Cement horn

[Ruben]

After discussing a bit about this in an other thread concerning the bass horn, I would like to ask the question here:

What do you thing about building a medium horn with this driver http://www.phlaudio.com/datasheets/25_pdf/3860.pdf in a CEMENT (don't laugh) horn?

I like that idea very much, because it is very difficult to find compression drivers that goes down to the 150hz region. And I believe a quite massive cement horn would be very stable in terms of sonic performances.

- What are your feelings about a cement horn?

- What do you think about the chossen driver? Has somebody an experience with PHL drivers?

Ave a nice day!

[HobbesJunior]

Very interesting idea indeed I'd say...

About the driver: do you need it to be 10"? ...the fs of 75 is just about too high IMO if you plan to play down to 150 Hz ...
if that dosn't bother you I can recomend JBL's 10" 2012H (promodel) --- you cant go wrong there...
another top choice (but not as loud!) is ScanSpeak's midwoofers (www.scan-speak.dk)

Good luck

Hobbes

[Brett]

Ruben,

Go here and download the tractix calculator, as well as the 3 articles by Dr Bruce Edgar. The Show Horn article has an excellent explanation of how to specify the driver for the type of horn configuration you want.

Bruce's articles are great, and the horns built from them have alway's worked very close to the design. Erik's calculator works well too, and the 150Hz trax midbass is very nice (I've built them).

I'm currently (when class/exams are over) another trax mid horn, and am finalising the design for a 60Hz hypex midbass with an EVM15L in it. The timber is on my living room floor just waiting for the time to have it cut and finished.

Also look at the LeCleach concrete horns (unfortunate JMLC's homepage is gone) and Vincente's round laminate horns. Mine are similar, but tractrix, and the new ones will be finished on a lathe.

Originally posted by HobbesJunior
About the driver: do you need it to be 10"? ...the fs of 75 is just about too high IMO if you plan to play down to 150 Hz ...

Nope. Depends on the parameters of the drive unit. 75Hz Fs will be too low if anything in a number of configurations.

There's a ton of info to be mined in Bruce Edgar's posts on AA in the High Eff speakers forum.

[Christer]

A slight sidestep perhaps, but since your discussing concrete
speakers. The swedish construction company Skanska
developed a special concrete for loudspeakers about 20 years
ago in cooperation with a local company called EAI who made
a pyramid-shaped concrete speaker called Cheops.

[GM]

No experience with PHL, but cement's an excellent medium for horn construction. Here's JML's horn calculator (which I recommend over Tractrix) and a page of examples, including his:

http://perso.club-internet.fr/ndavid...htm#ancre68820

http://perso.club-internet.fr/ndavid.../exemples.html

GM

[ronc]

I have cement fill in my fostex fe-166e horns.I have to say i did try them without fill and with fill and the sound improvment went up a great deal with the fill.LF response improved and the overall sound tightened up.The only drawback i can see is they weigh 114 lbs each now.
ron

[Kongen]

In speaker builder 6/95 theresan article on this called "a morning glory midrange horn" featuring a five sided horn (pentagonal), cutoff freqency of 208 Hz and utilizing a pair of old philips midranges...

[ashok]

I remember a concrete bass horn and matching upper range horn design in Wirless World magazine from the 70's. If someone has access to pre 1975 issues you will find it.
A friend built one but I don't remember how good it was. We didn't have much to compare with at the time.
Might be interesting to go over the article again. Unfortunately I don't have a copy.
Cheers,
Ashok.

[Ruben]

Many thanks for your replies!



Do you think I would need a compression chamber for such an horn? I've seen some front horns without any compression chamber, so I don't really know what would be the best solution to do it...

I'm now thinking about the way to use the cement and to build it.
mmmhhh.

Have a nice day!

[mikee12345]

http://www.users.bigpond.com/dmcbean/

try hornresp.
front chamber acts as a filter varying top end.


adrians 150hz tractix. http://www.geocities.com/adrian_mack/tractrix.html