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Mike C
05-16-2003, 04:10 PM
Hi guys, has anyone tried a 909 Altec driver on a JBL 2370 style horn?, and if so how would the sound compare to the 511 horn. Alternatey how about the 909 on a 2344a?.

Kenny Brant
05-17-2003, 09:33 PM
I have used my 902 8T's on 2370A's and I thought the 511b or 811 horn sounded better. They just seemed more full than the 2370. The 2370 seemed flatter, with not as much depth. For my room I think the 811 sounds the best, but I like the lower cutoff frequency of the 511, more powerful sounding because of the 500 hz crossover, but a more fuzzy, not as focused sound as the 811. But right now I am still leaning towards the 511b's. I have used JBL LE175's on 2370's and thought they sounded good. In fact the LE175's sound really fine on the 511's or the 811's also. They just won't go high enough without tweeters, that is why I went to the 902's. They do not need any tweeters at all!

Kenny

Todd W. White
05-18-2003, 07:26 PM
Kenny,

There's a reason that the 909 sounds better on the Altec horn instead of the JBL horn -

Every horn designer that is worth his salt designs his horn around a particular driver. The reasons for this are many, one of the most important being that, by doing so, he knows HOW the driver will behave.

By knowing the output characteristics of the driver (be if HF or LF), he can design a horn for it that COMPENSATES for the negative characteristics of said driver, thus improving the final sound that the listener hears.

The JBL horns were designed for the JBL drivers, which have their own peculiarties, as do the Altec's. Putting the Altec driver on a JBl for which it was not designed, or vice-versa, is a mistake because the two drivers are not identical in their frequency response, output impedance, etc.

For example - let's say that the JBL horn designer knows that a particular JBL driver has a peak at, say 800 Hz, but he has to design a horn for it anyway. He will be wise to design a DIP at that frequency to compensate for it so that, when they are bolted together, it evens out. This is, admittedly, a homely and VERY simplified illustration of the concept, but I trust it helps you understand what I am talking about.

The same is true for brass musical instruments - the H. N. White Co. of Cleveland used to match the mechanical resonances of the bells and bodies of their horns so that the thing would play better, rather than fight itself....

Thus, when you mounted the 909 on the JBL horn, it sounded less full - because of the differences in the drivers the original designers BUILT INTO the horns!

We used to cringe when we'd find, as sound contracotrs, Altec horns fitted with DuKane (puKane), JBL, EV, or other drivers, and vice-versa.

Iconic Manufacturing Co. is working on several new horn designs, as well as adaptations of older ones, but, rest assured, it is with these principles in mind....

scott fitlin
05-18-2003, 09:35 PM
That makes sense. For years I have had the feeling that certain drivers just sounded right on certain horns! And then someone would put a driver on a different horn and I would say NO, that dont sound right! Engineers would tell me Nah the driver works fine! I say I DUNNO!

Thank you for clearing this up, as I really wasnt sure and I have sometimes said I didnt care for the way a particular driver sounded! maybe I didnt get to hear the driver on the horn it was intended for!

Mike C
05-19-2003, 05:12 AM
Hi guys, thanks for the input. Question for todd, is there an Altec horn that will work real nice with the 909's other than the 811/511 style more like the JBL 2370 in appearance?

Kenny Brant
05-19-2003, 08:18 PM
I am sure that a driver and horn are matched to each other like you said. But, there are combinations that might surprise a person also. I don't know if the 2370A horn was designed to work with the JBL LE175 but it sounds good on it. But the LE175 doesn't sound as good on a 2370A as it does on the a 511b horn, in my opinion. I personally think the LE175 sounds better on the 511b than does the 902 8T on the 511b. If it wasn't for the lack of highs and having to use a tweeter with it I would prefer it. I also find this driver (the LE175) also sounds good with either a solid state amp or a tube amp. The 902 8T to me sounds a lot better on a tube amp. Don't get me wrong, I am not knocking the 902 at all, as it is a top notch driver for a 1 incher. But, I also like the 902 better on the 811 than I do on the 511. This, of course, is in my room with my equipment and I am using JBL M151's for lower midrange upper bass, and JBL LE14A's for subs. Changing out the 151's would probably voice the whole thing differently. This, of course, is just my opinion, and anybody can disagree with it and I would understand. It all goes back to a persons preference, you understand.

Kenny

jaymanaa
12-02-2006, 06:05 PM
Hello All, Thank you for the opportunity to post in this forum, and please forgive the "rookie" nature of my questions. I have recently been building my first all horn system which is utilising 511B horns with 902-8B drivers for everything above 500hz. I feel as though I may be missing something in the higher frequency range. I'm wondering about the horn itself, and where it cuts off at (high end). I'm fairly convinced that I will need another horn for the upper ranges, but am unsure of where I would want to cross it. FWIW the system is powered by 300B monos, and the low frequencys are handled by home made 15" rear loaded horns very similar to JBL 4350s. I am very happy with everything, except the very high frequencys. Any suggestions or comments would be most appreciated. This thread I found has been quite helpful allready in getting me thinking.:) Thanks Again, Jay

Thom
12-02-2006, 09:50 PM
since the 175 predated the LE prefix, for years it didn't carry it. Did they change the driver or one morning it was just part of the Linear Efficiency series. Just curious.

Zilch
12-02-2006, 09:51 PM
If you're looking for a VHF horn, 2370A isn't it.

Some recent work I did with 2370A:

http://audioheritage.org/vbulletin/showthread.php?t=13174

Study the data sheet carefully, in particular how the vertical beamwidth drops to only 20 above 10 kHz:

http://www.jblpro.com/pages/pub/components/2370a.pdf

Compare to 511B in Fig. 3 here:

http://audioheritage.org/vbulletin/showthread.php?t=7852

My advice? Spend $30 for a pair of the inexpensive 1" JBL Progressive Transition waveguides (Part #338800-001) and throat adapters (the horns are thread-on) and see if they work for you:

http://www.jblpro.com/ae/pdf/PT_WaveGuide.pdf

These are high frequency horns. Getting down to 800 Hz will be a push, depending upon how your drivers work with them. 500 Hz is out of the question, so it'll be three-way. Consider using JBL neodymium 2407H on the PT waveguide as a tweeter (threads directly on,) crossed anywhere 2 kHz or higher. They're showing up inexpensive from one vendor on eBay of late:

http://audioheritage.org/vbulletin/showthread.php?p=105370#post105370

jaymanaa
12-03-2006, 06:03 AM
Thanks for the links. It will take me some studying to try and understand some of the info, but at a quick look, I can see that they will be most helpful. This whole "horn" deal has been quite frustrating at times, but I think I am getting close. One more rookie question if I may. I have read some here about dust covers (or something like that) on these horn drivers. I bought mine used, and allready installed on the horns. The throats of the horns were quite dusty, and I'm wondering if I should remove the drivers for any kind of maintenance or cleaning. Would it also be a good idea to replace the diaphrams? Thanks for the help, Jay

Thom
12-18-2006, 03:13 PM
http://audioheritage.org/vbulletin/attachment.php?attachmentid=14645&stc=1&d=1144285092

has anyone tried cutting the neck back and welding on a new flange to mate 1.5 in drivers with 511B horn. What could be expected as results. I'm talking about going to where the throat is 1.5 and putting the flange there. I was thinking about 2435 driver. Would that defeat all of the advantages of that driver? I know they have a range of horn/ wave guides just for that but I don't have a gate pass for JBL.
Also can't seam to find those horn mounts. Are they after market?

Zilch
12-18-2006, 04:01 PM
Also can't seam to find those horn mounts. Are they after market?Yup, and them port plugs, too, both from the same source.... :p

No harm in sawin' off 511Bs and trying it, probably. I consider 243x drivers to be in the throatless "Optimized Aperture" family, but they seem to work with biradials, too....

Thom
12-18-2006, 09:00 PM
Yup, and them port plugs, too.... :p

No harm in sawin' off 511Bs and trying it, probably. I consider 243x drivers to be in the throatless "Optimized Aperture" family, but they seem to work with biradials, too....

I believe these are the ones that appear to have been made out of plastic and then left in the sun. But, the words entered into search only took me a couple of places and I couldn't figure out why it took me there.


Some of the wood horns I've seen don't look like rocket surgery or are there tricky measurements that don't show in brochures ?

I like this spell check. Now, as long as I don't spell too many wrong words.

Zilch
12-18-2006, 10:22 PM
http://audioheritage.org/vbulletin/showthread.php?p=139113#post139113

See:

http://www.jblpro.com/pub/technote/tn_v1n21.pdf

Also:

http://www.jblpro.com/ae/pdf/PT_WaveGuide.pdf

Thom
12-19-2006, 12:30 AM
Are these new enough that new is where you find them?

The writings make it sound as if this answers problems that had been bothering listeners for years but in some cases were subtle enough that you had to hear it "right" to realize it had been wrong.

Do you notice major difference compared to other horns?

Is this a JBL exclusive or do others just have to call theirs by other names.

Zilch
12-19-2006, 12:59 AM
You buy through JBL Pro parts. The PT Waveguides are under $100 apiece, some substantially under. The 2352 is more like $300 each. I got a pair for $35 apiece (returns, apparently,) in the Tent Sale. I doubt that will happen again.... :(

So far as I know, they are all proprietary to JBL.