2397 taper and lip [Archive] - Lansing Heritage Forums

Wardsweb

03-14-2011, 12:51 PM

Ruediger

03-14-2011, 01:31 PM

I think the shape of the lips is simply to achieve exponential growth in horn area.

A large mouth area is needed at low frequencies, to minimize reflections.

A narrow slot will improve diffraction, but You don't need much in the vertical plane.

I think JBL even recommends to add a kind of baffle.

Ruediger

Mr. Widget

03-14-2011, 01:55 PM

The original JBL lip is rounded. Widgets had a little more taper but still rounded.Widget's were an exact copy of a pair of "factory" 2397s I have... of course I did add an additional flat extension as suggested in the JBL data sheet. :D

As for the differences between the 2397 and the "Westlake" horn, based on the original Westlake horn that I borrowed and the original 2397s I have, the actual dimensions of the two horns and vane spacing is different between the two horns. Sonically listening to one or the other I didn't notice much of a difference, but the aesthetics of the Westlake is pretty hard not to like. The picture you posted is some sort of hybrid. The real Westlake horns and every clone I have made have a very sharp edge at the front lip. The chamfer at the front is close to but not exactly 45°.

Widget

Wardsweb

03-14-2011, 02:05 PM

Widget's were an exact copy of a pair of "factory" 2397s I have... of course I did add an additional flat extension as suggested in the JBL data sheet. :D

As for the differences between the 2397 and the "Westlake" horn, based on the original Westlake horn that I borrowed and the original 2397s I have, the actual dimensions of the two horns and vane spacing is different between the two horns. Sonically listening to one or the other I didn't notice much of a difference, but the aesthetics of the Westlake is pretty hard not to like. The picture you posted is some sort of hybrid. The real Westlake horns and every clone I have made have a very sharp edge at the front lip. The chamfer at the front is close to but not exactly 45°.

Widget
Yes your Westlake are pure art and beauty. From what I can tell, these are DIY Smith horns that someone cut a beveled edge into. I just didn't know if it made any real difference or if it was a personal taste kind of thing. You know me, esthetics are very important.

Lee in Montreal

03-14-2011, 02:09 PM

I am currently working on producing repros and the only thing I have slightly changed from the original design is the progression after the fins. I have tried to keep a continuous "expansion" rate instead of the flatter one. My understanding is that when the 2397 was produced, they didn't have the technology to make a nice curve toward the mouth. They didn't have CNC back then.. I am putting a 14" radius that starts right where the fins ends instead of just rounding of near the mouth. Looking at progression curves, it makes way more sense. Just my 2 cents.

As far as the Westlake horns look, I can't do but concure that they look like :eek:ss.

Wardsweb

03-14-2011, 02:21 PM

Lee in Montreal

03-14-2011, 02:35 PM

Are you still on track for a early summer release for distribution?

Yes, I expect to be on time, and even possibly early. Production is only 3 weeks but I am currently over my head with my core business. But hey, the goal is to be accurate, sexy and and above all: cheap. I will also be able to compare with a set of 2350 and Emilar 500.

BTW Can an expert explain why each center path is 22 degrees apart, but the ones on each end are 21 degrees? There must be a reason, but it makes no sense. I made them all at 22 degrees.

John

03-14-2011, 05:01 PM

I going to build some 2397 from bubinga. I'll practice on some MDF before I hit the hardwood and have a question on the lip of the horn. The original JBL lip is rounded. Widgets had a little more taper but still rounded. What difference would be created from having a sharper edge like a Westlakes? Should I just try to duplicate Widgets, as I know they are tried and tested?

I not sure if your aware that when Widget cloned the westlake's, he was borrowed a early example of the large westlake horn for reference. Westlake's current large wooden horn as found in the SM-1 is a bit different. :blah:

yggdrasil

03-15-2011, 09:08 AM

I am currently working on producing repros and the only thing I have slightly changed from the original design is the progression after the fins. I have tried to keep a continuous "expansion" rate instead of the flatter one.
Be sure to measure the altered horn before you produce too many of them.

AFAIK the parallell top and bottom of the Smith horn is there for a reason - vertical dispersion if I'm not mistaken.

Mr. Widget

03-15-2011, 11:04 AM

I not sure if your aware that when Widget cloned the westlake's, he was borrowed a early example of the large westlake horn for reference. Westlake's current large wooden horn as found in the SM-1 is a bit different. :blah:Yep... I am not sure of all of the changes that Westlake made, but the two I do know are that the height of the horn got taller and they did away with the JBL 2328 throat. I imagine that these two changes are related. I wouldn't be so sure that the change was for improved sonics as much as the cost of manufacture though it may have made an improvement in the narrow range Westlake asks their large horn to cover.

Be sure to measure the altered horn before you produce too many of them.:yes:

I'd proceed very cautiously in making any changes. Every "modification" I made over these tried and true designs produced inferior results. Another thing to consider... the majority of horns out there sound like... well, like horns. If you like that, great, but most of us have gravitated towards the 2397 or Westlake horns because of this lack of coloration.

Widget

pos

03-15-2011, 11:42 AM

Widget, with the experience you now have regarding the array1400, S9900 and D66000, do you still find the smith horn superior to the biradials? (when used with a supertweeter)

Lee in Montreal

03-15-2011, 11:45 AM

Be sure to measure the altered horn before you produce too many of them.

AFAIK the parallell top and bottom of the Smith horn is there for a reason - vertical dispersion if I'm not mistaken.

Don't worry. First batch is only 16 units (or 8 sets). Top and bottom indeed remain parallel to each other. Only the progression at the mouth will change.

I am just back from the CNC wood shop. Wood of the first batch will be 3/4" High Density Fiber. Fins are still aluminum. Kit to be stained, varnished and assembled at home. Timeline for the first pictures is 3 weeks from now. I will probably lend a set or two for those wanting to take audio measurements.

Mr. Widget

03-15-2011, 11:50 AM

Widget, with the experience you now have regarding the array1400, S9900 and D66000, do you still find the smith horn superior to the biradials? (when used with a supertweeter)The 1400 Arrays are in my living room playing as I type this. My 2397s and my beautiful Westlake clones are tidily packed away in my attic.

Don't worry. First batch is only 16 units (or 8 sets). Top and bottom indeed remain parallel to each other.Only :D

That is about how many I produced in total. I actually never counted but I certainly made less than 10 sets. But then I spent weeks just selecting the wood. For those who haven't guessed, I am very picky. ;)

Widget

Wardsweb

03-15-2011, 01:38 PM

The 1400 Arrays are in my living room playing as I type this. My 2397s and my beautiful Westlake clones are tidily packed away in my attic.

Widget
Attic :( that seems like such a waste. At least, I've got pictures of them to motivate me on building mine.

Lee in Montreal

03-15-2011, 02:40 PM

That is about how many I produced in total.

With automated CNC production, making a pair or making 8 sets would amost be the same cost. So why not share.. :D

I visited the CNC wood shop and we agreed on a production operation to achieve a nice curve near the throat. I saw some exemples that required minimal hand sanding to smoothen the stepped process. Just waiting for a cost estimate to actually start production. I saw your draft, as well as a French draft. There were some small discrepencies at the throat width. Not much. I just used both drafts, and made them more "logical" (equal 22° between each pathway, and a constant geometrical progression, not flatted after the "fins"). I make no claim as being the most this, or the uber that. I am just experimenting with a production process while having fun. ;)

Wardsweb

03-15-2011, 02:52 PM

With automated CNC production, making a pair or making 8 sets would amost be the same cost. So why not share.. :D

I visited the CNC wood shop and we agreed on a production operation to achieve a nice curve near the throat. I saw some exemples that required minimal hand sanding to smoothen the stepped process. Just waiting for a cost estimate to actually start production. I saw your draft, as well as a French draft. There were some small discrepencies at the throat width. Not much. I just used both drafts, and made them more "logical" (equal 22° between each pathway, and a constant geometrical progression, not flatted after the "fins"). I make no claim as being the most this, or the uber that. I am just experimenting with a production process while having fun. ;)

Keep us updated, I may get a pair. Then I can compare yours and the Smiths I build. I don't see a down side to having two sets of horns. :D

Lee in Montreal

03-15-2011, 03:15 PM

I don't see a down side to having two sets of horns. :D

I am going to have some JBL 2350, some Emilar EH-500 and these neo 2397... So, I am also for variety. :D

Mr. Widget

03-15-2011, 03:58 PM

With automated CNC production, making a pair or making 8 sets would amost be the same cost. So why not share.. :DEspecially true using MDF... I only used hardwoods, almost exclusively walnut and finding nicely figured 8/4 walnut in clear wide planks took a bit of hunting.

I was also using a CNC, but mine was only large enough to cut half of a horn at a time.

I do think the aluminum fins will add a bit of luster to them... looking forward to seeing them. :bouncy:

Widget

Wardsweb

03-15-2011, 04:27 PM

I do think the aluminum fins will add a bit of luster to them... looking forward to seeing them. :bouncy:

Widget

Especially after a full mirror polish. Maybe even forgo the hardwood and do a black piano finish on the mdf. Now that would be sweet. :hmm:

Mr. Widget

03-15-2011, 04:32 PM

Especially after a full mirror polish. Maybe even forgo the hardwood and do a black piano finish on the mdf. Now that would be sweet. :hmm:Mirror polish and gold plate them along with piano black and it will look like something from MBL... not really my flavor but quite an eye popper.

I think I'd go with satin black and brushed aluminum. :bouncy:

Widget

Lee in Montreal

03-15-2011, 04:48 PM

BTW MrWidget, I am pretty sure you have also noticed the discrepency on JBL's own litterature where they spec 2-1/8" as overall thickness of the 2397. The 2338 throat has 1-3/8" vertical opening that should match the 2397. If the 2397 was indeed 2-1/8" thick as stated in the litterature, then that would mean the plates are only 3/8" thick, which makes no sense...

50465

John

03-15-2011, 05:03 PM

Yep... I am not sure of all of the changes that Westlake made, but the two I do know are that the height of the horn got taller and they did away with the JBL 2328 throat. I imagine that these two changes are related. I wouldn't be so sure that the change was for improved sonics as much as the cost of manufacture though it may have made an improvement in the narrow range Westlake asks their large horn to cover.

Widget

Yes I know that they increased the height. And dropped the use of the 2328 throat. I am not sure if it was to lower cost? When ever Westlake is mentioned on this forum it is often stated that their philosophy is accept no compromises and cut no corners.:hmm:

If they did decide to go cheap, they sure did not pass on the savings to their loyal customers:no_wag:

I can tell you that they replaced the 2328 with a plate made from aluminum to attach the driver to the rear of the horn. This plate is 1/2" thick with a hole that acts like a throat extension to the driver. You simply secure the plate to the driver and then secure the plate to the horn.

I would have to measure my westlake horn again, but from memory I think the height between the top and bottom plates of the new design was 2":)

They use this horn on the Reference series SM-1, TM-3, HR-1,:cheers:

Mr. Widget

03-15-2011, 05:07 PM

When ever Westlake is mentioned on this forum it is often stated that their philosophy is except no compromises and cut no corners.:hmm:With all due respect to the folks at Westlake, I am not so sure that every one of their decisions has their loyal customers' best interests in mind.

BTW MrWidget, I am pretty sure you have also noticed the discrepency on JBL's own litterature where they spec 2-1/8" as overall thickness of the 2397. JBL's literature is full of misprints. That is hardly surprising.

BTW: Did you do a search and pull up one of my posts that has a accurate section view of the lip? Wardsweb asked me for a copy of the drawing, but I couldn't find one... I know I have posted it here a couple of times. I believe at least one was a full sized pdf.

Widget

Wardsweb

03-15-2011, 07:19 PM

BTW: Did you do a search and pull up one of my posts that has a accurate section view of the lip? Wardsweb asked me for a copy of the drawing, but I couldn't find one... I know I have posted it here a couple of times. I believe at least one was a full sized pdf.

Widget

Here is the thread with the full size Westlake PDF:

http://www.audioheritage.org/vbulletin/showthread.php?28146

Mr. Widget

03-15-2011, 09:03 PM

Here is the thread with the full size Westlake PDF:

http://www.audioheritage.org/vbulletin/showthread.php?28146That is a bit embarrassing... it was only a year ago and I didn't even remember creating or posting the drawings comparing the Westlake and the 2397. :o:

Well... it is certainly all there. Everything needed for anyone wanting to create either horn. You do need to provide your own 2328s though.

Widget

Wardsweb

03-15-2011, 09:24 PM

Well it looks like I'll be making my own vanes now. I pulled out the vanes I got from Bill Martinelli years ago and they only measure 6-1/4" long and 13/16" tall. They must have been for a smaller "smith" horn, maybe for a tweeter.

http://wardsweb.org/audio/JBL_C50/martinelli.jpg

Wardsweb

03-15-2011, 09:52 PM

Anyone remember this DIY from around 2005 on making the vanes? Was this here?

http://wardsweb.org/audio/JBL_C50/e0f4.jpg

http://wardsweb.org/audio/JBL_C50/e924.jpg

JeffW

03-16-2011, 07:56 AM

I bought a pair of horns that were made by "John W". I think they are Smith clones, or close to it, a 2328 will bolt up to them.

I think it's interesting that "John" above mentions the different adapter used as being just a flat plate. I made some flat plate adapters out of 3/4" plywood to mount a 3 1/4" bolt circle driver onto this pair.

The actual opening in the back of these horns is 1 1/2" X 4", so it's a hair wider than the slot in a 2328, but it makes it match up good with a 1 1/2" opening throatless driver. I am using the 435AL, I'm not sure the larger diameter 2452 would fit without counter-sinking the bolts that fasten it onto the horn.

Anyway, a 1 1/2" holesaw and a 1 1/2" wide chisel made short work of this, but I wouldn't use ply if I did it over again. I just wanted to see how the throatless driver worked on these horns and that's what I had handy. The 3/4" thick material allows the angle of the back of the horn to continue right down to the edges of the 1 1/2" hole, where it's very thin. You can see the entire bugscreen looking down the edge of the horn.

Anyway, I think they sound great, but since it's such a one-off niche application I haven't bothered to do any measurements.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=50272&d=1299305933

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=50270&d=1299305909

4313B

03-16-2011, 08:07 AM

That is a bit embarrassing... it was only a year ago and I didn't even remember creating or posting the drawings comparing the Westlake and the 2397. :o:

Well... it is certainly all there. Everything needed for anyone wanting to create either horn. You do need to provide your own 2328s though.I'm patiently waiting for you to come up with the drawings for us to make our own H4338 horns... I need a third one for my center channel.

Anyway, I think they sound great, but since it's such a one-off niche application I haven't bothered to do any measurements.Well, it could be nice to see how that short phase plug driver behaves on your horn.

1audiohack

03-16-2011, 08:28 AM

I'm patiently waiting for you to come up with the drawings for us to make our own H4338 horns...

I'm becoming impatient! ;) I want some, can I help?

Wardsweb

03-16-2011, 08:37 AM

http://wardsweb.org/audio/JBL_C50/westlake_template.jpg

Using the full size drawings, I had one of my design guys cut me some templates on the CAD table. It will make it so much easier to layout on wood. He actually made me three sets; one set for over all dimensions, one set with cut outs for vane placement and one set with a tang off the back that has the center point of the arc. Gotta love buddies and especially those with special tools; CAD tables, CNC machines, end mills, lathes, etc...

Lee in Montreal

03-16-2011, 09:35 AM

I shall have an estimate for the CNC wood cutting by Friday (top & bottom plates, pair of sides) and a prototype within 10 days, as well as an estimate from another of my metal CNC supplier for the aluminum fins. The first one quoted me $22 per fin for 100 units. It clearly meas they are too busy, GTFO... I laughed and called one of my other suppliers.

Kits will come unassembled (Ikea style) so that people can decide themselve what finish they want to apply. I found that a first coat of Shellac, then one or two coats of floor vanish (wet sanded) make for a very smooth foundation before a top coat of paint. The sides will be glued, or screwed too if you want. The top plate will have to Spaenaur wood inserts with 1/4"-20 thread. The fins will be bolted from the bottom up. No need to glue them. That will eliminate the usual loosening of the fins over time when the dovels dry out.

My set will most likely be painted gun metal with the shinny aluminum fins showing off. :D

BTW I checked out the Westlake horns and they had a constant 22° between all paths, unlike the 2397 that has the outer ones at 21°...:eek:

Wardsweb

03-16-2011, 06:46 PM

The templates allow me to choose how the grain runs in relation to how they're cut.

http://wardsweb.org/audio/JBL_C50/westlake_template2.jpg

Mr. Widget

03-16-2011, 11:50 PM

Nice work bench! Probably the prettiest one I have ever seen. :D

Widget

Wardsweb

03-17-2011, 04:55 AM

Nice work bench! Probably the prettiest one I have ever seen. :D

Widget
Its good for looking but not for cutting. ;)

Lee in Montreal

03-17-2011, 05:18 AM

I shall receive a hundred wood inserts on Friday. They will be used to assemble the top and bottom "clam shelves" (going thru the fins for exact positioning). I will do some tests with the CNC shop and see what bore dimension is best to fit those in the HDF without "forcing" the wood. I can't wait to start actual production. :bouncy:

50486

Wardsweb

03-17-2011, 06:00 AM

I can't wait to start actual production. :bouncy:

You and me both!

kartsmart

03-17-2011, 09:57 AM

Are they done yet :bouncy: Now :bouncy: Now :bouncy:
You know what I mean----------- can't ---wait

Mr. Widget

03-17-2011, 10:10 AM

I shall receive a hundred wood inserts on Friday. They will be used to assemble the top and bottom "clam shelves" (going thru the fins for exact positioning).You may be doing this already, but if not, let me suggest you keep the top free of holes by orienting your inserts and drilling like this:

louped garouv

03-17-2011, 01:00 PM

You may be doing this already, but if not, let me suggest you keep the top free of holes by orienting your inserts and drilling like this:

not your first rodeo, eh?

ie. that's pretty durn smart!

Lee in Montreal

03-17-2011, 01:05 PM

You may be doing this already, but if not, let me suggest you keep the top free of holes by orienting your inserts and drilling like this:

Tops will be free from any hole (at least if you look from the top). The bore is drilled from the bottom of the top plate. Top plate is 3/4" or roughly 19mm. The insert is 10mm, bore will be 12mm deep. So it won't show from the top as it won't be a thru hole.

The two holes in the fins are 0.257" and thru holes. So the bolts' head will be recessed on the bottom panel as it bolts from the bottom. I am using socket head caps screws. Two bolts per fin go thru the bottom panel, then the fin and into the insert in the top panel. Sides, top and bottom panels can even be clamped together, without using any glue if you want to take the horn apart and repaint it in a few years. A thin strip of double sided tape between the top/bottom panels and sides will do. Or just glue everything together. Or perhaps only small finishing nails to hold the sides together.

50494

macaroonie

03-17-2011, 06:11 PM

Lee , this is looking great. I like your attitude , very hands on practical. Personally I would have no objection to countersunk hex bolts visible on the top , that would be with the gunmetal plus alloy fins. A very engineered look. I'm very eager to see these complete.

Wardsweb

03-17-2011, 07:21 PM

Mr. Widget

03-17-2011, 07:23 PM

Tops will be free from any hole...Cool.

Looks good. I think I would still want some glue in there, but I tend to over do things. ;)

Widget

Lee in Montreal

03-17-2011, 08:07 PM

Editing my post. Will resubmit a clearer progression graph. Sorry guys.

jf65

04-03-2011, 09:53 AM

Hello,
At the exact moment i began reading this thread i had the opportunity to buy a pair of JBL 2397. I have a pair of 2445H with Radian diaphragms on Iwata horns.
I put the 2445 on the new horns, and ... not better, Iwata rules.

I decided then to measure them outside in the garden.
I then compared my measurement of the 2397 with the one made by Widget
5074650747

pos

04-03-2011, 10:19 AM

very interesting, thank you for posting that!
That 700Hz suck-out appears clearly on both measurements, I wonder what could be its cause.

jf65

04-03-2011, 12:27 PM

very interesting, thank you for posting that!
That 700Hz suck-out appears clearly on both measurements, I wonder what could be its cause.

550 and 350 are opposite, 700 is the same, except that on Iwata it's smaller.
I think all the irregularities below 1000 are caused by the mouth and the brutal change of direction of the sound waves in the 2397, less on the Iwata which has lips more curved. J M Le clea'ch has showed the importance of the mouth, look at his circular horns. If the mouth is cut sharply, the waves go back in opposition.
The Iwata expansion is made on all directions, everything is curved, the 2397 has straight lines which are interrupted suddenly. (i have some difficulties finding the words to express myself clearly)

I'm pretty disappointed by the 2397, i'll stick to the Iwata.

jf65

04-03-2011, 12:29 PM

pos

04-03-2011, 12:32 PM

Re the 700Hz suck-out, I was thinking about yours and Widget's measurement of the 2397.

Maybe using some putty to smooth the 2328/2397 transition would help in this matter?

jf65

04-03-2011, 01:41 PM

Re the 700Hz suck-out, I was thinking about yours and Widget's measurement of the 2397.

Maybe using some putty to smooth the 2328/2397 transition would help in this matter?

Sorry, i misunderstood. But the explanation should be the same, because it's the same horn, surely a phase problem at the mouth.
I imagine that it all comes from the desire to spread the directivity widely on a horizontal plane, which makes it particular, and the straight walls (easy to do).

It pleased me to see that, with a different driver, certainly different measurement tools and more than 6000 km between Widget and me, the results were pretty close. The only thing we had strictly in common was the horn, so the problem lies there.

What bothers me is not especilally the 700hz suckout which is a bit narrow but the general hole between 600 and 1200 with only a few peaks
I don't know if puttin putty will be enough to remodel the mouth and stop the phenomenom but it is worth trying, another option could be to absorb those waves at the mouth with anything, maybe a baffle with rockwool? But in any horn the most important thing is the shape and that can't be changed
Another option is to cut them above 1000 Hz in a 4 way system but the response is still a bit cahotic. Maybe a little EQ ?

Best regards,
Jean

pos

04-03-2011, 01:50 PM

JBL recommand to use 3" lips above and under the horn:
http://www.lansingheritage.org/images/jbl/specs/pro-comp/2397/page1.jpg

Maybe that would help wirth.
One could also fill the 2397 with reticulated foam, à la Geddes...

Concerning your measurement, I guess the iwata horn was much taller than the 2397, so at 50cm the diffraction from the mouth was less of an issue.

I guess the differences would be less obvious at 1 or 2m.

jf65

04-03-2011, 02:29 PM

J
Concerning your measurement, I guess the iwata horn was much taller than the 2397, so at 50cm the diffraction from the mouth was less of an issue.

I guess the differences would be less obvious at 1 or 2m.

Far from that, the farther you go the flaws of each horn grow bigger. To show you i join the measurements made at 2 meters, still in the garden.

50762

jf65

04-03-2011, 02:31 PM

By seeing the response, it's easy to see why the Iawatas are filtered at 600Hz.

Ruediger

04-03-2011, 11:06 PM

Far from that, the farther you go the flaws of each horn grow bigger.

This should make You doubt about the measurements.

You should measure in the far field, and away from reflecting surfaces. The ground plane is one.

If You can't do that, and if You can't do neither a ground plane measurement nor a gated measurement, then You should try to find an explanation for the peaks and dips.

You could make a measurement with the loudspeaker pointing up, and some measurements off-axis. Maybe this sheds some light on what is happening there.

ruediger

jf65

04-04-2011, 03:39 AM

This should make You doubt about the measurements.

You should measure in the far field, and away from reflecting surfaces. The ground plane is one.

If You can't do that, and if You can't do neither a ground plane measurement nor a gated measurement, then You should try to find an explanation for the peaks and dips.

You could make a measurement with the loudspeaker pointing up, and some measurements off-axis. Maybe this sheds some light on what is happening there.

ruediger

hello,
i'm well aware of the limitations of my measurements, and i take them for what they are, and i invite anyone who can do more accurately to proceed and post the results because i don't see many.

I went to the garden with no wall around but there is always the ground plane. I could try to put the horns and the mic higher but the Iwatas are very heavy. I will try pointing up next time, but there will still be the ground effect. The close measurements already tell the tale, i made those from 2 meters just out of curiosity.
Anyway, i usually listen on the ground, so how they behave in that position concerns me :D

I have just bought the 2397s, and wanted to compare them to the Iwata to make a choice. All things being equal, it's obvious that the 2 horns are very different, i don't think that the ground should affect one more than the other.

pos

04-04-2011, 04:54 AM

jf65

04-04-2011, 05:41 AM

As it is the 2397 has a very wide vertical dispertion, and needs 3" lips to achieve 60°. That might be a part of the problems shown in your measurements.
You could try to mount two 3" curved baffle around the mouth to see how things improve.
You could use thin mdf or even cardboard

Yes, that's an option, i will try it in a few days , but it will not take away the sudden change of expansion between the horn and the lips or baffle. I will try all the options before taking a descision on their fate.

I looked at post #21, JBL sure have nice graphs on their brochures! I see also that the lowest recommended crossover frequency is 800 Hz, which i would push up to 1200 (in a 4 way system that i'm building with a 2123H for the low-mids), so the problems below are not that important to me.
I'm more concerned by the response above 1000. I was trying to replace the big iwatas (crossed at 600 in a 3 way system until now), but it appears that they still might be better from 1000 to 8000 (with a little compensation they are flat up to 8000).

to be continued....

Ruediger

04-04-2011, 07:02 AM

jf65

04-04-2011, 07:34 AM

When You do new measurements:
1.) write down the exact height of horn and microphone, and the distance from horn mouth to microphone,
2.) take measurements at several distances between horn and microphone, vary the distance irregularly, not in equidistant steps,
3.) do some off-axis measurements as well.

ruediger
i agree , i did many of that but did not post it : 30 cm, 50cm, 1.50m, 2m 30°, 45°, i did some indoors also. In similar positions and distances, each horn kept his own personality. I suppose that if i put them both in better diverse positions the differences will still be there.

The goal was for me to see if 2397 could replace the iwatas in a 4 way speaker (more convenient size). I'm not doing 2397 bashing, i bought a pair based on the beautiful models presented in this thread, i've got 2 pairs of horns now and must decide which one to use.

In a few days i will try a new set of measurements to let no stone unturned, but it would be great if among the readers of this thread (who might have 2397s or westlakes) some would make some measurements for a more wide perspective.

Mr. Widget

04-04-2011, 09:11 AM

...it would be great if among the readers of this thread (who might have 2397s or westlakes) some would make some measurements for a more wide perspective.I agree... I see you have one of my plots posted above, I will caution that measurement I made of the 2397 was among the very first audio measurements I ever did using CLIO and may not be as useful or accurate as my later measurements... here is an example of a later on axis measurement comparing a TAD TD-4001 and JBL 2441 both on the Westlake horn and a TAD TD-4003 on a TAD TH-4003 horn. Even this measurement was fairly early in my measuring and I was just getting the hang of time windowing... I wouldn't trust the curves below about 1K to 1.5KHz... the windowing has likely clipped some information and overly smoothed the response.

I would offer to make additional measurements on both the Westlake with 2328 throats and the 2397 horns that I have in storage, but I do not have any 2" drivers to put on them.

Widget

yggdrasil

04-05-2011, 09:34 AM

@jf65 - what are your crossover frequencies?

jf65

04-05-2011, 10:17 AM

@jf65 - what are your crossover frequencies?

The Iwata is crossed at 600 Hz in a 3 way system.
I bought a pair of 2123H and moving to 3way, the horn (Iwata or 2397) is now crossed at 1200 Hz.
That's why i thought of the 2397 after reading this thread , because it's smaller than the Iwata used at the moment. But now i hesitate.
The tweeter is crossed at 8000 Hz.

reVintage

04-05-2011, 10:35 AM

Don´t know if this has been mentioned earlier in the thread but:
2397 should be used with 2328 and old style 2"(with short horn inside the driver) as these together has a flare of 160Hz. The horn is then cut at 800Hz mouth-area if I remember it right.

jf65

04-05-2011, 10:51 AM

4313B

04-05-2011, 11:14 AM

Widget, with the experience you now have regarding the array1400, S9900 and D66000, do you still find the smith horn superior to the biradials? (when used with a supertweeter)
The 1400 Arrays are in my living room playing as I type this. My 2397s and my beautiful Westlake clones are tidily packed away in my attic.That is such a nice, polite answer!

I agree... I see you have one of my plots posted above, I will caution that measurement I made of the 2397 was among the very first audio measurements I ever did using CLIO and may not be as useful or accurate as my later measurements...If I'm not mistaken, once saved, the CLIO files can be manipulated whenever desired, including windowing. The biggest factor appears to be getting anything meaningful below ~ 1 kHz in the typical home room or garage.

Mr. Widget

04-05-2011, 01:06 PM

If I'm not mistaken, once saved, the CLIO files can be manipulated whenever desired, including windowing.True, however I saved very few of my actual MLS files.

The biggest factor appears to be getting anything meaningful below ~ 1 kHz in the typical home room or garage.In my old 30' by 25' by 10'+ room once I learned what I was doing I was able to get accuracy down to about 500Hz if I was only measuring a single horn... I could mount the horn five feet from the floor and it would be almost five feet from the ceiling as well. With a larger speaker this obviously isn't physically possible. (This info pertains to measurements using time windowing. Most of the response plots that we see posted by individuals can not be time windowed due to the near by reflective surfaces and are therefore only indications of what the response is in a single location in a particular room at a particular time.)

Widget

Ruediger

04-06-2011, 11:01 PM

Far from that, the farther you go the flaws of each horn grow bigger. To show you i join the measurements made at 2 meters, still in the garden.

50762
The 2397 response looks like a comb filter response. All sound waves which are reflected by the ground and reach the microphone are delayed by the same amount of time and thus by a different phase. This is consistent with Your observation, that the bigger the distance the bigger the effect (more reflections). What is the vertical coverage of the iatwa horn?
Ruediger

reVintage

04-07-2011, 01:08 AM

jf65,
Must ask you about your measurements. Did you use the 2328-adapter on the 2397?

pos

04-07-2011, 02:32 AM

jf65

04-07-2011, 03:07 AM

The 2397 response looks like a comb filter response. All sound waves which are reflected by the ground and reach the microphone are delayed by the same amount of time and thus by a different phase. This is consistent with Your observation, that the bigger the distance the bigger the effect (more reflections). What is the vertical coverage of the iatwa horn?
Ruediger

You're right, I didn't measure the vertical coverage, i add it to the things i will do when i measure again.
By looking at the horns it would seem that the Iwata vertical coverage should be bigger, but it will be interesting to verify it.
I measured the horizontal coverage (but didn't post it as it looks like Widget's graph) and the 2397 is wider than the Iwata, not a surprise.

jf65

04-07-2011, 03:21 AM

jf65,
Must ask you about your measurements. Did you use the 2328-adapter on the 2397?

Yes, how could i put the driver without it? is there another way?

By the way, i see something "wrong", at least for me, in the shape of the 2328: it grows bigger then narrows at the end on the horn, kind of like in the Altec 511 if not exactly the same. Maybe there's a reason, but it could produce some more accidents. In l'Audiophile someone fixed this and said it was better:50792 i didn't try it as i discarded the 511s.

Mr. Widget

04-07-2011, 10:33 AM

And where are the TH4003 ? :DIn a different league.;)

Yes, how could i put the driver without it? is there another way?In later Westlakes, they just bolt the driver right onto the horn with a thick round holed plate. They also increased the height of the horn.

By the way, i see something "wrong", at least for me, in the shape of the 2328: it grows bigger then narrows at the end on the horn, kind of like in the Altec 511 if not exactly the same. Maybe there's a reason...I don't know the history or the reasoning, but both the Altec radial horns and the JBL 2328 throat adapter do seem to share a somewhat similar geometry... a geometry that is quite difficult to manufacture, so they must have had a pretty good reason to go that way.

The 2397 response looks like a comb filter response.I agree. I did find that for the 2397 or the Westlake to sound good, the room really needed a fair amount of treatment... i.e. they sounded far better in a dead room. I attributed this to the wide dispersion, but your point about the comb filtering could also be part of the reason.

Widget

reVintage

04-07-2011, 10:44 AM

Yes, how could i put the driver without it? is there another way?

You could for instance have made something less good by yourself......
So one could suspect that there was something wrong

Still the horn measurements indicates it is not the best horn you could live with.

Have seen quite a lot of smaller horns in the same style, or full radial, without a necessary round to radial adapter.

jf65

04-07-2011, 11:04 AM

Yes, how could i put the driver without it? is there another way?You could for instance have made something less good by yourself......
So one could suspect that there was something wrong

Still the horn measurements indicates it is not the best horn you could live with.

Have seen quite a lot of smaller horns in the same style, or full radial, without a necessary round to radial adapter.
Yes i understand, it was the real complete horn. As for round adapter , here's a comparison made on Iwatas (not by me):
50799