Subs and the Thump

[Randy]

When you set up Subs to your side or out in front, would adding speaker insulation help to avoid the back blast thump you get from your subs?

[HeadlineDJ]

Probably not, sub harmonics can propogate through most materials.

Their almost Seismic so will still give you back thump.

I get this myself from my main cabs, and I quite like it... a good solid chest thumping bass if I stand in the right spot [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

The other option is to try positioning the subs differently. Work out the wavelength of the subs and try to experiment with half and quarter wavelength setups... you can if positioned the correct distance apart cancel out a lot of bass, which might help... at the end of the day there's gonna be a compromise if you try to reduce the back thump without situating them further away.

[Randy]

Thanks, Our big problem is those tight setups in big rooms. I just keep telling my self, trust your set up. It's nice to have that great sound out front but sometimes the thump overides everything else (from our position). I'll have to work a little harder with the couples and venders on the set up room.

Another question, I am running 25 Ft. cables now if I move to 50 Ft cables what gague would you suggest?

[Jim Casey]

At least 12 guage if not 10 Randy...

Of course, you could do like me and NOT use bass bins at all...LOL

[HeadlineDJ]

Reverse thump and sound can be a problem if you can't get the chance to get out front and have a listen..

Sometimes it can sound very sweet from a DJ's point, you go out front and it's either too toppy or to muddy.

Tight setup's are always a problem, I set my EQ to get the best sound then pop my head around front and give it a quick listen from both sides to then re-adjust, I find although it can get rather thumpy where I am standing it's always a little toppy out front. So I endure the thump for the sake of the clients.. although I don't mind bass at all [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

[KJDJ]

The biggest problem people have with subs is they use 2 when 1 will do. 2 subs spaced 20' is a problem.
Wavelength calculations are a pain. If you figure for say 40Hz it won't do any thing for say 50Hz.


I have 2- 18" Killo-Max's in a pair of JBL boxes powered by a bridged PLX3402.
I do mostly 100-200 guest events. 90% of the time I use 1 sub.

Most folks run 2 subs and stand between them right in a standing wave.

If you must use 2 in a room put your full range on stands and set the subs side by side in front of you or on the floor if your on a stage. I have even put them to one side.

If you have the bass coming from 1 location the low end level will be much more even througout the room.

If your getting blasted, other areas of the room are also getting blasted. In our buisness it's always seems to be the grandparents table.

Table sign: RESERVED FOR GRANDPARENTS
CAUTION SUB BASS STANDING WAVES IN THE AREA
PLEASE TURN OFF PACEMAKERS

:tup

[Randy]

Thanks for the info, I use a crossover and bi-amp so might try to use my ADJ 1000 bridged to power one sub and then use my Crown 2000 for the mains.
[img]style_emoticons/<#EMO_DIR#>/dry.gif[/img] food for thought.

[djdonny]

Has anyone had problems with the sub thumps causing your CDs to skip, especially when the sub is so close to the CD players? I just bought a sub and haven't used it yet, but this is my main concern. Should I not be concerned?

Donny

[Randy]

Not if your CD Players have antiskip or a memory buffer. I have felt the vibration on my mixing bord and not had a skip.

[HeadlineDJ]

This didn't happen during a gig it was at home when I was messing around:

BUT

I had a speaker about 2ft from a PC I was using,, when the bass kicked in the PC rebooted.... Hmm I thought that was odd, the bass kicked in again, the PC rebooted again.. LOL

Turns out it wasn't so much the vibration or thump, more so the magnetic fluxes that were being generated as I found out when I held a screw driver between the two... LOL as the Bass was thumping away the screw driver was being pulled to the beat from my hand.

The moral of this story is , some bass drivers have huge magents and the radiating energy form these can cover quite an area especially when your pushing a fair few watts through them.

If setting up in very smll areas, it's an easy test to see if any magnetism is present near your critical equipment.

Another thing to check to reduce your standing waves is to make sure you enable any roll-off controls on your x-overs.. this will reduce some of the effect depending on the audio material of course.