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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Steven Carridale on April 19, 2010, 03:32:57 pm

Title: help adding sub, power amp, and crossover to existing PA system
Post by: Steven Carridale on April 19, 2010, 03:32:57 pm
Hello, I also posted this in general section of this forum, but I thought I would post it here as well in case I'm in the wrong section. First-time poster.

My current PA system setup, used for small stuff and home use, is a Yamaha EX512SC powered mixer, 2 Yamaha BR-15 main speakers, and a Yamaha A12M monitor speaker.

Recently, I purchased a Yamaha SW118V Club V PA Subwoofer, a Yamaha P7000S Stereo Power Amplifier, and a Behringer CX2310 Super-X Pro crossover to add to my existing setup. I am not very familiar with hooking up passive systems, and I can't figure out how to get all this working together correctly.

I've hooked everything up, and I can't get my sub to make any sound at all. I have a 1/4" to male XLR cable going from my mixer's main out (the Left Mono located at the bottom right of the mixer, just left of the power button) into the crossover's input (located on back, far-right). Next I have an XLR-XLR going from the Sub Out on the crossover (located back middle of the crossover) to the A Input of the power amp. Finally, I have a 1/4"-1/4" speaker cable going from the #3 A on the power amp (located top-right on the back of the amp where it says "Speakers") into the back of the sub.

When I turn everything on and give everything some juice, my sub is not working at all. My main speakers are working normally. I've messed with the knobs on everything, and I've tried plugging stuff up in different places to see if I was plugging it up wrong (such as plugging into the crossover's Low instead of the Sub Out), but I haven't been able to get the sub to work at all. I also don't understand if I should set the power amp on bridge or parallel, and if it needs to be set on Sub or Low Cut.

I have attached a picture that shows the exact equipment I have and where I am plugging cables into. Can you please tell me what I am doing wrong, and how I need to hook everything up to get my sub working properly? I was only allowed to post one pic on this post, but I have larger and clearer pictures of each piece of equipment if it helps (found on Google and Musicians Friend).

If I can provide any more info let me know and I will be happy to, and I would greatly appreciate any help you can give me.

--Steven Carridale

Title: Re: help adding sub, power amp, and crossover to existing PA system
Post by: Adam Kane on April 19, 2010, 09:04:51 pm
First off, I don't think you need that Behringer crossover as it looks as though the amp has a simple but perfectly functional crossover built in. Someone please correct me if I'm wrong.

It should go without saying (but I'll say it anyway) that all cables should be verified as OK.

Start eliminating pieces of the chain...divide and conquer.

1 - Plug the sub directly into the speaker output on the powered mixer.  Does it work?  If no, bad sub.  If yes, continue...

2 - Eliminate the Behringer from the chain. Set your amp to stereo mode for now.  Run directly from your powered mixer's line out into a channel of your power amp, then from same channel of the amp to your sub.  If you don't get anything (make sure level control for that channel is up), that means either a bad amp, or a faulty output from the powered mixer.  I'm not very familiar with your particular there a separate control (level or switch) for the line outputs?

3 - To check the amp, run a signal (i-pod, cd player...whatever you can find) directly into the amp with any speaker or sub connected.  If that works, that leaves the mixer output as the culprit.  Keep in mind that you may not get much volume with a source direct to the amp instead of running through the mixer first but that doesn't matter...all you're looking for is ANY signal at all.

4 - If you can get your hands on a powered speaker, run from the mixer output into that.  If you get nothing, that verifies that the mixer output is faulty (or turned off...or something).  If it works (AND #3 worked) then you need to re-check that your cables are properly terminated (correct conductors on each terminal at each end...etc).

As far as sub crossover frequency, start between 80hz and 100hz and adjust for what you think sounds best with your main speakers.  There's a lot more that goes into this parameter for larger and more complex systems, but for your application this method should suffice...need to get it working first, though.
Title: Re: help adding sub, power amp, and crossover to existing PA system
Post by: edwin jesas on October 01, 2010, 01:24:50 am
Nice post.
Title: Re: help adding sub, power amp, and crossover to existing PA system
Post by: Duane Massey on October 01, 2010, 10:32:17 am
Adam has some good suggestions. If all the gear is determined to be working, I would suspect the 1/4 to XLR cable. The 512 line out is not balanced, the this cable would need to be 1/4" mono wired to XLR as unbalanced.