extremely high efficiency

Coming out of retirement despite myself because the bullshit around here has piled up so high that I can smell it from my cosy little hideaway.

It might be worth checking your shoes.

So that's a measured maximum SPL and oh look, they included a repeatable measurement standard too! Yes, the M-Noise test method is an AES standard.

To copy and paste from M-Noise’s procedure page:

Verify the M‑Noise file used for testing is unaltered from the original by performing a checksum of the downloaded .wav file (SHA or MD5) and compare to the checksum value listed at M‑Noise.org. Put a calibrator on the SPL microphone and document that the microphone reads the correct SPL (most calibrators produce 94 dB). Look up the maximum electrical input and output voltages of all the audio devices used to ensure the loudspeaker can be driven to its maximum linear output, typically at least +18 dBu, and sometimes as much as +24 dBu. For example, if the playback device produces a maximum of +16 dBu and the maximum input to the loudspeaker system is +24 dBu, insert a device between them to add 8 dB of gain. Do not change this gain during the procedure. Document the audio devices used, their settings, and the signal path between them. Document the loudspeaker position and the SPL microphone position.

It also states:

“Document”: when used as a verb in this procedure means to record information in some way such that an audio professional who has access to the “documents” could replicate the procedure and get the same results. For example, “documenting” the microphone position could mean making a drawing, taking a picture, or writing a description in the notes field of a stored trace.

Here is a link to the page I quoted.

https://m-noise.org/procedure/ - https://m-noise.org/procedure/

I may have missed it, but I don’t see any documentation regarding the measurement procedure on the Danley website. Yes M-Noise is a recognised standard, but anyone can download the audio file and truthfully claim to have measured their device using the M-Noise signal. Without the documentation it doesn’t conform to the standard, which as you say is about repeatability. Without the set-up documentation how can you repeat the measurement? If anyone has a copy or link to Danley’s documentation I would be interested to see it.

If the figures are accurate, it is good news for the home constructor, because it shows that a simple calculation can get you quite close.

Sounds like a pretty good measure of overall efficiency to me. If you can cover the audience with a box that occupies a tenth of the truck pack volume, uses a third of the number of amplifier channels, and in half the weight of the equivalent 12-deep hang of a mid-format line array system, is that not a more efficient way to do the gig?

If you notice the last part of my statement that you quoted I said “unless by efficient you mean highest output from smallest box.” Generally, in engineering, this is not what is meant by efficient.

All the fancy images about line arrays and bodies

Could this be what is affecting your olfactory system. The images might look pretty, the information is probably correct, but it is the answer to a different question. In the context of this thread, comparing the Danley system to a large line array it is irrelevant. The original poster was asking about designing and building an efficient system, not whether a Danley system is comparable to a12 a side d&b KSL.

On the subject of flying things, it's worth noting that all of the array modelling is built on the basis of there not being a reflective/absorptive ground plane and audience, aka free-field conditions. If you simulate an array that's too low to the ground, it won't behave like the maths suggests. Not only are you pasting the poor bastards in the front row with brute force SPL while the people at the back can barely hear the vocals, you're going to cause more off-site noise issues more quickly like this. Hard to discuss the finer details of this approach on a site when the noise police just need you to STFU before Doris calls the council, of course.

I think that it is a reasonable assumption that anyone asking how to design a speaker cabinet, on this forum, is unlikely to be deploying their resulting work at a height sufficient to ensure free-field conditions. If this is the case then you agree that your calculations are irrelevant.

As the original poster has not returned since his three initial posts, perhaps he has found a solution to his question or got bored and moved on to some new project. If he is reading this perhaps he can let us know.