Riser Sub. new to Forum

[rolyasm]

Hi all,
New to the forum so I thought I would introduce myself and show my project. I am working on my first dedicated HT. Here is the sub I am building. The riser (sub box) is 18' wide, 9 feet deep and 21" high. I am using four 15" Avalanche drivers from Ascendant Audio. The models are discontinued. Each driver has dual 2ohm voice coils, which I have wired in series. The pairs of drivers I wired in parallel, creating a 2 ohm load per amp channel. I am using the Behringer EP2500 that is 2 ohm stable at 1200 watts pc. I am ready to fire them up. This is my first sub and my first EQ job, so I will be asking lots of questions. Here is the equipment I am using to EQ and setup. Behringer FBQ2496, M-Audio mobile external soundcard with phantom power, ecm-8000 pro mic, my laptop loaded with software, and my processor, a Sherwood Newcastle P-965. You will be seeing me a lot. hehe. You can see the equipment rack on the back wall. I don't like this, but he wife and room plans wouldn't allow a hidden closet or back panel access. It will be a major PAIN to get everything hooked up. The picture with the TV in it is my front wall where my screen (110" ?) will be. The wall picture is showing my 14" wide, double studded and seperated walls. They do a good job of blocking sound escape. The weak point is the solid wood door. If you have any suggestions on what I could build onto it, so it still opens and has a descent wife factor, let me know. Thanks all.
Roly

[F1 fan]

Hi rolyasm,
that is one fine looking room you have there.
I really like the sub riser idea and with 4 x15" bass output capabilities certainly won't be your limiting factor.

[Sonnie]

I can't wait to hear your thoughts on how it sounds... looks like a dynamite idea and it's looking good too.

[Chrisbee]

Hi Roly

You ought to consider trying your drivers in series pairs first. If this provides you with enough power then you don't need to use 2 Ohms.

I am using an EP2500 myself with 2 x 4 Ohm 15" pairs in series for 8 Ohms per channel in my IB. This is a kinder load on the EP2500.

Great project. Make sure that your stage top is stiff enough to cope with the acoustic loading from all those lovely drivers. Use lots of cross-bracing to tie the top down and don't try to spare on timber cross sections. Things really like to flex when driven hard at low frequencies. You would not believe how things can flex until you see it for yourself!

Fire doors are much heavier and less likely to cause problems than ordinary domestic doors. They are also better sealed.

[rolyasm]

Thanks all for the replies. The riser is built, carpeted and painted, so I hope it is sturdy enough. Below are some pics of how I built them. All connections were glued and screwed.
As far as the 2 ohm load, it has been haunting me. Another member mentioned the same thing about wiring in series to make them an 8 ohm load. I wrote Behringer and they said it would be fine, in fact their words were " the way you have it is the way you want to do it." Now understandably, if I fry my amp after the year warranty is up and have to replace it, well, so much better for Behringer. If it dies immediatley, bad for them. I really like wow factor and the headroom with the extra power, but he real factor is I hate to pull the drivers back off the front of the riser. It was a major PAIN installing them and I had an issure with one side splitting from taking out and re-inserting the screws. I worry that if I have to remove and replace these huge drivers too many more times I might destroy my riser front, and then I am in a world of hurt. However, I might have to take them off anyway to add more insulation for tuning and response. I may wait until then. If I have to take them off, I'll certainly change to series wiring, if not, I will have to do some soul searching.

Here is the second reply from Behringer, after I asked, yet again, if 2 ohms was ok.

The EP2500 and EP1500 power amplifiers are designed to be able to handle any load '2 ohms or higher' per channel when the amp is run in a stereo or dual-mono application, so there should not be a problem running the amp with a 2 ohm load connected to each output channel. At 2 ohms per channel the amp will be putting out 1200w per channel so make sure that's a complementary output power for the speakers. However at 8 ohms the EP2500 will put out 500w per channel, so if that would be a more appropriate output level for your speakers you could always go that way.

Roly