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[Dylan August]

Hi everyone,

   I am newer to the running sound business, and by that I mean that I just started running my own sound for a 3 piece folk/rock/singer songwriter band. I am learning a lot quickly, but I figured I would come to a place where everyone knows more than me. I initially bought a Behringer PMP6000,2 JBL JRX115's, and 2 12" peavey monitors. These have served me well, and I figured out how to hook everything up and get it to sound pretty good.

I wanted to add some more clarity and fullness to our sound, so I purchased one seismic audio 18" active sub to this. I heard the SA provides decent quality at affordable prices so I gave it a try. There was no manual with the sub when it came and several places to plug cords in on the back, so I wasn't exactly sure how to connect it. I read the PMP6000 user manual and it explained that an active sub should be run out of the Mono out jack, and it explained that you can use the sub filter as well to adjust frequencies sent to the sub. I ran a 1/4 in from the mono out to the R sub in/out on the sub and turned everything on. With the sub filter turned on on the mixer, everything was muffled and nothing was coming out of the sub. (I am in main/mono setting for Amp mode...i feel like this plays a role when using the mono out jack). I turned the sub filter off, and I could not really tell that the sub was on. I turned the volume ALL THE WAY UP on the sub and finally started to hear it, but it wasn't much. I feel like an 18 inch sub should not be cranked to full volume just to hear it.

So...after this huge explanation that might not make sense, I just wanted to see if anyone noticed that I was doing something wrong. Do I have to be in stereo mode (L/R) on my AMP setting?Did I plug in the sub wrong?should I sell my behringer powered mixer and just get an analog with power amps to make all of this easier?haha.

Any help is appreciated. Thanks!
-Dylan

[Paul G. OBrien]

I wanted to add some more clarity and fullness to our sound, so I purchased one seismic audio 18" active sub.

Ok.. but a quick search of the web turns up all kinds of different seismic active subs so exactly what model do you have?

I heard the SA provides decent quality at affordable prices so I gave it a try.

Well OK, I like finding bargains as much as the next guy but you got to wonder how durable a speaker can be at this price level, a subwoofer in particular carries a heavy accoustic burden so you generally have to pay real money to get something that will just survive typical use.

There was no manual with the sub when it came and several places to plug cords in on the back, so I wasn't exactly sure how to connect it.

That's never a good sign..

I read the PMP6000 user manual and it explained that an active sub should be run out of the Mono out jack, and it explained that you can use the sub filter as well to adjust frequencies sent to the sub. I ran a 1/4 in from the mono out to the R sub in/out on the sub and turned everything on. With the sub filter turned on on the mixer, everything was muffled and nothing was coming out of the sub. (I am in main/mono setting for Amp mode...i feel like this plays a role when using the mono out jack). I turned the sub filter off, and I could not really tell that the sub was on. I turned the volume ALL THE WAY UP on the sub and finally started to hear it, but it wasn't much. I feel like an 18 inch sub should not be cranked to full volume just to hear it.

So with this test what freq did you have the sub filter set at? And what were you using for source material.. a mic or recordings of some type? It's possible there was little or no audio content below the sub cutoff freq you had set, normally this is set somewhere around 80-100hz, but it's also possible this feature doesn't work correctly or quite as expected on your mixer, or that the sub is faulty or just poorly designed. On the sub is one input labelled mono by chance? It's often the L input and this is what's supposed to be used with a single channel input signal, the sub amplifier may not see enough signal level from the R input alone

[Dave Scarlett]

Hi Dylan, it sounds like the "sub filter" you are using might be a low frequency cut, so you are not really sending frequencies this speaker was meant to reproduce, turn this switch off. Often these are on the channel strips to eliminate low frequency rumble on vocal mics and the like.

It looks like your mixer has a 1/4 "mono out" female jack. Run that output to your new sub, you should hear some low frequencies now depending on your source material. The adjust the sub frequency somewhere around 100.

Rgds, Dave

[Dylan August]

Thanks for the quick replies! The specific model is the aftershock 18" powered sub....I have to look at the back of my sub closer, but I know there is a sub and satellite input/output on each side because I think this sub can power small satellite speakers as well. I was also wondering if running my system with mon1/mono as the amp mode instead of stereo main l/r would negatively affect using my sub.is there a way to control that mono out volume from the board or would I only control the sub volume from the back of the sub?(just trying to figure out why I have to have the volume on the sub turned up so high to hear it). thanks again for all of the help

[Dave Scarlett]

I see this sub can power your other speakers but I would not go that way, use the power from your mixer and connect the main speakers as you always have.

Take the mono out from your board, jack 63 in the manual to the sub. Probably turn the volume on the sub up full and then you can adjust it from the "Mono" slider (49) on your board. You should be all set.

[Dylan August]

The only problem with this is that the mono slider is what controls the volume of my mains because I use the mon1/mono amp setting...I use that setting because I run and power my mains from output B and my monitors from output A.i should probably just get a power amp for my monitors and run my mains using the stereo L/R amp setting

[Cory Short]

did you ever get this Seismic Sub rocking?   Is it any good??

[David Walmsley]

did you ever get this Seismic Sub rocking?   Is it any good??

My band has that same powered mixer and came across the same issue. That Mono output does not send enough of a signal to the sub. It's extremely low output and pretty much useless. Also there are no Aux sends to use either. Poor design. Better off using one of the main or monitor outs into a power amp>crossover>subs. Not sure what my BL is doing but he somehow runs a powered signal into the mains which are daisy chained to the powered subs (don't ask)! I'm totally confused with his setup. I've never run sound that way.

[Brad Weber]

My band has that same powered mixer and came across the same issue. That Mono output does not send enough of a signal to the sub. It's extremely low output and pretty much useless. Also there are no Aux sends to use either. Poor design. Better off using one of the main or monitor outs into a power amp>crossover>subs. Not sure what my BL is doing but he somehow runs a powered signal into the mains which are daisy chained to the powered subs (don't ask)! I'm totally confused with his setup. I've never run sound that way.

According to the PMP6000 specifications, all of the unamplified outputs are unbalanced with a maximum +21dBu level, which while perhaps a bit lower than the common +24dBu is not extremely low and should be quite usable.  And the PMP6000 does have aux sends, they are just labeled as "MON" for the two pre-fader sends and "FX" for the two post-fader sends.

The OP also appears to understand the sub filter correctly, it provides a low passed output to the mono output.  However, the manual does not indicate that it high passes the main outputs so it is apparently simply an adjustable frequency LPF on the mono output and not a crossover.

Related to that, apparently the Seismic subwoofer also has an adjustable low pass filter and if you have both the sub and mixer low pass filters in the signal path you may be filtering out more than you think.  Since the mixer filter does not appear to high pass the signal to the mains you might want to just turn off (bypass) the LPF on the mixer and use only the LPF on the subwoofer.  Or you could set the LPF on the sub for as high a frequency as possible and then use the 'sub' filter on the mixer.

However, I think there may be some other factors involved.  One is how well the Seismic sub can keep up with your mains and I would not be at all surprised if a single one of those subs had trouble keeping up with most decent, well powered mains.  The other factor is what you are expecting from a subwoofer.  Depending on the source content and low pass filter frequency you may not 'hear' that much from a sub.  And be aware that simply adding a sub will not necessarily improve clarity and 'fullness', in fact if not done properly it can instead reduce clarity and add 'mud', perhaps more of a concern in the application noted since there seems to be nothing high pass filtering the mains thus they are apparently still providing the same full range output as they were without the subwoofer.

[Brian Jones]

Have you tried the Left input? Many times for mono operation you need to use one or the other (usually left I think) assuming the equipment is set up that way.

Also, try running a test signal to the sub to see if the problem is your mixer output, or the sub.
Following the signal chain here is one way...

download a free single frequency test signal in the middle of your subwoofers range, probably around 80Hz.

Get a 3.5mm to RCA adapter from monoprice for $1.82 http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10218&cs_id=1021815&p_id=5596&seq=1&format=2

Buy the cheapest, smallest Behringer mixer in the Xenyx line, the Xenyx 502 for $44.99 from Sweetwater with free shipping  and 2 yr dealer warranty (you really might need the 2 yr warranty on this mixer) http://www.sweetwater.com/store/detail/502?utm_source=Google&utm_medium=PPC&utm_campaign=none&device=c&network=g&matchtype=&gclid=CKnFl8axmrgCFQSCQgoduD8ADw

Connect a 1/4 TRS to one of the master outs on the mixer -- doesn't matter which one -- and run that to the subwoofer.

Play the test signal and see if you can get your subwoofer to make some decent noise. If not, your subwoofer arrived already broken which would not be unheard of for an 18" pro powered subwoofer under $400.

If the test signal does produce decent output, then the powered mixer is the problem, either in the way you have it set up or because it is faulty.

[ProSoundWeb Community]