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[Josh Lyon]

I've spent countless hours messing with EQs and crossovers and moving the subwoofer to different locations, but nothing I do seems to give our subwoofer a distinct sound. It's muddy and lacks clarity. The drummer and worship leader on getting on me about it, so I want to fix it if I can.

Before I go and spend a bunch of money on a new subwoofer setup (which we have no budget for), what are some tricks I can use to tighten up bass response in the room? This is a Mackie SRS1500 Active Subwoofer, being fed from and aux send into a dbx driverack 4800. The subwoofer itself is sitting on the stage, which is covered in a thin carpet.
Thanks!

[Mike Galica]

I used to mix on a system with the SRS1500, and found that muddy bass is just kind of what you're stuck with.

The best I ever had them sounding was:
Mounted on a concrete floor with no basement, about 10 feet away from any walls.
A high pass at 35 Hz
-6 dB low shelf 60 Hz
+3 dB narrow Q peak around 80 Hz
Crossed over at 120 Hz (whatever the built in xover frequency is)
Also had to get creative around the crossover point otherwise there were some wonky interactions between the sub and the tops.

YMMV, but that's what kinda sorta worked for me.  Bass was still a little floppy, but better than out of the box.

[George S Dougherty]

Josh Lyon wrote on Tue, 13 April 2010 11:00

It's muddy and lacks clarity.

Hmmm... sounds like my impression of the Mackie sub.  Depending on the size of the room, you're probably asking too much from the little guy.

If you have little to no budget for a sub, checkout billfitzmaurice.com.

Anything in the Titan designs would be relatively easy to build, far less expensive than anything they'd be comparable to and outperform anything in the same cost range by a wide margin.  I run the larger Titan48 for the lower extension over the smaller Titan39 but not everyone would find it necessary.  With the better recommended drivers you can build and finish either design for $300-350.  They're very power efficient so you don't need an expensive amp to power them.  Something that'll do 4-500W is plenty in most situations.

For our sanctuary with a fire-marshall capacity of 450, 24ft ceilings and roughly 80x80 dimensions a single 30" wide Titan48 boundary loaded against a wall is plenty running off a bridged Mackie 1400i.  The amp coasts and the sub runs easy for services in the low-mid 90db range (A-weighted, slow, midway back in the sanctuary).

You could probably sell the Mackie and replace it with a Titan and a Craigslisted amp.

[George S Dougherty]

Another thought.  Roll the HP up towards 50Hz if you've got an adjustable HP filter in the system.  That'll give you more headroom and ask a little less from the driver.
Boundary loading is your friend in terms of output.  Stick it against a wall or in a corner for ~6db and ~12db of gain respectively.  Keep the driver within 2ft or further out than 8ft from any walls.

[Josh Lyon]

Thanks for the feedback, guys. I've messed around a bit more with the eq/crossover, but again I am left pretty disappointed with the muddiness, especially in the kick drum.

George, I imagine with building my own bass cabinet, I'd need a dedicated amp, which I do not have...so the cost goes up again. We're currently running straight out of the dbx driverack to the sub, since it is powered.

Can you recommend an affordable amp that'll do the job?

[Keith Shannon]

Josh Lyon wrote on Tue, 13 April 2010 15:55

George, I imagine with building my own bass cabinet, I'd need a dedicated amp, which I do not have...so the cost goes up again. We're currently running straight out of the dbx driverack to the sub, since it is powered. Can you recommend an affordable amp that'll do the job?

QSC RMX series. Simple, straightforward, raw power. You can get them up to 4000 watts bridged at 4 ohms (that's the 4050HD, which sells online for about $1400; wholesalers carry em cheaper). These things are tanks, and they weight about as much (the 4000W model is a whopping 68 pounds), so be careful if this system moves much.

[Josh Lyon]

Please keep in mind I have a $0 budget for this project. haha

[Jeff Foster]

George S Dougherty wrote on Tue, 13 April 2010 13:06

Another thought.  Roll the HP up towards 50Hz if you've got an adjustable HP filter in the system.  That'll give you more headroom and ask a little less from the driver.

I second this.  The biggest problem with low-end subs is people trying to get them to reproduce frequencies below their efficient range.

Get in that Driverack and move the HP filter up to around 50Hz, as George mentioned, and you should be able to get a little more volume out of it as well as reducing some of the muddiness.  When you try to drive a sub lower than it wants to go, the cone will start flapping around and ruin the whole sound.  Granted, this is a gross oversimplification, but will give you a basic idea of what the sub is doing.  If you raise the HP filter, it will remove the lower frequencies that start to break up and will "tighten up" the overall sound.

If 50Hz doesn't work as well as you want, go on up to 55Hz or even 60Hz.  There's nothing wrong with not having a system that goes as low as the neighbor kid with the way-too-loud car stereo.  

[Mike Galica]

Just thought about this, since it's your drummer getting on you about it.  What are you using to mic the kick and is it properly tuned?  Your kick may not be playing nice with those subs.

[Josh Lyon]

We're actually using electronic drums. I have the kick on its own channel...so it's not a matter of miking it.

[Kent Thompson]

What does you eq look like on the bass drum channel?

[Brad Weber]

Perhaps a little different approach...

What do you have running to the aux signal that feeds the subwoofers?

Are the drums in an enclosure?  Do you have a bass amp on stage?  Are there floor monitors?

What is the room like?  How large is it, what finishes, etc.?  What is the stage construction and is it built up over a slab?  Where is the sub located in relation to any walls?

What is the rest of the system?  What are your expectations as far as level, response, etc.?  Why is the drummer getting on you about this, is it because of what he hears on stage or is it what he is being told he sounds like to the congregation?

In your efforts to resolve the problem, what have you done?  Have you verified that it is not something simple like a reversed polarity?  Have you accounted for the sub's internal 120Hz crossover?  Are you just trying things and assessing the results by ear or do you have any analysis tools?  How it sounds is the final determination but some analysis tools could provide some valuable insights into what is happening.

[George S Dougherty]

Josh Lyon wrote on Tue, 13 April 2010 14:12

Please keep in mind I have a $0 budget for this project. haha

You can probably sell the SRS1500 for about $500 from what I'm seeing.  Do some research on that.

The QSC RMX's are good, most anything from QSC, Crown, Crest, Peavey (May have missed some other quality manufacturers) that can put out 3-400W/channel at 8ohms or run 1000+ in bridged mono should be adequate.  You can probably find those for a few hundred on Craigslist.

That'd be a nice upgrade, but it's worth it to get what you have working better.

That 4800 will do Linkwitz-Riley 48db/oct crossover filters.  Granted you're running aux-fed rather than full-range, but I personally found LR48 filters on a full-range configuration to give me almost as clean a sound as running aux-fed subs as long as you HP all the appropriate channels.  The steeper the slope, the more the filter will keep unwanted frequencies out of the sub and clean up the low-mids.

If you're running Butterworth filters and the subs and tops are at the same point, you've got a 3db gain centered at the crossover frequency.  I pull 8db at 100Hz on my sub output to counter its rising response and improve "clarity".  I don't think the SRS1500 needs anything like that, but a combination of slope, filter type and crossover frequency might be part of the issue.

+1 to Jeff's comment on running the HP even higher if necessary.  I don't think I'd go much past 55Hz, but you can always change up the filter type to more agressively cut out the bottom end.  That may allow you to leave the HP point lower.  Your kick drum needs mostly 60Hz+ and around 120Hz for its impact.

Low end from the monitors and the house combining on stage may also be muddying things up.  I cut the bottom off my wedges at the house crossover frequency and let the subs fill in any bottom end necessary for the monitors.

[Lee Buckalew]

I would add that, in addition to trying changes in the crossover you need to be sure that the amplifier can draw it's required current and voltage.  If it is plugged to a circuit that has voltage sag due to large voltage swings or that can't provide enough current due to many items drawing to much current from that circuit, the amp (in the powered speaker or a separate amp) will just not function properly.
This can result in a sound like compression occurring or it can sound distorted or just create poor sound overall, depends a lot on the amplifier type and design.  Generally this means that the bass sound will lack punch (transients are compressed) and can sound very loose.

This happens a lot in churches were many amps (and stage gear, and coffee pots and...) are plugged into vary few circuits.  Not just very few outlets but actual circuits.

His,
Lee Buckalew
Pro Sound Advice, Inc.

[Aaron McQueen]

Josh Lyon wrote on Tue, 13 April 2010 16:12

Please keep in mind I have a $0 budget for this project. haha

Do you really need a Driverack 4800? Are you all the features it offers? That unit is about $4K new.  You could sell that get a different processor and pickup a pair powered subs, something like the QSC HPR181.

[Brad Weber]

Just to explain why I asked those questions, there are many factors that may apply to your problem regardless of the equipment specific subwoofer and amplifier used.  If you have open drums, a bass amp on stage, multiple floor monitors, etc. then those could be contributing to the problem regardless of the subwoofer.  If you have sources run to the aux feed for the sub that do not need to be in it then that could make things worse.  If there are anomalies caused by the stage construction or room they would likely apply to most subs.  And so on.  Some of these other factors require little or no financial investment to assess and perhaps even resolve.  And addressing any deficiencies found would also likely benefit you regardless of what subwoofer you use.

Raising the high pass frequency to 55-60Hz on that particular sub seems to be fighting its natural response, which appears to peak around 60Hz

[Robert Sims]

Josh,

I mix electronic drums as well. The first thing I always check is my head phones. Solo up the kick and listen to it through head phones. Make sure his settings don't have some kind of low end hang over. There are certain drum settings that do this.

If that's OK, you can try a couple of EQ settings. I like to bring in the high end click (simulated drum beater on the head) to give it a nice click, some where around 8-10khz, tight Q and a good boost. I run the kick on 2 separate channels on my M7 I use one channel as my sub send and only allow low freq information to the sub via a low pass. On the second channel I send the kick to the mains, but only allow the higher freq info to the mains. This keeps the lows (crossover point) from the mains interfering with the subs. I only do this because I run subs on the floor in the center stage and mains on the wings. Since you effectively can only time perfectly to one location this helps me make sure that the low end only has one arrival and eliminates a lot of low end comb filtering with the mains at the crossover frequencies. I do the same with the bass guitar.

It could be many things but these are freebies if you have the resources.

[Josh Lyon]

Thank you so much everyone for all your input! I've tried a lot of different settings/tweaks/all sorts of stuff per your suggestions, but I'm just not happy with this thing! I'm actually going to rent a QSC HPR181i and mess around with it. The rental place/reseller was kind enough to let me rent one for $40 bucks for 5 days. I'll be able to A/B the QSC vs the Mackie with the drummer and worship leader. We'll see how much an improvement there is

[ProSoundWeb Community]