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
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
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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).
...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.
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
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.
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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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
Attachments
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
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
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Dipole needs some symmetry - a *single* compression driver is possibly not the best choice to do so...
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-3.html#post1996185
removing the back cup of a compression driver may yield other positive effects too – we've been through that some pages back...
Michael
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Hello Michael
What is wrong with Earls waveguide?? What's wrong with the PT Waveguides JBL uses?? I don't understand the importance you are putting on minimum phase?? Either Earls waveguide or the PT's are a step in the right direction. The only experience I have are with the PT Waveguides. There is no question they sound better than the average 80's vintage diffraction horns. I would hazard to guess Earls waveguides sound better as well.
CD horns are not an Ancient concept and compared to compression drivers are actually new kids on the block. That all started at EV in the late 70's early 80's.
What is a minimum phase contour?? If I look at the PT's I use they look fine as far as minimum phase is concerned. So does the Exponential 2307 Horn I posted previously. The real audible differences between the two is that one is CD and the other is not. I don't see where MP comes into this.
Rob
Hi Rob,
Regarding my naming of "Min Phase" horn contour I can't explain any better as already did – its putting emphasis on the benefits we can have from the concept of "min phase" in audio – when understood and done right – meaning we have to be after a smooth and consistent sound field that tracks in frequency response over an as wide as possible bandwidth and room angle.
I can't put JBL's PT horns into perspective as I have no experience whatsoever with these – I only could guess that there are strong mouth reflections going on as its basically a cut conical at this point. (probably you can point me to polar measurements?)
Some pretty enlightening simus for this case I've shown some pages back in Earl's thread – accurately confirming what people have measured ~ 100 years ago.
As for Earl's attempts, I'd like to outline that to a great degree its been his preaching of the importance of directivity control that made me aware of how important this topic actually is.
So – as much as we seem to be in conflict with each other – there *is* a basis where we are in full accordance and I'm even thankfully that he called my attention there.
What exactly is wrong with oblate spheroid contour (besides "lowest diffraction" theory behind )?
Actually IMO it's pretty well performing in the CD context but there is a severe dis-consistency in the sound field it produces (on-axis somewhere at ~4kHz IIRC).
I have show simus in Earls thread that are confirmed by his own measurements he courtesy sent me for CSD analysis – also shown by me some pages back .
The issue here (and possibly in my Manazita quasi min phase dipole horn) is the same as I've outlined for the PT horn – just less pronounced as Earl tries to minime mouth reflection by a arbitrary round over (I've shown simus how much different round over's help in his thread also some pages back).
Sadly we have not seen yet measurements of the huge Min Phase horn of the DIY show in Gelsenkirchen – nor have we seen measurements yet from what I found to be even more promising Min Phase horn simus from soongsc.
Hey soongsc ! – any news on that ones?
Michael
Regarding my naming of "Min Phase" horn contour I can't explain any better as already did – its putting emphasis on the benefits we can have from the concept of "min phase" in audio – when understood and done right – meaning we have to be after a smooth and consistent sound field that tracks in frequency response over an as wide as possible bandwidth and room angle.
I can't put JBL's PT horns into perspective as I have no experience whatsoever with these – I only could guess that there are strong mouth reflections going on as its basically a cut conical at this point. (probably you can point me to polar measurements?)
Some pretty enlightening simus for this case I've shown some pages back in Earl's thread – accurately confirming what people have measured ~ 100 years ago.
As for Earl's attempts, I'd like to outline that to a great degree its been his preaching of the importance of directivity control that made me aware of how important this topic actually is.
So – as much as we seem to be in conflict with each other – there *is* a basis where we are in full accordance and I'm even thankfully that he called my attention there.
What exactly is wrong with oblate spheroid contour (besides "lowest diffraction" theory behind
)?Actually IMO it's pretty well performing in the CD context but there is a severe dis-consistency in the sound field it produces (on-axis somewhere at ~4kHz IIRC).
I have show simus in Earls thread that are confirmed by his own measurements he courtesy sent me for CSD analysis – also shown by me some pages back .
The issue here (and possibly in my Manazita quasi min phase dipole horn) is the same as I've outlined for the PT horn – just less pronounced as Earl tries to minime mouth reflection by a arbitrary round over (I've shown simus how much different round over's help in his thread also some pages back).
Sadly we have not seen yet measurements of the huge Min Phase horn of the DIY show in Gelsenkirchen – nor have we seen measurements yet from what I found to be even more promising Min Phase horn simus from soongsc.
Hey soongsc ! – any news on that ones?
Michael
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I'm not sure which you are talking about. I have already posted data on four designs, and do not intend to post any more until someone else matches that number. Quoting data from others don't count.
I second that.
An externally hosted image should be here but it was not working when we last tested it.
taken from:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-66.html#post1916139
Have you posted measurements for the upper one? - I must have missed it - could you please point me there ?
Showing simus only "does not count"
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I give up on trying to explain / justify that one - gonna take some English lessons ....
Michael
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Those are just part of analysis of a new design, which also depends on a new driver. There is no firm date for that driver yet.An externally hosted image should be here but it was not working when we last tested it.
taken from:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-66.html#post1916139
Have you posted measurements for the upper one? - I must have missed it - could you please point me there ?
Showing simus only "does not count"
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Summary is here, but you would have to dig through the thread to recall the details.
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-320.html#post1887771
Kidding - eh ?
Don't think I would have missed *any* measurements form you in this thread connected to the topic at hand
Michael