Vertical stacking is there a limit?

[Zootsuitbass]

I think the logic of the wall of sound bass column was that its a high as the lowest notes fundament wave is long. IE 28 feet?

 

[MVE]

There is a TBer on here that uses two Berg 610s under an SVT and posted a photo of them stacked.
Definitely glorious overkill.

 

[Kirk Bryant]

Limits be damned. Rules were made to be broken.


No officer, I wasn't speeding, um yea, thats its!

 

[Rick James]

There's lots of disinformation in the replies here. None of the claimed negatives about line sources are true, if the array is correctly engineered. This paper explains how to engineer them: http://www.audioroundtable.com/misc/nflawp.pdf

Where bass cabs are concerned true line arrays operating in the nearfield would be way too high to be practical. The Dead Wall of Sound worked well enough, but it wasn't at all practical. They needed two of them, one for the gig they were playing, the other leap frogged ahead to the next gig, because it took two days at least to set it up. We still use the same tech, but just with the PA.

 

[Lobster11]

I think the logic of the wall of sound bass column was that its a high as the lowest notes fundament wave is long. IE 28 feet?

Interesting hypothesis. Sounds like just the kind of thing Owsley and his buddies would have thought about.

Here's a diagram of the entire system:

It can't be a coincidence that the two bass arrays are taller than all the others; they weren't just making everything as big as it could be. And 28 feet sounds about right for a stack of 18 fifteen-inch drivers with the cabs stacked in the orientation these are (i.e., with minimal vertical distance between drivers).

 

[Downunderwonder]

Whoa. Where can I go further into detail about this? I was thinking (from bottom) 15/1212/410 then Horn and tweeter, all stacked vertically, 2 separate inputs 15 and 210 for one crossover, 1212 and 210 for the other. Would that be feasible for the frequencies?

I think the proper term is musing.

 

[agedhorse]

SO is this why flown line arrays are usually in an arc shape?

In part this helps distribute the lobe energy so it's less noticeable (though it's still present). The other reason is to help achieve the required vertical coverage, which along with different volumes (and sometimes horizontal coverage) from each cabinet, helps balance the energy density and thus SPL as you move from front to back. Common is the close (front fill) cabinets will be lower in volume and wider horizontal coverage to account for geometry.

With a decent floor (or ground outside), the floor boundary doubles the array height. Picture a mirror instead of the floor surface; the reflections you see of loudpeakers are where the sound reflections will appear to eminate from. A stack of 4 loudspeakers outdoors on a parking lot will also have 4 virtual sources "below ground" - the stack height is doubled. Even one speaker will have a virtual source due to this reflection. If you do this for all the boundaries (walls, ceiling) in a room, you'll end up with a lot of virtual sound sources, and the comb filter at any given listeing position is the result of all of them adding together - different lengths from each source to each place you might want to listen.

The most audible effects, though, are typically at low frequencies, where the nulls (places where a note drops out a lot) are big - low frequencies have long wavelengths, which makes those nulls big. If you have parallel ceiling and floor sufaces (a box shaped club), and a floor to ceiling array, with the boxes close together, the net result will approach "infinite" reflections (refelections of reflections adding height to the array ad nauseum, due to the ceiling and floor boundaries. Doing this, all those reflections will actually reduce the comb filtering effects - you'll have less nulls in the vertical plane, reducing their effects somewhat. So, if you spend enough money, there is a free.....OK, an expensive lunch.

So, a floor to ceiling stack does have benefits. Then again, the only gig I play where I bring an amp, I just have to keep up with an unamplified acoustic piano, and the ceiling is....probably 40 feet tall, so practically, I'm not going to be the one to do this experiment. We need someone with a full wallet, and a regular gig in a club with a low ceiling to do this. Remember, it's for Science. Tell your wife that, as you rent a big van to get your amp to the bar. Let us know how it goes.

This is a very complicated set of concepts to describe accurately, as you have shown. Tremendous tradeoffs, for example the floor boundary is a double-edged sword, especially where the array is flown, as there can be a big gap in distance at critical 100-500Hz. Ground stacked, this gap is minimized, and the mirror more accurate, but then there's higher frequency reflections that weren't as much of a problem that (can) rear their ugly heads

Boundaries are both your friend and your enemy, outdoors eliminates many of these, but not all. Fortunately a single ground plane is the least offensive boundary as an only boundary.

 

[Rick James]

SO is this why flown line arrays are usually in an arc shape?

Watch this:

 

[J-Bassomatic]

It's dawned on me that the limit would be where the atmosphere would be so thin that sound waves wouldn't carry very well, maybe 8 or 10 miles high. But it would be the eighth wonder of the world, unless the music was bad. Just demonstrating how feeble minds work. Move on folks, there's nothing to see here.

 

[chaosMK]

3 cabs is my current limit

 

[JWH91]

Science stuff.... I knew it was coming.

I know right??? I love it when @agedhorse gives his 2 cents, more like a plethora of knowledge. I'm always googling stuff he speaks, you need to teach classes my man

 

[Super Bass]

Stacking all my Mesa cabs leaves me no room for the head (in my basement)! But 2 15s and the 2x10 are a great sounding rig..

 

[JWH91]

We need someone with a full wallet, and a regular gig in a club with a low ceiling to do this. Remember, it's for Science. Tell your wife that, as you rent a big van to get your amp to the bar. Let us know how it goes.

Will do! for SCIENCE!!!

 

[JWH91]

View attachment 2806622 View attachment 2806623 Stacking all my Mesa cabs leaves me no room for the head (in my basement)! But 2 15s and the 2x10 are a great sounding rig..

Rack mount that head man! Or use a Coffee table lol

 

[MultiScaleMale]

The limit would be the point where the weight of the cable pulls the cab of the top of the stack.

 

[dbsfgyd1]

What is considered overkill for example two 410s stacked vertically sounds louder than side-by-side. Now my question is let's say we have an 810, would eight individual 10" drivers stacked vertically sound louder than your standard 810?

For those who already know me on this forum, as you can see I am sober and clearly ready to learn some theory on speaker amplification and sound waves, for the next 15 minutes at least lol

I’m not going to add much in the way of theory, but from a subjective point of view I have a few thoughts. I’m going to assume that with that much horse power, you are playing larger venues with a FOH system. That being the case, and you are having trouble hearing yourself, take a look at your EQ. If you are scooping the low mids and boosting the super lows that may be your issue. I use 2 210 cabs stacked and power each with 300 watts and I have zero problems hearing myself, and also find I have an agreeable amount of low end thump. That’s playing outdoors and concert hall venues. What else I found is that the sound guys are always really happy with me not creating problems for them.

If you are playing ambiently with guitar turds, and a drummer that plays with telephone poles, maybe a 2nd cab is needed, but you will also need hearing aids soon, so try stacking the the 2 810 cabs lying on their sides ( max floor contact is great for bass).

Also, you will get more sound having your cab flush on a wall, and or in a corner.

 

[Downunderwonder]

3 cabs is my current limit

View attachment 2806547

To get the Mesa rack up there you made stairs out of the spare cabs or you are 8ft tall?

 

[chuck3]

my current maximum vertical stack is 3 x 12 - this gets loud -

 

[JWH91]

you have some type of delusion about cabinet set up.....its overkill...not needed...sheer posturing...get over it..

Well I didn't say 10 cabs in your first post I was referring to 8 10" speakers in a vertical stack. Instead of 4 side by side in your standard 810, also delusion? Man why does the new challenger hellcat have over 800hp? Why can a Kawasaki zx14 go over 218mph? Why are there over 40,000 satellites in orbite? To each his own my friend.

 

[micguy]

It's dawned on me that the limit would be where the atmosphere would be so thin that sound waves wouldn't carry very well, maybe 8 or 10 miles high. But it would be the eighth wonder of the world, unless the music was bad. Just demonstrating how feeble minds work. Move on folks, there's nothing to see here.

Your mind is actually in the right place for certain things. A lot of people want to have microphones or loudspeakers that focus, like a lens on a camera. In theory, that's possible, but...(I've done the calculations*) to get a loudspeaker array to focus as well as a cheap camera does for visible light (1 cm lens) at 20 Hz, you'd need a loudspeaker array that's circular, and...200 miles in diameter - which is larger than the atmosphere. As you've pointed out - by 8 or 10 miles up, you're running out of gas (literally).

*One of the hazards of being a Physicist is you calculate these kinds of things - for fun.