To stack or not to stack..

[jonnythenotes]

Is there any difference in the sound of two cabs stacked on top of each other, or the same two cabs side by side on the floor ? I realise that I will hear more of the sound with the cabs stacked, as obviously, the top cab is much nearer my ear, but what I want to know is the will the sound in the venue, or put another way, the sound an audience hears be any different..( louder or have more bottom end,) using either of the two configurations. The cabs in question are Ashdown abm neo 4x8's, and any answers should take into account both a solid floor, and a hollow stage. Both cabs have rubber feet on each corner, but on occasion, I have even played with them (stacked) on there side so the full surface area of the side of the cab is in contact with the floor. It's a question that is bound to have been asked before,so apologies in advance for that... Thanks....

[Weststarx]

All speakers and amps should be head height for the best sound in my opinion regardless of the type of venue or floor.

[Phil Starr]

There's some fairly simple physics here. If you stand to the side of a speaker it will take longer for the sound to arrive at your ears from the most distant speaker, a few thousandths of a second. In this time the speaker may have traveled forwards and now be travelling back. This means the sound from one speaker is out of phase with the nearer speaker and the sounds will cancel and you will hear very little. All this depends upon the frequency and the exact dimensions.

In practice this means that any frequency where the furthest parts of the moving cones are more than one wavelength are radiated in an increasingly tight beam of sound, all your mids and highs. Placing your cabs next to each other will mean only people in line will hear your sound properly.

Put another way stacking speakers vertically means the sound is radiated in a broad flat beam across the audience, on their side and the beam is narrow and pointing at the ceiling and floor.

[Michael J]

Vertical stacking will probably give a better horizontal dispersion, which is likely to result in a more even spread of sound in the room. Vertical linear arrays can be excellent.

Placed side by side there will be increased tendency to "beam" directly forwards and for comb-filtering to occur across the room, but the ceiling is likely to get a better spread (which is not of much benefit in most cases). This arrangement amounts to putting the cabs right up to a wall, it may boost bass but could well create boom (regardless of the nature of the floor).

You can eliminate some of the latter problems by angling the speakers inwards, so they fire across each other. This makes them act more like a point source.

[jonnythenotes]

That....is so eye openingly useful guys...... Thanks....

[onehappybunny]

Interesting stuff... do you think that there would be much difference in horizontal dispersion when using 2 x 12's (like the TKS S112's) vertically rather than horizontally as they only have one 12" speaker each?

[jonnythenotes]

This may be a complete myth, but someone years ago told me as sound leaves a speaker, it spreads in a way similar to the shape of an ice cream cone..and that the size of the speaker, eg a 12 inch means the sound is at its best 12 feet away, a 15inch, 15 feet away etc. so what I have read above would make sense in that the speakers nearest the floor, as the sound leaves them, the ice 'cream cone' shape would distort as the sound hits the floor, whereas the higher the speaker off the floor, the longer the 'cone' will keep its shape, ie, the sound will travel before bouncing off the floor, and changing 'the shape' of the sound. Does this make any sort of sense, or is a load of nonsense.

[Michael J]

[quote name='onehappybunny' timestamp='1427460854' post='2730645']
Interesting stuff... do you think that there would be much difference in horizontal dispersion when using 2 x 12's (like the TKS S112's) vertically rather than horizontally as they only have one 12" speaker each?
[/quote]
Same thing applies, a 12" speaker is large enough to show phase issues at mid/high frequencies all on its own, more than one of them just exacerbates the issue.

Using speed of sound in air = 340 m/s, at 340Hz the wavelength is 1m. As long as your source is relatively small compared to the wavelength then it acts "pointlike" which is good. You can regard 1/10th as small. If the source is of similar order in size as the wavelength then you can have problems, and if the source is large then you will have more problems.

The G string of a regular bass is 98Hz fundamental, wavelength of about 3.5m, but the sound you hear is not a pure sine tone, it is replete with harmonics which may be many times that frequency. Playing the G normally at the 12th fret means the fundamental is 196Hz and harmonics are now multiples of that. 196Hz can be regarded as "of similar order" to 340Hz for our purposes so, as above, our source needs to be "small" relative to 1m or so, and smaller still for the harmonic overtones. A 12" driver is about 0.3m diameter, which is heading out of small and into similar order territory at a few hundred Hertz. At 3.4KHz the wavelength is 10cm, and any source larger than an inch or so in diameter will exhibit some phase issues just due to the size of the driver.

Edited March 27, 2015 by Michael J

[TimR]

Yes. Stack them vertically one on top of the other with the label the right way up and the feet at the bottom. So you have a two cones wide by four cones high configuration.

They're not ideal anyway because you'll have two speakers side by side which will cause combing. From an audience point of view the bass will get louder and quieter and louder again as you walk across the hall.

Putting the cabs side by side will give you much more bottom end but you'll not be able to hear the mids because the higher frequencies will be beamed past your knees. Coupled with the increased bass it'll sound awful.

I use 2 2x10s so I have one cone wide and four cones high. Sounds great.

Edited March 27, 2015 by TimR

[Michael J]

[quote name='jonnythenotes' timestamp='1427463453' post='2730690']
This may be a complete myth, but someone years ago told me as sound leaves a speaker, it spreads in a way similar to the shape of an ice cream cone..
[/quote]
This is quite basic physics. [url=https://www.google.co.uk/search?q=diffraction+of+sound&prmd=ivns&source=lnms&tbm=isch&sa=X&ei=tG8VVZDrNMnbasL0gIAC&ved=0CAUQ_AU]Diffraction of sound[/url] is similar to the behaviour of light except that the velocity is low, the wavelength is large, and the resulting diffraction is considerable. For very small aperture/source relative to wavelength the diffraction is virtually complete, i.e. spherical wavefronts and sound goes round corners.

A free point source radiates spherically, equally in all directions. Block off the backward-directed radiation (e.g. with a cabinet) and you are left with a hemisphere, which is the basic form of the radiated wavefront from a relatively small source located in a large flat baffle.

[onehappybunny]

Thanks Michael - so, if I understand this right... two 1x12" cabs stacked vertically on top of each other, will disperse sound better than two 1x12" cabs stacked horizontally on top of each other (i.e. not side by side) even though in both cases the speakers are vertically aligned

[Michael J]

Are the boxes not square?

[onehappybunny]

This is what I meant... the cabs are[size=4] [/size][size=3][color=#000000][font=verdana][size=4]52x38x33 cm [font=arial,helvetica,sans-serif]so stacking them leads to an overall height of 104cm vertically (2x52) or 76cm horizontally (2x38), but in both cases the speakers are aligned directly above each other. [/font][/size][/font][/color][/size]

[size=3][color=#000000][font=verdana][size=4][font=arial,helvetica,sans-serif]Obviously the sound is nearer your ears if stacked vertically but wondered if there were any benefits with dispersal as well. Sorry if I'm being thick about this, but I'm genuinely interested[/font][/size][/font][/color][/size]

[Bass_Guardian]

[quote name='Michael J' timestamp='1427468759' post='2730801']
This is quite basic physics. [url="https://www.google.co.uk/search?q=diffraction+of+sound&prmd=ivns&source=lnms&tbm=isch&sa=X&ei=tG8VVZDrNMnbasL0gIAC&ved=0CAUQ_AU"]Diffraction of sound[/url] is similar to the behaviour of light except that the velocity is low, the wavelength is large, and the resulting diffraction is considerable. For very small aperture/source relative to wavelength the diffraction is virtually complete, i.e. spherical wavefronts and sound goes round corners.

A free point source radiates spherically, equally in all directions. Block off the backward-directed radiation (e.g. with a cabinet) and you are left with a hemisphere, which is the basic form of the radiated wavefront from a relatively small source located in a large flat baffle.
[/quote]

Done Higher Physics and I can barely understand what you're saying...to me basic physics is distance = velocity x time (probably got that wrong too )

[Michael J]

@onehappybunny,

It looks like they are designed to go either way, try both and see which you prefer. Use a long instrument lead so that you can hear what it is like 20-30' or so away and wander about in the far field.

Edited March 27, 2015 by Michael J

[onehappybunny]

Ok thanks Michael

[thebrig]

My brain hurts!

I'm lost, but I admire all you guys who are a minefield of information.

[blue]

I like to hear my signal from my stage monitor, right in front of me.

Blue

Edited March 27, 2015 by blue

[Donnyboy]

[quote name='thebrig' timestamp='1427474725' post='2730919']
My brain hurts!

I'm lost, but I admire all you guys who are a minefield of information.
[/quote]

Me too!

However I do think that stacked on top of each other does look pretty good. Yip, shallow.

[dadofsix]

I gotta tell you, I'm impressed with the knowledge here.

I learned a long time ago to do what sounds the best in the biggest area possible. But it does take an effort to listen critically, sometimes. Now I play wireless. It really does help to hear the sound from many parts of the room when I'm using two 4x10 cabinets. Usuallly, though, I'm using a single 6x10 cabinet, so it's more a question of where to point the cab. YMMV

[JTUK]

IMO, it is a stage issue rather than anything else..

[blue]

[quote name='JTUK' timestamp='1427528383' post='2731398']
IMO, it is a stage issue rather than anything else..
[/quote]

That's why I depend on a decent signal from the stage monitor. I have been in some rooms where I'm standing right in front of my amp and can't here my bass at all.

Blue

Edited March 28, 2015 by blue

[grandad]

I found it helpful to imagine spraying the audience with water from a garden hose. As the frequency gets higher so I'm turning the control nozzle from a fine wide spray to a jet.

With 2 hoses together, either side by side or one on top of the other, the jets will collide and the water will tend to spray verticaly or horizontally.

Reading back I'm not to sure whether this explanation will serve to confuse or clarify but I'll post it anyway and await the puns on my aqueous analogy.

[Bikenbass]

Ok, I'll bite.

[quote name='grandad' timestamp='1427534115' post='2731450']
I found it helpful to imagine spraying the audience with water from a garden hose. As the frequency gets higher so I'm turning the control nozzle from a fine wide spray to a jet.

With 2 hoses together, either side by side or one on top of the other, the jets will collide and the water will tend to spray verticaly or horizontally.

Reading back I'm not to sure whether this explanation will serve to confuse or clarify but I'll post it anyway and await the puns on my aqueous analogy.
[/quote]

Water you saying? Spray that again please.
(Sorry)

[dadofsix]

[quote name='blue' timestamp='1427475360' post='2730932']
I like to hear my signal from my stage monitor, right in front of me.

Blue
[/quote]

I can truly appreciate that. However, I am also a vocalist and all I want to hear from my monitor is vocals. That's why controlling my onstage sound is so important. Our soundman HATES me because i will not relinquish control of my onstage sound to him. lol If he had his way I'd be using a direct box into the FOH and relying solely on the wedges to hear my sound. Nope! Not gonna happen.

<><Peace