New Measurements on sub, any thoughts?

[rolyasm]

Hello all,
I have been working on a DIY sub for a bit now. Using 4 15" subs in the front of my riser powered by a Behringer EP2500. I have the subs wired in series, and each set in Parallel (dual 2 ohm voice coil on each) for a load of 2 ohms per each channel, and 1200 wpc. I ran some tests using Room EQ Wizard, and I am kind of surprised by the results. I see others doing tests on smaller, single-driver subs and they seem to be getting better results with the same 80 dB reference target. My Behringer Amp is set so the low cut filters are off. Gain is 50%. Any thoughts on how to improve my low end, or on what could be the problem, would be appreciated. Thanks.
roly
Edit: Here is my manual EQ on the Room EQ Wizard. I also turned up the gain 25% on my amp which helped the lower end.

 

[Buckeyefan 1]

What are the 4-15" subs? Sensitivity? Specs?

Does the EP2500 appear it has enough power to push all 4 drivers? When you refer to 1200 watts at 2 ohms, you know that's driving a pair of speakers at 1000Hz. When you're talking 20Hz, there's quite a curve on power demand - especially pushing 4 - 15" drivers. That amp is more conservatively rated at 650W into 4 ohms down to 20Hz into two channels.

I don't konw what the spl or power handling is of each driver, but for kicks and giggles, I'd disconnect two of the drivers and run the remaining two independently to each of the two amp channels on the EP2500 to see if you find any more gain. My guess is you're taxing that amp beyond it's capability. 2 ohms is a very tough load.

Can you provide pics? Sounds like a cool setup.

 

[rolyasm]

Hello, Thanks for the reply.
The 4 drivers are Avalanche 15", now discontinued. Here are the specs.
XBL2 technology
27mm of linear one-way xmax
dual 2 ohm coils
Don't see a sensitivity
Fs 15.7Hz
Qms 3.5
Qts .305
Vas 300.6 liters
Re 3.2 Ohms
Znom 4 ohms
Xmax 27mm
Vd 4.04
Pnom 800 watts
weight 37 pounds

Here are some pics. I may toy with the idea of disconnecting 2 of them and seeing what happens. Or, I could rewire the entire thing to run series/series instead of series\parallel and give it an 8 0hm load. I just hate to take these drivers out. They are heavy.
Roly

 

[majorloser]

Depending on how each speaker is enclosed, the two drivers that are disconnected might start acting as a passive radiator.

Just a thought.........

 

[rolyasm]

Good call,
The way I have this built, the 4 drivers are all interconnected. Here is a pic of how I framed it.

 

[bpape]

Besides a terribly difficult load on the amp, wiring them in series will cause 1 pair to be slightly out of phase with the other pair - which can cause some issues. IMO, you'd be better off with 2 drivers in parallel on each channel of a stereo amp (or 2 mono amps) - assuming the amp will do it.


In the before graph, there appears to be a large, wide hump. This could be a combination of driver spacing, room modes, mic distance, and cabinet resonances. It appears you've had to use a lot of EQ to dial it in but it worked.

My only concern is the additional amp gain coupled with the boost applied for any non-cut EQ could be getting that amp to the edge of stability. One way to find out. Put on the scene from War of the Worlds where the alien craft comes up out of the street and let it rip and see if the amp shuts down.

Just some thoughts.

Bryan

 

[rolyasm]

Currently my room is bare. I have the equipment to run my subs, that is it. I could run the DVD through my computer, but all I would get is bass. I guess that is what I want. Maybe I'll try it. If they explode or something, I'll let you know.
Roly