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Old 18th October 2012, 07:04 PM   #501
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Originally Posted by keyser View Post
Thanks David,

What do you think about the multi-sub approach and sound-transmission to the neighbors? In comparison to a single sub, multiple subs in general radiate more sound power for a given level at the listening position, so you might say there will be more transmission. On the other hand the extra power is used to cancel modes.
Thats kind of back to the previous question. If SPL next door is related to sound power, then you want to do anything that gives you more pressure at the listener location with less total radiated power. I wold have thought that more subs would go in the direction of increasing SPL faster than power?

If 2 subs give you +6dB SPL but only +3 PWL, then thats a help. If you can have subs closer to you and increase your listening position SPL (hence you can turn down the subs a little) thats a help too.

With room modes being what they are, I don't know why nearfield subs isn't discussed.

David S.

Last edited by speaker dave; 18th October 2012 at 07:06 PM.
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Old 18th October 2012, 07:16 PM   #502
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If you can have subs closer to you and increase your listening position SPL (hence you can turn down the subs a little) thats a help too.
I took numerous measurements today and found that a near field sub needs about 10dB less power to produce the same SPL as a "far field" sub. That's quite a welcome difference.

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With room modes being what they are, I don't know why nearfield subs isn't discussed.
Weird, isn't it. It's the cheapest, most effective solution for really good bass reproduction, especially in rooms with rigid walls. That kind of quality is usually only available from purpose-built listening rooms.
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Old 18th October 2012, 07:18 PM   #503
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Yes. Maybe not in yours but it is in mine.

This is also what Griesinger explains about bass externalisation, as without interaural fluctuations there will be inside the head locatedness.

Apparently there is no fluctuations in the nearfield bass since the sound remain inside my head.
I've been reading a couple of room/bass related papers by Griesinger and they are very eye opeing.

http://www.davidgriesinger.com/asa05.pdf

"the placement that is optimal for spatial properties might be different than a speaker placement that is optimal for low frequency response smoothness."

His arguement is that flat pressure in the room won't guarantee good LF sound, that LF spaciousness is desirable and it comes from lateral velocity (differential pressure between the ears). Being in the right position relative to the modes can achieve this.

Worth thinking about.

David S.
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Old 18th October 2012, 07:24 PM   #504
Elias is offline Elias  Finland
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Single mono dipole? Orientation? What EQ settings did you apply?



Of course not and as I already said, I don't get in-head localization like you do. All I get is deep, clean, tight, fast, articulated, ultra-smooth bass - best signal modulation reproduction

Maybe you're running the sub too high? Or it produces too much noise/distortion.
Didn't you find the smoothness of the frequency response quite enjoyable?

Single mono dipole, main axis towards the head, symmetrically to median plane. EQ was to compensate for the dipole loss. The elelement was 12" Peerless XLS. Low pass between 70-100 Hz, 4th order LR.

Sure the freq response is good as it is with head phones, but just on the wrong side of the skull..
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Old 18th October 2012, 07:31 PM   #505
Elias is offline Elias  Finland
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Originally Posted by markus76 View Post
I took numerous measurements today and found that a near field sub needs about 10dB less power to produce the same SPL as a "far field" sub. That's quite a welcome difference.



Weird, isn't it. It's the cheapest, most effective solution for really good bass reproduction, especially in rooms with rigid walls. That kind of quality is usually only available from purpose-built listening rooms.

Nearfield certainly reduces the effort to achieve SPL, but it comes with too heavy other penalties like you have to bolt your head to the chair.

I like to listen in various locations in my room. This is why I went for the my single speaker stereo in the first place.


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Old 18th October 2012, 07:34 PM   #506
keyser is offline keyser  Netherlands
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Originally Posted by speaker dave View Post
Thats kind of back to the previous question. If SPL next door is related to sound power, then you want to do anything that gives you more pressure at the listener location with less total radiated power. I wold have thought that more subs would go in the direction of increasing SPL faster than power?

If 2 subs give you +6dB SPL but only +3 PWL, then thats a help. If you can have subs closer to you and increase your listening position SPL (hence you can turn down the subs a little) thats a help too.

With room modes being what they are, I don't know why nearfield subs isn't discussed.

David S.
Actually, I was thinking about how multiple subs can be used to cancel modes, which actually leads to a decrease in overall sound level at the lowest frequencies. So, more power is radiated, but standing waves are diminished. This means that also at the room-boundaries there'll be less severe peaks in pressure.
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Old 18th October 2012, 07:35 PM   #507
Elias is offline Elias  Finland
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Originally Posted by speaker dave View Post
I've been reading a couple of room/bass related papers by Griesinger and they are very eye opeing.

...


His arguement is that flat pressure in the room won't guarantee good LF sound
That is what I've been saying all the time from the beginning of this thread 3 years ago


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Last edited by Elias; 18th October 2012 at 07:38 PM.
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Old 18th October 2012, 07:41 PM   #508
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For bass perception body is needed more than ears. And since bass without higher frequencies does not exist in nature it has to be phase coherent. I have subwoofer historically behind my left shoulder, like 3 meters from the seating position is opening in the floor, and despite it works below 40 Hz it is annoying to feel that it fires from the rear left corner. Also since cones generate distortions it is audible.
I don't know, probably in smaller room it would be inaudible, I never tried.
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Old 18th October 2012, 08:05 PM   #509
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Originally Posted by Elias View Post
Single mono dipole, main axis towards the head, symmetrically to median plane. EQ was to compensate for the dipole loss. The elelement was 12" Peerless XLS. Low pass between 70-100 Hz, 4th order LR.

Sure the freq response is good as it is with head phones, but just on the wrong side of the skull..
Griesinger's quote:

"Reproduced sound in a small room lacks this living quality. Often low frequencies are not perceived as external, but inside the head. This is because the low frequencies lack any pressure gradient; the interaural time delay is zero, and remains zero when the head is rotated. Not knowing how to localize these sounds, we perceive them as internal."


It's odd, but I've never experienced this. In fact, after informally testing a fairly wide group of people, I can't remember a single person making a similar comment.

For me, those I've tested, and presumably Markus - the result isn't "in head" but rather indistinct and "in room".

Example (..one of the better DIY'ed designs presented/recorded on youtube):

DIY Speakers ( ScanSpeak+SBAcoustics+B&G) - YouTube

Everything except the bass guitar (and a lower freq. drum) has some localization feature (to me). The bass guitar (and lower freq. drum) however is just "plummy" and indistinct and is associated within the listening room, NOT my "head". Of course this is a recording of a stereo reproduction (..you can't "remove" the effects of the room perceptually, or at least I can't), and therefor it isn't quite the same as if you were in the room listening to it. Still, that's pretty much the same effect that I get with most NON-dipole/cardiod setups.
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Old 18th October 2012, 08:23 PM   #510
Elias is offline Elias  Finland
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Originally Posted by ScottG View Post
Griesinger's quote:

"Reproduced sound in a small room lacks this living quality. Often low frequencies are not perceived as external, but inside the head. This is because the low frequencies lack any pressure gradient; the interaural time delay is zero, and remains zero when the head is rotated. Not knowing how to localize these sounds, we perceive them as internal."


It's odd, but I've never experienced this. In fact, after informally testing a fairly wide group of people, I can't remember a single person making a similar comment.
I think it is rarely mentioned because people do not know to pay attention to it.

Griesinger may well be ahead of his own time Maybe like after 20 years from now it will taken seriously..
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