• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Banishing bass sound..

hyoshim

hyoshim

May 5, 2004
780
54
Los Angeles
#1
While I was walking around (back and forth) inside the sanctuary with bass playing the open E string, I noticed that the bass sound simply banishes about in the middle of the room. It sounded like some sort of cancellation was going on. I was thinking may be the standing wave in the room is canceling my bass. If that is the case, what would the fix for it?
 
#2
I think you mean "vanishes", not "banishes". You are correct, it's likely due to standing waves. Are you playing through an amp or direct into the PA? Try moving the speakers from where the bass is coming; if you're through an amp try moving it near a corner if possible. You can also address the problem with acoustic treatment of the room, but that's probably not feasible here.
 
#5
brendanbassist said:
I think you mean "vanishes", not "banishes". You are correct, it's likely due to standing waves. Are you playing through an amp or direct into the PA? Try moving the speakers from where the bass is coming; if you're through an amp try moving it near a corner if possible. You can also address the problem with acoustic treatment of the room, but that's probably not feasible here.
Click to expand...

Thanks, and I was playing through a GK 700 combo, 2x10 which was placed not at the center (left side). The wall is basically smooth concrete with no acoustic panel of any sort. May be it will be better with the congregation filling the room or installing acoustic foam on the wall may fix?
 
#6
Look up boundary effect. Moving your amp a foot or two can make a big difference.

Best, when the sanctuary is empty, put your bass amp out where you are concerned with getting the best sound to somebody sitting. Like in the middle. Then walk around the stage, move your head higher and lower, until you find the best sound. Put your amp on stage where your head hears the best sound.
If you're cell phone has a decent SPL app, that handles bass frequencies you can use it as a sound meter to confirm what you hear.
 
#7
seamonkey said:
Look up boundary effect. Moving your amp a foot or two can make a big difference.

Best, when the sanctuary is empty, put your bass amp out where you are concerned with getting the best sound to somebody sitting. Like in the middle. Then walk around the stage, move your head higher and lower, until you find the best sound. Put your amp on stage where your head hears the best sound.
If you're cell phone has a decent SPL app, that handles bass frequencies you can use it as a sound meter to confirm what you hear.
Click to expand...

Thanks,

I looked it up and it refers to basically increase of the low frequency up to 12 dB depending where you are sitting (hearing). In my case, it "vanish" or reduced down to almost zero. Anyway, thanks for the responses. I am learning a lot ^^*
 
#13
Thanks for the answer on the PA. Glad to hear you're using only your amp. Too many sanctuaries do the low-end portion of their PA (and sometimes even the low end of their on-site organ) all wrong. Going through a poorly-architected PA often comes out worse than forgoing it altogether and relying instead on the bass amp. Even worse would be going through both at once because of the additional phase anomalies, unless the bass amp were being run quiet to act only as the player's personal monitor.

Some sanctuaries are just not "fixable." They were built for one job: to carry a minister's voice to the back rows. They do that well. But for the same reasons they do that well, they often stink at supporting a full band's low end.

The sanctuary I play at has high hard walls and a tall (50' more or less) vaulted ceiling. Also strict rules around where the amps can be located. So, you can hit a loud note, check your phone for text messages, and when you're done, that note is still wandering around looking for a place to land. Getting a decent BG sound anywhere in the room under those conditions -- let alone everywhere -- is just not possible.

So, a lot of this has to do with managing expectations in light of architectural, stage-layout, and budgetary constraints.
 
#14
Because freq's below 100hz or so are omni directional.......

Having a bass cab 3.5' above the floor, and 3.5' from a back and side wall.
That gives you 3 boundaries that are canceling 80hz.

Place bass cabs or subs either 7' or more, or less than 3' from back and side walls.

The formula is speed of sound at approx 68-70 deg F 1130 ft per sec
Divided by freq 80hz= 14.125
Divided by 4 = 3.5'

1/4 of the wavelength distance causes cancelation. The wavelength bounces/reflects off the wall/boundary
And the reflected wave is out of phase with the original, canceling a lot of it.

1/4 of a 40hz wave length is 7'.

Placing LF cabs close to boundaries can increase output.

Google:
Boundary cancellation
Boundary coupling
 
#15
There will always be spots of destructive interference. When I demonstrate waves each year, I let my physics students wander the room while a 50Hz or 60Hz tone plays through my amp. There will be super loud spots (constructive) and super quiet spots (destructive). It's unavoidable. But, that spot that your open E is inaudible in? That spot is specific to that frequency. Your lowest A is likely to be entirely audible there.

So it's a problem you can't eliminate, only minimize with the tips others have given you here. And, no one listening will be unable to hear you play.. they just might get a few notes here or there dropped out.
 
#16
4StringTheorist said:
There will always be spots of destructive interference. When I demonstrate waves each year, I let my physics students wander the room while a 50Hz or 60Hz tone plays through my amp. There will be super loud spots (constructive) and super quiet spots (destructive). It's unavoidable. But, that spot that your open E is inaudible in? That spot is specific to that frequency. Your lowest A is likely to be entirely audible there.

So it's a problem you can't eliminate, only minimize with the tips others have given you here. And, no one listening will be unable to hear you play.. they just might get a few notes here or there dropped out.
Click to expand...

And to add to that, going from physics to psycho-acoustics, if anyone is listening from that spot in the room, their mind will actually fill in the missing frequencies.
 

Latest posts

Top Bottom
Back