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-   -   Nearfield sub response (http://www.diyaudio.com/forums/subwoofers/229583-nearfield-sub-response.html)

454Casull 8th February 2013 03:04 AM

Nearfield sub response
 
Markus Mehlau posted an article on his site showing that the response at the listening position was extremely good for subs placed close to the listening position.

Comparison of different near field and far field subwoofer configurations

dantheman was not able to reproduce his results.

audio blog: Dry (fast) Bass...

Does anybody have an idea of what's happening here?

weltersys 8th February 2013 10:54 PM

Different rooms, different subs in different locations, different test systems = different results.

454Casull 9th February 2013 01:48 AM

So there is no causation in nearfield subs = smoother response?

sreten 9th February 2013 02:41 AM

Hi,

Near or far field has no real effect on interaction with room modes.

The shape of the room, the listening position and placement of
the subs affects the perceived response, its probably fair to
say there is no such thing as nearfield and farfield for subs.

rgds, sreten.

head_unit 10th February 2013 03:51 AM

"Nearfield" has a very specific definition from (IIRC) JBL's Mark Gander, a quite nice guy who wrote the paper describing the concept.

"Nearfield" means you are so close to the subwoofer that the environment is not affecting the sound pressure.* As a corollary, if you moved a measurement microphone back and forth a tiny amount, the sound pressure would not change. It means you are almost touching the woofer cone.

Bill Basore at Q-Logic once did a demo at CES where they had a subwoofer right smack behind a car seat. You didn't hear much in the room, but sitting in the seat you had firm smooth bass.

So if you could put the subwoofer next to your head, you could get amazing results. Once your ears get some little distance away, you're not in the near field, and "your mileage may vary."


*Well, the environment's loading can affect the raw response of the woofer. But "near field" implies the sound has not had any chance to spread out, so neither room modes nor dispersion are not changing the raw SPL the woofer emits.

markus76 10th February 2013 07:59 AM

Quote:

Originally Posted by 454Casull (Post 3360613)
Does anybody have an idea of what's happening here?

Dan's subs were too far away (1m). Please see http://www.geddes-audio.com/forum/sh...ld-results-but...

markus76 10th February 2013 08:03 AM

Quote:

Originally Posted by sreten (Post 3362098)
Hi,

Near or far field has no real effect on interaction with room modes.

The shape of the room, the listening position and placement of
the subs affects the perceived response, its probably fair to
say there is no such thing as nearfield and farfield for subs.

rgds, sreten.

Get out your measuring gear. You'll find that in the near field there's virtually no room interaction.

markus76 10th February 2013 08:10 AM

Quote:

Originally Posted by head_unit (Post 3363516)
"Nearfield" has a very specific definition from (IIRC) JBL's Mark Gander, a quite nice guy who wrote the paper describing the concept.

I wasn't aware such a paper exists. Do you have more information about it?

badman 13th February 2014 08:21 PM

I implemented nearfield subs last night- they're monopoles placed immediately behind either end of the sofa, with the 12" about 12" from the back of the heads on either end of the sofa. The passive radiators (14Hz tuning) are at floor level.

So far I like it but there's more tuning to do. I had to run 50ft cables and use isolation transformers to kill grounding buzz from the subamp being on a different outlet than the main system.

I will say that it does seem quieter for a given SPL (at listening position), and seems more intelligible than previous setups.

markus76 13th February 2014 08:37 PM

^
Don't use ported subs. This will give unpredictable results when listening so close. Especially when the port is far away.


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