Putting a sub underneath a lorry deck / Stage

[ukpartydj]

Bit of an odd one...

I'm setting up a PA for a rally for next weekend and I've got the plan through and I'll be setting up on a Lorry deck which will be great as lots of room to share with the band.
My concern is that if I put the subwoofers up on the stage the sound may disappear? I've only ever put them on floor level.
Now I may be able to put a RCF 705as underneath the lorry deck and my theory is that it will stop the sound evaporating into the air. I will have a pair of my QTX subs on the deck but I'm not expecting anything substantial from them.

From experience the lorry decks are normally a minimum of 1m off the ground. Any thoughts?

[musicology]

Outdoors will make no odds if they're under the lorry or on the deck. They will move as much air outdoors as they are capable of and that's it. Also, are you providing sound for the band or is this an externally sourced pro sound engineer jobby? If the latter, you may be going through the main band pa anyway.

[ukpartydj]

Outdoors will make no odds if they're under the lorry or on the deck. They will move as much air outdoors as they are capable of and that's it. Also, are you providing sound for the band or is this an externally sourced pro sound engineer jobby? If the latter, you may be going through the main band pa anyway.

Oh right, I've done a few similar gigs to this before but I'm not normally that high off the ground!
It may not make a difference to performance but would the crowd hear more if it's lower to the ground regardless of the deck?

I'm not providing sound for the band they will have their own system.

[funktions]

I did a carnival float many years ago, were on the back of a curtain bed artic trailer, ended up in the main arena with plenty of happy people round us, i had 2 15" longthrow subs and 2 15" normal subs, along with 2 twin 10" mid top cabs and 2 15" full range drivers, sounded great to us. only thing we found was having to turn the volume up a little further than expected due to the wonders of the open air. back in the day was a grand total of 1k amps available but it did us happy ..

[Nakatomi]

In venues it's not unknown for subs to be flown. How far it goes is all down to the dispersion pattern of the sub(s) (or in the case of really big rigs, the array) and of course local conditions. Some sub designs (I know not which) are better for long throws than others.

[musicology]

Oh right, I've done a few similar gigs to this before but I'm not normally that high off the ground!
It may not make a difference to performance but would the crowd hear more if it's lower to the ground regardless of the deck?

I'm not providing sound for the band they will have their own system.

I would think they would hear more if the subs were clear of bodies near the stage so high would likely be good.

[ukpartydj]

Interesting, sounds like on stage will be best then!
Luckily it's a stationary lorry deck inside a grain store so wont be quite as bad as open air but I don't expect it to be too much better!

[Excalibur]

Luckily it's a stationary lorry deck inside a grain store so wont be quite as bad as open air but I don't expect it to be too much better!

I hate those. Young Farmers? Usually a trailer well past its best, unstable, and hard to access. Now that the goalposts are stationary, the idea of an RCF underneath does indeed make sense. Coupled with the floor, it will provide a lot of bass near the " dancefloor". The QTX above them will round out the sound, and take some pressure off your tops.

[Benny Smyth]

My understanding of subs must be wrong. I was led to believe that subs need to be on the floor as it uses the floor to aid delivering it's sound.

[ukpartydj]

I hate those. Young Farmers? Usually a trailer well past its best, unstable, and hard to access. Now that the goalposts are stationary, the idea of an RCF underneath does indeed make sense. Coupled with the floor, it will provide a lot of bass near the " dancefloor". The QTX above them will round out the sound, and take some pressure off your tops.

You are correct. I'm already arriving plenty in advance so I may just try it and see but in my experience you can try these things and once the guests arrive it changes everything.

I'm going to have 1rcf 705as 2 x rcf 310a up high. 2x Mackie srm450s a little lower then 2 x qtx sub also so I'll have plenty of power if setup correctly.

[Excalibur]

I was led to believe that subs need to be on the floor as it uses the floor to aid delivering it's sound.
Not only subs. If you place full range cabs on the floor, you usually notice an increase in bass response.



I'm going to have 1rcf 705as 2 x rcf 310a up high. 2x Mackie srm450s a little lower then 2 x qtx sub also so I'll have plenty of power if setup correctly.
It ought to be a walk in the park for the tops. I think you'll need all the bass you can muster. Have a good one.

[Imagine]

Not only subs. If you place full range cabs on the floor, you usually notice an increase in bass response. .

I'll second that one. Put a pair of Yammy DXR15's on a wooden floor and the bass response is unbelievable!

Now here's a poser which is slightly off topic, but still sort of relevant.....

I did a gig tonight where bass was definitely going to be needed. Normally, I don't take subs out these days as the DXR's are more than capable of delivering the range needed to most parties (still the best money I've ever spent, despite their weight). So, I ratchet strapped my pair of QTX 15" active subs together under my booth. This was on a wooden stage (only about 18" above the dance floor)....the bass response was superb (and the stage was certainly bouncing underfoot as well).

Here though is the poser.....

My microphones really didn't like this setup. Every time the mic was opened, it screamed....and that was with everything flattened and the gains right down.

Now the normal procedure for most of us would be to put the subs under the tops with satellite poles. That's not going to happen with the DXR's...they're too heavy so under the booth seems like the best option.

Any ideas how I can stop the feedback from the mic when/if I do this arrangement again?

[Nakatomi]

I'll second that one. Put a pair of Yammy DXR15's on a wooden floor and the bass response is unbelievable!

Now here's a poser which is slightly off topic, but still sort of relevant.....

I did a gig tonight where bass was definitely going to be needed. Normally, I don't take subs out these days as the DXR's are more than capable of delivering the range needed to most parties (still the best money I've ever spent, despite their weight). So, I ratchet strapped my pair of QTX 15" active subs together under my booth. This was on a wooden stage (only about 18" above the dance floor)....the bass response was superb (and the stage was certainly bouncing underfoot as well).

Here though is the poser.....

My microphones really didn't like this setup. Every time the mic was opened, it screamed....and that was with everything flattened and the gains right down.

Now the normal procedure for most of us would be to put the subs under the tops with satellite poles. That's not going to happen with the DXR's...they're too heavy so under the booth seems like the best option.

Any ideas how I can stop the feedback from the mic when/if I do this arrangement again?

I'm assuming you had feedback in the bass region, not the usual squeal - this is a problem which can affect my mic in one of the hotels I play - the subs' position & the size & shape of the room make a nasty peak somewhere in the bass area. The only thing I can do is strike a compromise between my voice sounding like a nice baritone growl & the PA having a bellyache. That is, I turn the bass down a bit, mid & top up a bit & the overall mic gain down a bit.

If you had a PA mixer, you might be able to take the very low end off the mic (which is generally not a bad idea) with a 70Hz rolloff switch. But seeing as you don't, try to get a compromise between your voice sounding good on the mic & the onset of feedback at a working volume before anybody arrives.

[ukpartydj]

Just got a picture through of the setup and it's got a concrete floor and brick walls so that'll go a long way to helping subwoofers I'd imagine.
Although there is no chance of me getting sub on the floor as there are steps in front on the stage :(

I reckon I'll be fine with the bass now I've seen a picture. I've done a larger gig in a marquee with grass and it sounded just about acceptable with this setup so hoping it'll sound quite nice :)