Hi All! I am working on a low profile wall-mount design similar to a Procella P5V or a Grimani Rixos, and I want to prioritize off-axis response. Normally I would perform a ground plane measurement or 4pi gated measurement, but in this case it seems like the wall will be an integral part of the speaker.
Would it be better to lay the speaker flat on the ground and suspend the microphone over it? I haven't been able to find a standard procedure for this, I'm not quite sure what to call it but I think I saw a photo of it being done once.
Any advice is appreciated, thank you!
Would it be better to lay the speaker flat on the ground and suspend the microphone over it? I haven't been able to find a standard procedure for this, I'm not quite sure what to call it but I think I saw a photo of it being done once.
Any advice is appreciated, thank you!
I think your measurement method should be for half-space, as the wall would act like a large baffle. However, the full-space measurement should be more or less similar, except for the reduced bass (think < 500 Hz). The situation is very similar to a cinema surround speaker.
Ah, thank you! Googling for "half space" measurements is producing far more useful results than what I was searching before.
I once dug a hole in my back yard and lined it with thick plastic to take infinite baffle measurements. I ended up lining the hole with concrete because it worked so well and had baffle inserts for most driver diameters. I lived at that location for 10 years and turned it into a BBQ pit just before I moved.
Not really that important to mention, but I just remembered how many speakers I designed with the help of that facility.
Not really that important to mention, but I just remembered how many speakers I designed with the help of that facility.
That is precisely what you have to do. The only challenge will be that you will have to move the mike in a hemisphere or half circle above the speaker to get the polar, a turntable for the speaker obviously won't work. Using two ropes attached to the mike and two points on the floor so that the three points form a triangle would enable that.
Some ideas for measurements of in-wall/on-wall speakers in page 13:
http://www.hannover-hardcore.de/infinity_classics/!!!/Aries M Dokumentation.pdf
http://www.hannover-hardcore.de/infinity_classics/!!!/Aries M Dokumentation.pdf
That's what I would do as well.
Better yet, build a speaker that is mounted in the the wall to eliminate the diffraction effects of the protruding box and comb filtering effects from the wall bounce. FR will be much smoother and your job designing the crossover will be much easier. I have measured in-wall speakers before by mounting them in a baffle in a storm drain in a parking lot.
Before McIntosh had an acoustic chamber Roger Russell used to bury speakers in a field and measure them with the mic suspended above. He would then estimate the baffle step and factor that into the crossover design.
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So are you saying I’d be better off doing a four-pi gated measurement on a turntable without the wall?
I do agree that in-wall would be even better, but due to what’s on the other side of the wall I’d prefer not to. Also I feel like this on-wall solution could be useful to a lot of my friends who live in houses and apartments that are too small to get the speakers >3ft from the wall but are also unable/unwilling to mount inside the wall.
Close to the wall is actually recommended - for typical monopole speakers. Bass boost it gives is beneficial for 90% of stand-mount 2-way speakers on the market. Floorstanders might become bass-heavy, but we have tone control and eq for that.
Monitor Placement - Genelec.com
Monitor Placement - Genelec.com
Well, Genelec is putting it too simple, I guess. No hunch of the classic acoustic divisions with which a room should be appraised. Sure one would be able to identify a front wall cancellation, but the room modes likely will prevail.
Got it.
Your idea of "the wall is an integral part of the speaker" makes perfect sense since that part of the acoustic environment is always the same. Also if you do it outdoors you can measure to a much lower frequency than with a gated turntable measurement.
Both measurements should be the same above the transition frequency where λ = baffle circumference. The only difference is below the transition frequency the on-ground measurement won't have the 6db baffle step and will have wall interference that you can't do anything about.
What I do is measure outside away from reflective surfaces, flat on the ground.
Then use a microphone standard to place the mic.
I also made a crude triangle from wood, so I can easily make measurements of axis.
It's much easyer than in room measurements, because there are no reflections no gating is nessesary.
Then use a microphone standard to place the mic.
I also made a crude triangle from wood, so I can easily make measurements of axis.
It's much easyer than in room measurements, because there are no reflections no gating is nessesary.