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Old 22nd April 2013, 12:37 AM   #2171
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Quote:
Originally Posted by markus76 View Post
I believe that approach radiates too much energy into the room.
I had always thought that the purpose of a speaker was to radiate energy into the room.
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Old 22nd April 2013, 06:59 AM   #2172
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Quote:
Originally Posted by Elias View Post
But CBT is no flooder, it has vertical beamwidth of only about +-22 degrees. It will not illuminate the ceiling in typical home listening room to provide a strong enough ceiling reflection to lift the image from the floor.
yes indeed and what follows from that fact proves my point exactly!

You might ask how so?

here is how:


Quote:
Originally Posted by Elias View Post
How do we know that ? Maybe it is coming from the floor
contrary to any "theoretical" expectations I know of no single report of any sound coming from the floor phenomenon with CBTs

why? to answer that it suffices to answer to Your question:

Quote:
Originally Posted by Elias View Post
Then how is CBT different in perceptual sense ?
one important thing is perceptually absent - the floor reflection

and this seems to confirm that I was right about the causes of the low image in case of Snell Type One - it wasn't the problem of "too much of the direct sound", it was the problem of the floor reflection of the midwoofer sound
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Last edited by graaf; 22nd April 2013 at 07:09 AM.
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Old 22nd April 2013, 12:55 PM   #2173
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Originally Posted by Don Hills View Post
I had always thought that the purpose of a speaker was to radiate energy into the room.
Sure but not into angles that only increase the level of the indirect field without adding anything beneficial (like increased spaciousness). A reflection free zone and low masking level isn't easy to achieve in a small room.
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Old 22nd April 2013, 02:43 PM   #2174
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Quote:
Originally Posted by graaf View Post
and this seems to confirm that I was right about the causes of the low image in case of Snell Type One - it wasn't the problem of "too much of the direct sound", it was the problem of the floor reflection of the midwoofer sound
I don't think so, since the proposal to correct the too low image was to raise the tweeters at the ear level.
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Old 23rd April 2013, 09:38 AM   #2175
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Quote:
Originally Posted by Elias View Post
I don't think so, since the proposal to correct the too low image was to raise the tweeters at the ear level.
but raising the tweeters at the ear level introduces a new elevation cue, absent before, and which is strong enough to override any cues from midwoofer and lower frequencies

the problem of the original Snell Type One was that the only elevation cue created by the speaker configuration resulted from the midwoofer sound floor reflection
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Old 23rd April 2013, 11:46 AM   #2176
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Originally Posted by graaf View Post
the problem of the original Snell Type One was that the only elevation cue created by the speaker configuration resulted from the midwoofer sound floor reflection
while in the flooder approach speaker configuration creates no elevation cues of itself, therefore only those elevation cues that are preserved in the recording are audible

ps. and it creates no distance cues of itself either
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Last edited by graaf; 23rd April 2013 at 11:56 AM.
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Old 25th April 2013, 07:23 AM   #2177
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Elias, have You tried up-firing speakers with the direct sound blocked ie. virtual ceiling speakers?
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Old 25th April 2013, 11:39 AM   #2178
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Originally Posted by graaf View Post
while in the flooder approach speaker configuration creates no elevation cues of itself, therefore only those elevation cues that are preserved in the recording are audible

ps. and it creates no distance cues of itself either
Sound wavefront emanating from a point located at the floor is an elevation cue essentially -> the sound is coming from the floor. HRTF will reveal that.

By blocking the direct sound and having a strong ceiling reflection lifts the image upwards towards ceiling. Again HRTF.

There must be a fine balance of floor and ceiling reflected sound, and propably direct sound too, in order to have image at realistic elevation somewhere in the vertical middle.

If there are multible almost simultaneous reflections from floor and ceiling (and walls), HRTF elevation cues does not seem to work but image is a huge and tall cloud. It seems that in order to have only elevation cues of the recording audible, we would need to eliminate room contribution.


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Old 25th April 2013, 12:14 PM   #2179
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Quote:
Originally Posted by Elias View Post
Sound wavefront emanating from a point located at the floor is an elevation cue essentially -> the sound is coming from the floor. HRTF will reveal that.

By blocking the direct sound and having a strong ceiling reflection lifts the image upwards towards ceiling. Again HRTF.

There must be a fine balance of floor and ceiling reflected sound, and propably direct sound too, in order to have image at realistic elevation somewhere in the vertical middle.
You said that:

In my monoflooder test the speaker was facing the ceiling. In that case I could not locate the speaker.

Then I tried to turn the speaker facing the listening area, and immediately the speaker was localisable or the sound was coming from the floor.


Have You considered what happened exactly when You turned the speaker towards the listening area?

because You said that:

It was a normal 2-way 12 l box with 1" dome tweeter and 6.5" bass.

so do You really think that what changed after You had turned it towards the listening area was the "fine balance of floor and ceiling reflected sound, and propably direct sound too"?

Could be this fairly typical two-way speaker with 1" dome tweeter that You used for Your test so atypically directional?
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Old 25th April 2013, 12:20 PM   #2180
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[reposted]

interesting discussion:
A round table about room acoustics, and bass traps.

Mr Peter Lyngdorf:

Quote:
I’ve done a lot of testing on the effects of reflections in rooms, and there was a big, big project in Denmark about twelve years ago, with a lot of companies involved in investigating effects of reflections in rooms. I had the pleasure of being a test person, where we could actually simulate the audible effect of the floor reflection, sidewall reflection, ceiling reflection, and so on independently. The single most disturbing reflection in the room is the floor reflection. That is what makes the speaker sound like a radio and not like the actual event. ... The floor reflection absolutely must be handled
it was I believe the Archimedes project led by Bech

floor reflection

floor reflection

floor reflection
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Last edited by graaf; 25th April 2013 at 12:23 PM.
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