Time/transient smearing of the arrival of sound from multiple sources.

Oct 25, 2018
69
8
8
58
Bideford, Devon. UK
Hi All,

I have been searching to no avail for anecdotal information or preferably white papers regarding the implications for the reproduction of transient events (lets imagine a simple 'click' track for now) in multiple-driver speaker systems such as PA line arrays and tall domestic column-style speakers. It doesn't take too much imagination to picture the wildly differing path lengths to the listener in such speaker systems, but even if phase, amplitude, and frequency shading are used alone or in conjunction, a solution could only be approximated for one listening position. I am fairly clear on the rules governing the spacing of drivers to achieve friendly summing (up to a given frequency limit), however the timing of the arrivals to the ear seem to me to be an uncorrectable artefact in general terms, suggesting that a single driver speaker should always have a superior transient response compared with a plurality of sources, other things being equal.

Am I missing something here or is it simply that Dr. Haas is hard at work in the spectacular sound processing unit which is our brains? Your comments please.

Stay safe, Carl.
 

Caleb Dueck

Junior
Jan 11, 2011
504
5
18
Montana
No white paper links, but would comment that this varies with frequency, as we're dealing with simple delay offset times rather than phase shift. IE - a 1ms physical offset in time could have a negligible affect at 50Hz vs 10kHz.

I too would like to see impulse responses from, say, a full line array hang vs a Danley Jericho.
 
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Peter Morris

Senior
May 8, 2011
1,009
98
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Australia
Something that behaves as a point source with the appropriate directivity for the space its in will always sound the best. As you flatten phase response it will sound more real and the stereo image will have more depth. We can hear very small time arrival differences, that's how we can determine where things are located in space.

The trick is being able to combine multiple drivers to cover the required frequency range and SPL needed. In this respect I think Danley has done better than anyone if you need something that goes loud.

The next trick is being able to get multiple reasonable size/weight boxes (e.g. <100kgs) to combine in a scalable fashion and get good results. This is where the line array comes in; early attempts were OK but some of the new designs are much much better.

They don’t sound as good as a point source but they offer flexibility and scalability in a reasonable size enclosure … pick your compromise.

Danley don’t really offer this scalability.

The spacing rules are not as simple as some think. The drivers do not behave as a pure point source. They are more of a plane source and if you can cover about 82% of the radiating area/line with a rigid diaphragm and get the diaphragms close enough then all is good … but you can’t get that much area coverage with a round diaphragm.

Some of the elements are horn loaded where the shape of the wave front coming from the horn is important and the distance the mouths are apart becomes critical not the spacing of the compression drivers.

Then you may need to control what happens at the top and bottom of the array … and … and …
 
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Jan 19, 2011
915
32
28
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Oslo, Norway, Norway
drbentsen.no
Something that behaves as a point source with the appropriate directivity for the space its in will always sound the best. As you flatten phase response it will sound more real and the stereo image will have more depth. We can hear very small time arrival differences, that's how we can determine where things are located in space.

The trick is being able to combine multiple drivers to cover the required frequency range and SPL needed. In this respect I think Danley has done better than anyone if you need something that goes loud.

The next trick is being able to get multiple reasonable size/weight boxes (e.g. <100kgs) to combine in a scalable fashion and get good results. This is where the line array comes in; early attempts were OK but some of the new designs are much much better.

They don’t sound as good as a point source but they offer flexibility and scalability in a reasonable size enclosure … pick your compromise.

Danley don’t really offer this scalability.

The spacing rules are not as simple as some think. The drivers do not behave as a pure point source. They are more of a plane source and if you can cover about 82% of the radiating area/line with a rigid diaphragm and get the diaphragms close enough then all is good … but you can’t get that much area coverage with a round diaphragm.

Some of the elements are horn loaded where the shape of the wave front coming from the horn is important and the distance the mouths are apart becomes critical not the spacing of the compression drivers.

Then you may need to control what happens at the top and bottom of the array … and … and …

All of this leads me to believe you'll end up with two approaches in the long run:

- High quality point sources.
- Steerable arrays like EAW Adaptive.

Just the ease of rigging, weight savings and small footprint points towards a box like EAW Anna for a lot of show sizes. I really like that PA and enjoy deploying/mixing on it every time I'm lucky enough to get the opportunity.
 
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Douglas R. Allen

Sophomore
Jan 11, 2011
230
1
18
Maine USA
KV2 Audio has worked on point source for some time now. Their new VHD5 looks interesting. I always thought a round array , much like the VHD5 would be interesting. A horn in the center circled by the midrange drivers circled by low frequency drivers. Sort of like what Danley does with some of his horns that have slots that load into the horn. Now that high power amps and DSP processing is the norm point source arrays may be on the return. A single array like the VHD5 should be less to transport and deploy as well which would save money which as we all know always ends up the driving factor in sound systems. https://www.kv2audio.com/products/vhd5.html