book on a table or hard floor - but a lot of the time the noise floor of the room masks it.  A little "for instance" moment:  I had to do some physical measurements of our PAC's concert hall auditorium and under balcony area.  I've been in that space hundreds of times, but always with the air handling system running.  At 2am, it was silent and the flutter echo under the balcony (side to side, the up/down wasn't as bad) was plainly audible.  Similar acoustic charms were found in the middle of the house, too.  {/moment}  I'd encourage you to do a 'walk/clap/listen' next time you encounter something like that, it's very revealing.  Here's another "when you have the chance" things - hook up 1 subwoofer put it on a cheap furniture dolly and set it against a physical boundary like a wall (ideally in the center of a 40' long wall, but we can't be picky here), play some pink noise and listen as a helper moves it away from the wall (closer to you).  Baby baby, where did our sub go?  This is something I mentioned earlier - you don't need a DSP for physics to bite your butt here - and is how Otto Eq and a lot of humans get fooled into thinking the problem can be fixed with Majik Electronik.  Remember:  acoustic solutions to acoustic problems.

Marty McCann, the now retired clinician from Peavey Electronics has a white paper on boundary cancellation here:
http://assets.peavey.com/pv/support/soundsystems/new_boundary_cancellation.pdf

Getting back to tuning - tuning is getting the system to play nicey-nice with itself and my preference is that it exhibit linear operation.  That's when a change in the electrical input to the system results in an identical change in the acoustic output of the loudspeaker system.  That's the tabula rasa of PA.  Notice that I didn't say "flat", either...  With most "top box over a sub" type systems tuning is a one-time thing, or at least not a routine exercise.  It's the idea that you have a consistent and acoustically valid starting point every time.  The room may change but until you see what the room presents you, don't automatically assume the *PA tuning* must change.

Next comes voicing, making the PA tonally conform to your sonic desire.  This is where we might haystack the subwoofer send, where you might decide less 400Hz in L/R is what you need, or that with your band maybe a cut at 6.3kHz is the thing to do... but these are mostly subjective, artistic decisions you make based on how the rig sounds to you and how you want the band to be presented.  This is also where you'd make temporary main EQ changes based on venue variables.

Finally, if you need more gain before feedback, this is the time you ring out those last 2 or 3 feedback points.  Corrective EQ, so to speak.

PA tuning - transducer/pass band delays, drive levels, polarity, etc, once determined, get set in your 360.  If you find the system *always* needs a particular EQ change, make that at the 360's input EQ.  Do your voicing EQ with the console output EQs.

The way I might do things is certainly not the only way to achieve the desired result and I encourage thoughtful experimentation.

Well, most know I agree with Mr Tim....
Back when I bought my EV QRX212s, I consulted with EV on the best bi-amp settings for MY DSP. I then set up a pair outdoors and using the SMAART Spectrograph, I figured out the best compromise for cabinet splay doing the least comb filter damage I could.

These days, a long time from my configuration days, there are only 2 changes I make to the DSP for a gig. The routing (dual PA or not, Aux sub or not), and mains delay depending on placement of the mains vs stage. Thatís it. As Tim said, voicing is done before the DSP.


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Jonathan Barrett

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Re: dbx Drive rack 360 Venue
« Reply #21 on: May 30, 2019, 02:44:05 pm »

Distributed systems are a valid approach to system design; when there is no practical point source design (hotel ball rooms/salons) and when a point source system cannot achieve sufficient intelligibility are a couple of good reasons. :D

Regarding your hotel acoustics:  many acoustic "charms" can be heard with simple impulse excitation - hand claps, dropping a book on a table or hard floor - but a lot of the time the noise floor of the room masks it.  A little "for instance" moment:  I had to do some physical measurements of our PAC's concert hall auditorium and under balcony area.  I've been in that space hundreds of times, but always with the air handling system running.  At 2am, it was silent and the flutter echo under the balcony (side to side, the up/down wasn't as bad) was plainly audible.  Similar acoustic charms were found in the middle of the house, too.  {/moment}  I'd encourage you to do a 'walk/clap/listen' next time you encounter something like that, it's very revealing.  Here's another "when you have the chance" things - hook up 1 subwoofer put it on a cheap furniture dolly and set it against a physical boundary like a wall (ideally in the center of a 40' long wall, but we can't be picky here), play some pink noise and listen as a helper moves it away from the wall (closer to you).  Baby baby, where did our sub go?  This is something I mentioned earlier - you don't need a DSP for physics to bite your butt here - and is how Otto Eq and a lot of humans get fooled into thinking the problem can be fixed with Majik Electronik.  Remember:  acoustic solutions to acoustic problems.

Marty McCann, the now retired clinician from Peavey Electronics has a white paper on boundary cancellation here:
http://assets.peavey.com/pv/support/soundsystems/new_boundary_cancellation.pdf

Getting back to tuning - tuning is getting the system to play nicey-nice with itself and my preference is that it exhibit linear operation.  That's when a change in the electrical input to the system results in an identical change in the acoustic output of the loudspeaker system.  That's the tabula rasa of PA.  Notice that I didn't say "flat", either...  With most "top box over a sub" type systems tuning is a one-time thing, or at least not a routine exercise.  It's the idea that you have a consistent and acoustically valid starting point every time.  The room may change but until you see what the room presents you, don't automatically assume the *PA tuning* must change.

Next comes voicing, making the PA tonally conform to your sonic desire.  This is where we might haystack the subwoofer send, where you might decide less 400Hz in L/R is what you need, or that with your band maybe a cut at 6.3kHz is the thing to do... but these are mostly subjective, artistic decisions you make based on how the rig sounds to you and how you want the band to be presented.  This is also where you'd make temporary main EQ changes based on venue variables.

Finally, if you need more gain before feedback, this is the time you ring out those last 2 or 3 feedback points.  Corrective EQ, so to speak.

PA tuning - transducer/pass band delays, drive levels, polarity, etc, once determined, get set in your 360.  If you find the system *always* needs a particular EQ change, make that at the 360's input EQ.  Do your voicing EQ with the console output EQs.

The way I might do things is certainly not the only way to achieve the desired result and I encourage thoughtful experimentation.


Great info, particularly the highlighted, thanks
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Re: dbx Drive rack 360 Venue
¬ę Reply #21 on: May 30, 2019, 02:44:05 pm ¬Ľ


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