Dispersion?

[Pirellithecat]

Hi,

Local Jam session yesterday - in front of the "communal" bass cab all fine, off to the side ...... (where I was) couldn't hear a thing .....

So I was wondering, what "brands" are known for having great dispersion (and maybe, ) which aren't.    I've never really considered it before but it might be something to delve a bit deeper into.   I'm about to either "double up" my cabs or, depending on what people think about dispersion, maybe changing altogether.  

Anyone any pointers?

 

[Downunderwonder]

Nearly anything in the old 410 610 810 style beams horribly. Barefaced are a notable exception as they low pass one side of their cabs so directional frequencies only come from the other side in a vertical column. That gets you away from the comb filtering.

 

There are 3 way cabs that split the frequencies and much improve dispersion over full range drivers.

 

The distance to each 'side' of a driver varies with the angle it presents to us enough to get a cancellation. The larger the diameter the lower the frequency / less angle required for the effect to occur.

 

A 215 stack isn't too flash for dispersion. The old aluminum dust caps help to even the score zinging away independently so everyone gets the zing. Upper mids not so much.

[Pirellithecat]

Thanks Downunderwonder. 

I'll re-look at Barefaced.   Probably need something like 2 of the 2x10 cabs.   And Old School to boot!!

[Phil Starr]

More of the above really. Speakers beam depending upon how far apart the moving parts that make the sound are, it is related to wavelength and you can't escape the physics you have to work with it.

 

There are two ways practically you can have enough bass output and still have decent dispersal, split the frequencies or have a tall narrow column of speakers. Funnily enough you don't have to worry about the bass itself because that is pretty much omnidirectional but the mids are what you need to really hear what you are playing.

 

So anything with a horn is going to improve things, your horn is typically going to have a 1" exit point for the horn driver and the horn itself can be shaped by the designer to control dispersion. If you delve into the detail you'll see horns specified for dispersal and a typical horn might say something like 90x60 which means it 'beams' 90deg wide and 60 high. You'll only see this if you self build though.

 

As to the 'column' speaker though the smaller the speaker the wider the dispersal of higher frequencies and the smallest bass speakers from most manufacturers are 10's and that is still quite large. The width of the speaker is the distance between the extremes of the speakers though so a 2x10 on its side is as far as radiation is concerned 20" plus the gap between the speakers and a single 15 is better than a 2x10 on it's side. You can buy 8's or even 5's and a 4x8 vertical column is probably as good as you can get to have full output bass from a cab without a crossover. The column though only works in one plane, a column creates a wide flat radiation pattern for the midrange and upper frequencies.

 

So in a practical sense there are a few things to do. Get two speakers and stack them vertically to get the wide flat pattern. This will also raise the top speaker to head height which helps a lot, no sense in blasting the back of your knees with precious mids when your ears are fixed to your head! Alternatively look for a kickback speaker so that can be pointed at you.

 

Better still though look for something with a horn and preferably sit that on top of another cab to get that up high too. If you really don't like a horn sound then turning the horn off in the bottom cab is an option that can give the audience the sound you like but lets you hear your own sound better. The best solution might be in-ears though, but that is another story.....

[bertbass]

A Barefaced 2x10 is pretty much as loud as a  normal 4x10 so you may only need one and because the crossover in the cab you get maximum dispersion which ever way you have the cab.

[Lozz196]

I found that no matter where I stood (except directly behind of course) the Schroeder cabs I had sounded the same. 

[Al Krow]

Another +1 for Barefaced. I was very pleasantly gobsmacked how much better the lateral dispersion from my BF SC was compared to the very decent MB 112 I had been using beforehand.

[Pirellithecat]

OK - so we're looking at taller than wide and if possible as near to your lugholes as practical (height wise clearly!!).   So that's Barefaced 2x10's or 2x12's, in "portrait" orientation or something similar.  All on a crate!   And yep, Al, it's lateral dispersion I'm after - it was a salutary lesson yesterday!  

[funkydoug]

While vertically stacked drivers is great advice the other solution is a three way cab with each driver crossed over before it starts to beam (as mentioned above also).

It is a good one cab solution. The Fearless cabs and the markbass 123 cab are examples of this approach. Each driver should produce very widely dispersed sound in each frequency band. There’s a Dr Bass 1260 like this on eBay right now (not mine btw).

 

 

[agedhorse]

Respectfully, to counter the common argument that the polar pattern (response versus frequency versus axial angle) of a speaker depends only on the diameter of the driver and the spacing to adjacent drivers, this is only partially true.

 

It is possible (and commonly done in the real world) to alter the polar patter of a driver at higher frequencies by changing the cone depth, shape and the size/material and location of the dust cap. All of these elements contribute to the non-theoretical aspects of a driver's radiation pattern, and is why 10 different 15" drivers will have 10 different polar patterns.

 

As an extreme example, the JBL D-130 utilizes a shallow, light weight curvilinear cone, and an aluminum dust cap that is directly bonded to the top edge of the bobbin. This dust cap acts to radiate the higher frequencies differently that the cone itself.

 

As another extreme example of what could also be called a secondary radiator, the "wizzer cone" concept is a dust cap with a radiation element that is bonded directly to the top of the bobbin and can extend both the frequency response and polar pattern by an octave or more.

 

Polar patterns are something that designers consider when developing transducers for practical applications.

[Downunderwonder]

One more thing, ''let the audience see the cab''. One time I am rocking out and all of a sudden my sound goes to total hell. I turn around expecting to see someone effing with my EQ but it's the sax player getting a back massage.

[warwickhunt]

How a 4x10 should look!    

[funkydoug]

37 minutes ago, agedhorse said:

Respectfully, to counter the common argument that the polar pattern (response versus frequency versus axial angle) of a speaker depends only on the diameter of the driver and the spacing to adjacent drivers, this is only partially true.

 

It is possible (and commonly done in the real world) to alter the polar patter of a driver at higher frequencies by changing the cone depth, shape and the size/material and location of the dust cap. All of these elements contribute to the non-theoretical aspects of a driver's radiation pattern, and is why 10 different 15" drivers will have 10 different polar patterns.

 

As an extreme example, the JBL D-130 utilizes a shallow, light weight curvilinear cone, and an aluminum dust cap that is directly bonded to the top edge of the bobbin. This dust cap acts to radiate the higher frequencies differently that the cone itself.

 

As another extreme example of what could also be called a secondary radiator, the "wizzer cone" concept is a dust cap with a radiation element that is bonded directly to the top of the bobbin and can extend both the frequency response and polar pattern by an octave or more.

 

Polar patterns are something that designers consider when developing transducers for practical applications.

Great post, thanks.

In such a case as this, where the dust cap is used intentionally to increase frequency response and dispersion does it still make sense to use a single vertical stack? Or can two columns of speakers (as in a trad 410 or 810) be used?

I would think the dust caps perform better if they are vertically aligned but cabs like the PJB ones don’t use the single column approach, and I seem to recall that they do make the point that those aluminium dustcaps are intended to work as you’ve described.
I’m not questioning Phil Jones’ design at all, I just don’t understand it  … yet!! 

[Downunderwonder]

1 hour ago, funkydoug said:

Great post, thanks.

In such a case as this, where the dust cap is used intentionally to increase frequency response and dispersion does it still make sense to use a single vertical stack? Or can two columns of speakers (as in a trad 410 or 810) be used?

I would think the dust caps perform better if they are vertically aligned but cabs like the PJB ones don’t use the single column approach, and I seem to recall that they do make the point that those aluminium dustcaps are intended to work as you’ve described.
I’m not questioning Phil Jones’ design at all, I just don’t understand it  … yet!! 

If you put them side by side you undo a lot of the good work.

[Bill Fitzmaurice]

Quite right. Any time you have side by side sources they will suffer from destructive interference off-axis in the high frequencies and reduced dispersion in the mids. Barefaced gets around the destructive interference in the highs by removing the high frequency content from one side, but within the midrange frequencies where both sides are operating dispersion is still halved compared to a pure vertical line of drivers.

[agedhorse]

3 hours ago, funkydoug said:

Great post, thanks.

In such a case as this, where the dust cap is used intentionally to increase frequency response and dispersion does it still make sense to use a single vertical stack? Or can two columns of speakers (as in a trad 410 or 810) be used?

I would think the dust caps perform better if they are vertically aligned but cabs like the PJB ones don’t use the single column approach, and I seem to recall that they do make the point that those aluminium dustcaps are intended to work as you’ve described.
I’m not questioning Phil Jones’ design at all, I just don’t understand it  … yet!! 

Maybe, maybe not. It depends on what you are after with your tone, and if the (constructive/destructive) interference between point sources is a problem, or perhaps something that you actually prefer.

 

A single vertical column still has constructive and destructive interference, it's just in the other plane and it may or may not be an issue as well.

 

I remember when large flown line arrays first came into fashion, and the claims of no interference between cabinets was often touted as the biggest benefit. What many of these folks making these claims didn't understand is that the interference in the vertical plane is there and it's necessary for the line array to work as a line source. In fact this is the the basis for one of the two ways of coupling the mid and high frequency elements into the array... either each element has a narrow vertical pattern and they are all placed so that they overlap as needed for the coverage, or they are a wider vertical pattern and while they are guaranteed to overlap, they do so in a more gradual manner but with a little less control. The earlier cabinets with narrow vertical elements would lobe as you walked from the stage out to FOH, whereas in a horizontally arrayed point source system they would lobe as you walked horizontally across the auditorium. 

 

It's just 2 ways of dealing with the real world interference that occurs between any 2 point sources (no matter how they are arrayed). It also occurs with reflections off of boundary surfaces, at some point you can't do anything practical about it, it is what it is and you move onto more important things like catering and getting paid.

[stevie]

15 hours ago, agedhorse said:

Respectfully, to counter the common argument that the polar pattern (response versus frequency versus axial angle) of a speaker depends only on the diameter of the driver and the spacing to adjacent drivers, this is only partially true.

 

It is possible (and commonly done in the real world) to alter the polar patter of a driver at higher frequencies by changing the cone depth, shape and the size/material and location of the dust cap.

 

Can you point us to a bass guitar driver with a superior off-axis response, @agedhorse?

 

In the meantime, here's some information on polar response, with measurements:  http://www.troelsgravesen.dk/Beaming.htm  

[Pirellithecat]

Thanks Everyone - so if I did need 2x Barefaced 2x10's, and stacked them as per a traditional 4 x 10 I'd be rather defeating the objective (in terms of dispersion)?  Better to go a vertical 2 x 12 configuration eg Barefaced Super Twin, to get the headroom/wattage etc or just continue with my 2 x 112 Vanderkleys.    Any thoughts on how the Mesa Subway Ultra-lite 1x12 stacked on top of a Subway 1x15 might fare?

 

    

[warwickhunt]

Just now, Pirellithecat said:

Thanks Everyone - so if I did need 2x Barefaced 2x10's, and stacked them as per a traditional 4 x 10 I'd be rather defeating the objective (in terms of dispersion)?  Better to go a vertical 2 x 12 configuration eg Barefaced Super Twin, to get the headroom/wattage etc or just continue with my 2 x 112 Vanderkleys.    Any thoughts on how the Mesa Subway Ultra-lite 1x12 stacked on top of a Subway 1x15 might fare?

 

    

 

Can't you stack the BF vertically (invert one cab)?  

 

Mixing speaker diameters in an array... a whole new can of worms there my friend!    

[Bill Fitzmaurice]

23 minutes ago, warwickhunt said:

 

Can't you stack the BF vertically (invert one cab)?  

 

That would be the way to do it, placing the full range drivers adjacent and the low passed drivers at the top and bottom of the stack.

[Phil Starr]

18 minutes ago, Pirellithecat said:

Thanks Everyone - so if I did need 2x Barefaced 2x10's, and stacked them as per a traditional 4 x 10 I'd be rather defeating the objective (in terms of dispersion)?  Better to go a vertical 2 x 12 configuration eg Barefaced Super Twin, to get the headroom/wattage etc or just continue with my 2 x 112 Vanderkleys.    Any thoughts on how the Mesa Subway Ultra-lite 1x12 stacked on top of a Subway 1x15 might fare?

 

    

Actually I think you should pause here. It's interesting to know a bit about dispersion but it is only one of many things when choosing cabs. Unless you are going for FRFR then surely the most important is how the cab sounds. Dispersion was a problem in the rehearsal room but might not have been with the Vanderkleys  (vertically stacked of course). Are you unhappy with the sound of the Vanderkleys or just fancy a change? Nothing wrong with looking at all the options or just being bored and wanting to move on but dispersion is a thing, but just not the only thing.

 

 

[Pirellithecat]

Not sure how stable a vertically stacked pair of 2x10 would be but I hadn't thought about that solution - interesting, I'll have to enquire to BF. 

The dispersion "obsession" is probably just that, but I've been the victim of it twice in the last week and if I am going to change cabs then, all things being equal, I'd like to minimise the dispersion issue.  but you're right ..... Phil,  the objective is to find a cab/sound I like and then worry about the dispersion.  The Vanderkleys, stacked vertically do not seem to have the dispersion issue, but, whilst I still find them excellent, they are rather long in the tooth and are, perhaps, a little "modern", so  thought I'd try out the Barefaced  2x10 option.   Being fairly loud, and not liking any hint of "speaker fatique" I was just a little concerned that one BF 2x10 might not be enough .........  so thought I'd ask for help.  And here we are ..... 

 

The Vanderkleys are consigned to our rehearsal space, I have tried a single BB2 which was great but at (8ohms) not on it's own (with my amp) and I really couldn't justify getting a second one at the time.    I was thinking of a Mesa Subway 15 inch plus 12inch stack as an alternative - at present it's be a toss up between the 2 options.

 

Hey Ho - should probably just practice playing and not worry too much ........

 

  

[Downunderwonder]

2 hours ago, Pirellithecat said:

Thanks Everyone - so if I did need 2x Barefaced 2x10's, and stacked them as per a traditional 4 x 10 I'd be rather defeating the objective (in terms of dispersion)?  Better to go a vertical 2 x 12 configuration eg Barefaced Super Twin, to get the headroom/wattage etc or just continue with my 2 x 112 Vanderkleys.    Any thoughts on how the Mesa Subway Ultra-lite 1x12 stacked on top of a Subway 1x15 might fare?

 

    

Stacking two BF 210's the traditional 410 way turns them into a BF410. Stacking them in the tall tower per Bill with the two full range drivers in the middle also valid.

[BigRedX]

The other thing to remember is that dispersion and the sound of your cabs are both fairly irrelevant if the bass also goes through the PA.

[Lozz196]

Good point, certainly applies to all the gigs I’ve done since 2014, onstage gear purely for on stage sound, and even then the sound was also through the monitors.