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Author Topic: Best position for groundstacked pair of subs  (Read 8526 times)

Brad Weber

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Re: Best position for groundstacked pair of subs
« Reply #10 on: February 13, 2011, 10:23:24 am »

That is what I am afraid of Ivan.  Many members of our congregation comment that they are missing a sort of visceral impact or bass power from the current system which they felt was present with our previous all groundstacked system we had prior to building this facility.  So it is the old "ground coupling" idea that I am wondering about partly.
I think Pat Brown and Dave Gunness have pretty well addressed that what people often think is happening with ground stacked subs is not what is actually happening, so I would not necessarily assume that is the problem or the solution.

One question I had is how the current system is run, is it LCR, L/R plus mono or mono?  Is everything always run to all three subs or signals primarily going to one sub?  And how are you going to adapt the system to using two subwoofers?
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Tim Talbot

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Re: Best position for groundstacked pair of subs
« Reply #11 on: February 13, 2011, 11:19:16 am »

For best coverage and the smoothest sound place both together in the middle (center of room)

Mono summed of course :)

Loren Jones

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Re: Best position for groundstacked pair of subs
« Reply #12 on: February 13, 2011, 10:08:14 pm »

I think Pat Brown and Dave Gunness have pretty well addressed that what people often think is happening with ground stacked subs is not what is actually happening, so I would not necessarily assume that is the problem or the solution.

One question I had is how the current system is run, is it LCR, L/R plus mono or mono?  Is everything always run to all three subs or signals primarily going to one sub?  And how are you going to adapt the system to using two subwoofers?

Well it is currently set up to be run true LCR.  The desk is an ML5K with panning such that you can pan to 1, 2 or all 3 of the clusters in any ratio you want.  Our speaker install doesn't cover the room correctly to run truly LCR though.  Usually though I leave bass guitar, bass drum panned to all three speaker clusters evenly.  To adapt the current system to a pair of (mono) subs on the floor I would mix the L, C, and R sends in the input section of the system processor (dbx 480) to create the signal to be processed for the subs.  Alternatively I could run them on an aux.

I should be clear I am more experimenting here than contemplating any big changes that will cost money etc.  We have the other subs, I was just curious to swap over and try them out for a week or two and see what seems to sound better (and in which ways) in our application.

Do you have any more info on the Pat Brown and Dave Gunness work you mentioned?  I would love to read it.

Thanks,
Loren Jones
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Ivan Beaver

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Re: Best position for groundstacked pair of subs
« Reply #13 on: February 14, 2011, 07:49:58 am »

I think Pat Brown and Dave Gunness have pretty well addressed that what people often think is happening with ground stacked subs is not what is actually happening, so I would not necessarily assume that is the problem or the solution.


But one of the things you do get when ground stacked is the fact that the subs are closer to the people.  Level is one thing, but direct to reverberant is quite another.

When they are close-they are getting much more of the direct sound, rather than the sound of the subs and the room.

This can make for a "tighter" experience.  Less sloppy sounding.  But that is only for the people up close.  The ones at the back of the room are still pretty much getting the same sound as if the subs were flown.

OF course the whole idea of even coverage goes out the window at that point, but for some people that is fine.  They just need to be aware of it "going in".

You have to choose what is more important
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Ivan Beaver
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Ivan Beaver

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Re: Best position for groundstacked pair of subs
« Reply #14 on: February 14, 2011, 07:53:23 am »

Well it is currently set up to be run true LCR.  The desk is an ML5K with panning such that you can pan to 1, 2 or all 3 of the clusters in any ratio you want.  Our speaker install doesn't cover the room correctly to run truly LCR though.  Usually though I leave bass guitar, bass drum panned to all three speaker clusters evenly.  To adapt the current system to a pair of (mono) subs on the floor I would mix the L, C, and R sends in the input section of the system processor (dbx 480) to create the signal to be processed for the subs.  Alternatively I could run them on an aux.

I should be clear I am more experimenting here than contemplating any big changes that will cost money etc.  We have the other subs, I was just curious to swap over and try them out for a week or two and see what seems to sound better (and in which ways) in our application.

Do you have any more info on the Pat Brown and Dave Gunness work you mentioned?  I would love to read it.

Thanks,
Loren Jones
I would suggest running the subs off of an aux, rather than as the low freq of your mains.  that way you have much more control over what goes into them.

I would also look at getting your system so that works properly as an LCR (coverage wise).  Putting your bass instruments into seperated systems is asking for all kinds of problems.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Brad Weber

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Re: Best position for groundstacked pair of subs
« Reply #15 on: February 14, 2011, 06:55:16 pm »

Loren,

http://www.prosoundweb.com/article/tools_of_the_trade_how_boundaries_affect_loudspeakers/P1/
http://www.fulcrum-acoustic.com/wordpress/wp-content/uploads/2010/11/Comments-On-Half-Space.pdf

Two of the points I got from these are that the gain from boundary loading due to the floor surface is often reduced if not negated as it is to some degree a shared boundary with the receivers (the listeners) and as a result much of the increase in level attributed to boundary loading of subwoofers is actually due to an increase in the indirect sound levels rather than an increase in the direct sound levels.

But one of the things you do get when ground stacked is the fact that the subs are closer to the people.  Level is one thing, but direct to reverberant is quite another.

When they are close-they are getting much more of the direct sound, rather than the sound of the subs and the room.
You are right, simply getting the speakers closer to the listeners does increase the direct level and the D/R ratio.  Then there's aligning flown mains and ground stacked subs.  Like you said, trade-offs.
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Randall Hyde

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Re: Best position for groundstacked pair of subs
« Reply #16 on: February 16, 2011, 02:20:04 pm »

Hi all,

I am aware that there are lots of discussions on this and I have read through many of them.  I've also read the recent "avoiding Power Alley" article on PSW.

Ditto from me, too. While this thread has some interesting links and comments, I have a couple of questions:

1) I read an article somewhere (probably not in the study hall as I made my way through all 400+ articles without finding what I was looking for) that talked about setting up the subs in front of the stage in an arc (arcing forward or backward) to produce the best sound. Can't find the article again. What I'm looking for is what delay (or distance) to use for each sub when creating the arc (I assume this is based on the frequency response of the subs). Any links to such articles (or comments explaining this)?  I watched a Dave Ratt video where he said a "couple of msecs" delay between each subs lined up in front of the stage, but I'd like to know how to calculate the actual delay (or distance) and what effect this has on the sound.

2) Yeah, I (too) have read all the "power alley" articles in the study hall. I believe I understand the phenomenon well enough. Now, how do I calculate where to put the subs to achieve the most even response? Any pointers to articles?

Thanx,
Randy Hyde
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Brad Weber

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Re: Best position for groundstacked pair of subs
« Reply #17 on: February 16, 2011, 02:52:27 pm »

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Randall Hyde

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Re: Best position for groundstacked pair of subs
« Reply #18 on: February 16, 2011, 08:58:37 pm »

I don't know if these are what you were referencing or not, http://www.bennettprescott.com/downloads/SubwooferArraying.pdf and http://www.bennettprescott.com/downloads/AdvancedSubwooferArraying.pdf.

They weren't the articles I remember reading, but they're exactly what I was looking for.
Thanks,
Randy Hyde
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ProSoundWeb Community

Re: Best position for groundstacked pair of subs
« Reply #18 on: February 16, 2011, 08:58:37 pm »


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