Jean Michel on LeCleac'h horns

:confused:
I had a good plan but almost free edgar horns with Tad td4001 and Vcaps crossed my way than ET703 and Tm 1201 so I set it up for jollies. Gives me a headache haha.
 

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Jmmlc said:
Hello, Sqlkev,

You can find some informations about compression drivers modelling in that thread:

http://www.diyaudio.com/forums/showthread.php?postid=1746146#post1746146


Best regards from Paris, France

Jean-Michel Le Cléac'h



thank you Jean-Michel,

I think I'll use the TAD2001 specs that you provided for now.

I have a few more questions,
Does the program Hornresp schematic diagram for the LeCleac'h horn correct?
I don't see the mouth's profile in my diagram
did i do something wrong? or is it something to be implemented later?

As far as the T goes,
what is recommended for midrange horn, and what's recommended for a tweeter horn?
Or is that something I'll have to experiment with the compression driver and make a judgement call?
 
soongsc said:
Has anyone else done measurements on these types of horns? Any data to show?
Out of curiosity, I did a draft sim with the lips like the reall thing will be made. See how the lip effects the response? Not so good.
An externally hosted image should be here but it was not working when we last tested it.

A finer run has been in progress for some 12 hours now. I don't expect the trend to be much different.
 
Hello sqlkev,

Yes ,Hornresp, thanks to David McBean, has the right profile for a Le Cléac'h horn.

In the input window, when you enter whatever value for S2 while designing a Le Cleéac'h horn, you'll have in the right bottom corner a note in red indicating the max value for S2. This value corresponds to the value of S2 for a horn the mouth angle of which will be 360° (tangentail angle of 180° versus the axis of the horn).

As an example see the screen copy I attached for a Le Cléac'h horn having Fc = 320Hz. The S2 value I entered is 1900cm², this leads to an incomplete profile the mouth angle of which is around 180°. You can see that the red note indicate that the max value for S2 is 2838,86 cm². So you may enter that value in order to have a complete 360° profile.
You'll see superimpsed on the graph the sketches of the 2 horns, one with the incomplete 180° mouth and the other one with the complete 360° mouth.


sqlkev said:


Does the program Hornresp schematic diagram for the LeCleac'h horn correct?
I don't see the mouth's profile in my diagram
did i do something wrong? or is it something to be implemented later?

As far as the T goes,
what is recommended for midrange horn, and what's recommended for a tweeter horn?
Or is that something I'll have to experiment with the compression driver and make a judgement call?
 

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Hello Soongsc,

I think that there is something wrong about the way you enter the profile of the horns + lips in the space.

Before you stop to consider the lips, please verify that you run the simulation with the horn set free in the space and not fixed on a planar baffle at the level of the driver (the grey horizontal axis on your diagram...).


Best regards from Paris, France

Jean-Michel Le Cléac'h



soongsc said:

With the lip. I think I'm not going for this.
An externally hosted image should be here but it was not working when we last tested it.
 
Hello Sqlkev,


About the choice of the T value for a given loudspeaker, we have first to consider what effect the T value has on the response, loading, etc for a perfect driver.

In order to illustrate this, as I did'nt have at the moment simulation with a perfect drievr, I took a 160Hz Le Cléac'h horn mouted with a TD2001 and I did simulations inder Hornresp with T values between 0 and 1.5 (unfortunately Hornresp doesnt' allow T values over 1.5...)

As you can see on the graphs, the effect of the T value seems weak at hogh frequencey but can be very important at low frequency. Generally values of T between 0,7 and 0,8 will lead to the most linear response with good compression drivers. Values lower than 0,6 will be more useful for large format low cut-off frequencey horns. Using a T value lesser than 0.6 on a medium horn will result in a response with a decreasing slope and with a bump around the cut-off frequency. This can help with some drivers...

For tweeters, T value of 0,8 or more may be preferred.

Notice than nobody until know seem to have design a horn with a T value of 0. Such horn will be intersting for low-mid but will require a steep slope for the high-pass crossover. It could be also interesting for a bass horn having a very low cut-off.

Best regards from Paris, France

Jean-Michel Le Cléac'h



sqlkev said:



As far as the T goes,
what is recommended for midrange horn, and what's recommended for a tweeter horn?
Or is that something I'll have to experiment with the compression driver and make a judgement call?
 

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Jmmlc said:
Hello Soongsc,

I think that there is something wrong about the way you enter the profile of the horns + lips in the space.

Before you stop to consider the lips, please verify that you run the simulation with the horn set free in the space and not fixed on a planar baffle at the level of the driver (the grey horizontal axis on your diagram...).


Best regards from Paris, France

Jean-Michel Le Cléac'h



Jean-Michel, Thanks for pointing this out. Looking at the dimensions, I was wondering the same thing. I just need to figure out how to do it with this software. Right now it seems like extending the horn so that the baffle is far away from the lip is the only alternative, so I may just put the horn 1 meter in front of the baffle.
 
Thank you Jean-Michel for the thorough replies. I finally understand how to use hornresp to use for modeling your horn profile.
I guess this summer will be the perfect time to start this project.


Has anyone use a LeCleach horn with a non-compression/regular cone driver?

I'm just thinking this outloud
Would a low distortion dome or possibly 5-6" cone drivers work well in a 250hz horn/midrange/midbass horns?

and to those who are running horns,
what type of xover are you using?
Would a dcx2496 do justice for a system of this scale?

(btw...i tried the Lecleach xover the other day on my current system and it made a difference in coherence
well done Jean-Michel :up: )
 
Jmmlc said:
In the input window, when you enter whatever value for S2 while designing a Le Cléac'h horn, you'll have in the right bottom corner a note in red indicating the max value for S2. This value corresponds to the value of S2 for a horn the mouth angle of which will be 360° (tangential angle of 180° versus the axis of the horn).

Hi Everyone,

Just to add to Jean-Michel's comments, and for the sake of completeness - Hornresp actually has two information messages relating to the mouth size of a Le Cléac'h horn.

The first message is displayed when S2 is less than the mouth area required for a horn having a flare tangent angle of 90 degrees - the value of S2 required for Fta = 90 deg is displayed.

The second message is displayed when S2 is equal to or greater than the mouth area required for a horn having a flare tangent angle of 90 degrees, but less than that required for a flare tangent angle of 180 degrees - the value of S2 required for Fta = 180 deg is displayed.

The example given by Jean-Michel refers to the second message.

Kind regards,

David
 
Hello sqlkev,

I guess that in France we have much more people using Le Cléac'h horns with compression drivers but in USA and other countries most probably there is much more people using Le Cléac'h horns with cone loudspeakers.

Good examples of horns that one could use with cone loudspeakers are Martin Seddon's AH204 and AH160
http://www.azurahorn.com/azurahorn_horns.html

Here is an example of use of the AH160 with a Lowther loudspeaker.:
http://www.arduman.com/aa/Sayfalar/slagle/slagle.htm

Cone loudspeakers are also used in Le Cléac'h horns built by Azzolina Audio like in the Gran Sfera
http://www.azzolinaaudio.com/page3/page5/page5.html

You'll see many examples of Le Cléac'h horns using cone loudspeakers at:
http://www.azurahorn.com/azurahorn_gallery.html

Best regards from Paris, France

Jean-Michel Le Cléac'h





sqlkev said:
Thank you Jean-Michel for the thorough replies. I finally understand how to use hornresp to use for modeling your horn profile.
I guess this summer will be the perfect time to start this project.


Has anyone use a LeCleach horn with a non-compression/regular cone driver?

I'm just thinking this outloud
Would a low distortion dome or possibly 5-6" cone drivers work well in a 250hz horn/midrange/midbass horns?

and to those who are running horns,
what type of xover are you using?
Would a dcx2496 do justice for a system of this scale?

(btw...i tried the Lecleach xover the other day on my current system and it made a difference in coherence
well done Jean-Michel :up: )
 
Lynn Olson said:
Here's one of the reasons we didn't build a T = 1.34 version; this shows frequency response at emission angles from zero to 90 degrees off-axis. It looked fine in the BEMs, nearly indistinguishable from the T = 0.707 version. But the FR would be non-trivial to equalize.

The models presume theoretically perfect drivers; real drivers are worse, frequently much worse. Combine the two sets of responses, and you can start to see why 1/3 to 1/6 octave response smoothing is so common in the high-efficiency world.


I'm not sure why we see a rising HF response... but the slope of the upswing looks very much like a simple 1st order slope that could be flattened perfectly with a small series inductor?

Then the 10 deg and 20 deg would show a slight falloff...


_-_-bear
 
Hello sqlkev,

That's probably due to the thrill in my spine when I listen to such good drivers as Onken, Goto, Western Electric... I never experienced such with cone drivers mounted on horns, even if some of them were very good sounding compared to 90% of the commercial stuff

The resonance frequency (mounted on the horn it may differ than the one mesured on planar wave tube) plays a role for sure in the sound. Generally I try to avoid the resonance frequency to be in the middle of the useful bandwith of the horn

The Goto and the WE possess low resonance frequency, may be that's one of the reasons why I liked them so much.

Best regards from Paris, France

Jean-Michel Le Cléac'h

sqlkev said:
Is there a reason why you prefer compression drivers over cones?
I thought that the fs on those don't go low enough for the bigger horns. :xeye:
 
J-M,

When I pulled the original articles (many years ago) out of the Western Electric technical journal on the WE555, I was blown away to see images of the test setup and the specs.

There was a picture of a lab with the plane wave tube sticking out the window... not enough linear floor space apparently.

They showed the lower usable frequency as 75Hz.!! :bulb:

All of a sudden a whole lot of things about compression drivers and their design points crystalized instantly. :djinn:

_-_-bear


Unfortunately, by the time I had done this the opportunity to find them at any reasonable price had long past, and that was more than a decade ago now... and the only place that I could possibly get to that had copies of the journal was in Philadelphia - about 5 hours drive away.
 
Jean Michel

have you ever made direct listening comparisons between a regular tractrix horn, and LeCleac'h horns ( everything the same : drivers, frequency range, crossover etc. ? ) is there a substantial and perceivable difference in performance ?

does it make sense to use such a big horn as the last pictures shown of melaudia homepage, with the Radian 950pb, if its Fs is 500hz ? have you heard this system ? do you not loose delicacy in the treble, using a TAD-2001, compared to a dedicated super tweeter ?

which is the system, which most impressed you so far ?

Angelo
 
Hello Bear,

If my memory serves me correctly (which is to demonstrate those days...) during the design/development of the famous Western Elecric compression driver WE555, in order to measure its frequency response in power, Osmer used the calibrated condenser microphone invented by Thuras at the throat of a 30meters long planar waves tube which one loaded the WE555.

If we use hornresp to simulate the acoustical impedance of the device we can see (attached graph) that there is some peaks (negative and positive) below 50Hz. We can see also smaller resonance peaks around 250Hz (which is around the frrequency of resonance of the driver used for the simulation). It is probable that the fiber mass used at the end of the tube used by Osmer and Thuras was efficient in reducing such resonances above 200Hz but have no effect on the peaks observed below 60Hz. That's probably the explanation for your sentence :

"They showed the lower usable frequency as 75Hz.!! "

Best regards from Paris, France


Jean-Michel Le Cléac'h


bear said:
J-M,

When I pulled the original articles (many years ago) out of the Western Electric technical journal on the WE555, I was blown away to see images of the test setup and the specs.

There was a picture of a lab with the plane wave tube sticking out the window... not enough linear floor space apparently.

They showed the lower usable frequency as 75Hz.!! :bulb:

All of a sudden a whole lot of things about compression drivers and their design points crystalized instantly. :djinn:

_-_-bear


Unfortunately, by the time I had done this the opportunity to find them at any reasonable price had long past, and that was more than a decade ago now... and the only place that I could possibly get to that had copies of the journal was in Philadelphia - about 5 hours drive away.
 

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Hello Angelo,

Well that's dificult to have the same driver and cut-off frequency for such comparison.

Here in France most of the DIY tractrix horns have a square mouth.

Some horns are also modified tractrix (they use some curvature back at the mouth.

I used to listen a 2 inch compression driver on a large Avant Garde modified tractrix horn (with a throat adapter) and it was excellent, even if the Le Cléac'h horn succeed in giving a better 3D sound image.

So I'll never say that the Tractrix are bad, they are not.

Remember also that using my spreadsheet to calculate a horn having an exponential expansion the obtained profile is quasi similar to the tractrix profile on more than 80% or 90% of its length (but the mouth, so important IMHO, does the difference).
The mouth of the Kugewellen horn is more similar to the one of a Le Cléac'h horn (see attached graph)

Best regards from Paris, France

Jean-Michel Le Cléac'h



angeloitacare said:
Jean Michel

have you ever made direct listening comparisons between a regular tractrix horn, and LeCleac'h horns ( everything the same : drivers, frequency range, crossover etc. ? ) is there a substantial and perceivable difference in performance ?

does it make sense to use such a big horn as the last pictures shown of melaudia homepage, with the Radian 950pb, if its Fs is 500hz ? have you heard this system ? do you not loose delicacy in the treble, using a TAD-2001, compared to a dedicated super tweeter ?

which is the system, which most impressed you so far ?

Angelo
 

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