Jean Michel on LeCleac'h horns

[Jmmlc]

Hello sqlkev,

Tthe B&C drivers are quite good. I know a bit the DE250 which must be used above 1000Hz min and which is quite smooth sounding.

A cutoff of 400Hz for the horn will be a bit high for the Adastra driver. Remember that it should be better to use a 400Hz horn above 800Hz...

I think that there is no vertical plot for the J322 because Cyrille Pinton found that the response in the vertical plane was the same as in the horizontal (due to the axial symetry).

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally posted by sqlkev


that's just about the perfect bandwidth i was looking for

although a 200hz horn

What do you think of the B&C compression drivers?

I plan to use a set on the tweeter horns. I don't need the extra high efficiency since the subs will probably be dipole using the eminence alpha 15s with a pair per side.


wow, i'm quite impressed with the linear responses of the J322
(the vertical plots are missing from the .gif though)

[sqlkev]

would it help at all if i use steep xover filter to highpass it?
a 200hz horn is quite huge and I'm not sure if i'm up for such project just yet


your reasoning for the lack of vertical plots makes perfect sense


i'm looking at this de10 to try out just for fun (it's cheap enough like the midrange driver you recommended)
http://www.prosoundservice.com/m9_vi...tem=B%26C-DE10

[soongsc]

sqlkev,

It is possible to conduct measurements and compare gainst sims. I have done it for one design so far, and preparing to look into the second one. However, it is important to understand that sim conditions are different from the measurement conditions, also certain sim settings will effect how clean the sim is. So sims will probably never be accurate enough to be exactly like the measurements, but if we understand the limitations of sims, it can be a good reference for a first cut. It can also be used to find out the more probable causes of problems in a design. Bear in mind that sims are used across various industries significantly as a cost effective measure to reduce risk. In high budget projects, sim models are adjusted extensively to be more accurate using measurement data, I doubt any audio company will do this because the returns are not justified. The technology is there, but not the budget to make it happen.

[Jmmlc]

Hello sqlkev,

a steep crossover will not help too much. The main problem I see when using a driver in a frequency interval very near of the acoustical cut-off frequency of the horn is the voice seeming to come from very far inside the horn. This can be explained by the group delay that rises very fast when the frequency decreases under 2.Fc . Imagine the fundamental of the voice or of an instrument seeming coming 1 meter or more beneath its harmonics, this lead to a strange effect (a strain in the image of the sound source).

A square horn like the one built by my friend Nicolas Davidenko is easy to build using the profile of the cuts you have to perform in a plywood sheet as given by my spreadsheet.

http://ndaviden.club.fr/index.html


Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally posted by sqlkev
would it help at all if i use steep xover filter to highpass it?
a 200hz horn is quite huge and I'm not sure if i'm up for such project just yet :cannot be:

[sqlkev]

hmmm....a set of 200hz horns

btw
what's the accuracy/precision are we talking about in making our own horns here? 1+-mm the whole profile or it's only crucial at the throat and outer lip?

[revintage]

hmmm....a set of 200hz horns

To work well from ca 200hz the horns will need to to be almost 100*100cm ! If you mount them against the sidewalls you can probaly slice at least 30cm off from the "wall-side" of the horns. Attached is an image of a Swedish system with sidewallmounted Lowthers working from 150hz up.

[Pano]

Originally posted by Jmmlc
Those horns are "JBL 2380A", "Beyma TD-400", and a Le Cléac'h horn "Musique-concrète J322".

Thanks very much for that, JM. A good read. It's easy to see that the big, round horn beams more than the more complex JBL & Beyma. And Mr. Pinton points this out in his text.

Otherwise the big horn does quite well. It looks very clean.

I've noticed that very "pure form" horns tend to beam badly. That's why so much work was done on the CD horns. But the purer, simpler shapes always sound better, sound less colored. At least if the beaming is taken into account.

Is that always going to be true of a horn without the CD "tricks"?

[soongsc]

After finishing some draft measurements of the horn/guide with the LeCleach type expansion with OS type diffraction throat, I though it would be interesting to look at all three horn/guide measurements together. Last made is on top.

It's going to be interesting trimming the last one a bit.

[soongsc]

And a look at sims vs measurements. Note some trends are similar yet there are some differences.

[tinitus]

Originally posted by soongsc


LeCleach type expansion with OS type diffraction throat,

That I dont understand

Hard to see what is what in your measurements