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ran into an odd sound phenom yesterday

TinyE

TinyE

Jan 31, 2013
1,063
905
portland,or
#1
We have a rectangular studio where we rehearse. If i had to guess, something like 25x15. I have 2x410's stacked, pointed across the short part of the room, straight at the other wall. I was moving around last night, checking out the mix, etc... and discovered that right in front of the cabs and some small angle off of straignt, was pretty much a dead zone. I could hear the bass, but just barely. But when I moved back to the side of my cabs (say 90 degrees from the front), it was booming and full.

So I grabbed the cab, and pointed it roughly 45 degrees to the adjacent wall. All of a sudden, no matter where I stood, the sound was booming, the tone was full and rich. It was like I had just completely changed rigs. The other guys around the room noticed it too and commented on it.

What happened? Did I have some sort of standing wave interference that was killing the sound by bouncing off the opposite wall and cancelling out the sound waves? We have sound board all over the place, and there is gear around the entire wall. But there was a distinct difference once I turned the cab just a little.

I am attaching a [very] crude drawing of what the room conditions are. it's just the room and bass cab, but you get a rough idea.

sound.png
 
#3
So-called "sound boards" sold for acoustic dampening is kind of a rip-off. Okay, it has some effectiveness, but only in the very high frequencies. In the OP's use, and when it's simply hung on a flat wall or surface, it has no effect on dampening the low-end whatsoever. At the lower frequencies, it's pretty much as reflective as the solid wall.

Damping low-end requires space, angles, and traps. The more and more extreme, the better.

The OP was experiencing some kind of reflection that, in just right place, was causing a null. Moving the cab just changed what sound was going where. Had nothing at all with the sound board.

The sound board is effective when combined with lots of angles and space. Do a search on "acoustic bass traps" and "acoustic dampening". It's quite an extensive subject and way too deep to get into here.
 
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#4
It could be the "Allison effect" or "Boundary effect"
The ceiling counts also.
There's lots of good information from places that sell room treatment. Even home theater sites.

Low bass is omni, so real lows and pointing the cab to a different wall isn't going to matter much until you get up to the mid freqs.
It might be that you also are just hearing diminished mids when the cabinet points to a different wall, it can make you think the bass is stronger when mids are turned down. Happens :)
There's many bass players who turn their cabinets around to face the wall in small spaces. Keeps the mids from beaming straight to the person who would be right in front of the cab.
 
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#5
seamonkey said:
Low bass is omni, so real lows and pointing the cab to a different wall isn't going to matter much until you get up to the mid freqs.
Click to expand...

Well, sort of...(and if we are to trust the OP's description of what he noticed, then there was something going on as he moved his cabinet around)

If it's a single driver, as in a single 15" or 18", or even a 12" in the right cabinet, the single-driver source will act as a (mostly) omni-directional source.

When you use multiple drivers, you get some coupling and a varying degree of pattern control. When I quit playing in the 90s, I was using a 1-18"/2-10s bi-amped bass cabinet. When I started playing again last year, I got my first 410 cabinet and I was shocked at how directional it was, even down to really low frequencies (I could have pulled out my measurement software from the PA days and made some measurements, but I wasn't that worried about it since I was more interested in playing). This is due to the natural coupling of the drivers being close together. As well as the stuff that makes line array PAs seem like magic when they really aren't. Just good ol' acoustic principles (with some digital processing) at work.

Okay, do I get the topic swerve award for today?...:roflmao:
 
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#8
"25 x 15 rehearsal space... And you're using 2 4x10's ? Seriously ? If you are winding that rig up, I'd say your biggest issue is that you and your band mates are deaf..."

"just crazy 8 x 10s in a small room, you hate your bandmates?"

Even SVTs have volume controls. I'm gonna give the OP the benefit of the doubt and ASSume that he plays at an appropriate volume for the space they are rehearsing in.

And I'm far more concerned about the drums and cymbals in a place that small.
 
#9
Geri O said:
"25 x 15 rehearsal space... And you're using 2 4x10's ? Seriously ? If you are winding that rig up, I'd say your biggest issue is that you and your band mates are deaf..."

"just crazy 8 x 10s in a small room, you hate your bandmates?"

Even SVTs have volume controls. I'm gonna give the OP the benefit of the doubt and ASSume that he plays at an appropriate volume for the space they are rehearsing in.

And I'm far more concerned about the drums and cymbals in a place that small.
Click to expand...

When my band rehearses in a tiny space, I can barely hear anything over the drums. But man... the OP probably only needs one of those cabs for a space that size.
 
#10
bolophonic said:
When my band rehearses in a tiny space, I can barely hear anything over the drums. But man... the OP probably only needs one of those cabs for a space that size.
Click to expand...

Very much so here, too.

I gotta admit, when we rehearse, I use both my EBS 410 cabinet and the 115 cabinet underneath the top one. I leave the bottom unplugged, but it elevates the 410 closer to my ears.

Hopefully, in the next couple of weeks, our rehearsals will be on our monitor rig with an X32 and everyone on ears. That should solve a lot of issues in the small room.
 
#11
TinyE said:
We have a rectangular studio where we rehearse. If i had to guess, something like 25x15. I have 2x410's stacked, pointed across the short part of the room, straight at the other wall. I was moving around last night, checking out the mix, etc... and discovered that right in front of the cabs and some small angle off of straignt, was pretty much a dead zone. I could hear the bass, but just barely. But when I moved back to the side of my cabs (say 90 degrees from the front), it was booming and full.

So I grabbed the cab, and pointed it roughly 45 degrees to the adjacent wall. All of a sudden, no matter where I stood, the sound was booming, the tone was full and rich. It was like I had just completely changed rigs. The other guys around the room noticed it too and commented on it.

What happened? Did I have some sort of standing wave interference that was killing the sound by bouncing off the opposite wall and cancelling out the sound waves? We have sound board all over the place, and there is gear around the entire wall. But there was a distinct difference once I turned the cab just a little.

I am attaching a [very] crude drawing of what the room conditions are. it's just the room and bass cab, but you get a rough idea.

View attachment 518375
Click to expand...

Could be comb filtering, standing waves, or both.
 
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#12
4Mal said:
25 x 15 rehearsal space... And you're using 2 4x10's ? Seriously ? If you are winding that rig up, I'd say your biggest issue is that you and your band mates are deaf...
Click to expand...


Haha. Yes. I run my amp between 2-3 on vol. I only used to use 1 410, and then I saw the rbh410 on CL for $100. I bought it, refinished it, and am now just sitting on it. That said, our drummer is too loud, and the guitar player plays stereo through 2 amps. I wear earplugs even at that level.
 
#13
4Mal said:
25 x 15 rehearsal space... And you're using 2 4x10's ? Seriously ? If you are winding that rig up, I'd say your biggest issue is that you and your band mates are deaf...
Click to expand...

http://en.wikipedia.org/wiki/Earplug

I went ahead and checked three different calendars just to make sure, but I did not, in fact, stumble into a bizarre rip in the space-time continuum capable of transporting me to 1200 BC, before the first recorded use of earplugs.

I can only assume, then, that you and several other posters in this thread must have traveled from that time through such a portal, and therefore I bid you, one and all, WELCOME TO THE WORLD OF TOMORROW!!!

...where such devices have not only been invented but are ubiquitous enough to be purchased at practically any corner grocer's or pharmacist's.
 
#14
Standing waves. Depending on where the sound source is located and the dimensions and construction of the room, the standing waves cause peaks (reinforcement) and valleys (reduction) in the bass response at various locations in the room. Move the source and you move the standing waves.
 
#16
callofcthulhu said:
http://en.wikipedia.org/wiki/Earplug

I went ahead and checked three different calendars just to make sure, but I did not, in fact, stumble into a bizarre rip in the space-time continuum capable of transporting me to 1200 BC, before the first recorded use of earplugs.

I can only assume, then, that you and several other posters in this thread must have traveled from that time through such a portal, and therefore I bid you, one and all, WELCOME TO THE WORLD OF TOMORROW!!!

...where such devices have not only been invented but are ubiquitous enough to be purchased at practically any corner grocer's or pharmacist's.
Click to expand...

Actually the world of tomorrow is that of in ear monitors for many of us... In the world of tomorrow there is Whirled Peas and flying cars and the Volume Wars are consigned to the dust bin of history...
 
#17
TinyE said:
Haha. Yes. I run my amp between 2-3 on vol. I only used to use 1 410, and then I saw the rbh410 on CL for $100. I bought it, refinished it, and am now just sitting on it. That said, our drummer is too loud, and the guitar player plays stereo through 2 amps. I wear earplugs even at that level.
Click to expand...

I used to feel your pain, then I got a drummer that can actually keep time in an interesting manner without busting the walls or my ear drums. Yep... It's a blessing... Working with folks that know to let the FOH do it's thing and waking up without my tinnitus screaming at me...
 
#18
callofcthulhu said:
http://en.wikipedia.org/wiki/Earplug

I went ahead and checked three different calendars just to make sure, but I did not, in fact, stumble into a bizarre rip in the space-time continuum capable of transporting me to 1200 BC, before the first recorded use of earplugs.

I can only assume, then, that you and several other posters in this thread must have traveled from that time through such a portal, and therefore I bid you, one and all, WELCOME TO THE WORLD OF TOMORROW!!!

...where such devices have not only been invented but are ubiquitous enough to be purchased at practically any corner grocer's or pharmacist's.
Click to expand...

That's a nice story, but apparently, your time machine missed that time rip that had a monitor mixer and the IEMs in it. Like I mentioned earlier.

Also, it missed the part where musicians are famous for shoving ear plugs into their ears and then gradually turning things up to compensate.

Whatever....
 
#19
callofcthulhu said:
http://en.wikipedia.org/wiki/Earplug

I went ahead and checked three different calendars just to make sure, but I did not, in fact, stumble into a bizarre rip in the space-time continuum capable of transporting me to 1200 BC, before the first recorded use of earplugs.

I can only assume, then, that you and several other posters in this thread must have traveled from that time through such a portal, and therefore I bid you, one and all, WELCOME TO THE WORLD OF TOMORROW!!!

...where such devices have not only been invented but are ubiquitous enough to be purchased at practically any corner grocer's or pharmacist's.
Click to expand...

I live in the world of today. It's an awesome place where people rehearse at volumes so low, we don't need earplugs. :D
 
#20
There was a hall I used to play in many years ago that had a hard brick wall at the back of the stage and a hard brick wall at the other end. The echo was about 1/7 of a second. It was comically difficult to play at anything other than 100BPM.
 

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