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Old 3rd September 2012, 06:01 PM   #1661
el`Ol is offline el`Ol  Germany
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Originally Posted by graaf View Post
of course they have
Bose direct/reflecting is an entirely different thing, with purely pseudoscientific, quite absurd "theory" behind it
The BOSE 901 is placed about a half meter away from the wall, eight drivers facing the wall, four speakers tilted ~30 inwards, four drivers ~30 outwards. When the name Bose is mentioned there is nothing else than bashing, even that A.B. has invented something mustn't be said.
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Old 3rd September 2012, 07:16 PM   #1662
Colin is offline Colin  United Kingdom
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Originally Posted by midrange View Post
On the subject of ideas from the 70s does anyone remember an Alison?
Yes, I remember those. John Cockcroft had some dotty TL designs in Speaker Builder magazine which referenced them.

Here's an interview with Roy Allison from 2010

Roy F. Allison Interview | Hi-Fi


and a Stereophile interview which talks more about room boundary effects

A Glorious Time: AR's Edgar Villchur and Roy Allison Allison Part 1 | Stereophile.com
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Old 3rd September 2012, 07:22 PM   #1663
Colin is offline Colin  United Kingdom
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Actually Bose and Allison's designs are discussed on p2 of the first interview

Page 2 | Roy F. Allison Interview | Hi-Fi
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Old 4th September 2012, 07:43 AM   #1664
graaf is offline graaf  Poland
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Originally Posted by el`Ol View Post
The BOSE 901 is placed about a half meter away from the wall, eight drivers facing the wall, four speakers tilted ~30 inwards, four drivers ~30 outwards. When the name Bose is mentioned there is nothing else than bashing, even that A.B. has invented something mustn't be said.
all I say is that theory of the "ideal" direct:reflected ratio of 8:1 is completely unscientific and that even from that theory it doesn't follow that You can realize that "ideal" in home hifi by using one speaker firing in the direction of the listener and 8 firing back and sideways into the walls as in Bose 901

this is all that I say, is it really "bashing"?
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Old 4th September 2012, 10:30 AM   #1665
Colin is offline Colin  United Kingdom
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The logic of the Bose system was somewhat flawed (it's adding room reflection to the reflected sounds from the concert hall) but some people I know heard it and liked the effect. I've heard smaller Bose systems and thought they sounded fine for their intended, non-purist market.

The Jimmy Hughes ideas may be more specific to his type of speakers. The commercial Impulse design grew from the Lecson HL1 from the 70s. That had a mid horn from 400Hz and a treble horn above that. The original WW design, from which the Lecson was derived, had only one horn from 400Hz to cover mid and treble. The treble horn was added to make it sound better in showrooms (according to one of their major retailers with whom I corresponded at the time).

The Impulse has horn plus a dome tweeter, AFAIK. I'm not sure the same reflecting technique would necessarily work with all other types of designs, particularly if they had a broader spread of sound.

I'm sure reflector systems can be made to work - I heard an experimental one recently which sounded very good - but it may depend heavily on speaker/room combination.
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Old 4th September 2012, 12:56 PM   #1666
el`Ol is offline el`Ol  Germany
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this is all that I say, is it really "bashing"?
You said it's an entirely different thing, IMHO it's basically the same.
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Old 4th September 2012, 01:20 PM   #1667
graaf is offline graaf  Poland
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Originally Posted by el`Ol View Post
You said it's an entirely different thing, IMHO it's basically the same.
as I understand the speakers that Jimmy Hughes' used in his setup were some highly directional horn designs so when one directs such speakers towards the back wall then basically what one hears (in the frequency band critical for spatial hearing) is just reflection off the back wall whereas with Bose 901 we have both full range direct sound which reaches the listener first and then a lot of reflections which generally come from behind the speaker

for me those two approaches are rather different but perhaps I am wrong
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Old 4th September 2012, 01:24 PM   #1668
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Originally Posted by graaf View Post
all I say is that theory of the "ideal" direct:reflected ratio of 8:1 is completely unscientific
Look up the chapter about the Klippel experiments in Toole's "Sound Reproduction". From his experiments, a diffuse field of +3 to +5 dB (relative to direct SPL) was preferred by listeners, depending on the type of signal.

The problem that remains is that reverberant sound in typical listening rooms is not really diffuse, so it could very well be dependant on room size, acoustics. It might be more useful to measure the level of early reflections. Who can say?
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Old 4th September 2012, 02:41 PM   #1669
6.283 is offline 6.283  Germany
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The problem that remains is that reverberant sound in typical listening rooms is not really diffuse, so it could very well be dependant on room size, acoustics. It might be more useful to measure the level of early reflections. Who can say?
In my room with an estimated critical distance of ~90cm (Omni) and a listening distance at 1.8m or a bit less it just works fine although the soundfield is not really diffuse. And you can easily hear when you are too far out in the room.
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Old 4th September 2012, 09:03 PM   #1670
graaf is offline graaf  Poland
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Look up the chapter about the Klippel experiments in Toole's "Sound Reproduction". From his experiments, a diffuse field of +3 to +5 dB (relative to direct SPL) was preferred by listeners, depending on the type of signal.
yes, +5 dB for music

Quote:
Originally Posted by a_tewinkel View Post
The problem that remains is that reverberant sound in typical listening rooms is not really diffuse, so it could very well be dependant on room size, acoustics. It might be more useful to measure the level of early reflections. Who can say?
no problem - Klippel results are valid for typical listening rooms - exactly therefore Toole refers to him, it is because "diffuse" in this context means just "reverberant" or even "reflected" as it becomes clear when Toole concludes (page 459) about: "a requirement for a 3 to 5 dB difference between the reflected and direct sound fields"
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