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Old 17th February 2010, 11:01 PM   #451
Pano is offline Pano  United States
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graaf & markus. Keep on topic please. No personal arguments.
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Old 18th February 2010, 07:17 AM   #452
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Quote:
Originally Posted by panomaniac View Post
graaf & markus. Keep on topic please. No personal arguments.
erased quotation from Floyd Toole wasn't "on topic"?

I ask because before typing it in again (I haven't it in digitalized form so I can't just copy and paste) I would like to know whether it violates forum rules

Can I ask Markus whether He tested "Beolab 5" speakers (or just gave them 5 minute listen somewhere) before concluding that they are "one of the worst" or will it be regarded as "personal argument"?

I would just like to know the rules. I desire to obey them.
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Old 18th February 2010, 01:49 PM   #453
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OT posts removed.
You may discuss audio. Personal insults are not allowed. Keep to the audio. If you want to use quotes to insult or provoke another member, those quotes will be erased.
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Old 18th February 2010, 03:14 PM   #454
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Originally Posted by graaf View Post
Can I ask Markus whether He tested "Beolab 5" speakers (or just gave them 5 minute listen somewhere) before concluding that they are "one of the worst" or will it be regarded as "personal argument"?
Looks like you're allowed to ask. I don't know how you define "test" but if someone says "I once heard the Beolab 5" then this is no indication for a (double) blind test but an informal sighted listening session.

I listened to the Beolab 5 at the B&O shop in Munich, Maximilianstrasse. The speakers were set up symmetrically about 50cm from the front wall. I was sitting on a leather couch in about 3m distance. The room opens to a larger space behind the sofa. We closed all windows to minimize noise and calibrated the speakers. I had CDs with me that I'm very familiar with and listened about 45 minutes.
The sound was non-transparent. Very hard to listen through the recording and to follow single instruments. Localization was ambiguous. A huge "cloud" of sound, a creamy soup instead of a minestrone. The bass calibration was disappointing - there were still huge modal peaks, overall bass level was too low and a serious lack of energy below 50Hz (the speaker is advertised "EFFECTIVE FREQUENCY RANGE 20-20,000Hz").
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Old 22nd February 2010, 09:55 AM   #455
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an interesting patent and AES-paper:
Patent US4496021
AES E-Library: Loudspeaker Directionality and the Perception of Reality

what makes it interesting is not so much the "orthospectral tweeter" itself but some statements in the "background of the invention" section - see image attached

those statements seem to give basic theoretical explanation for Linkwitz's "wall effect"
see: ORION++

Quote:
it is a widely held belief that reflections destroy transients and diffuse phantom images. Reflections must be avoided. Yet they are important for energy distribution in the room. This belief has been slowly changing (e.g. Moulton, Toole), but only for lateral reflections. The space behind the speakers has always been suspect for changing the sound unfavorably, and rightfully so. Almost all loudspeakers illuminate this space unevenly and sonically colored. I now also understand why flush mounted speakers sound off-the-wall to me. They completely lack rear wall reflections and thus important spatial cues.

One might postulate that the wall reflection will add a sameness to all sound playback because the listening room acoustics from reflections right close to the loudspeakers get mixed in heavily with the recorded acoustics. The exact opposite is heard. Recordings become more differentiated, the whole range from dead to wet acoustics is clearly perceived.
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Last edited by graaf; 22nd February 2010 at 10:04 AM.
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Old 22nd February 2010, 12:18 PM   #456
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This doesn't explain anything. The influence of reflections is not fully understood. Everybody is guessing and declares his own experience the truth. This dogmatic approach to small room acoustics is most evident in the history of control room design (see Jan Voetmann "50 Years of Sound Control Room Design", AES Convention Paper 7140).

Toole himself asks the right questions in his AES paper "Loudspeakers and Rooms for Sound Reproduction—A Scientific Review". There is strong evidence that number, spectrum, angle, level and delay of single reflections are the key. We just don't know yet what the important properties are and how to measure them.

Best, Markus
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Old 22nd February 2010, 01:13 PM   #457
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Quote:
Originally Posted by markus76 View Post
The influence of reflections is not fully understood. Everybody is guessing and declares his own experience the truth.
(...)
There is strong evidence that number, spectrum, angle, level and delay of single reflections are the key. We just don't know yet what the important properties are and how to measure them.
and from that it follows that various unorthodox approaches discussed in this thread are equally valid than eg. constant directivity waveguides and so on, doesn't it?
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Old 22nd February 2010, 02:00 PM   #458
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In the light of facts only one approach is reasonable: make the sound field in the listening space similar to the sound field of the original, whereas the original is the sound field of the mastering/mixing room. In my opinion only loudspeakers with high, constant directivity will provide such a sound field in domestic listening rooms that don't allow for major room acoustic optimizations.

How the optimal sound field should look like and how recording and mixing techniques would need to adapt is a different discussion.

Best, Markus
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Old 22nd February 2010, 04:02 PM   #459
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But with a constant directivity it is virtually impossible to make the first reflections the same as the direct sound. Since the bass will be omni and the treble directional the bass will always be reflected back at you before the highs and will not be the same spectral balance. An omni will make the reflection times shorter but remains roughly the same spectral balance regardless of which angle is reflected at your ear first.
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Old 22nd February 2010, 04:22 PM   #460
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Wrong, only constant directivity will make the indirekt sound field similar to the direct sound.
Earl describes it in more detail here: http://www.gedlee.com/downloads/directivity.pdf
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