General Sub-placement question.

[Marko]

First, I'm familiar with "Coupling","Boundary Effect" and "Power Alley".

 

It's kind of a general question, but just in case someone asks, I'll just state my actual situation, and if you don't need that, just skip down to the last question.

 

Two or three times a year, we let the kids do a Talent show where I teach (for a couple different reasons), with poetry reading and various singing/dancing stuff the kids perform. We're doing one in a couple weeks.

 

The seating area is wide - I'm guessing 40' or so, the stage area is pretty shallow, and Staff is all along the outside and back wall.

 

I usually just put one sub/top (118/115) stack on each side, in front of the mic line and spread out to the outer edges of the seating, maybe 30' apart (they use the whole area) and turned in.

 

My reasoning is that the audience is so spread out that each Sub/stack is pretty much taking care of one half of the seating.

 

I was thinking it would be cool maybe putting just the Subs together on the back wall behind the seating, but I'm just running passive from the Subs up through the Mains, all being fed from one Amp. I know that you guys don't do it that way, but it's just simple for me, and considering the small nature of my providing, I'm not sure I want to change that. (The lounge I mixed bands in had their house system, and they retired and closed.)

 

I thought it would be a good general question that might help someone else.

 

If anyone asks how it sounds, I can't say, as I never felt comfortable leaving my station to walk around... nobody knows how to handle a mic.

 

I guess the question is, at what distance (of Subs) does Power Alley become mute, and I can get ideas from the answers.

 

Thank you much!

[where02190]

Your subs will be massively out of time alignment with your mains, and, since they are all fed from the same source, would be impossible to time align.

 

If you want to couple them for efficiency, do it in front of the stage, not the back of the room.

[Marko]

Yeah, I should have thought of that, putting the Subs in the rear of the room would cause that problem... I didn't think before typing that in there.

 

I might be able to put them center, although in my particular situation, they'd likely be in the way, shallow stage area and seating right there... no dance floor area, just stage area, like maybe 16 feet deep (usually no risers, just flat floor) and seats right there. This is in the "commons", just an open area, chairs put on the floor.

 

I guess I should have just submitted the general question, as my situation is probably not fixable.

[where02190]

are you simply looking to experiement, or are the issues with the low end?

 

If what you are using works, I'd say it's probably your best option.

[Marko]

The original post was meant to be a general question regarding the distance between subs and "Power Alley", but since I did describe the situation that brought that question to mind, you very-nice and helpful people focused on my actual situation.

 

I guess at some distance, it ends up being two separate PAs.

 

Since I did take the time to descibe it, it would seem that it was on my mind... maybe a subconcious cry for help... lol.

 

After I posted, I went to bed and thought maybe I should've just not asked the question - then I started thinking about my actual situation, and thought of another weird idea.

 

Now I AM asking for feedback (the good kind) regarding my situation, and the following idea... maybe a NEW "general sound-related question" lol. ("Good Morning", by the way)

 

First I want to add to the scenario the shallow stage area (not really a stage) with a brick wall right behind it making foldback a problem, especially with the lack of room for monitors with the seats placed right at the front of the performance area.

 

What if I put the speakers (PA) against the back wall, facing the back of the audience and toward the stage. Aside from the psycoacousic issue, this would solve ALL the problems (that I can think of).

 

That would eliminate the need for monitors, or at least the issue of the performers hearing themselves, and less chance for feedback (the bad kind).

 

I remember reading about that type of placement (short of all details, I'm afraid) on another popular SR forum site, and I recall some positive comments regarding that type of placement - placeing the PA on the back wall facing the stage. Also, we're not talking Bands playing, making timing less of an issue... sometimes an instrument being played for one number, but mostly just kids singing/dancing, and poetry reading.

 

Maybe the positives would outweigh the negatives, at least in my case.

[Scodiddly]

Putting the mains behind the mics is extremely rare, because it vastly reduces the amount of volume you can get before feedback. Difficult at best.

 

Just about any question about subs is a good one, though. The usual "each side of the stage" approach is still the most common and convenient, and also one of the worst because of issues like the power alley and off-center comb filtering. But if you've a low stage (like 12") there's basically nothing you can use in front center that won't be taller than the stage.

 

In one small club I used to regularly work I sometimes had good luck just turning off the sub on one side. It would seem that there would be a huge imbalance, but in reality a small venue tends to carry the lows all over the room and so it was more even than having both subs running. And most subs are pretty much omnidirectional in output.

 

Depending on the size of the room your idea for putting the subs together on the back wall isn't really that bad. It's something that might be worth fooling around with if you can get off-hours access to the venue.

[Marko]

By "Back wall", I meant the wall opposite the stage, behind the audience, facing the stage.

 

The two subs on one side is what I usually do in a bar, but the spread here is so wide and the audience so close/cramped to speaker line that I thought it would make for too much sub on one side and not enough on the other, but...

 

as to putting the whole PA on the Back Wall, it's only about 35/40 feet from the stage, and the area is less deep than wide, so the PA wouldn't be that far away from the performers.

 

I'm at school now; I'll go pace off the area later, cause I could be real off with the measurement, but it's a little less deep than wide.

 

Thanks

[Dan Magers]

This java applet demonstrates interference between two sources of sound waves.

 

http://www.falstad.com/interference/

[Marko]

Originally posted by Mark G. Hinge Now I AM asking for feedback (the good kind) regarding my situation, and the following idea... maybe a NEW "general sound-related question" lol. ("Good Morning", by the way) First I want to add to the scenario the shallow stage area (not really a stage) with a brick wall right behind it making foldback a problem, especially with the lack of room for monitors with the seats placed right at the front of the performance area. What if I put the speakers (PA) against the back wall, facing the back of the audience and toward the stage. Aside from the psycoacousic issue, this would solve ALL the problems (that I can think of). That would eliminate the need for monitors, or at least the issue of the performers hearing themselves, and less chance for feedback (the bad kind). I remember reading about that type of placement (short of all details, I'm afraid) on another popular SR forum site, and I recall some positive comments regarding that type of placement - placeing the PA on the back wall facing the stage. Also, we're not talking Bands playing, making timing less of an issue... sometimes an instrument being played for one number, but mostly just kids singing/dancing, and poetry reading. Maybe the positives would outweigh the negatives, at least in my case.

 

[Ear Abuser]

For school talent show , I'd just forget the subs altogether. In the typical "Multipupose Room " they are just going to add a bunch of low end mud, but it depends on the room.

I do a talent show in a school gym with just a 15+1 top and it has plenty of low end. This year we added a couple of 12+1 tops delayed halfway back and it really helped with the intelligibility in the back half of the room.