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Old 11th December 2009, 03:09 PM   #6501
mige0 is offline mige0  Austria
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directivity control – in old school thinking – is driven by and aimed towards audience coverage.
directivity control as I use it is driven by and aimed towards optimisation of advanced equalisation.

Two veeery different starting points yielding the same results.
Same as for waveguides – they are simply (CD) horns too.
Same as for "Min Phase" horns - they are simply (CD) horns too

The development is : what's the basic idea behind (and how far could we possibly come)?


Michael

Last edited by mige0; 11th December 2009 at 03:16 PM.
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Old 11th December 2009, 03:20 PM   #6502
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Michael, is that supposed to "speech" instead of "speach"?
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Old 11th December 2009, 04:32 PM   #6503
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Originally Posted by mige0 View Post
Yes this is the paramount point you were teaching us.

The pointe behind min phase that I see is that the way you looked at this in audio was the starting point to look at advanced equalization as a possibility to come to close to ideal behavior over a wide room angle (response shaping at will).

Hence I have choosen "Min Phase" horn rather than "Michael Gerstgrasser" horn - together with what I see unique as my "diffraction alignment" concept for horn contours in general I think its a justification to establish a "new" name.

Michael
You seem to be mincing words to me. Directivity control is, and as far as I know, always has been about getting uniformity of response over a specific listening window. Minimum phase playes little roll. The consequences of whether or not the response is MP will only impact whether or not MP eq will correct time and amplitude response as opposed to only time response. But to correct time and amplitude response over a wide window the response must be constant over that window, MP or not. When I say "response" I mean amplitude and phase (with the exception of a spacially varing delay).
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Old 11th December 2009, 06:44 PM   #6504
mige0 is offline mige0  Austria
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...could not find out what you exactly mean with "mincing" - just hope, I didn't offend you in any way.

Might be I'm wrong - but as I see "directivity control" - its a old concept to describe what you outline.
On the other hand "directivity" is poorly defined and also it is a concept from the days where audience coverage was top on list. No body in these days I assume to have thought about advanced equalisation (response shaping at will).

Sure - in the end we may come to more or less the same solutions - as said - CD in one way or another - but its worth to note that there is a veeery different point of origin and way of thinking about very basic design issues.

This is what I mean when I consider "diffraction alignment" and subsequent "Min Phase" horns as part of a new paradigm in audio design.


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Originally Posted by john k... View Post
Minimum phase playes little roll. The consequences of whether or not the response is MP will only impact whether or not MP eq will correct time and amplitude response as opposed to only time response. But to correct time and amplitude response over a wide window the response must be constant over that window, MP or not. ...
I can not see where we are in disagreement - are we?
I do not relay *only* on MP but also on CD. Diffraction alignment is the powerful tool at hand


Michael

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Old 11th December 2009, 07:45 PM   #6505
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I do not relay *only* on MP but also on CD.

Michael

Just what do you see as the roll of MP?
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Old 11th December 2009, 09:25 PM   #6506
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I do not relay *only* on MP but also on CD.
Any horn that measures reasonably flat in it's bandwith will be "MP". Doesn't matter what type of horn it is. Here is a JBL 2307 Exponential, about as far away from CD as you can get. Depends of the directivity to EQ on axis response. On axis response and GD ploted using CLIO Excess Phase, time of flight, removed.

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Old 11th December 2009, 10:33 PM   #6507
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I have never heard a compression driver with its rear chamber removed to allow the generation of dipole radiation. Has anyone researched dipole compression drivers, or listened to speakers with them?

Would the same CD waveguide loading be used on both the front and rear side of the dome?
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Old 11th December 2009, 10:35 PM   #6508
mige0 is offline mige0  Austria
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Originally Posted by john k... View Post
Just what do you see as the roll of MP?
it makes a speaker's performance accessible – almost fully mouldable - by equalisation (IR FR CSD – not so regarding distortion).
Why you ask ? – after all its been you who had a hard time to make that point clear?

I'm aware we not have to *make* a speaker "min phase", though – the "honouring" of the term "min phase" as I use it in combination with horns that perform well in the context I described is to stay clear that its a basic fact these designs rely on.

When I became clear about that fact its been *my* paramount turning point.

You might say "Min Phase" horn is kinda pleonasm – I agree - but on the other hand its of such importance and not at all clear or accepted by anybody (as you remember right from Earl – easily to look up some pages back ) - I simply found it the best naming

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Originally Posted by Robh3606 View Post
Any horn that measures reasonably flat in it's bandwith will be "MP". Doesn't matter what type of horn it is. Here is a JBL 2307 Exponential, about as far away from CD as you can get. Depends of the directivity to EQ on axis response. On axis response and GD ploted using CLIO Excess Phase, time of flight, removed.

Rob
Yeah – but what *if* we finally come to a "min phase horn" contour that combines CD with a "smooth and consistent" sound field over a useful bandwidth?

Then add some appropriate equalization - and there we are....

Neither usual (ancient) CD concepts nor Earls oblate sheroide actually do that for us and Jean-Michel's contours actually having "smooth and consistent" sound field sadly ain't any close to CD.

Non was actually *intended* to act as "min phase horns" nor where the tools easily available until now nor has the underlying philosophy been framed...


Michael

Last edited by mige0; 11th December 2009 at 10:53 PM.
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Old 11th December 2009, 10:42 PM   #6509
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I could be remembering wrong...

Doesn't GR Research and Bastianis remove the rear chamber on their compression drivers?
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Old 11th December 2009, 11:02 PM   #6510
mige0 is offline mige0  Austria
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Originally Posted by LineSource View Post
I have never heard a compression driver with its rear chamber removed to allow the generation of dipole radiation. Has anyone researched dipole compression drivers, or listened to speakers with them?

Would the same CD waveguide loading be used on both the front and rear side of the dome?
Dipole needs some symmetry - a *single* compression driver is possibly not the best choice to do so...

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removing the back cup of a compression driver may yield other positive effects too – we've been through that some pages back...

Michael

Last edited by mige0; 11th December 2009 at 11:08 PM.
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