Classroom Sound

[joetech]

I teach Technology at a local high School. This summer my room was renovated. I also have a pair of BIC Formula 4's that were donated to use and a 100wpc reciever and DVD/CD player. I also have an old karlson with a 15" EV wolverine speaker. I made a 2nd order crossover for the karlson so I can use it as a sub.
The room is 30'x50'x14' ceilings with steel beams. Walls and floor are concrete. 10 formica tables that are 7'x2' with computers for the students. The front wall (30' wide) has a screen and projector. Pretty good setup. So far I've only used the speakers setting up on some boxes in the back of the room and they sound pretty good considering are the hard surfaces. I good some pipe hangers and chain and would like to mount the speakers off the beams in the front beside the screen. School theater deluxe.
I plan to mount the speakers upside down so the tweeters are on the bottom are more directed at the class. When I hang then they will be at a slight angle back. The karlson is can put just about anywhere but the top surface makes a nice place for the reciever/CD player.
Any thoughts,comments or cautions before I go ahead?

 

[markw]

Sounds good as long as those speakers can cleanly fill the room and the amp isn't driven into clipping in he attempt to do so. Neither was designed to cover that large an area to room-filling levels, particurarly on an extended time frame. Listen carefully for any nasty, harsh, garbled or cracking sounds. If that happens, you're red lining the system.

You are using a separate amp for the Carlson/EV bass box, aren't you? (hint.. .answer "yes" and I really wouldn't consider it a "sub")

Putting the CD player on top of the bass box opens up the possibility (probability) of nasty vibration transfer that could adversely affect playback.

 

[mtrycrafts]

I teach Technology at a local high School. This summer my room was renovated. I also have a pair of BIC Formula 4's that were donated to use and a 100wpc reciever and DVD/CD player. I also have an old karlson with a 15" EV wolverine speaker. I made a 2nd order crossover for the karlson so I can use it as a sub.
The room is 30'x50'x14' ceilings with steel beams. Walls and floor are concrete. 10 formica tables that are 7'x2' with computers for the students. The front wall (30' wide) has a screen and projector. Pretty good setup. So far I've only used the speakers setting up on some boxes in the back of the room and they sound pretty good considering are the hard surfaces. I good some pipe hangers and chain and would like to mount the speakers off the beams in the front beside the screen. School theater deluxe.
I plan to mount the speakers upside down so the tweeters are on the bottom are more directed at the class. When I hang then they will be at a slight angle back. The karlson is can put just about anywhere but the top surface makes a nice place for the reciever/CD player.
Any thoughts,comments or cautions before I go ahead?

Your other issues on top of what mark posted will be your acoustics. Seems to be very reverberant and it is a long space, conducive to echo like effects.

 

[joetech]

Thanks for the input. As I stated I have set this system up temporarily on tables etc. and the sound isn't pretty good. The room use to be carpeted but was old and smelly and current building codes won't allow carpeting in classrooms.
The amp seems to be more than adequate. I never come close to turning it up all the way. Those BICs are very efficient. I don't remember the exact specs I found on them but they're from the 70's when 35 watts was an average amp output. They have 10" woofers, a horn mid and a cone tweeter that looks a lot like a JBL 25 or 20.
My only real concern was with room acting differently. I am assuming that if they sound OK from the back of the room they should be OK from the front. The room isn't exactly symetrical but it's close.
I do have a separate amp (8 watt Tube) I could use to power the Karlson. I've used it before successfully.

 

[Seth=L]

Thanks for the input. As I stated I have set this system up temporarily on tables etc. and the sound isn't pretty good. The room use to be carpeted but was old and smelly and current building codes won't allow carpeting in classrooms.
The amp seems to be more than adequate. I never come close to turning it up all the way. Those BICs are very efficient. I don't remember the exact specs I found on them but they're from the 70's when 35 watts was an average amp output. They have 10" woofers, a horn mid and a cone tweeter that looks a lot like a JBL 25 or 20.
My only real concern was with room acting differently. I am assuming that if they sound OK from the back of the room they should be OK from the front. The room isn't exactly symetrical but it's close.
I do have a separate amp (8 watt Tube) I could use to power the Karlson. I've used it before successfully.

I wouldn't use a tube amplifier to drive a low frequency driver. I would get an inexpensive pro grade amplifier for that.

 

[Savant]

What, specifically, are you teaching in the room? Will/does it involve critical listening of playback material? More importantly, does it involve making decisions based on what the students are hearing? If that's the case, you might consider getting some good ("better than standard") acoustical treatments in the room. (Many vendors subscribe here and will be happy to chime in with their opinions.)

If you simply require a decent room for playback that does not involve teaching the students, e.g., how to mix for video, or something like that, then you can probably go with the general requirements outlined in the ANSI classroom acoustics standard for the size of room you have. (ANSI S12.60 is available free of charge from http://asastore.aip.org/) Namely, low noise (≤ 40 dBA) and reverberation according to Annex C.

Best of luck!

 

[joetech]

finished

Last weekend I went in and did what I said above. Sounds pretty darn good. I hung the BICs upside down from an I-Beam. They naturally tilt back about 15 degrees. They are about 8ft from each side wall and stand off from the front wall about 1Ft.
I don't detect any reverb in the room. I have a tone generator program in my computer and one speaker develops a buzz at 70Hz. Only one. I opened it up and discovered an mouse or something had gone up into the vent of these speakers and used the insulation for bedding. (the guy that donated these had kept them in his garage the last couple of years. Also this one had signs of having been dropped so I think the glue joins were a bit weakened.) I took some foam from some old school bus seats and stuffed into the box and put a few screws into the corners. Buzz is gone. I can play a recording of the 1812 Overture complete with cannons at very loud levels without a problem. I haven't even tried out hooking up the Karlson yet.