If a crossover is designed with the speaker in an anechoic chamber...what would it sound like in a real room?

[johnmath]

The key is in understanding the pitfalls and limitations of whatever measurement system is being used, for the purpose it is being used.

I am not sure if you are a proponent of Arta, which is of course a gated measurement system as well.

 

[hifijim]

Ground plane measurements work well at low frequencies. You simply need flat ground with a distance of 1/2 wavelength to the nearest wall or structure. Ambient outdoor noise is a challenge, just as with any outdoor measurement. But there is no need for tall towers and all that. I found it easy to get resolution from 20 Hz up to 1 kHz. Bikinpunk (Erin, of Erin's Audio Corner) has a thread where he was able to do ground plane measurements with good resolution all the way up to 20 kHz (!)
https://www.diyaudio.com/community/...how-close-is-close-enough-to-anechoic.353347/Overall, it is an excellent thread, very informative.

 

[vacuphile]

I think Mark ist right on this one. You have to distinguish between roomgain and construktive Interferance. I belive what Mark means with roomgain is a pressurisation of the whole room via the displaced airvolume of the moving cone.

That is only possible in airtight and stiff rooms.

You come to a firm conclusion based on a believe, which is the scourge of this time. Assumption is the mother of all you know what. Since I have no camel in this stew, I grant you your believes.

 

[vacuphile]

I've measured subwoofers outdoors. A mate of mine (actually a manufacturer of large THX approved commercial cinema systems) constructed a pit in a field that allowed for true 1/2 space loading, i.e. baffle flush with the ground surface.

I find this peculiar.

You could measure individual drivers this way, but not loudspeaker systems. The reason is that if you bury the enclosure, you miss out on the interaction between the driver and the morphology of the enclosure. Which is what you are after.

 

[johnmath]

I find this peculiar.

You could measure individual drivers this way, but not loudspeaker systems. The reason is that if you bury the enclosure, you miss out on the interaction between the driver and the morphology of the enclosure. Which is what you are after.

I didn't say he measured full-range systems flush in the ground, the discussion was around measuring low frequencies. I think by the time the Krix company was developing THX systems the outdoor measurements had long been abandoned as impracticable. However the very first commercial cinema system installed by Krix used a virtual infinite baffle with soffit mounted speaker systems (i.e.1/2 space loaded) behind the perforated projection screen, and they went on to do installations in many cinemas in Australia like this. Decades later they were sued by THX when THX patented the idea. THX hadn't existed when Krix started doing this, although it's predecessor Ultra-Stereo was making electronic processors for film playback. I don't know the details but assume some settlement was reached. I believe Krix make the only 4-way THX certified cinema systems in the world; the others, JBL, et al only make 3-way systems.

 

[vacuphile]

If you want to measure loudspeakers correctly outdoors, that actually is the poor man's dead room, and a darn good one if properly understood.

http://www.mh-audio.nl/Acoustics/Groundplane.html