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[Tim Tyler]

Dave -

The QW218 sub is factory wired as 2 x 8 ohm speakers seperately wired to the nl4/nl8 connector with the bottom driver wired to 1+- and the top driver wired to 2+-.  Unless the box has been internally rewired to parallel the drivers, you must use a 4-wire speaker cable to get performance from both drivers.

I agree with earlier comments about your issue being one of proper wiring.  Reversed polarity within the box, from the amp to the box and/or between boxes should be considered as problem areas.  A bridged 3602 will give plenty of performance, if properly deployed.

-Tim T

[Joe Jordan]

i'm currently using a PLX 3602 Bridged driving a pair of SRX 718. The only issue I've had is getting enough power to them. As long as the AC is solid there is plenty of "thump"

[Mac Kerr]

The QW218 sub is factory wired as 2 x 8 ohm speakers seperately wired to the nl4/nl8 connector with the bottom driver wired to 1+- and the top driver wired to 2+-.  Unless the box has been internally rewired to parallel the drivers, you must use a 4-wire speaker cable to get performance from both drivers.

I agree with earlier comments about your issue being one of proper wiring.  Reversed polarity within the box, from the amp to the box and/or between boxes should be considered as problem areas.  A bridged 3602 will give plenty of performance, if properly deployed.

If the OP is using the ch1 NL4 on the amp, which has both channels on it, and is using a 4 wire NL4 cable, putting the amp in bridged mode will drive the 2 speakers in the box out of polarity. We don't know that polarity is the problem, but until the OP comes back with more info it's about all we've got.

Mac

[Jonathan Betts]

i'm currently using a PLX 3602 Bridged driving a pair of SRX 718. The only issue I've had is getting enough power to them. As long as the AC is solid there is plenty of "thump"

Have you tried running the 718's in stereo? They will perform just as well and last much longer.

[Stu McDoniel]

I have a problem with my 2 PLX3602 that I hope you all can shed some light on.

First the specifics:

Running four (4) Peavey QW 218 subs, powering 2 of these with bridged 3602's, the other two with bridged Peavey CS3000's.

Played a smaller room last night and only used 1 sub per side. Initially was running the subs of of the 2 PLX3602s and there was no low end. The kick drum sounded all "100-125" hz. No thump...sounded like pounding on a KFC bucket!!! Switched to the CS3000s and was rattling the walls with the subs!!!

The 3602s are in bridge mode, with the switches set to full range on the back...no need for the internal crossover, we cross these subs at either 125 or 140hz, depending on the room.

One of the 3602s is brand new...just bought it. They both are exhibiting this behavior!

Thoughts??

Thanks!!

Dave

The QSC is a switching power amp design.  What is your AC setup for your amps?
A good AC feed is a probably a good start.

[Bob Leonard]

I have a problem with my 2 PLX3602 that I hope you all can shed some light on.

First the specifics:

Running four (4) Peavey QW 218 subs, powering 2 of these with bridged 3602's, the other two with bridged Peavey CS3000's.

Played a smaller room last night and only used 1 sub per side. Initially was running the subs of of the 2 PLX3602s and there was no low end. The kick drum sounded all "100-125" hz. No thump...sounded like pounding on a KFC bucket!!! Switched to the CS3000s and was rattling the walls with the subs!!!

The 3602s are in bridge mode, with the switches set to full range on the back...no need for the internal crossover, we cross these subs at either 125 or 140hz, depending on the room.

One of the 3602s is brand new...just bought it. They both are exhibiting this behavior!

Thoughts??

Thanks!!

Dave

Because both are cabled incorrectly. Buy some banana jacks and wire your cables with the banana jacks to the amp and NL4 to the speakers using pins 1+/1-. Make sure your DIP switches are set correctly, and make sure that channel 2 sensetivity is turned to off.
 
The 3602 is not my choice for subs but when properly powered the amp will work fine. The problems I found years ago, and discussed at length here, were heat and sensetivity issues to low power, both of which can be show stoppers. I swapped my 3602s from powering my subs to powering my 725s, then replaced them all with 4050HDs for tops and subs in my dual system. I have not had a problem since other than a heavy rack. My 3602s now run vocals and monitors only. Not bridging your amps will actually give you better sound and reliability, so you might try running your speakers in stereo mode, you might just like what you hear.   

[Dave Batistig]

Because both are cabled incorrectly. Buy some banana jacks and wire your cables with the banana jacks to the amp and NL4 to the speakers using pins 1+/1-. Make sure your DIP switches are set correctly, and make sure that channel 2 sensetivity is turned to off.
 
The 3602 is not my choice for subs but when properly powered the amp will work fine. The problems I found years ago, and discussed at length here, were heat and sensetivity issues to low power, both of which can be show stoppers. I swapped my 3602s from powering my subs to powering my 725s, then replaced them all with 4050HDs for tops and subs in my dual system. I have not had a problem since other than a heavy rack. My 3602s now run vocals and monitors only. Not bridging your amps will actually give you better sound and reliability, so you might try running your speakers in stereo mode, you might just like what you hear. 

Thanks to everyone for the input. I will double check the wiring. I am using 4 conductor cable wired to the binding posts, then to  4 conductor speakon connectors mounted in a patch bay. I will make sure all these are wired correctly. With the way the subs sound...a phase issue makes the most sense!!

Thanks!

Dave

[Dave Batistig]

Dave -

The QW218 sub is factory wired as 2 x 8 ohm speakers seperately wired to the nl4/nl8 connector with the bottom driver wired to 1+- and the top driver wired to 2+-.  Unless the box has been internally rewired to parallel the drivers, you must use a 4-wire speaker cable to get performance from both drivers.

I agree with earlier comments about your issue being one of proper wiring.  Reversed polarity within the box, from the amp to the box and/or between boxes should be considered as problem areas.  A bridged 3602 will give plenty of performance, if properly deployed.

-Tim T

To be more specific with how I "think" I have the rack wired....

I have +1 and +2 twisted together and on the Positive binding post, and -1 and -2 twisted together and on the negative binding post. This then feeds a 4 conductor speakon connector in the patch panel. There are a total of 4 speakon connectors like this in the patch panel for the subs....one wired to each amp.

[Dave Batistig]

The QSC is a switching power amp design.  What is your AC setup for your amps?
A good AC feed is a probably a good start.

almost all the clubs we play have a dedicated 240V line for the bands...my whole PA runs off my distro, so power insn't typically an issue, and wasn't at this last gig. The Peavey CS3000s performed flawlessly. It looks like it is a wiring issue, with the way the subs sounded, it sounds like a phasing issue. I will double check the wiring.

[Tim Perry]

To be more specific with how I "think" I have the rack wired....

I have +1 and +2 twisted together and on the Positive binding post, and -1 and -2 twisted together and on the negative binding post. This then feeds a 4 conductor speakon connector in the patch panel. There are a total of 4 speakon connectors like this in the patch panel for the subs....one wired to each amp.

can you post a picture?

If i understand this description you need to move the wires from the negative terminal to the unused positive terminal for bridged operation.

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