About dance stacks..

[mitchiemasha]

As for the loss of 3db or the gain of (depending on situation), myth/misunderstanding... you're not getting less or more energy out of the speaker, it's simply being radiated differently.

There is another factor to consider, which I don't know or have ever seen the value given. Loss of sound energy to kinetic energy. If you were to stick a bass bin on a pole it's no longer anchored to the ground. The friction between the weight of the cabinet and the ground reduces the speaker throwing the cabinet backwards and forwards. Not that we'd stick a bass bin on a pole but surely there would be some loss of sound energy to this movement.

[conanski]

There is another factor to consider, which I don't know or have ever seen the value given. Loss of sound energy to kinetic energy. If you were to stick a bass bin on a pole it's no longer anchored to the ground. The friction between the weight of the cabinet and the ground reduces the speaker throwing the cabinet backwards and forwards. Not that we'd stick a bass bin on a pole but surely there would be some loss of sound energy to this movement.

That isn't a thing, what influences bass output in that case is the distance from boundaries which sets up cancellation nodes in the listening environment.

[Incognito]

As for the loss of 3db or the gain of (depending on situation), myth/misunderstanding... you're not getting less or more energy out of the speaker, it's simply being radiated differently.

The measured SPL difference between half space vs full space for subs, this is all myths you say? Sound being radiated "differently" is the same as energy in a circuit, if you start with 100% efficiency but lost a percentage due to heat, that's a loss in over all efficiency even though it's just energy "radiating differently". Basically it's the listeners position that counts, if you have wasted db being radiated in a manner that isn't a beneficial gain where it is useful then it gets counted as waste. This waste can be measured & be seen in the form of many graphs for speakers measured over the years.

[Coronaoperator]

EDIT2 : Also, I read somewhere that lifting a sub from the floor attenuates the sound by ~3dB... is this true? (I'm too lazy to try and I don't have a db meter..)

Here is a whole thread on the issue of flown/ground stacked subs with measurements: http://forums.prosoundweb.com/index....,158814.0.html

Essentially the crowd is almost always (unless there is a human cannon) on the ground in half space and as such no matter where you put the subs vertically outdoors, you will get half space loading for the crowd. Possibly flown subs and high up bleachers may change that but for the most part it doesn't matter.

[efinque]

Also, acoustically speaking, would it be possible to feed some of the low frequency (30-50hz) to the scoop (edit : ie. additional rumble, since that's what they're really good at) using a notch filter in the "punch"-range (50-150hz or so) of the lows, which is mainly handled by the 186/1850?

EDIT : For example, instead of feeding it with the (edit : crossovered) midrange signal, just put a 2,5kHZ lowpass filter inside the cab (or in the xover) and feed it with a notched fullrange signal

[mitchiemasha]

Oh dear, i had to speak,lol... 1st of all... Bill knows a thing or 2 about speakers and

No.

That isn't a thing, what influences bass output in that case is the distance from boundaries which sets up cancellation nodes in the listening environment.

We're not beginners here. We know this... I was simply pointing out something that is "a thing" (it's all physics) but I've not seen anything on the subject to satisfy my thoughts on how the science might play out, they're a lot of factors to think about. I like to keep my posts as short as possible and presume certain details don't need to be added. Just think about a basket throwing itself backwards and forwards in a frame that had little holding itself in place.

Basically it's the listeners position that counts.

Yes i totally agree but you completely missed the point of my post... See the "i like to keep" point above... I did use "misunderstanding". The point is the +3/6db can be confusing to people as it leads them to believe the speaker is producing more energy. This goes against any basic teachings of science. There is the same amount of energy, simply that energy is being more focused.

Obviously a flown bass bin at the incorrect height will see a loss as it's cancelling but that isn't the issue.

There are many things we are taught that are kind of true but not true, depending on how you look at it but some people are a firm believer of polar opposites on this subject, regardless to parameters drawn into the situation. I've read countless threads upon it.

[conanski]

Also, acoustically speaking, would it be possible to feed some of the low frequency (30-50hz) to the scoop (edit : ie. additional rumble, since that's what they're really good at) using a notch filter in the "punch"-range (50-150hz or so) of the lows, which is mainly handled by the 186/1850?

EDIT : For example, instead of feeding it with the (edit : crossovered) midrange signal, just put a 2,5kHZ lowpass filter inside the cab (or in the xover) and feed it with a notched fullrange signal

Efinque.. are you even reading any of these replies? Scoops(the box itself) don't do mids they do bass. A 15" driver can produce sound up into the midrange but it's not real great at it... a 10" is much better, and besides at that point you're listening to the driver only the scoop is doing nothing so if that is what you want forget the scoop and just put the drivers in small sealed or sealed and straight horn loaded enclosure aka MT102.

Mixing different cabs in the same frequency range is also a bad idea, you get as much cancellation as anything so the practice is to be avoided.

[conanski]

We're not beginners here. We know this...

The OP of this thread is a beginner.

I was simply pointing out something that is "a thing" (it's all physics) but I've not seen anything on the subject to satisfy my thoughts on how the science might play out, they're a lot of factors to think about. I like to keep my posts as short as possible and presume certain details don't need to be added. Just think about a basket throwing itself backwards and forwards in a frame that had little holding itself in place.

That I will give you and I have seen the effects of that with a pair of moving heads mounted on a lightweight aluminum t-bar stand. With this setup the momentum the heads generate when moving in sync produces a sway in the stand.. just as physics predicts it should. But the amount of movement the heads generate is rather large and the speed(frequency) very low compared to what a speaker driver generates so in comparison the momentum generated by the speaker is very low. How low? It not something you can see or even feel over the vibration of the cab itself so while I can't say it doesn't exist I can say with some confidence that it's not significant.. that is what I meant by "not a thing", the major factor influencing low frequency reproduction in a room is the speakers proximity to boundaries.

[mitchiemasha]

Here is a whole thread on the issue of flown/ground stacked subs with measurements: http://forums.prosoundweb.com/index....,158814.0.html

Actually... The issue of unanchord subs is mentioned in that thread but so far not explored in detail, Newtons 3rd law. So i'd likely of picked it up from somewhere, not dreamed it up myself. I've still not seen dedicated maths to the subject. Especially to the accuracy of the speaker, transient response. Imagine a basket throwing itself forward as the cab has backwards movement, reaching the limits of the speaker earlier, the resistance in suspension, overshooting the magnet, bottoming out, with less air been moved. But the air will be getting moved backwards more so would the resulting air pressure not stay the same... I don't know, I'd like to read a lot more on this subject. [S]Other than the same old, comb filtering, half space, whole space, inverse square argument. A desire to move forward, not go round in circles[/S].

Edit: actually i retract that last line, I'd still like to have a better understanding on those subjects... Strike through didn't work!

[efinque]

Actually... The issue of unanchord subs is mentioned in that thread but so far not explored in detail, Newtons 3rd law. So i'd likely of picked it up from somewhere, not dreamed it up myself. I've still not seen dedicated maths to the subject. Especially to the accuracy of the speaker, transient response. Imagine a basket throwing itself forward as the cab has backwards movement, reaching the limits of the speaker earlier, the resistance in suspension, overshooting the magnet, bottoming out, with less air been moved. But the air will be getting moved backwards more so would the resulting air pressure not stay the same... I don't know, i'd like to read a lot more on this subject. Other than the same old, comb filtering, half space, whole space, inverse square argument. A desire to move forward, not go round in circles.

Isn't the power (edit : by power I mean the overall volume in dB) measured from 1m distance in watts (in a vacuum?) I'm fully aware of the floor reflection thing..