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Title: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 03:19:47 am
I'm a long time lurker around here, but not much of a poster.

I am helping select gear for a 200 seat lecture hall.  The dimensions/layout of the room are very interesting.  I would love to get some thoughts on this.  There is about a $20-25K budget for speakers, mixer, cabling, and some lavs.

The room is 18' wide x 117' deep.  The first 33' of depth are flat ground with only 27 seats, a 12' x 18' x 10" riser/stage, and a large projection screen.  The remaining 84' are stadium seating at about a 15 degree incline.  Ceiling height is 13' in the flat area and narrows to 11' at the 11th row.  After the 11th row, the room opens up. I know... like I said, interesting. 

I'm not very good at Sketchup yet, but I attached my best effort.

The room will be mostly for lectures and videos, but also for occasional small live performances.

So far, I'm thinking 1x SRX835p per side in the flat area.  These will be angled to point toward the center of the 13th or 14th row, just past where the ceiling opens up.  I'll need something smaller as a center front fill for the first couple rows.  Once I figure out what I want to do for the front fill and subs, this will comprise "Zone #1".

For the rest of the room, "Zone #2", I'm thinking 2x SRX812p's on each side spaced evenly and pointing down.  I'll have to mess with delay times on these. 

This room is so long that I'm still not sure what to do for subs.

Any thoughts would be much appreciated.

Thanks
-AE 

   
Title: Re: Install in a lecture hall
Post by: Ivan Beaver on September 18, 2015, 08:10:43 am
Since the room is primarily a SPOKEN WORD place- a SINGLE source of sound would best-especially since the room is deep and narrow.

Add a sub for low end when needed-and turned OFF when being used as a lecture hall.

Title: Re: Install in a lecture hall
Post by: Scott Hofmann on September 18, 2015, 08:55:44 am
A long group of line-array column speakers on each side at the front of the stage might cover that distance although their typical wide dispersion would be a problem. Or one set for zone 1 and another set at the second projection screen for zone 2.  SLS, JBL, TOA, others.
Title: Re: Install in a lecture hall
Post by: Scott Carneval on September 18, 2015, 09:27:12 am
18' wide is pretty narrow.  Do you NEED stereo?  I would agree with Ivan that a single center speaker would work well.  Another single center speaker back where the room 'opens up' should cover that area also.  You might want to go a little higher than 11' in the 'open' area, as this will allow more even coverage front to back.  The first few rows of the 'open' area will be out of the pattern of the speaker above them, but they should be adequately covered by the speaker at the front of the room given that it's only 20' away. 

You might also consider some small fill speakers at the stage and again just before the room opens up. 

Where are you located? One of us might be nearby. 
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 12:03:26 pm
Since the room is primarily a SPOKEN WORD place- a SINGLE source of sound would best-especially since the room is deep and narrow.

Add a sub for low end when needed-and turned OFF when being used as a lecture hall.


The owner would like to watch movies and show student-created videos in the space.  Because of this, it needs to be stereo.  Also, for low end rumble effects, it needs to have a sub in at least the front part of the room.  The sub will definitely be turned off for lectures.
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 01:50:16 pm
A long group of line-array column speakers on each side at the front of the stage might cover that distance although their typical wide dispersion would be a problem. Or one set for zone 1 and another set at the second projection screen for zone 2.  SLS, JBL, TOA, others.

I believe that doing the line-array route right would end up being out of my budget.  The SRX835p has 60 x 40 coverage.  With two boxes, it's still wider than I need for such a narrow room.  The narrower angle should help with a tighter/longer throw though.
Title: Re: Install in a lecture hall
Post by: Jason Lavoie on September 18, 2015, 02:26:10 pm
I'm a long time lurker around here, but not much of a poster.

I am helping select gear for a 200 seat lecture hall.  The dimensions/layout of the room are very interesting.  I would love to get some thoughts on this.  There is about a $20-25K budget for speakers, mixer, cabling, and some lavs.

The room is 18' wide x 117' deep.  The first 33' of depth are flat ground with only 27 seats, a 12' x 18' x 10" riser/stage, and a large projection screen.  The remaining 84' are stadium seating at about a 15 degree incline.  Ceiling height is 13' in the flat area and narrows to 11' at the 11th row.  After the 11th row, the room opens up. I know... like I said, interesting. 

I'm not very good at Sketchup yet, but I attached my best effort.

The room will be mostly for lectures and videos, but also for occasional small live performances.

So far, I'm thinking 1x SRX835p per side in the flat area.  These will be angled to point toward the center of the 13th or 14th row, just past where the ceiling opens up.  I'll need something smaller as a center front fill for the first couple rows.  Once I figure out what I want to do for the front fill and subs, this will comprise "Zone #1".

For the rest of the room, "Zone #2", I'm thinking 2x SRX812p's on each side spaced evenly and pointing down.  I'll have to mess with delay times on these. 

This room is so long that I'm still not sure what to do for subs.

Any thoughts would be much appreciated.

Thanks
-AE 

 

Can the top row even see the screen?

if it has to be stereo I'd be looking at 2-3 sets of column speakers on the walls with a sub up front.
How you do it depends on the surfaces and where you can get wiring to.

Jason
Title: Re: Install in a lecture hall
Post by: Mark Cadwallader on September 18, 2015, 03:32:45 pm
Can the top row even see the screen?

if it has to be stereo I'd be looking at 2-3 sets of column speakers on the walls with a sub up front.
How you do it depends on the surfaces and where you can get wiring to.

Jason

The drawing indicates there is a secondary screen on the wall that's about halfway back. I didn't see it at first, either.
Title: Re: Install in a lecture hall
Post by: Mac Kerr on September 18, 2015, 04:43:36 pm
The drawing indicates there is a secondary screen on the wall that's about halfway back. I didn't see it at first, either.

Of course with a room that deep the audio is only going have acceptable lip sync in the front half of the room. Two frames of mismatch looks like bad cable TV, that happens 60' from the first speakers. Beyond that it is progressively worse. This will be true for a lecture with IMAG as well.

Mac
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 05:42:54 pm
18' wide is pretty narrow.  Do you NEED stereo?  I would agree with Ivan that a single center speaker would work well.  Another single center speaker back where the room 'opens up' should cover that area also.  You might want to go a little higher than 11' in the 'open' area, as this will allow more even coverage front to back.  The first few rows of the 'open' area will be out of the pattern of the speaker above them, but they should be adequately covered by the speaker at the front of the room given that it's only 20' away. 

You might also consider some small fill speakers at the stage and again just before the room opens up. 

Where are you located? One of us might be nearby.

I do need stereo.  The owner wants to be able to watch movies in the space.  What do you suggest for the small center and fill speakers?

One of the reasons I like the SRX835p is the built-in DSP.  So I'd like the fills to have something similar.

-AE
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 06:42:19 pm
Of course with a room that deep the audio is only going have acceptable lip sync in the front half of the room. Two frames of mismatch looks like bad cable TV, that happens 60' from the first speakers. Beyond that it is progressively worse. This will be true for a lecture with IMAG as well.

Mac

Good point.  I don't know if they have thought this part out.  If Zone #2 audio is delayed to make up for the distance, that will make it out of sync with the live video feed going to the secondary screen.  Is it normal practice to delay the video to match the delayed audio?
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 18, 2015, 07:08:10 pm
Any thoughts on the EV ETX-10p as fills?

-AE

Title: Re: Install in a lecture hall
Post by: Scott Holtzman on September 19, 2015, 03:42:33 am
Any thoughts on the EV ETX-10p as fills?

-AE

Aaron, can I suggest you concentrate on the concepts being discussed then pick the hardware?

Once the design is complete the hardware that fits the role will be able to be clarified.

Title: Re: Install in a lecture hall
Post by: Martin Morris on September 19, 2015, 07:29:47 am
Of course with a room that deep the audio is only going have acceptable lip sync in the front half of the room. Two frames of mismatch looks like bad cable TV, that happens 60' from the first speakers. Beyond that it is progressively worse. This will be true for a lecture with IMAG as well.

Mac
Title: Re: Install in a lecture hall
Post by: Mac Kerr on September 19, 2015, 11:04:24 am
Aaron, can I suggest you concentrate on the concepts being discussed then pick the hardware?

Once the design is complete the hardware that fits the role will be able to be clarified.

Yes, this.

Mac
Title: Re: Install in a lecture hall
Post by: Jason Lavoie on September 19, 2015, 04:00:01 pm
The drawing indicates there is a secondary screen on the wall that's about halfway back. I didn't see it at first, either.

In that case, the design choices become much clearer. put speakers on each side of the secondary screen to cover the top section and then put speakers down front to cover what is left.
of course delaying the upper speakers will be really important to everyone in the transition zone.

Jason
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 20, 2015, 12:26:43 am
Aaron, can I suggest you concentrate on the concepts being discussed then pick the hardware?

Once the design is complete the hardware that fits the role will be able to be clarified.

Sorry, trying to get too much done at once.

-AE
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 20, 2015, 10:50:02 pm
In that case, the design choices become much clearer. put speakers on each side of the secondary screen to cover the top section and then put speakers down front to cover what is left.
of course delaying the upper speakers will be really important to everyone in the transition zone.

Jason


Thank you all for the replies.

Below is an updated version of the Sketchup.  It shows the approximate position for mains (orange) in Zone 1.  These will be out from the wall a little, angled slightly down and in, and flanking the riser.  The two smaller green ones are fill positions; again, angled.  The red and blue are the Zone 2 options we're exploring right now.  Like Jason said above, I think that just the reds flanking the secondary screen should be enough if they're angled right and delayed.  However, I'm wondering about the advantages/disadvantages of going with the blues in Zone 2 instead of the reds.

Thanks again.
-AE 
Title: Re: Install in a lecture hall
Post by: Jason Lavoie on September 21, 2015, 08:58:50 am

Thank you all for the replies.

Below is an updated version of the Sketchup.  It shows the approximate position for mains (orange) in Zone 1.  These will be out from the wall a little, angled slightly down and in, and flanking the riser.  The two smaller green ones are fill positions; again, angled.  The red and blue are the Zone 2 options we're exploring right now.  Like Jason said above, I think that just the reds flanking the secondary screen should be enough if they're angled right and delayed.  However, I'm wondering about the advantages/disadvantages of going with the blues in Zone 2 instead of the reds.

Thanks again.
-AE

The reason the reds are preferable to the blues is that the reds can be delayed to match up with the mains and will supplement that wavefront that spills into the upper section. the blues are (I'm assuming) down/side firing so if you delay them (which might require 2 delays now) you can only make it right for people seated above them. everyone for the first few rows in front of each set of blues will hear incorrect timing from them.

If the reds aren't enough to reach the back then ideally another (maybe smaller) set of directional speakers closer to the back, making 3 zones. but always keeping the speakers in front of people and facing them.


I'm not sure what your intention is with the center 'fill' speakers. the room is so narrow that you shouldn't have much of a hole in the middle.
Also, if you really want stereo that means that the left speakers have to cover every seat, and the right speakers have to cover every seat, making a center speaker redundant or at best tricky to decide how to use it.

Jason
Title: Re: Install in a lecture hall
Post by: Keith Broughton on September 21, 2015, 09:28:35 am
I have recently worked in 2 rooms very similar to this and had to use a comination of the suggestions put forward. Not quite as deep but similar enough to have come to some conclusions.
The installed equipment included 2 x side hung colum "arrays", 2x side hung powered 2 way cabs and ceiling speakers.
I have tried them in different combinations.
For the video playback, these were fine but for spoken word, not good.
Too many sources and too many unresolvable time alignment issues to allow for  nice clean, clear and comfortable dialogue reproduction.
I have had much time to sit in these rooms and figure out what might work better.
A single, high cohenrent speaker ( eg: Danley SM80, SM96) covering each section would be a better solution for dialogue and, if required, a separate stereo or 5.1 system for video playback.
Just my opinion...
Title: Re: Install in a lecture hall
Post by: Chrysander 'C.R.' Young on September 21, 2015, 02:02:02 pm
A single, high cohenrent speaker ( eg: Danley SM80, SM96) covering each section would be a better solution for dialogue and, if required, a separate stereo or 5.1 system for video playback.
Just my opinion...

OP, in case you missed it, this is the golden nugget of wisdom that you should pay attention to.  Instead of a complex compromise, two simple and effective solutions is often a better route.
Title: Re: Install in a lecture hall
Post by: Aaron Estes on September 26, 2015, 10:36:40 pm
OP, in case you missed it, this is the golden nugget of wisdom that you should pay attention to.  Instead of a complex compromise, two simple and effective solutions is often a better route.

Ok… so this is what we're thinking so far:

There will be two stereo zones, but the subs will be in mono.  The oranges are a SRX835p and SRX818sp per side in Zone #1.  The reds are also SRX835p's that will be delayed for Zone #2.  The yellows will function separately from the others as mono single point source for dialogue.  This will all be working off of an A&H QU-16 > DBX1231 > DBX Venu360.

Once again… thoughts?   
Title: Re: Install in a lecture hall
Post by: Tim Padrick on September 27, 2015, 12:14:31 pm
I'd forget the yellows.  At least until you have the oranges and reds in and know that you truly need the yellows.
Title: Re: Install in a lecture hall
Post by: Keith Broughton on September 27, 2015, 12:59:00 pm
I'd forget the yellows.  At least until you have the oranges and reds in and know that you truly need the yellows.
Also forget 2 subs and go with 1 only against the back wall in one of the corners, or 1 sub flown centre.