How far down in frequency will the JBL 2482 (phenol) load on a 140 Hz tractrix horn?

[PeterK]

Hi,

I consider getting a pair of JBL 2482 (phenol) drivers, but only of they load down to 200 Hz (or lower) on a pair of 140 Hz tractrix horns (my bass horns don't sound good above 200 Hz). Will the 2482 do that?

Thanks!

Best regards
Peter

[Allanvh5150]

Hi Peter,

The 2482 data sheet specs say it's usable range is from 300Hz as is its lowest recomended frequency. It is one hell of a tough driver but I wouldnt like to run it any lower.

Allan.:)

[Hoerninger]

Hi Peter,

even with a proper hornloading the drawbacks are dissortion and small sound pressure level at the low end. Even worth - you risk damage I suppose.

For the low/mids it is better to use a cone driver with the horn.
Do you have any pics of your horns?
___________
Peter

[PeterK]

Hi Hoerninger and Allan,

Thanks for your replies! Just to clarify, I will only use the driver for home use (not PA), and I can use high order (digital) active high pass on the driver/horn. I have no pictures, sorry. I will not go for the horns, if the combo will not load down to 200 cycles or below!

Best regards
Peter

[Hoerninger]

I can use high order (digital) active high pass on the driver/horn.

This will not prevent from (much too?) large excursions in the low range. You simply have to try it out.


I will not go for the horns, if the combo will not load down to 200 cycles or below!
Too bad there are no pictures. In case you did not built the bass horn yet, what about this one (http://www.audioheritage.org/vbulletin/showpost.php?p=121158&postcount=3), I used it up to 500 Hz (with a slight decrease). There were built four but In a living room one per side are sufficient.
____________
Peter

[PeterK]

Hi Peter,

Thanks for responsding. Well, I thought you meant the 140 Hz low-mid horns:-) The bass horns are built!

Here is a picture (the bass horns are the same, the mid/high horns are no longer the same):
http://gallery.audioasylum.com/cgi/upload.mpl?u=5808&f=New_system_with_Fostex_T825_tweeter.jpg&v=f&UserImages=5808&session=480294740&invite=&w=1000&h=750

Best regards
Peter

[carolus]

Hi PeterK & Allan & Peter .....
My practical long use 2482 on a WE66A horn....
It's a "acousical-musical illusion" to go down below 300Hz ....
If so you have a real "dip" in music (micro) information & acoustic power (& mismatch).....
In fine: Respect the tech data sheet Fxover 300Hz (or higher) even in "domestic" use ...(cfr.: Allen) ...
Allez, salukes and good musical experiences.
Karel

[PeterK]

Hi Carolus and all others!

Thanks for your reply, Carolus. Well, I guess I have just have to drop the idea then! Thanks to all for taking the time to respond!

Best regards
Peter

[Mr. Widget]

I consider getting a pair of JBL 2482 (phenol) drivers, but only of they load down to 200 Hz (or lower) on a pair of 140 Hz tractrix horns...Are your tractrix horns 70Hz cut off or 140Hz cut off. I ask because many people don't realize that the cut off frequency must be at least one octave below the lowest crossover frequency. To get a horn loaded midbass down to ~140Hz, there are some crazy expensive solutions from ALE Acoustics, but I think your best bet would be to use a 10-12" horn loaded cone driver.


Widget

[speakerdave]

There's also a rare Emilar.

[PeterK]

Thanks for responding Speakerdave and mr. Widget!

Mr. Widget:
I haven't got the tractrix horns yet (and I doubt that I will now that it turns out that the whole idea may be based on a wrong premise). The tractrix horns I had in mind was 140 Hz horns (not 70 Hz horns) from Stereo Lab (Germany).

At the moment I am actually using a horn loaded cone, but, as you know, some of us can't help thinking about possible improvements.-)

Speakerdave:
I remember that Mike Bates (aka 'Magnetar' on the AA board) had a pair of 6" EC600 Emilar compression drivers on very large horns at some point. These may be the drivers/horns you are thinking about. The ones I am thinking about sure looked great by the way:-)

Once again, thanks for your help! I guess my idea is history now!

Best regards
Peter

[spkrman57]

Here is a prototype I threw together using a midhorn and Eminence Delta 10A that is -3db @ 300hz and -10db @ 150hz. You can just see the dustcap in the pic of horn in the middle.

Regards, Ron

Forgot to add: this is a conical horn. A tractix horn for the same flare frequency would only work down to approx 400hz.

[Hoerninger]

At the moment I am actually using a horn loaded cone, but, as you know, some of us can't help thinking about possible improvements.-)

Good alternatives are nevertheless
18Sound6ND410 (http://www.eighteensound.com/renderPdf.aspx?pid=244) and
AUDAX PR 170 M0 (http://www.audax-speaker.de/content.php?seite=shop/produkte.php&hauptrubrik=8&details=29)
Both are very high efficient 6 inch cone drivers.
___________
Peter

[speakerdave]

Might also be worthwhile studying JBL's use of horn-loaded cone midranges recently in sound reinforcement products. They have a couple of special drivers for that, one being the 8" 2250.

http://www.audioheritage.org/vbulletin/showthread.php?t=17663&highlight=2250

[Steve Schell]

PeterK I think you are on the right track. You have been given some good and conservative advice, but my tendency would be to build it and try the results. You are unlikely to harm the 2482 as long as it is adequately loaded by the horn. This driver is intended for very high output down to 300Hz., so 200Hz. shouldn't stress it in a home system. The longer the horn and slower the flare the better. Haven't measured a 2482, but an Altec 290 phenolic driver on a plane wave tube is flat to 100Hz. or so. If you can make this work you will enjoy the dynamics, attack and clarity of a compression driver down to 200Hz., a very worthwhile goal.

[PeterK]

Gentlemen,

thanks a lot for all the constructive advices! Denmark, where I live, is no "horn country", so there are not many 2482 drivers around and almost no <150 Hz horns, if any. I would really like to try a 2482 on large horn in order to obtain the presence and clarity that Steve Schell talks about, but since I do not know whether it's really possible, I do not dare to take the chance. If it only loads to, say, 250 Hz, then I will still have to listen to my bass horns above 2300 cycles, and I would like to avoid that! Unfortunately, I have not got the money, just to try it out - although I sure wish I had! So I guess I will stick to the cone driver route for now!

Thanks for all the comments!

Best regards
Peter

[jerv]

Peter: You probably already know of these: http://www.hifi4all.dk/ksb/Annonce.asp?id=110220 ?

Espen

[PeterK]

Hi Esben,

Yes, I had seen these, but thanks for the tip anyway! I guess the price is fair enough, but getting the 140 Hz tractrix as well as the JBLs is a pretty expensive 'experiment' (at least for me). The point is, that if the 2482 does not load below 200 cycles, then I will just be stuck with the combo, since there is no (affordable) alternative 2" driver to try that will go as low...

Best regards
Peter