Home Theater Forum and Systems banner

1 - 14 of 14 Posts

·
Registered
Joined
·
80 Posts
Discussion Starter #1
Hello all. First post on this forum. I'm considering building a 3cf internal sub using the Eminence Lab 15 and two APR 15's with a Behringer XLS 1500 amp. This is for a friend who is trying to go to about 13Hz for a research project he's working on.

Question, how many washers/weights would I need on the APR's to tune as low as possible in 3cf internal? Any suggestions would be appreciated. If I'm trying to reinvent the wheel please advise. I saw Jeff Bagby's post at the PE forum about this recently. Thanks.
 

·
Premium Member
Joined
·
19,397 Posts
Welcome to the forums.

The lowest tuning frequency you can achieve with a pair of APR 15's in 3 cu.ft. is just under 24 hz. That is with 900 grams of mass added to each PR which is what they are rated for.

As for the amp, Behringer has the EP and iNuke series, Crown has the XLS series.

Has the Eminence Lab 15 already been purchased? If so do you have the WinISD driver file for it?

Can you explain a little more about the 13 hz research project?
 

·
Registered
Joined
·
80 Posts
Discussion Starter #3
Mike, thanks for the response. I haven't purchased anything yet. The research deals with paranormal investigations. I'm not part of the research but my friend wants to study the effects of subsonic (13-19 Hz) frequencies on people at seminars he does around the country. Apparently, there is a theory that these frequencies are perceived by humans to be "paranormal" in nature.

He wants to have a sub that he can take with him in his SUV to seminars and get the lowest response available. It doesn't sound like the LAB 15 will get to that point. I saw Jeff B's post about getting low response using the Lab 15 and two APR15's. I'm open to other suggestions. The box could be a little bigger if necessary. Thanks for your help.
 

·
Registered
Joined
·
80 Posts
Discussion Starter #5
Wowsers!!! That's out of his budget. I need to regroup and try to come up with something. His overall budget is $1,100.00 including the Behringer amp.
 

·
Registered
Joined
·
80 Posts
Discussion Starter #7
Now we're talkin!!! I think that would work Mike. I think 100db at 13 Hz would be plenty. I explained to him the tradeoffs involved with box size, budget etc. Thanks for all your help!!!!
 

·
Premium Member
Joined
·
19,397 Posts
A 24" external cube is about 6 cu.ft. net volume. A TRIO12 driver with a pair of APR 12's loaded with 900 grams each would be a 13 hz tuning frequency. Required power is 100 watts. Modeling shows 99 db at 13 hz.

TRIO 12 SPL.JPG

With 100 watts cone excursion is under 5 mm at 13 hz and voice coil heat won't be a problem.

excursion.JPG

At 13 hz the PR's will be producing most of the sound, with a excursion of 19mm of a possible 29 mm they can go all day long.

PR excursion.JPG

The driver and 2 PR's are $219 shipped.

http://creativesound.ca/details.php?model=TRIO12DUALAPR12

A Behringer A500 would be more than enough for an amp.

The budget would allow for building 2 of these subs which a single A500 can power, total cost for subs and amp would be under $700.
 

·
Registered
Joined
·
80 Posts
Discussion Starter #11
Thanks a ton Mike. I love this setup. It is cheaper than the other setup and should fit the bill. I will probably buy the Behringer EP2000 since it's so cheap and my friend can have it available for other uses if necessary. I was suggesting a double (1.5") thick outer walls with 3/4" thick mdf inner shell and 3/4" baltic birch ply outer shell. The ply will stand up to abuse better since he will be moving this monster around a lot. Obviously, will brace well. Is that overkill? Thanks a lot Mike for all your help.
 

·
Premium Member
Joined
·
19,397 Posts
3/4" baltic birch ply single ply well braced is all you need and will keep the weight down.
It won't take much to burn a coil with a Behringer EP2000, I suggest he get a SPL meter to verify the SPL output to ensure too much power isn't going to the drivers. As long as the SPL is under 100 db he'll be fine. There is no warranty on burnt coils.
 

·
Registered
Joined
·
80 Posts
Discussion Starter #13
Got the trio package order and just received the EP2000 amp. It is HEAVY!!!. Buddy wants double thickness box so he'll get it. He will have fun moving it by himself! Mike thanks for all your help on this. I'll post pics later on the build.
 
1 - 14 of 14 Posts
Top