E2 clone

[Ian Mackenzie]

Pending what you expect out of a system like this there are perhaps some basics.

-Matching the dispursion of the woofer and horn at the crossover point.

-Proper loading of the driver down to the crossover point.

-A horn profile with a diameter / mouth size at least 1 wave length and shorter in depth than the width if using a horn that that does not sound.

That criteria really narrows down the choices and I guess its why we dont see many non compromise horn system made commercially.

Non of this is rocket science.

Today many designs appear to focus on directivity control and less on loading the driver because drivers are more powerful. That appears a fatal mistake if you want a high quality sound. Otherwise use a direct radiator system like a high quality 8 or 6.5 inch driver from 500-5000 then a small horn / tweeter for the midrange and HF.

On the basis of the above at the moment I am looking at a P Audio 1.5 inch bum horn much like the 4435 bi radial, an Azurahorn 550 T = 0.8/ 425 T = .7 9Le leach) really only useful up to 5-7000 hz before it becomes directive, one of the DDS CD 100- 110 x 40 1.5 inch horns.

The probability of a diy Everest horn happening in the near future is remote based on cost and finding a fabricator.

If I can find a 2352 locally or import at a reasonable price I would like to include that in my trials.

I have not defined the woofer yet and wold need to look at the LE14H4 and the 1200FE specs (pending availability). Otherwise a 2234 (recone) could be an option to use as a base line.

Ian

[pos]

Very interesting thread, thanks guys!
I particularly envoy reading about 4313's designs!

Ian, here are some simulations I made comparing the 2234H in its 4435 implementation to the new LE14H-4. The two curves (red and white) nearly overlap all the way!
The old LE14H-X where very similar to 2235's in their behavior, whereas this new one really looks like a 2234 alternative!

[Hoerninger]

Somebody estimated 277 Liters. You get an A. We figure the active volume is around 270 l. As with all Japan intended systems, the low end is deliberately lean. The published curve is an anechoic curve which is very hard to interpret with regard to real in-room response. The system has 3 dB more output at 30 Hz than a S9800. It has the tightest and best defined bass reproduction of any JBL, ever.

Pos,
thank you for contributing.
Mister GT gave me an "A" but I have not had the data you do have.
It would be interesting to see how two LE 14H-4 would behave in a 270 l enclosure.
Or what would happen in a slightly reduced enclosure - the E2 is very huge.
(14 inch / 15 inch)power3 * 270 liter = 220 liter)
___________
Peter

[Ian Mackenzie]

Can someone tell me the internal flare rate of the 2435?


http://www.audioheritage.org/vbullet...4&postcount=25
http://www.audioheritage.org/vbullet...5&postcount=26
http://www.audioheritage.org/vbullet...8&postcount=30

http://www.audioheritage.org/vbullet...ad.php?t=14369

http://www.audioheritage.org/images/...-045be-imp.jpg
http://www.audioheritage.org/html/pr...logy/435be.htm


Well look and you will find:

Another unique feature of this driver is that it does not have a traditional throat. The phase plug terminates at the driver exit. It results in an effective flare rate of 550hz. Previously, virtually every compression driver made had a 180hz flare rate whose origin dates back to the original AT&T Labs designs from the 1930's. This low rate was necessary to accommodate the low cross-over points used in early two-way loudspeakers. However, this low rate compromised high frequency performance. Given that there was no need for such low frequency output for the 435Be, the flare rate could be optimized to result in a 6db drop in second harmonic distortion.

[Robh3606]

Hello Ian

There is no flare. It's a throat less driver. It opens up right at the top of the phase plug. To me that means no issues with changes in flare rate to generate Hom's ala Geddes. You just have to make sure that the horn is really well centered so the "edge" doesn't overlap the phase plug and form a discontinuity to cause difraction back into the driver.

Rob

[Ian Mackenzie]

Based on what I have gleen so far I am looking very closely at an Azurahorn AH 550

The AH-550 has a mouth diameter of 300 mm and an axial length of 205mm to a 1” throat. Throat sizes can be made from 1” to 2” or larger.
The Le Cléac’h flare rate is 550Hz at 0.8 T factor, calculated from a 1” throat size. Some modification mybe required to suit the 2435 Be.

I have no idea how it will meaure up and so that remains to be seen. The thought of using a small ribbon tweeter on a small wave guide has also crossed my mind

Pending what happens I may still look at other options but the opportunity of trying out one of these horns is very apprealing based on advice from a certain source.

[Hoerninger]

Hello Rob,

I would say there is a flare. The phase plug starts with very narrow slots which open up. If the areas at the beginning and the end would be known, the length is about one inch, then the flare could be calculated.

But more important is that there is no lengthy part with a not needed flare rate (180 Hz) which produces unnecessary reduced directivity.
___________
Peter

[Ian Mackenzie]

Thanks guys for the replies.

I have some really exciting news in the pipeline.

I got an email from the M.D local manufacturer tonight who is in the process of CNC machining some wood horns for hi end audio. This firm oem for people like Whise.

I have no further details as this stage.

The M.D has sent me data files of some very impressive kevlar based 15 inch cone drivers for studio monitor applications and a prototype in the works as a replacement for a Tad woofer!

When more details come to hand I will let you know.

Ian

[4313B]

Ian, here are some simulations I made comparing the 2234H in its 4435 implementation to the new LE14H-4. The two curves (red and white) nearly overlap all the way!
The old LE14H-X where very similar to 2235's in their behavior, whereas this new one really looks like a 2234 alternative!

It would be interesting to see how two LE 14H-4 would behave in a 270 l enclosure.
Or what would happen in a slightly reduced enclosure - the E2 is very huge.

The dual fifteen boxes have always been pretty big.

Dual LE14H-4's could be quite interesting.

My dual twelves are in 130 l which I'm pretty happy about. The footprint is quite nice.

[Robh3606]

Hello Peter

I would say there is a flare. The phase plug starts with very narrow slots which open up. If the areas at the beginning and the end would be known, the length is about one inch, then the flare could be calculated.

Your right, I believe that is where the "Effective 550hz flare rate" comes from.

Hello Ian

Based on what I have gleen so far I am looking very closely at an Azurahorn AH 550

The AH-550 has a mouth diameter of 300 mm and an axial length of 205mm to a 1” throat. Throat sizes can be made from 1” to 2” or larger.
The Le Cléac’h flare rate is 550Hz at 0.8 T factor, calculated from a 1” throat size. Some modification mybe required to suit the 2435 Be.

Yeah I was looking at the Edgar Salad bowls for a while. Not sure what the the directivity is for the horns you mention. From what I have seen in other forums it can get quite high in the upper ranges.

As long as you are able to match them through the lower crossover point you can still meet your posted criteria. The upper crossover point will be an issue no matter method you use but experience with the 4344/4345 has shown it's not nearly as critical as the lower crossover point.

Are you going to physically offset the horn to align the voice coils?? It sounds like the actual offsets may end up close too the 2122, 2425?2307 in the 4345. It seems from some of you more recent posts you want to move away from the offset to try to get a more coherent source in that 1-3K range??

Rob

[4313B]

I have some really exciting news in the pipeline.

When more details come to hand I will let you know.

Ok, we all hope you end up with a system you really like.

[Hoerninger]

Yeah I was looking at the Edgar Salad bowls for a while. Not sure what the the directivity is for the horns you mention. From what I have seen in other forums it can get quite high in the upper ranges.

I do chime in here as the dimensions of this Le Cléac’h horn (AH550) are comparable with a Kugelwellentrichter (spherical). These are shorter than a comparable "Edgar salad bowl", which follows the tractrix contour.
So the AH550 spreads wider than an equivalent salad bowl.

___________
Peter

[Zilch]

Like I posted above, I like the waveguide better than the H5800 horn. Are you basing your lack of success with the PT-F95HF and 2435HPL on your posted graphs? The 2452H-SL and waveguide is a very nice combination.

Yes, and the most pleasant surprise for me once we worked out a suitable compensation filter for it here, I was able to dial the actual crossover frequency considerably lower without coloration than I imagined would be possible with so compact a waveguide.

It seems to be less about loading than about how low the driver will competently play under these conditions, and the 4" damped diaphragm would appear to be a significant factor in this.

I hope Rob and others will also pick up on working with this combination so that we may all learn more about it. My own results have been quite satisfying.

Does TechBot have 2452H-SL engineering specs to post for us, please?

[Ian Mackenzie]

Ok, we all hope you end up with a system you really like.

.

Well if there is something even remotely attractive on your door step it pays at least to have a look at it.

At the end of the day its all got to be viable and be at least better then what I already have. I mean if I can buy something that does the job for the value of the equivaltent cost of freight and shipping from overseas I have to at least look at it. But only time will tell.

FYI, a couple of files attached.

I have not runs any sims yet.

Ian

[Ian Mackenzie]

Hello Peter




Hello Ian

As long as you are able to match them through the lower crossover point you can still meet your posted criteria. The upper crossover point will be an issue no matter method you use but experience with the 4344/4345 has shown it's not nearly as critical as the lower crossover point.

Are you going to physically offset the horn to align the voice coils?? It sounds like the actual offsets may end up close too the 2122, 2425?2307 in the 4345. It seems from some of you more recent posts you want to move away from the offset to try to get a more coherent source in that 1-3K range??

Rob

Hi Rob,

Yes to your question.

I think its a case of balancing the compromises.

I want this to be a 2 or 2.5 way system. ie a swept up 4430/4435.

The woofer horn transition is key factor if this is going to be worth while at all. The alignment is part of it, the woofer/ horn dispersion and balancing what the compression driver likes to do.

A lot depends on how the woofer behaves in the 700- 1.5k area as well.

Your are right , sorting out the upper crossover point is not as hard as one would think.

To sum up ...the end result. When I heard John Nebel's 4435 along size his 4343B and the LRS the 4435 was the most life like and listenable system.

Pity JBL dont make a 1 inch Be driver!

I may end up with something quite different at the end.

Ian