The Dispersion Issue

[Korladis]

I care to some extent. I generally avoid 4x10 cabs, but that's partly due to their low height (my ears aren't on the back of my knees). I use a 2x15 cab. Not the best for dispersion, but not the worst, either.

 

[Mystic Michael]

Cool. So what type of cabs or configuration do you run to address the issue?

Personally, I'm a big fan of the modular 1x12 cab configuration. Preferably with a small midrange speaker, or less optimally, a tweeter. Crossed over at the proper frequency, with the right components and a dispersion-friendly box design, it is a thing of beauty. Stack as many as needed.

Yes! We all know about it and the "dispersion police" here on TB are always sure to point it out, but I wonder how many of us actually address it with our bass rig.

The "dispersion police"? Hey sport, nobody here is forcing you to sound good.

MM

 

[BassOnTheSide]

I'd say same for me. Stacking them vertically is cheap and easy.

 

[Ric5]

So how many of you consider dispersion or off-axis response when buying a bass cab/speaker? I know this is important for people that play live that may or may not have good FOH support, but for some (including me), I don't really think about it when selecting/buying a cab. If it sounds great with me sitting right in front of it, I'll say "it's great" and probably buy it based on that. I know this is probably a bit naiive, but that's the truth.

I know from a technical perspective that it's really important, and it greatly affects what the crowd hears at different angles, but does the crowd really care? Do you really care?

Dispersion off axis is only for higher frequencies ... The low end will disperse more evenly ... To disperse the high frequencies well you need 2 or more tweeter speakers separated and above 7 feet tall. To properly disperse low frequencies you want one source and you want it front and center of the band and low. That is how a professional pa system does it. Also in that type of situation your bass amp is for stage volume only so you can hear your self play. The audience hears the PA system.

The best "amp" to for dispersing your sound off axis is one of these ...

But off axis dispersion is more of a problem for guitar players than bass players. And if the whole band runs through a good PA system that is properly set up then the whole band sound will be properly dispersed on axis and off axis.

 

[Ric5]

I have 3 ampeg bass heads and 6 bass cabs. The 6 cabs are 2 1x15, 1 1x18, and 3 2x10. All cabs are 8 ohm. I will run 2 2x10 together, or 2 1x15 together, or a 2x10 with a 1x18. When I have PA support I will stack the cabs. When I do not have PA support I will usually separate the cabs. Sometimes I side wash the stage with one and put one point out front, or I put one on either side of the stage. This can help and hurt. It will help disperse high frequencies but it can potentially cause comb filtering for low frequencies.

 

[Chris 'Wighat' Jordan]

I've been using a JBL single 18 as my main rig for a while now. It seems beamy to me but I use that to my advantage. I just make sure it's pointing right at me but not the audience. I get plenty of stage volume and the level is just right out in the crowd.

 

[Rick James]

To disperse the high frequencies well you need 2 or more tweeter speakers separated and above 7 feet tall.

That's not true. The height of an array has no effect on the horizontal dispersion. That's why arrays are used in PA, so that as many speakers as are required for the crowd size can be stacked and there's no loss of horizontal dispersion. You don't need tweeters either. Six or even eight inch midranges go as high as bass needs. You don't even need two sets of speakers for PA, but stacking a big PA rig in the middle of the stage would be somewhat inconvenient.
Every time this topic comes up you have the guys who understand how speakers work in the one camp, and those who don't in the other. It shouldn't be an 'issue' at all. If you want to have as much of the audience as possible hear the same thing standing off to either side as you do standing in front of the cab you keep all of the speakers in a vertical line. If you don't care put them side by side. It's only an 'issue' if you want to make it one.

 

[smogg]

My ears have always been pleased with vertically aligned 12's compared to the 410's/810's I used to use.
I used vertical 15's for a long while but the lighter weight & smaller footprint of the 212 was too good to pass up.
My rig in 2006 before I learned anything about this subject:

My rig in 2015 after I learned a little about this subject:


More often than not I use the 212 with a micro head. But the 3X12 is way more fun with or with out PA support.

 

[MultiScaleMale]

I care, but it's a balance. If a cab has better tone and worse dispersion, I'll go with tone. Dispersion is also difficult to gauge until you drop the cab into a bar room. So, if the cab that has tone that I like ends up having good dispersion when I walk around the bar with my wireless, then it's a bonus.

 

[agedhorse]

To disperse the high frequencies well you need 2 or more tweeter speakers separated and above 7 feet tall. To properly disperse low frequencies you want one source and you want it front and center of the band and low. That is how a professional pa system does it.

Not at all true.

The length of the column affects primarily the vertical pattern, the longer the column length the narrower the vertical pattern. This is why the array is bent, to increase a pattern that becomes too narrow. The greater the bend, the lower the acoustic energy density in that area. This is one way that level versus distance can be normalized.

As far as 2 sources being necessary for high frequency coverage, this too is not true. High frequency coverage is a function of the geometry of the horn (for a horn loaded device) or for wider patterns, the diffraction slot (that may or may not be coupled to a waveguide). It is possible to get 120 degrees of horizontal coverage at 15kHz with a single diffraction device (like the QSC Wideline Array).

Stereo, or 2 sources separated by a distance, is used to add special imaging to a program, but different program composition makes up the different source material.

There are plenty of high quality single point source and line array clusters used out in the real world because they can beca better solution for some acoustic environments and seating configurations.

 

[Jeff Genzler]

So how many of you consider dispersion or off-axis response when buying a bass cab/speaker? I know this is important for people that play live that may or may not have good FOH support, but for some (including me), I don't really think about it when selecting/buying a cab. If it sounds great with me sitting right in front of it, I'll say "it's great" and probably buy it based on that. I know this is probably a bit naiive, but that's the truth.

I know from a technical perspective that it's really important, and it greatly affects what the crowd hears at different angles, but does the crowd really care? Do you really care?

If I can join in, as a player, designer and manufacturer I've always felt offering the widest dispersion and smoothest response it a cabinet system as an ultimate goal. Not just for the audience or various venues (with or w/o FOH support) but for my fellow band mates. If we can hear "ourselves" better as musicians on a stage, then we stop trying to listen "for" each other and start listening "to" each other more...and hopefully as a result we can fall into the groove easier than trying too hard to establish that collective groove as a band.

Taking a different look at how we design cabinet systems and what we ask of each of the speaker components in a system to reproduce frequency wise certainly opens up new innovations. There are plenty of examples of that throughout TB.
As well, as cabinet designers, the less "beaming" we can counter act in a speaker system, the more blend we can offer to the player and his ultimate performance and personal tone. Though there are many single speaker cabs out there or those that add another component for high end response, there are many new products that take into account dispersion as a critical design element, which in my opinion is just as important as Power, LF Response, etc.

I think this a very worthy discussion.

Jeff

 

[fdeck]

Yes! We all know about it and the "dispersion police" here on TB are always sure to point it out, but I wonder how many of us actually address it with our bass rig.

In my view, only a fraction of bassists are aware of or directly concerned about any detailed technical issues surrounding amplification. My own view is that gear is actually quite forgiving, and a lot of stuff can be made to would pretty good on stage, but it's a personal preference of mine -- and a hobby in its own right -- to know how my gear works.

Those who care about things like dispersion, and those who don't, have managed to coexist on TB, which is one reason why it's a good forum. There have been some TB'ers who were slightly less than politically correct about their views, but I don't think they are posting regularly here right now.

I'd be more concerned about dispersion if I ever needed more than a single small driver for all of my needs.

 

[Passinwind]

So how many of you consider dispersion or off-axis response when buying a bass cab/speaker? I know this is important for people that play live that may or may not have good FOH support, but for some (including me), I don't really think about it when selecting/buying a cab. If it sounds great with me sitting right in front of it, I'll say "it's great" and probably buy it based on that. I know this is probably a bit naiive, but that's the truth.

I know from a technical perspective that it's really important, and it greatly affects what the crowd hears at different angles, but does the crowd really care? Do you really care?

My current style and instrument choices lend themselves to people often not hearing me at all that well. A lot of that is by design and I'm good with it and so are the people I play with, but I can't see any benefit in using cabs that exacerbate that situation. If I can possibly avoid playing right in front of my cab(s) I always do, as I'm all about hearing the other players first, then myself. As Jeff says, everybody on stage hearing the mix is the thing. But as always, just depends.

 

[Ric5]

Not at all true.

The length of the column affects primarily the vertical pattern, the longer the column length the narrower the vertical pattern. This is why the array is bent, to increase a pattern that becomes too narrow. The greater the bend, the lower the acoustic energy density in that area. This is one way that level versus distance can be normalized.

As far as 2 sources being necessary for high frequency coverage, this too is not true. High frequency coverage is a function of the geometry of the horn (for a horn loaded device) or for wider patterns, the diffraction slot (that may or may not be coupled to a waveguide). It is possible to get 120 degrees of horizontal coverage at 15kHz with a single diffraction device (like the QSC Wideline Array).

Stereo, or 2 sources separated by a distance, is used to add special imaging to a program, but different program composition makes up the different source material.

There are plenty of high quality single point source and line array clusters used out in the real world because they can beca better solution for some acoustic environments and seating configurations.

Most venues don't have the space for a curved vertical array ... but the curved vertical array is the best solution ... I have worked in cover bands with very expensive PA systems ... we never had a vertical array ... But perhaps the price will come down and the size will get smaller where an average band can afford and implement that solution ...

 

[Ric5]

That's not true. The height of an array has no effect on the horizontal dispersion. That's why arrays are used in PA, so that as many speakers as are required for the crowd size can be stacked and there's no loss of horizontal dispersion. You don't need tweeters either. Six or even eight inch midranges go as high as bass needs. You don't even need two sets of speakers for PA, but stacking a big PA rig in the middle of the stage would be somewhat inconvenient.
Every time this topic comes up you have the guys who understand how speakers work in the one camp, and those who don't in the other. It shouldn't be an 'issue' at all. If you want to have as much of the audience as possible hear the same thing standing off to either side as you do standing in front of the cab you keep all of the speakers in a vertical line. If you don't care put them side by side. It's only an 'issue' if you want to make it one.

If you are playing a gig with a dance floor you HAVE to get the tweeters above the dancers otherwise the high frequencies will be absorbed by the dancers and at the back of the room you will hear mostly low end. I have experienced this first hand.If your audience is sitting and you are playing from an elevated stage then you can set the tweeters lower.

High frequencies sound better with some natural reverberation ... that means the sound comes at your ears from multiple directions and arrives there milliseconds apart ... that is why we add reverb to guitar and vocals ... we electronically simulate that natural acoustic effect.

Also it is condescending to accuse those who disagree with you of not understanding. I am an architect. I have studied the design of theaters, and other venues of entertainment, and I have experience of gigging in many different situations.

 

[Coolhandjjl]

That's not true. The height of an array has no effect on the horizontal dispersion. That's why arrays are used in PA, so that as many speakers as are required for the crowd size can be stacked and there's no loss of horizontal dispersion. You don't need tweeters either. Six or even eight inch midranges go as high as bass needs. You don't even need two sets of speakers for PA, but stacking a big PA rig in the middle of the stage would be somewhat inconvenient.
Every time this topic comes up you have the guys who understand how speakers work in the one camp, and those who don't in the other. It shouldn't be an 'issue' at all. If you want to have as much of the audience as possible hear the same thing standing off to either side as you do standing in front of the cab you keep all of the speakers in a vertical line. If you don't care put them side by side. It's only an 'issue' if you want to make it one.

Yes and no... but as you stack higher, the vertical dispersion will begin to collapse.

 

[BassOnTheSide]

OK. We need one of the designers/builders to make us a curved vertical array for bass!

 

[bikeplate]

I love the sound of my rig but I never play a show without PA support. Depending on size of the room, it's a mix of my cab and pa. The bigger the room, the more the pa is my tone. Also, I send the soundman a signal that is before my amp.

All that being said, I just buy a cab if it sounds good. Or should I say if it says Bergantino one the front

 

[agedhorse]

Most venues don't have the space for a curved vertical array ... but the curved vertical array is the best solution ... I have worked in cover bands with very expensive PA systems ... we never had a vertical array ... But perhaps the price will come down and the size will get smaller where an average band can afford and implement that solution ...

A curved vertical array is necessary only where the coverage pattern requires it. When designing a system for a venue, we look at energy density (broad band SPL) and configure the array to deliver as uniform results as possible. Because of the inverse square law (section of spheres), the coverage for far throw will use more boxes tightly splayed to increase the energy density, better matching spl with more loosely splayed near throw areas. There is software available (model specific) that simplifies the calculations, but the concept of uniform energy density is the same.

Since most of the venues I work in are 1000+ seats, I see bent arrays used almost always, but there is one venue (4000 seat arena) where the trim height of the array and the height of the bleacher sections covered dictate a flat front array for uniform coverage.

 

[Bill Whitehurst]

OK, let me be the guy that points out that there is a big difference between
designing for a big venue, fixed system and finding something that you can set up
in your local dive with ease.
For me, playing local bars or private partys, The PA is for vocals only.
My solution is a fEARful.
I want to hear what I am doing, no matter where I am on stage.
I want the audiance to hear, even if they are in the back corner of a sleazy dive.
I really want my band mates to hear me.
Maybe not perfect, but about as good as you can get in a small, portable package.

It works for me.
YMMV