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HenryW
06-21-2004, 01:42 PM
While I was thoroughly enjoying myself over at the "way off topic" forum, I asked an old forum aquaintance (Maron - whom I was having a minor disagreement with at the moment) what his preference was for the horn to attach to a 2425. I have tested a 2345 and it measured OK, but my ear liked the sound much better when I was about 5 feet beyond where I would be listening to the speaker in my room. My way of stating the problem with the horn was the throw was too long. So finally we have come to my question:

Since medium to long throw is probably wrong for the environment, what do you folks consider your favorite short to medium throw horns that can comfortably be used down to 800 hz or even as low as 400 - 500hz with a compression driver? Please do not limit it to the 1 inchers (althought that best fits my current) but feel free to wander - just the discussion alone should be very educational.

The woodsmith is a darn attractive alternative and the 2344 "Plumber's" cheeks would be the least attractive solution (visually), but your impression of sound and driver combination is what I most want to hear.

Mr. Widget
06-21-2004, 02:12 PM
What is the woodsmith you are refering to? Is it the wooden "Smith" horn?

For 2" drivers I really like the 2397. I listen to my Westlake version at about 10' away.

If I were hell bent on using a 1" driver I would probably go with a "Salad Bowl" tractrix horn from Dr. Edgar. See below.

HenryW
06-21-2004, 03:13 PM
Yep - 2397 was what I should have said - I have only seen pictures.

I continue to miss catching up with the good doctor, his was my original choice - I was very pleased with one I heard using a 2426.

I saw some of your thoughts on the 2397 - Are you strong in your opinion that it best fits a 2" driver?

Mr. Widget
06-21-2004, 03:39 PM
I originally wanted to make a two way with the 2397 and 2421 and 2235H. I tried out the 1" driver on the 2397 and was very disappointed with the sound. The highs were rolled off and the mid range sounded rough. Even with EQ I was dissatisfied. When I used a 2441 and 2405 it was lightyears ahead in quality.

If you would like to try out a pair of 2397s with 2327 and 2328s I could send you a pair if you want to pay shipping both ways... probably not too cheap, but I thought I'd offer.

Widget

Hofmannhp
06-21-2004, 04:21 PM
Originally posted by Mr. Widget (edited by HP)
...... I tried out the 1" driver on the 2397 and was very disappointed with the sound. The highs were rolled off and the mid range sounded rough. Even with EQ I was dissatisfied. When I used a 2441 and 2405 it was lightyears ahead in quality.
......Widget

Hi all,

I can confirm Widget......I tried it also some days ago with 2327 and 2421 ......(the difference is like day and night) the 2397 are only top with the 2441.

HP

linkalley
06-21-2004, 05:39 PM
i had a pair of 2397 horns. dumbest thing i ever did was sell them. they wre really nice with the tad 4001 drivers. anybody out there want to sell their 2397 horns??? how about the 2328 adapters???
link in ok.land!!

Robh3606
06-21-2004, 07:21 PM
Sorry but I'm a plumbers cheeks man:confused: Yikes that sounds awful how about I love the Dolly Partons!! Sounds much better. :D Think of them as sculpture. They are a bit strange looking but they sound real nice. Image very well and don't sound like a horn at all. At least there is no disernable coloration from them. Just clone the comp from the 4430/4435 and you are set.

Rob:)

HenryW
06-21-2004, 08:56 PM
I have some 2404 baby cheeks - I just took the analogy plumber in a wierd play off the 2404. The 2404 will be my Tweeter on this project.

I will trust you folks on the 2397 - I need this to be a good mid and there are too many votes against - thanks widg for the offer, but I think everyone has done a good job of telling me it is not the best use of the horn.

The 2344 is tentative on the specs at 800 hz Rob - do you think it would work fine at that crossover point?

And I didn't mean to seem to diss the 2370 - any thoughts on it?

Mr. Widget
06-21-2004, 09:42 PM
I am not a fan of the 2370. I think there are a few others that would concur and some who love it.

HP,

You have both the 2397 and the 2344. I know you listen to a variety of horns for different moods. Could you describe the differences between them. I realize they are not interchangeable nor do they use the same drivers well, but I would be curious of your opinions about them.

Widget

Robh3606
06-21-2004, 09:54 PM
Well the spec gives that as the lowest but they don't give you a slope. It loads that low but I wouldn't use it that low but then again I haven't tried it that low either. I like being up at least 1/2 to an octave above the usable low limit at crossover so it doesn't unload on the bottom end. What kind of slopes??? Electronic or passive?? You could try 4 order would probably work better than 2nd order. That said it might work just fine. I use mine at 1.2K crossed from a 2123 10" midrange. I wouldn't mess with trying to integrate a 2404 either. At least not with a 2344. the 2344 will get you up to about 18K or so. Not worth the problems for the last 3k. But that's just me there are a couple of guys that either use that combo or have successfully integrated it. I would be concerned with matching the directivity at crossover with the 2404. A 2344 is a close match. Maybe at say 7K or so you may be able to juggle it but you would have to modify the stock 4430/4435 compensation. Leave out the inductor and juggle the cap value and a parallel resistor. I think a 2370 would definately be better down low but the directivity?? Horizontal may be OK. Vertical not even close. May not be an issue though. You can cross the 2404 low at say 5K-7K and see what the 2370 is doing there. As far as how a 2370 sounds?? Never had the pleasure. The only way to know is try it or clone an existing system. I don't recall all that many JBL systems with a 2404 over a 1" driver. I think most were over a cone midranges or 2" large formats in the Concert Series so the pickins may be slim to find a JBL network as a baseline.

Rob:)

Ian Mackenzie
06-22-2004, 12:00 AM
Henry,

I will try not to be too grung..sorry could not resist.

I assume you already have the 2426 driver.

The issue is then a good near field horn...look no further than the JBL 2344 , if you plan to use a JBL horn.

This driver is limited below even 1000 hertz for any monitor quality, its just too challenged to load up down there.

Rob is spot on, without knowing your woofer setup, the best bet is to get a 2123 or a 2118 mid and mate with a 2344 horn.

The 2397 is more a large format horn for mid field listening and then you have the expense of a 2441 etc.

If you opt for a 2307 you will need to add a 2405 slot.

Beyond that an Edgar horn could be useful.

In summary I am incline to think any close listening with a horn is best done above 1000 hertz with your driver.

Ian.

ps Back to being a grung buster...LOL



:bouncy:

Hofmannhp
06-22-2004, 06:00 AM
Originally posted by Mr. Widget
....HP,
You have both the 2397 and the 2344. I know you listen to a variety of horns for different moods. Could you describe the differences between them. I realize they are not interchangeable nor do they use the same drivers well, but I would be curious of your opinions about them.
Widget

ok Widget,
I will try to explain what my experiancies are.

The comparision is not perfect, cause I tested the systems not in standing beside each other (the project speakers are in my "living garage" and the 4435 in my living room).

2397/2328/2441:
tested with the project speakers (see early thread).
coupled at 900 Hz to 1. open end and 2. to 8kHz + 2402.
Wide dispersion and very smooth sound over the complete response also in the vertical plane, no horn sound, very honest human voice reality. Without 2402 and 8kHz lowpass there's the want for some eq for additional heights.

2397/2328/2441:
tested with the 4435 instead of the 2344, internal crossover without additional chokes, but with a little damping resistance.
coupled at 1kHz .
Wide dispersion and very smooth sound over the complete response also in the vertical plane, no horn sound, very honest human voice reality. I miss again a little heights, but with eq'ing it's perfect. I like it a little more then the 2344 with the right eq.
For my opinion the original set in the 4435 also needs a little push of 6dB for the UHF. (Widget I can now imagine how your "Westlake-like" cabs with the woodhorn sound.......great)

2397/2328/2327/2420:
tested with my project speakers.
smooth but some ups and down in the 1k to 4kHz section, good heights only in the axis spot. Again missing the 2405.


2309/2310/2441:
tested with the project speakers
Nearly as smooth as the 2397, but a little more mid sound (can easy be eq'ued) horizontal dispersion is fine, also as the vertical. Sameefficiency as the 2395 but needs also a 2402/2405.

2395/2441:
tested with the project speakers.
A little heavy mids between 800 and 1.5kHz but also smooth with a wide horizontal dispersion (no wonder with a 36" lens). a little more efficiency against the 2397 but a critical vertical dispersion with differencies between sit down and stand up. Also needs a 2402/2405. When using the 2402 +4dB eq for the heights is fine.

SHORT:
for living room, my vote is for the 2397/2441 + 2405. I like this a little more then the 2344/2427 as I wrote above. I think that also the original setup of the 4435 will get a little nearer to my taste with +6dB L-pad or an uhf driver.
For larger audits I like the 2309/2310 also as the 2395 (this looks so brutal nice) both carefully eq'ed and with 2405. Therefore I think about to add a switch in the crossovers for this driver and horn combos.

HP

HenryW
06-22-2004, 07:08 AM
Thanks so much to all for the thoughtful and experienced responses.

HP - your review will be printed for further look see - great stuff.

I have mentioned it here before, but here is what I will start with:

2225 (reconed 2205)
2425
2404

LF crossover is 3110 and HF crossover is 3105.

I have modeled the bass box and (Lo and behold) WinISD, Box Plot and Unibox all give me something akin to the JBL recommended enclosure. The horn section will be separate on top of the bass box and will house the crossovers as well. This gives me a bunch of freedom in tweeking the crossover and changing horns and drivers. Looks like a bunch of folks will tell me I shorted myself with the one inch mid and if I want this type of config I should go with a 2 inch - that option will remain available. I want the low freq to cross at 800hz (or nearby) due to the usable upper limit of the woofer being about 1200hz. A fourth order does seem a decent fit with a fairly extreme slope.

My intent is to build then measure and see what I have to do with Xover tweaking. I may find that the Xover points don't match my ear and head out shopping again (I treat this like a disease - I hide the purchases from my family, lie and say things were given to me and repeatedly say to the therapist that I am not near as bad as my friends - we need a twelve step program). Something stuck in the back of my head tells me I am close with this config, but the mids keep getting a soft thumbs down.

Good stuff here folks. With Giskard and others previous help I am beginning wood selection - I am thinking Cherry with Mahagony accents but could go Baltic Birch with cherry accents.

Hofmannhp
06-22-2004, 07:29 AM
Originally posted by HenryW (edited by HP)
......I have mentioned it here before, but here is what I will start with:
2225 (reconed 2205)
2425
2404
LF crossover is 3110 and HF crossover is 3105.
.

thanks for your kind words Henry,

..no one said that a 1" driver like the 2425 is a bad driver.
the system your'e thinking about is very near to one of my oldest system in use.

In 1980 I filled two Altec Valencia cabs with 2205H (new in this time) 2420, 2370 with DIY lens and 2405 added a DIY crossover and had (have) a very nice sounding system, which I frequently used for disco. The 2205 woofers aren't that bad for this cause they have a very dry and fast pulse answer instead of the deep res softedge woofers. Never cooked a speaker in this cabs working over 10 or more hours with extremly high level. They sound as good today and are lightly compact.

Try it with the above stated fine systems, figure out a good crossver and relaxe.


HP

Maron Horonzakz
06-22-2004, 07:43 AM
My first encounter with a wood SMITH horn was over 25 yrs ago. A friend of Paul KLipsch...George Ashworth had made his own Smith horns to sit on top of a Klipshorn. The unit was quite large about 30 wide. With a cut off of about 180hz . The driver was a JBL 375. He also had a smaller Smith horn sitting on top . A 1" version to use with smaller driver of that time. Thats how I got the Idea to incorperate a tiny Smith horn to sit on top of my JBL 2397. But you have to make your own coupling adapter to driver for the 1" smaller horn. On the larger Smith horn George was messing not only with 375 but also 2482 type phenolic diaphrams to xover at 300hz. Yes you can comfortably use these in your living room without being blown out of the house. very pleasing sound with very good dispersion....George was a MONO man. didnt think stereo would amount to mutch He had one unit upstairs & the other downstairs.

Hofmannhp
06-23-2004, 02:50 AM
Widget--->

Hi Widget,
as I know, you had (have) the project May drivers 435BE in your shop.
Can you tell us differencies comparing with the 2441 (and 2421) ? well knowing the usage of different horns.

HP

Tom Loizeaux
06-23-2004, 06:38 AM
I have been quite happy with the 2307 horn mounted behind the 2308 slant lens. This was a vary popular choice for JBL, as its used in many large studio monitors. Though there does seem to be a sweet spot, the lens seems to spread the 1" driver pretty well. A JBL 15, 1" compression driver with the 2307/2308 horn/lens, and a 2405 to finish off the top is still a very nice combination. The obvious improvement is adding a 10" mid as JBL has done on the 4343 speakers.
Others here have done many A/B tests, so I would listen to their opinions, have a listen to the above combination from JBL, and go from there.

Tom

Alex Lancaster
06-23-2004, 06:56 AM
Tom:

There is no real bass JBL 15" that will go up to 1200Hz, to match the 2307īs cutoff, either You use a 2312 (H92) 800Hz, or, as You say a 10", or even better IMHO an 8".

Alex.

Robh3606
06-23-2004, 07:57 AM
Yeah a 2118 is a nice driver. Make a nice midrange driver.

Rob:)

Mr. Widget
06-23-2004, 12:53 PM
Originally posted by Hofmannhp
Widget--->

Hi Widget,
as I know, you had (have) the project May drivers 435BE in your shop.
Can you tell us differencies comparing with the 2441 (and 2421) ? well knowing the usage of different horns.

HP

Unfortunately I never fired up the 435Be drivers. While I had them I was so busy with 12 other projects I never had time to set up a decent test to do that comparison with CD EQ and all so I decided I didn't want to do it in a half assed fashion.

As for the 2421s I don't currently have any 1" drivers.

I wish I had done the 435Be H9800 horn comparison with the 2441 Westlake combo. I hope to do it at some point in the future.

I am currently trying to get a pair of TAD 4001s to try out on the Westlakes. According to Oldmics that combo is about as good as it gets.

Widget

JonFairhurst
06-24-2004, 02:27 PM
I used to have the 2307/2308 combination. I found it fine for live use - I could leave off the lens for a long throw, but I never liked the sound at all in smaller spaces.

The 2344As (and my alder versions) sound much smoother to me. I do miss the UHF range a bit, but with a bit of EQ I'm happy.

I'd love to get my hands on the top end from the 9800s though. Nice main horn and a UHF horn in close proximity. I heard them at CES in 2003 and loved the top-end sheen.

-Jon Fairhurst

Jan Daugaard
06-25-2004, 03:19 AM
I have a 4.0 surround sound system composed of 2 pairs of S3100, and they contain a 2426H compression driver mounted on a H2600 horn.

The H2600 is asymmetric and is intended to provide a large sweet spot, but the opposite is the case in my experience. There is, however, one significant advantage to the asymmetry, namely that they can be placed in corners to boost the bass -- the horn has so little radiation to the one side that there will be no annoying reflections from the adjacent wall.

There is extensive equalization built-in to the cross-over, and the result is fine, as long as I'm sitting exactly in the middle between the 4 speakers.

Robh3606
06-25-2004, 08:25 AM
Hello Jan

Wow so they don't throw a large image?? I wonder how they compare to the Everest horn. Can see they look similar. How is the imaging in the sweetspot?? Can you get up close or does the image fall apart in close?? How far away are you?? You can move around some what right??

Rob:)

Jan Daugaard
06-25-2004, 10:38 AM
The horizontal polar response for the H2600 horn is the best answer to your questions, Robh3606.

Jan Daugaard
06-25-2004, 10:48 AM
... and here is the horizontal polar response for the Everest. The upper cross-over frequency is 7500 Hz, so the polar response above that frequency is that of the 2405H.

Ian Mackenzie
06-25-2004, 01:22 PM
Does any one use the Edgar Horns?

I realise this a slightly off topic but they do have a following among horn lovers.

Ian

Mr. Widget
06-25-2004, 02:41 PM
I don't use or abuse them, but I have heard them on several occasions and have liked them.

I made a pair of my Westlake clones for a silent forum member who was using the 2" salad bowls and his initial response was that the Westlakes were smoother, less forward sounding, and very open sounding. I haven't talked with him since he first got them so I don't know if that was a temporary infatuation (we've all been there with a new speaker) or if he still preferred the Westlakes. He was using both horns with 2441s.

Ikecarumba has had a variety of Edgar and other tractrix horns. He is definitely a tractrix advocate.

Widget

Robh3606
06-25-2004, 02:52 PM
I have heard the salad bowls with 2441's too. They sure sounded nice!

Rob :)

Robh3606
06-25-2004, 02:55 PM
Hello Jan

Looking at the plots you toe them in at all?? Looks to me like in close or close together you can miss the boat with them. Everest horn's look like they cover a wider area.

Rob:)

HenryW
06-26-2004, 06:37 AM
I was very impressed with a salad bowl and a 2426. When I decided to have the box take a variation on the traditional look it dropped from my consideration. However, It made me sketch a possible next project - they would sound great and look kinda neat as a couple of freestanding stacked horns on top of a bass horn bin (just what I need - complicate project 1 with thoughts of project 2)

Bernard Wolf
06-28-2004, 12:34 PM
[QUOTE]Originally posted by Jan Daugaard
[B]I have a 4.0 surround sound system composed of 2 pairs of S3100, and they contain a 2426H compression driver mounted on a H2600 horn.

The H2600 is asymmetric and is intended to provide a large sweet spot, but the opposite is the case in my experience. "

I have to correct you on this statement Jan - I too have the 3100 and the CD lens is meant to provide a large listening area wherein which it is possible to get a stable image off axis. This, the 3100 it does admirably. Nothing worse - especially in a home cinema set-up - than to only hear what is coming out of the speaker directly in front of you. The sweet spot is still for one person only though, as in every other speaker in existence.



"There is, however, one significant advantage to the asymmetry, namely that they can be placed in corners to boost the bass -- the horn has so little radiation to the one side that there will be no annoying reflections from the adjacent wall".

I like to listen to mine set up out in the room and away from room boundaries but there is no dening the advantage they posses in confined quarters.

Bernard

Bernard Wolf
06-28-2004, 12:54 PM
Originally posted by Robh3606
Hello Jan

Wow so they don't throw a large image?? I wonder how they compare to the Everest horn. Can see they look similar. How is the imaging in the sweetspot?? Can you get up close or does the image fall apart in close?? How far away are you?? You can move around some what right??

Rob:)

Hi Rob - as I have the s3100 I can answer some of these questions for you. They throw a sound stage as least as wide as they are apart which in my case is 9' center to center. Also, as I fire mine across a corner and about 10' out from the corner I also get at least that much stage depth. When I kick in my side/rear mounted hafler rear speakers - which is a small 2-way grundig speaker - I get a 15-20 ' soundstage !! The imaging is fantastic, and don't take my word for it. For what it is worth, Dominic Baker who now heads up JM labs development dept. in his July 1996 Hi-Fi World review of the S3100 said " it (3100) has qualities that place them on par with Quad ESL 63s in my opinion. They are completely different from the Quads, their strengths lying in other areas, but the level of fidelity is similar. Both the 3100 and the Quads image especially well; both are a reference to others in this respect". I concure having owned ESL 57s.

I can get as close a s a 3-4' before the image dissapears and as I mentioned in a previous post I can sit well off center and still enjoy a credible soundstage. A great accomplishment. I'm surprised they stopped using this design. The only dowside I can think of is that because of the directionality of the horn one does not hear as much of the room. Many would find this to be a plus but I am experimenting with rear firing ambience retreaval super tweeter to quite good effect to offset this for my taste.

Bernard

Bernard

aust-ted
07-02-2004, 02:52 AM
Hi

I have read this thread late but have found it most interesting as I was intending to construct a pair of conical horns to go with a pair of 2451s.

Currently my system is comprises

Dual 2235H in
2450/ 2380A
2404

with active xovers at 800Hz and 5Khz

This is my first JBL system and I have been impressed by it. However I have yet to try other mid horns.

Firstly has anyone else tried the 2380, or its big brother the 2360, CD horns in a home environment?

Secondly I want to get the bass/ mid xover point out of the critical listening range if possible. Therefore I intend to build conical horns with a 500 Hz capability and even try 300Hz with 2482s as Maron has raised. However I have been advised that to minimize mouth distortion I should aim at around 30 inch for the mouth width for 500Hz .

The objective behind the conical horns is to reduce mouth distortion and frankly they should be easier to construct.

Any suggestions/ comments?

Ted

Ian Mackenzie
07-02-2004, 03:11 AM
You may wish to email or pm to Steve Schell, he is a horn fanatic.....

Ian:)

Robh3606
07-02-2004, 05:40 AM
Hello Aust-ted

Well if you can't do the horn for size look at the 10" drivers in that range. Either a 2122 or a 2123 could get you through that 300hz-1.3k range without the space issues.

Thanks Bernard


Rob:)

aust-ted
07-02-2004, 06:28 AM
Rob

Thanks

I am aware of the benefits of using the 10" or like as an upper bass etc especially if you make it a 4 way like some of the better JBL monitors.

However space should not be a problem. I have made my twin 15" cabs fairly deep (about 4ft) and low (about 2 ft high) so I can put the horns on top and keep their centre at ear level. The cabs are about 15 cu ft ea. They are made out of 1 1/2" veneered particle board with a lot of internal bracing.

I am keen to retain high efficiency which was a main reason for going to twin 15" drivers as I am using a mimiscule fraction of their power handling. However I am currently using a Perreaux 6000B commercial mosfet amp (500W at 4 ohm) for the bass and a 17w triode wired Leak St 50 tube amp for the mids. I suspect I rarely put more than a few watts into any of the drivers.

I have a copy of a construction article on conical horns which I believe originates from Peavey. Another option is to make a pair of2360 wooden CD replicas (I have the throats). Or make a Tractrix like the Edgarhorn salad bowl. As I am a relative novice, I would appreciate any advice or suggestions on these or other options.

Regards
Ted

Ian Mackenzie
07-02-2004, 06:46 AM
Ted,

There are many ways you can do this.

An option as per a Kilipsch modifcation to change out their mid horn was to use 2 x 2123 drivers , this gives very high sensitivity, over 100 db. You could still use your tube amps and maintain accuracy of a cone.(The 2123's do turn up on ebay a bit) .

Ian

aust-ted
07-02-2004, 07:16 AM
Ian

Thanks

I have heard very good things about the 2123.

However at this stage I would like stay with three ways and 24xx series compression drivers for mids as I have acquired some.

One of my motivations with considering 2451s with conical horns is that I understand you can do away with the tweeter and go to a two way. From reading posts by Dr Earl Geddes on the DIY forum and from his book, I understand the use of conicals with their greater expansion rates give less throat distortion which from my layman's perspective I understand provides for a better HF response from a driver such as the 2451 on a conical horn, or have I got this wrong?

Regards
Ted

Mr. Widget
07-02-2004, 10:22 AM
My understanding is that conical horns, that is horns with a conical rate of expansion as opposed to exponential or tractrix rates and not to be confused with the conically shaped exponential horns JBL used to use with the 10" slant plate lenses, have some theoretical advantages with lower throat distortion but they have a very high HF roll off. I haven't read Dr Earl Geddes' work, but he must be using significant equalization in conjunction with his horns if he is suggesting you can use a conical horn in a two way.

I will look him up and check out his work as you have piqued my interest.

Widget

aust-ted
07-02-2004, 04:01 PM
Mr Widget Wrote in part >"My understanding is that conical horns, that is horns with a conical rate of expansion as opposed to exponential or tractrix rates and not to be confused with the conically shaped exponential horns JBL used to use with the 10" slant plate lenses, have some theoretical advantages with lower throat distortion but they have a very high HF roll off. I haven't read Dr Earl Geddes' work, but he must be using significant equalization in conjunction with his horns if he is suggesting you can use a conical horn in a two way. "

Hi Mr Widget

My understanding, which is limited at this stage, is that you are correct. Conical horns do require equalization as do the 2380 and 2360 Constant Directivity horns. However I thought the equalization was linear and easy to implement but I have not tried it yet. My JBL active xover has equalization in built for 2380 and 2360 CD horns

I must clarify that it was not Dr Geddes that suggested I try two way. However he has contributed to discussions on the DIY forum where he has discussed the issue of conical horns which he calls waveguides. He certainly discussed the question of throat distortion.

He also kindly responded to a query I emailed him on the subject and I have since purchased a copy of his book though I am yet to fully absorb it.

A local retired sound engineer suggested I try 2451s with conical horns as a two way. I understand that some of the more recent JBL horns are described as Progressive Transition Waveguides (eg PT- H95HF) and are essentially conical . These are discussed in JBL Technical Notes Vol1 #31 which I downloaded from the JBL Pro web site.

Also your observation re "conically shaped exponential horns JBL used to use with the 10" slant plate lenses" is spot on. Dr Geddes recently made a post on the DIY forum in which he referred to difraction horns negatively. Dr Geddes wrote "Diffraction horns sound the worst, being obviously flawed by all of the internal reflections and non-planar wave propagation that result from the diffraction points, this is widely acknowledged." I understand that the slant plate lenses are what he is referring to. Hope I got that right.

Regards
Ted

Regards
Ted

Mr. Widget
07-02-2004, 06:29 PM
Originally posted by aust-ted
Dr Geddes recently made a post on the DIY forum in which he referred to difraction horns negatively. Dr Geddes wrote "Diffraction horns sound the worst, being obviously flawed by all of the internal reflections and non-planar wave propagation that result from the diffraction points, this is widely acknowledged." I understand that the slant plate lenses are what he is referring to. Hope I got that right.

Regards
Ted

Regards
Ted

Could be, but it is most likely he is referring to diffraction horns like the EV 8HD diffraction horn or perhaps even the JBL 2397 which is also a diffraction horn. I would agree with him about the EV and many others, but disagree about the 2397. I don't doubt that the theoretical disadvantages of the diffraction principle may be valid, but in practice the 2397 is a fine sounding horn.

The conically shaped exponential JBL 2307, 2311, and 2312 use the 10" slant plate lens that uses the principles of a diffraction gradient to guide the sound waves. These are not diffraction horns, but do have many reflections and do have their detractors.

Widget

Ian Mackenzie
07-03-2004, 01:59 AM
To as spice to your posts, this is certain to cause some more replies.......here are some measurements of the 2307 exponential horn with and without the 2308 lense.

The measurements were done near field and all room reflections were time gated out of the near field. The horn is mounted in the 4345 baffle and feeb via the passive network.The other drivers have been padded fully down.

Note the straight horn is remarkably smooth with a slight rise after 6000 herts, the divisions are 6 db so this is very flat for any horn.

Ian

Ian Mackenzie
07-03-2004, 02:19 AM
This curve is with the 2308 lense under identical measurement conditions.

The sensitivity overall is lower somewhat and there appear lots of ripples in the response. I have not done any detailed listening tests to confirm any audible difference yet. I will do that in the morning as Sunday is a JBL day.

Ian

aust-ted
07-03-2004, 02:44 AM
Ian

Thanks Very Interesting

On a separate but related point, I acquired a pair of 2309 horns some time ago, unfortunately without the 2310 lenses. I am intending to play with them when time permits but was hoping to pick up the lenses separately or home make something that approximates them.

Just looking at the horns gives me the impression that without the lenses that they would be very long throw and not suited to home use. I assume the 2310 lenses purpose is to make the horns more useful for nearfield and off axis listening? I am aware these are different to the slant plates you are discussing but again I suppose the purpose is similar. Have I got that right?

Regards
Ted

aust-ted
07-03-2004, 02:53 AM
Ian

I forgot to comment on the obvious lifted 2307 lower freq response you obtained with the lens even though, as you comment, the horn with out the lens has a much smoother response in the 1.5k to 9k freq range. I assume this lifted low freq response relates to an apparent larger mouth brought about by the lens.

Regards
Ted

Ian Mackenzie
07-03-2004, 05:16 AM
Ted,

The LF anomally is a glitch in my measurement system regards gating the LF artifacts.

I would suggest this horn is a near/mid field device.
I have no experience with the 2310 lens

Now, we have played the with and without lens scenario tonight and without a doubt in this instance the exponential horn alone is a non starter!.

Firstly, we compared in the near near field with/without lens and could not detect any degradation of acoustic transmission.

In the near field secenario without the lens it could be likened to a very listenable 604 duplex with the honky effect as soon as you moved slightly off axis without the lense.

We then changed out the lens a number of times with the complete JBL 4345 monitor system operational.

The effect of the lens was more of the spatial imaging (realism of presentation) than of tonality. Without the lense it as likened to a 1950's radio!!

With the lens in place, the overall accuracy, imaging and sound stage improved remarkably in IMHO.

So from the data presented above, it would appear that response measurements alone are not a deciding factor of system subjective performance.

Clearly, there is much to learn about the application of horn loading.

Theses are the impressions gained from a JBL engineered monitor and may not apply to other specific applications.

Ian

aust-ted
07-03-2004, 05:55 AM
Ian

Thanks for the further insights. Your listening experience with and without the lens is most interesting but I suppose comes as no surprise as JBL must have put a lot of thought into the design at the time. Would have been very surprised if the horn functioned better without the lens.

Perhaps someone can explain why the lens contributed so much to spatial imaging. I assume you tried this with both horns in a stereo pair.


I believe your response measurements are valuable, and from my limited capacity to comprehend, probably support Dr Geddes' conclusions.

On the other hand it is probably unfair to consider the 2307 without the lens as a useful horn in its own right. As you probably know better than I there would be a number of other measurements you would have to undertake (eg off axis response) to determine whether a 2307 sans lens is useful for home listening. I am not suggesting these tests be done as it appears from your subjective listening that the off axis results, for example, would probably be woeful.

On the other hand I am confident that a properly designed and used conical horn or waveguide would be a different game altogether. I am hoping that there are other members of this forum who have first hand experiences with them.

Regards
Ted

Ian Mackenzie
07-03-2004, 05:22 PM
TEd,

Here are the JBL specson the 2307/2308 combination.

Like most thongs there is a trad off somewhere.

In this case the horn does not have a constant power response with increasing frequency liek the new bi radial horns. Thus it its not possible to equalise for flat on axis and off axis response with this design.

JBL played to this shortcoming when the 4430/35 monitor was development with the then new 2344 bi radial horn in a white paper in the AES in the early 1980's. The design features of this monitor and the new horn were attractive at the time for reasons of studio acoustics and equalisation preferences. Interestingly JBL never marketing the 2344 horn in a consumer design to the home market.

There is much debate as to how important flat power response is in in the home listening environment. I suppose again its a preference thing but the ability to control and direct a sound field with a horn has a lot of merit.

Ted , I look forward to hearing more about your project

Ian

aust-ted
07-04-2004, 06:28 AM
Hi Ian

Would not mind getting a pair of 2344 to play with. Perhaps I should try to replicate a pair in wood as I believe Jon Fairhurst has done with his beaut pair that I saw in this thread. I suppose you really need a live one first though to copy accurately.

BTW I believe you forgot to attach the JBL specs on the 2307/2308 to your last post. Would not mind looking at them if possible. They do not appear to be on the JBL pro site.

The relevance of flat power response to the home listening environment is something I am not qualified to comment on.

I would appreciate any advice contributors this forum could provide on it though. I assume the Constant Directivity (CD) horns such as the 2360 and 2380 have a similar objective.

All I can comment is that my 2380A horns coupled to the 2450 drivers provide a pretty good midrange sound but I do not have the experience to compare them to other horns discussed in this thread. I have read in other places both positive & negative comments about the 2380 in the home environment. Virtually nothing about the huge 2360s which must have a poor spouse acceptance factor but which can easily go down to 500Hz . Has anyone on this forum tried them?

I would be happy to keep you in touch with my proposed conical horn project but you will need to be patient as I have yet even to decide on how to attack it.

Regards
Ted

Ian Mackenzie
07-04-2004, 07:11 AM
Horns specs

Sorry, operator error.

Ian

Robh3606
07-04-2004, 07:58 AM
Hello Aust-ted

One of the things I like about a horn with flat power response is the balance of the speakers does not change as you change positions on the room. I have a Urei based coax 801C center channel that uses an "exponential horn?". Their is some EQ built into the crossover but the majority of the on axis balance is from the result of the increasing directivity of the horn. It has a very well defined listening window. If you move both inside and outside the window you can hear the balance change. On the the 2344's I use on my mains you have to go way off axis to hear this. It is also much less pronounced. I have not compared the 2344 to the 2307/H94 set-up I have but will shortly once I get my cabinets done. I will post my impressions when I do.


Rob:)

Guenter
07-04-2004, 07:18 PM
[QUOTE]Originally posted by aust-ted
[B]Hi

Firstly has anyone else tried the 2380, or its big brother the 2360, CD horns in a home environment?

Hi Aust-ted, you may want to check this forum for posts by
'Dieter' who has the 2360 horns and appears knowledgeable in that he has successfully, apparently, implemented them in his near-field environment.
I am myself dithering with my home brew system with midbass
and without and am now also - seeing that Dieter seems to have implemented them without problems. I particularly like the aspect of minimizing the system's electronics overall. specifically I believe to implement a 4-way system successfully needs much skill - which sadly I don't believe I have even with my impulse-type measuring system.

- cheers, Guenter

aust-ted
07-05-2004, 01:48 AM
Guenter

Thanks Good tip. Had a good read of Dieter's posts to the forum. Gave me some hints re my earlier post about designing passive xovers for CD horns. Will try to contact him to see what his latest developments and listening impressions are.

Dieter's speakers certainly look good and are one way to get an acceptable SAF. I am really surprised that more people on this forum have not used 2360s. They can be picked up cheaply on eBay even thgough I gather they were originally very expensive.

I actually bought a pair on eBay along with a pair of 2450s from a guy in LA but had to leave the horn bells behind because shipping to Australia would have cost much more than the horns were worth. I have the throats and have not completely given up on fabricating a pair from wood.

The difference between Dieter' bass speakers and mine are essentially mine are close coupled, both close to the floor with the top of the cabs less than 2 ft from the floor. I chose this configuration hecause I had spots wide enough and I want to be able to have the horns centred at my ears in the horizontal plane if possible regardless of whether I go the 2360 or conical horn route.

Has anyone tried mounting a HF driver (eg 2405) in the centre of the mouth of a large format horn?

Regards
Ted

Guenter
07-05-2004, 07:17 AM
[QUOTE]Originally posted by aust-ted

Has anyone tried mounting a HF driver (eg 2405) in the centre of the mouth of a large format horn?

Excellent idea!! ... never thought of it .... when I get my 2460's I will definitely try to do just that.

cheers

aust-ted
07-14-2004, 06:44 AM
Originally posted by Mr. Widget
My understanding is that conical horns, that is horns with a conical rate of expansion as opposed to exponential or tractrix rates and not to be confused with the conically shaped exponential horns JBL used to use with the 10" slant plate lenses, have some theoretical advantages with lower throat distortion but they have a very high HF roll off. I haven't read Dr Earl Geddes' work, but he must be using significant equalization in conjunction with his horns if he is suggesting you can use a conical horn in a two way.

I will look him up and check out his work as you have piqued my interest.

Widget

Widget

I just found a web reference to a paper describing Charles Hughes " Quadratic - Throat Waveguide which helped spike my interest in conical horns. It is at http://aa.peavey.com/downloads/pdf/qwp1.pdf

Because they are straight sided, I have assumed these waveguides are essentially conical horns.

It also gives a summary of other horn types and constructional details which I am tempted to try.

My apologies if it is well known to members of this forum

Regards
Ted