Live Sound & Production

[Thunderbroom]

My band played a new venue (for us) last night. There was a house PA (don't know much about it so don't ask). The speakers were hanging from the rafters and there were a lot of them. There were between 500 and 1000 people in the room we were playing.

During the first set, we started getting this insane low end rumbling that was on the stage and was feeding through the FOH. The soundguy ask me (the bassist) to turn down. I did so. The rumbling was still there. There were even times when I wasn't playing at all and the rumbling still occured.

Towards the end of the first set, he got it under control and I was allowed to turn back up. I played the last third of our first set without hearing myself. The second set was fine.

Afterwards, I talked with him about it. His thought was that my 15" bass cabinet (I was playing a 210/115 stack) was coupled to the stage (which has a thin top, is about 3 feet or so high, and is hollow underneath was transmitting soundwaves that were feedbacking into the guitarists' mic'd cab and the kick mic.

I asked what I could do to prevent this in the future. He suggesed casters on the 115 cab. I don't want to do that. He also suggested getting it off the floor.

What's the best way to do this? I've read that the Auralex Grammas are good for this. I've also heard of people using milk crates.

I'm here looking for answers.

Thanks!

[tlbonehead]

Originally posted by Thunderbroom
My band played a new venue (for us) last night. There was a house PA (don't know much about it so don't ask). The speakers were hanging from the rafters and there were a lot of them. There were between 500 and 1000 people in the room we were playing.

During the first set, we started getting this insane low end rumbling that was on the stage and was feeding through the FOH. The soundguy ask me (the bassist) to turn down. I did so. The rumbling was still there. There were even times when I wasn't playing at all and the rumbling still occured.

Towards the end of the first set, he got it under control and I was allowed to turn back up. I played the last third of our first set without hearing myself. The second set was fine.

Afterwards, I talked with him about it. His thought was that my 15" bass cabinet (I was playing a 210/115 stack) was coupled to the stage (which has a thin top, is about 3 feet or so high, and is hollow underneath was transmitting soundwaves that were feedbacking into the guitarists' mic'd cab and the kick mic.

I asked what I could do to prevent this in the future. He suggesed casters on the 115 cab. I don't want to do that. He also suggested getting it off the floor.

What's the best way to do this? I've read that the Auralex Grammas are good for this. I've also heard of people using milk crates.

I'm here looking for answers.

Thanks!

My answer would be anything that gets it off the floor. Sounds like you could have used a better sound person though.

[Thunderbroom]

Originally posted by tlbonehead
My answer would be anything that gets it off the floor. Sounds like you could have used a better sound person though.

So, anything will work...a couple of milk crates...the Gramma...a piece of plywood nailed to some 2x4's...a stool?

[agedhorse]

By any chance were they using a D112 kik mic? This is one challange with that mic live.

If there's that much low end rumble, I wonder where the subs were located? How much excess low end gain was being used? Were high pass filters being used on channels other than thgose that required the low end to begin with?

These are questions that always come to mind when presented with this scenario. Generally, the fix is pretty simple.

IF it was the bass cabinets coupling with t he guitar mic then the HPF needs to be used on the gtr channel and better MIC isolation from the stage may be another approach to consider.

[tlbonehead]

Originally posted by agedhorse
By any chance were they using a D112 kik mic? This is one challange with that mic live.

If there's that much low end rumble, I wonder where the subs were located? How much excess low end gain was being used? Were high pass filters being used on channels other than thgose that required the low end to begin with?

These are questions that always come to mind when presented with this scenario. Generally, the fix is pretty simple.

IF it was the bass cabinets coupling with t he guitar mic then the HPF needs to be used on the gtr channel and better MIC isolation from the stage may be another approach to consider.

Yep. Should have the low cuts on all chanels that don't need the bottom octave. (guitar mics, vocal mics, all drum mics except kick and maybe the bigger toms,etc) Sounds like the tech didn't do much, if any searching to find out where the problem was actually coming from. Punching out channels one by one, cutting and sweeping the mid control on the offending channel(s) to find and eliminate the offending frequencies(if the sweep area goes low enough) Even cutting the mains and seeing if there is a problem at the source, especially if he thought it was the coupling of the bass cab to a hollow floor) All areas and ideas that should have been checked out.

[Thunderbroom]

I can't vouch for his technical prowess or lack thereof. I know very little about live sound myself.

About the coupling, will anything do as far as raising the cab off the floor? Is the Auralex Gramma a solid product or a gimmick?

[tlbonehead]

Originally posted by Thunderbroom
I can't vouch for his technical prowess or lack thereof. I know very little about live sound myself.

About the coupling, will anything do as far as raising the cab off the floor? Is the Auralex Gramma a solid product or a gimmick?

No idea what it is. But anything will work.

[Thunderbroom]

Originally posted by tlbonehead
No idea what it is. But anything will work.

Link

[tlbonehead]

Originally posted by Thunderbroom
Link

I'm sure it works but that's a lot of money to spend for a solution that can cost nothing otherwise. And remember, you still don't know for sure if your cab was causing the problem.

[Unalaska]

I'll bet the kick was heavily compressed and the result being a loud channel when nothing is happening. This would be on the soundperson to fix. When I hear this type this it's the first place I look...
p

[strategy400]

someone suggested tennis balls cut in half under the cab.

[Dogoth]

Originally posted by strategy400
someone suggested tennis balls cut in half under the cab.

Depending on the weight of the cabinet (an Ampeg SVT Cab might just crush them), that sounds like a great Idea (and priced right as well). I personaly couldn't see spending big money for some gucci product to do such a simple job (unless it was an extreme case).

[where02190]

Originally posted by Thunderbroom
There were even times when I wasn't playing at all and the rumbling still occured.

It had NOTHING to do with you then, and everything to do with an incompetent engineer.

[agedhorse]

Originally posted by Unalaska
I'll bet the kick was heavily compressed and the result being a loud channel when nothing is happening. This would be on the soundperson to fix. When I hear this type this it's the first place I look...
p

Also a good candidate for this problem, ESPECIALLY with a D112

[Mogwix]

Dude needs a gate on the kick. If anything it'll make the kick mic feedback, not the guitar mic.

[tremendo]

I can't see that his bass amp was the problem. And if it was, hit the HPF on the guitar and you're fixed.

I wouldn't spend a dime trying to fix the bass, it wasn't the probem. If you play there again, don't piss the guy off, but try to work it out. If the problem eventually was fixed and the 2nd set was fine, he probably found the problem and fixed it. But, he didn't want to look bad and said you were at fault.

[Mogwix]

I mentioned this in that "stupid stories" thread but at battle of the bands at a local high school, there was the low-end rumble (which was caused by my bass amp, which was placed directly in front of the kick drum and mic..), so to fix it, the "sound guy" ran up and first told us that the mics were too close to the amps. I sort of stand there in a daze trying to comprehend what was just said, and my guitarist just goes "okay" and moves the mics like three feet away from the speakers, just to smite him. Later, feedback is still happening and the "sound guy" again runs up to the stage and this time tells everyone backstage to turn off their cell phones and stuff, he says they're causing feedback. Again, I sit there with my head in my hands trying to comprehend what I've just heard.

Oh well.

[dswanson]

Just tell who ever is running sound to put a gate on the kick (if one is present). Because the kick is hollow, it has a tendency to resonate at low freq, especially with a D112. Another solution, if possible, would be to put the drums on a riser. Your bass amp or the guitar mic won't cause that kind of feed back unless the sound guy has the low end freq cranked. Which at that point he/she should be fired.

[yzf125]

I had this same problem at a out door show, The band was inside a "Band shell trailer" and caused all kids of different problems.

The source of this was the mic on the guitar amp so i press the low cut button on that channel and problem solved :thu:

[Thunderbroom]

We're playing this Saturday at a place that we've played before. We didn't really have problems with my amp but did get these massive vibrations through the stage (which is not a stage at all but just the dance floor as we set up on one side of it). We're certain that it was the subs. I'm wondering if setting the subs on a couple of 2x4's to get them off the floor might solve this problem.