Two questions for all of you that know much better than me this topic.
1. as the impulse reponse (vs. time) can be determine by the FT of the pressure (vs. frequancy) (am I right ?), is it possible to get a spectrogram starting from pressure (vs. frequency) ?
2. if the respinse is yes, is there any esplanation on how to do that ? please don't point me any (closed) tool or some code in Matlab: me, I can use Mathcad and Mathematica (I would like to get the same results using those tools) and I don't fear at all even advanced mathemathics (but I don't want to spend the next two years in studying the topic.
Many thanks
1. as the impulse reponse (vs. time) can be determine by the FT of the pressure (vs. frequancy) (am I right ?), is it possible to get a spectrogram starting from pressure (vs. frequency) ?
2. if the respinse is yes, is there any esplanation on how to do that ? please don't point me any (closed) tool or some code in Matlab: me, I can use Mathcad and Mathematica (I would like to get the same results using those tools) and I don't fear at all even advanced mathemathics (but I don't want to spend the next two years in studying the topic.
Many thanks
Hello,
If you didn't read Earl Geddes post in the "Geddes on waveguide" thread:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-428.html#post2213078
" Makarski at Achen... clearly showed HOMs in action. It was only a few years later that Lidia and I published (although we already had the data) how small time perturbations - like HOM - could be audible well below the point of actually having a notable effect on the polar pattern. And most significantly - that these effects become MORE audible at higher SPLs. Can you say "horn harshness"? - very subtle time delayed echos, that can be quite annoying."
Best regards from Paris, France
Jean-Michel Le Cléac'h
If you didn't read Earl Geddes post in the "Geddes on waveguide" thread:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-428.html#post2213078
" Makarski at Achen... clearly showed HOMs in action. It was only a few years later that Lidia and I published (although we already had the data) how small time perturbations - like HOM - could be audible well below the point of actually having a notable effect on the polar pattern. And most significantly - that these effects become MORE audible at higher SPLs. Can you say "horn harshness"? - very subtle time delayed echos, that can be quite annoying."
Best regards from Paris, France
Jean-Michel Le Cléac'h
The way your phrase this, what is it you are looking for? Sound like you want someone to explain things to the detail of a textbook, yet you don't want the code that could explain the detail.
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Hello,
In the Hornresp thread, in the message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-109.html#post2167471
I proposed to write for the Hornresp software a spectrogram routine inspired by my quasi wavelets routine.
As Hornresp is written in Visual Basic and as we had to keep run time acceptable I had to modified deeply my quasi wavelets routine written in Matlab language. The original gaussian type Fourier window could not be used anymore so I used a simpler window and, with some further optimization the resulting spectrogram brings the same information as the original quasi wavelets graph with very few artifacts due to the used window.
I have to thanks David Mc Bean who accepted to included the routine in Hornresp version 27.00. Read his message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-123.html#post2217011
Hornresp version 27.00 is now downloadable for free at:
Telstra BigBlog -
Best regards from Paris, France
Jean-Michel Le Cléac'h
In the Hornresp thread, in the message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-109.html#post2167471
I proposed to write for the Hornresp software a spectrogram routine inspired by my quasi wavelets routine.
As Hornresp is written in Visual Basic and as we had to keep run time acceptable I had to modified deeply my quasi wavelets routine written in Matlab language. The original gaussian type Fourier window could not be used anymore so I used a simpler window and, with some further optimization the resulting spectrogram brings the same information as the original quasi wavelets graph with very few artifacts due to the used window.
I have to thanks David Mc Bean who accepted to included the routine in Hornresp version 27.00. Read his message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-123.html#post2217011
Hornresp version 27.00 is now downloadable for free at:
Telstra BigBlog -
Best regards from Paris, France
Jean-Michel Le Cléac'h
No honk?
This past weekend I finally got to listen to a full GOTO system.
No foam, no mouth roll-over, no fancy profile but no honk. A very clean system.
However, I did not like the way it was voiced. Too bright, too thin for my taste. So an interesting combination of very clean drivers horns and electronics - with less then optimum tonal balance.
This past weekend I finally got to listen to a full GOTO system.
No foam, no mouth roll-over, no fancy profile but no honk. A very clean system.
However, I did not like the way it was voiced. Too bright, too thin for my taste. So an interesting combination of very clean drivers horns and electronics - with less then optimum tonal balance.
Attachments
It never ceases to amaze me the difference in "personal reference" systems and the generosity of those willing to share their passion. As individual in taste as the engineer / designer that applied their time & resources. Some short notes about the room issues and upstream signal processing would also be appropriate to the listening observations...
Hello Panomaniac,
I used to listen to few Goto systems and I agree that their mid horns and "upper" low-mid horns doesn't have audible honk.
BUT, the Goto horns must be used inside the quite small interval of frequency they were conceived for.
In fact the straight round horns commercialized by Goto were inspired by the Western Electric 11A horn
see:
which inspired also the Vitavox 75"
and other straight horns (Marconi, ...).
One of the reason why those horns cannot be used in a larger interval of frequency is because their profiles were calculated using the (wrong) hypothesis that the wavefronts were plane and orthogonal to the axis.
This is why you find generally those Goto horns + Goto drivers in 4 ways systems (or more like this one: MELAUDIA :: écoute chez Jean-Yves Kerbrat ) .
I like a lot their drivers (even if they measure quite badly) and several of their horns like the "upper" low-mid horns+ drivers, the mid horns and their horn tweeter. But I don't like the "lower" mid-bass horns and bass horns, they have a tuned pipe sound which lead to decays having an exagerated durations with a certain lack of dynamics.
Best regards from Paris, France
Jean-Michel Le Cléac'h
I used to listen to few Goto systems and I agree that their mid horns and "upper" low-mid horns doesn't have audible honk.
BUT, the Goto horns must be used inside the quite small interval of frequency they were conceived for.
In fact the straight round horns commercialized by Goto were inspired by the Western Electric 11A horn
see:
An externally hosted image should be here but it was not working when we last tested it.
which inspired also the Vitavox 75"
An externally hosted image should be here but it was not working when we last tested it.
and other straight horns (Marconi, ...).
One of the reason why those horns cannot be used in a larger interval of frequency is because their profiles were calculated using the (wrong) hypothesis that the wavefronts were plane and orthogonal to the axis.
This is why you find generally those Goto horns + Goto drivers in 4 ways systems (or more like this one: MELAUDIA :: écoute chez Jean-Yves Kerbrat ) .
I like a lot their drivers (even if they measure quite badly) and several of their horns like the "upper" low-mid horns+ drivers, the mid horns and their horn tweeter. But I don't like the "lower" mid-bass horns and bass horns, they have a tuned pipe sound which lead to decays having an exagerated durations with a certain lack of dynamics.
Best regards from Paris, France
Jean-Michel Le Cléac'h
Sure, but I didn't want to hi-jack with electronics.
I heard the system with 2 different triode amps, CD, SACD and phono. Passive crossover. Always the same tonal balance. The room was medium sized with tall ceiling. Old house, 19th century.J-M. Thanks for the photos. Funny, Vitaphone also did an 11-A horn IIRC. It was a smaller version of the W.E. 15A
Hello,
The spectrogram in Hornresp has been improved.
The new calculation runs faster and the quality of the spectrogram is much better due to the use of a new Fourier window equivalent to a gaussian window.
See David McBean's message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-128.html#post2223790
A test spectrogram is attached to this message
Best regards from Paris, France
The spectrogram in Hornresp has been improved.
The new calculation runs faster and the quality of the spectrogram is much better due to the use of a new Fourier window equivalent to a gaussian window.
See David McBean's message:
http://www.diyaudio.com/forums/subwoofers/119854-hornresp-128.html#post2223790
A test spectrogram is attached to this message
Best regards from Paris, France
Attachments
Hello,
The classical "shoot out" of the European Triode Festival was this year 2010 devoted to horns and waveguides.
16 horns were brought by participants to ETF2010 for the contest.
Aside of the official shoot-out I could measure all the 16 horns in the same excellent conditions (a very large room with a very late first reflection).
You may find the link to the report I wrote at the bottom of ETF2010 "shoot out" page on the Triodefestival.com website:
European Triode Festival - ETF 2010 Shootout
A direct link to the report is:
http://forums.melaudia.net/attachment.php?aid=1760
Pictures taken before and during the shoot out can be seen at:
MELAUDIA :: ETF 2010
I think the results of the measurements performed and specially the presentation of the wavelets graph can add some thoughts to the discussion about honkness.
Best regards from Paris
Jean-Michel Le Cléac'h
The classical "shoot out" of the European Triode Festival was this year 2010 devoted to horns and waveguides.
16 horns were brought by participants to ETF2010 for the contest.
Aside of the official shoot-out I could measure all the 16 horns in the same excellent conditions (a very large room with a very late first reflection).
You may find the link to the report I wrote at the bottom of ETF2010 "shoot out" page on the Triodefestival.com website:
European Triode Festival - ETF 2010 Shootout
A direct link to the report is:
http://forums.melaudia.net/attachment.php?aid=1760
Pictures taken before and during the shoot out can be seen at:
MELAUDIA :: ETF 2010
I think the results of the measurements performed and specially the presentation of the wavelets graph can add some thoughts to the discussion about honkness.
Best regards from Paris
Jean-Michel Le Cléac'h
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It's a very interesting document, but I continue to think the impedance measurement is better measurement for highlighted the sound transmission of horn.
For example, I think the distinction of reflected and diffracted waves is ambiguous in terms of sound transmission; it's the same thing on impedance measurement.
"Better" is a funny word, but I rather agree. The impedance measurement will reflect (pun intentional
) a lot of acoustical problems. Those problems don't show up easily in typical frequency response measurements. Cepstral analysis, maybe...Hi,
I designed that system (more or less) for the Goto distributor. I did not hear it as setup at the show or with the show electronics so whatever effects the room and electronics had on the sound I can't say, but yeah, the tonal balance was a bit on the bright side. I got it to the point where I thought it was subjectively flat in-room based on outside measurements, but the problem with that is that if you don't play music at realistic levels it will then always sound thin. I did this to try to maximize the sensitivity of the system for low power amps. I think I will be trying to change the crossover a bit to make it a bit less bright in the future.
Very, very interesting that the shootout seems to have favored sonic characteristics that do not show up clearly in measurements ?
What a pity no AMT dipole horn was in the competition
On the other hand, going down 600Hz would have been too low for the AMT drivers available.
LOL
Seems one has to knock together a biiig ALNICO or field coil AMT
Michael
What a pity no AMT dipole horn was in the competition
On the other hand, going down 600Hz would have been too low for the AMT drivers available.
LOL
Seems one has to knock together a biiig ALNICO or field coil AMT
Michael
Hi John, nice to meet you, virtually speaking.
It is too bad you were not there, I'm sure you would have tuned the system differently. It may have been as simple as bringing down the level of the mid horn.I agree, but we may be alone in that.
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