Jean Michel on LeCleac'h horns

Hello Esperado,

A quick google search for Earl Le Cleac'h gives:

Savourez la Bretagne - EARL Le Cleac'h

Notice : "EARL" in France stands for
"exploitation agricole à responsabilité limitée" which can be transalted as "limited liability farm "

reference:
L'exploitation agricole à responsabilité limitée (EARL) - Ministère de l'agriculture, de l'alimentation, de la pêche, de la ruralité et de l'aménagement du territoire

Best regards from Paris, France,

Jean-Michel Le Cléac'h


Did-you tried to make your Earl ? (bad joke)
I have send-you a PM.
 
MDF

I have made a CAD design for a small horn. I am very anxious to build a prototype. Will aluminium do? Or will it ring? Is MDF a better material?

MDF will cost less, but will require more work to finish.

Aluminum will ring. The question is at what frequency? For a prototype, if it rings, coat the exterior with an automotive sound damping material or enclose it in a box full of sand.

Regards,

WHG
 
So, am I right to say that when T=0 the horn will be substanial deeper/longer, and therefore loading better down towards Fs? Is this the reason for using T=0 when the horn is made for a dome driver like a fullrange etc. and thereby have the possibility to go down to 250hz with the JMLC 200, compared to approximatly 350hz with the JMLC 200T that is used with a compression driver?
 
Hello sanax,

With T = 0, the horn will compensate the reponse of a compression driver having a response a bit weak between 200 and 350Hz (as it is often the case, as seen on mesurements of certain drivers on the 200T having a T = 0.8).

This should allow a cut-off very near of 200Hz.

Best regards from Paris, France

Jean-Michel Le Cléac'h


So, am I right to say that when T=0 the horn will be substanial deeper/longer, and therefore loading better down towards Fs? Is this the reason for using T=0 when the horn is made for a dome driver like a fullrange etc. and thereby have the possibility to go down to 250hz with the JMLC 200, compared to approximatly 350hz with the JMLC 200T that is used with a compression driver?
 
Ok, so you would normally use a T=0,8 with a compression driver, but some of them need a horn that has T= 0, to compensate for the response between 200-350hz? Do you know which drivers?

What about a fullrange driver, that of course can be used in a horn? Is there any consensus to what T value one should use, and why? I would assume it is not that critical for a fullrange driver as with a compressiondriver (inner slot) regarding the throat of the horn.
 
I am proposing to make some adaptors to reduce the throat of my 250Hz Le Cleach horns down from 160mm (for Lowther) down to 52mm for a 2" compression driver. When i used the Le Cleach calculator i have found that the profile does not simply extend backwards. Looking at the spreadsheet it looks as if the natural expansion routine it is using will give a different profile for every throat size. Attached is a graph showing how the profiles differ - what should i do, curve fit a profile "that smooth" from my current throat backwards or ?? suggestions please, as i dont know how sensitive the throat portion of the horn is.
i will be making flanged fibreglass extensions which will bolt on to the back of the existing horns.
 

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Vanilla Salmon

I am proposing to make some adaptors to reduce the throat of my 250Hz Le Cleach horns down from 160mm (for Lowther) down to 52mm for a 2" compression driver. When i used the Le Cleach calculator i have found that the profile does not simply extend backwards. Looking at the spreadsheet it looks as if the natural expansion routine it is using will give a different profile for every throat size. Attached is a graph showing how the profiles differ - what should i do, curve fit a profile "that smooth" from my current throat backwards or ?? suggestions please, as i dont know how sensitive the throat portion of the horn is.
i will be making flanged fibreglass extensions which will bolt on to the back of the existing horns.

For the math you need to do this, see my post
http://www.diyaudio.com/forums/multi-way/140190-jean-michel-lecleach-horns-119.html#post2686127
Do not worry about the wave front dimensions in the neck, just apply Salmon's formula using ordinal dimensions. You will be primarly concerned with the radii (dia/2) and tangent angles at the driver and horn exits between which your adapter is to be placed.
Regards,
WHG
 
All JBL 2" exit diameter drivers have the same throat dimensions.

I have made a replacement throat for a 2440, and these are the measurements I get from it: The throat is 68,5 mm long. The entry diameter is 39 mm. The exit diameter is 49 mm. Most probably the expansion is exponential. Entering this in hornresp gives an exit half angle of 3,9 degrees and 192 Hz cutoff frequency.

download.php
 
M10,
You have entered the wrong length! I measured entry to 38,5mm, but maybe you had a better chance to measure when you took you driver apart. Still gives a 183Hz exp flare whatever we use your figures or mine.

Vinylvalves,
Exit angle according to HR is 4,67 degrees so 5 degrees is what you could use.
 
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