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Old 7th May 2013, 07:06 AM   #501
Jmmlc is offline Jmmlc  France
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Quote:
Originally Posted by weltersys View Post
As far as the Iwata horns, if one is not concerned with constant directivity, a relatively low cutoff is not hard to achieve.

The Paraline which I posted polars for in post 496 has usable response down to 167 Hz (EV DH1AMT driver), and is only about 11.5 inches (29 centimeters) in length. It holds a uniform in horizontal response of 90 degrees from 500 -16 kHz, the much longer Iwata 300 goes from about 100 degrees to 15 degrees over the same range.

Art
Hello Art,

The design shown in message #497 is not an Iwata horn it is a very different design! The Iwata while having a lower horizontal directivity compared to the axisymetrical Le Cléac'h horn is not designed to control directivity. The new horn in #497 was designed in order to follow the current trend for controled directivity (even if for myself and others that want to benefit of a real 3D imaging from good stereo records there is no need for controled directivity as we listen only at the sweet spot andin the near field...)

What is seen in the frequency response of the Paraline you gave is that the ripples in the response curves could result in (multipaths) reflexions/diffractions inside the device, something that is avoid in Le Cléac'h horns.

Best regards from Paris, France

Jean-Michel Le Cléac'h
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Old 7th May 2013, 03:04 PM   #502
Zero D is offline Zero D  United Kingdom
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Quote:
Originally Posted by weltersys

The T-35 horizontal dispersion goes from 110 degrees at 3kHz to 85 at 10kHz, a 25 degree range, the horizontal from 160 to 60, a 100 degree range. That "seems" a rather large difference to me.
I was looking at the circles & triangles.

Quote:
The Paraline which I posted polars for in post 496 has usable response down to 167 Hz (EV DH1AMT driver), and is only about 11.5 inches (29 centimeters) in length. It holds a uniform in horizontal response of 90 degrees from 500 -16 kHz,
Impressive specs indeed, for such a short length But a +- 7dB fr to 1kHz = ?
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Old 7th May 2013, 04:31 PM   #503
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Quote:
Originally Posted by Zero D View Post
I was looking at the circles & triangles.
Impressive specs indeed, for such a short length But a +- 7dB fr to 1kHz = ?
I also was looking at the circles and triangles which is why I noted the T-35 horizontal dispersion has at 3kHz to 85 at 10kHz, a 25 degree range, while the vertical has a 100 degree range in the same pass band, a rather large difference.

As Jean-Michel Le Cléac'h said in post #501:
"What is seen in the frequency response of the Paraline you gave is that the ripples in the response curves could result in (multipaths) reflexions/diffractions inside the device, something that is avoid in Le Cléac'h horns."

The Paraline ripples and pattern flip are something that can be easily avoided using a conical horn with flared throat and mouth, (though a 90 degree conical won't go as low) which I have pointed out several times in this thread.

As far as the Paraline's low frequency response, one can see that the Iwata- 300 you linked in post 498 has around +/-16 dB response from 200 to 1000Hz, while the Paraline is only +/-6 dB in that range.

Whether the horn is half empty or full of it depends on one's point of view.

Art
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File Type: png Iwata:Paraline.png (285.6 KB, 628 views)
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Old 7th May 2013, 06:52 PM   #504
Zero D is offline Zero D  United Kingdom
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@ weltersys

Time for some glasses for me i think

Paraline points taken, but +/-6 dB is still naughty

Quote:
The Paraline ripples and pattern flip are something that can be easily avoided using a conical horn with flared throat and mouth
That's good to know.

Quote:
Whether the horn is half empty or full of it depends on one's point of view
You're not wrong
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Old 22nd June 2013, 03:01 PM   #505
jwmbro is offline jwmbro  United States
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Hi, been a while since I've been able to do any speaker projects due to other obligations, but I've recently dug out an older idea I had and was hoping some of the people more knowledgeable than me might be able to help me out.

The idea I have in mind is a sort of modular 2-way unity style horn with paraline HF entry. Main design criteria is highest possible voltage sensitivity from a small box, so it can be run on battery power in it's most mobile configuration. For higher SPLs it can supply a bit more voltage from a power connector, and be stacked in multiples. That's the way I imagine it anyway. It's inspired in part by the VTC EL210 as well as a design I've seen on the forum many moons ago, which I'm pretty sure was Art Welter's, but I haven't been able to find via search.

My idea is to use two Eminence Alpha(lite) 6As in parallel for the midrange (low 100s through about 2kHz) and a fairly cheap compression driver above that. Sensitivity should be at least 100dB at 2.83V, though each individual box doesn't need a huge amount of power handling.

Here's a rough sketchup of what I am thinking
Click the image to open in full size.

Outer dimensions are 20cm high x 60cm wide x 40cm deep (8x24x16 inches)

My thought was that the paraline + horn shape should make for a fairly wide horizontal dispersion pattern, with a narrow vertical dispersion. However in light of what I've read here I'm concerned about diffraction at the long edges and pattern flip from the quite small vertical dimensions when used as a single box instead of a line array. Unfortunately I'm very inexperienced when it comes to horn directivity issues, and my simulations in hornresp only go so far (Only allows a single segment horn, only considers midrange, only allows for symmetrical horns, etc) - I've tried using multiple simulations, one with a 90 degree expanding conical horn, and one with 0 expansion parallel tube, in order to judge the directivity response in both axes seperately, but again, I still have no idea what the tweeter is doing here.

Any thoughts on this build concept? Oh yeah, this is paraline related, probably going to use 4mm or 5mm thick material for that, to allow wave lengths up to 20k to pass through, assuming that doesnt constrict too much. But I'm a bit more concerned how the directivity of a final unit is going to wind up.
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Old 23rd June 2013, 09:57 AM   #506
Nissep is offline Nissep  Sweden
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O if i only had time to actually learn abec from the guys behind akabak.
I ask for a price on that product but got an invite to be a beta tester for the latest version.

This example is not far from your ideas.
http://www.randteam.de/_Docs/ABEC%2021%20Sealed%203.pdf

This is of no help for you right now but i just had to show that pdf.
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Old 23rd June 2013, 04:04 PM   #507
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Quote:
Originally Posted by jwmbro View Post
Hi, been a while since I've been able to do any speaker projects due to other obligations, but I've recently dug out an older idea I had and was hoping some of the people more knowledgeable than me might be able to help me out.

The idea I have in mind is a sort of modular 2-way unity style horn with paraline HF entry. Main design criteria is highest possible voltage sensitivity from a small box, so it can be run on battery power in it's most mobile configuration. For higher SPLs it can supply a bit more voltage from a power connector, and be stacked in multiples. That's the way I imagine it anyway. It's inspired in part by the VTC EL210 as well as a design I've seen on the forum many moons ago, which I'm pretty sure was Art Welter's, but I haven't been able to find via search.

My idea is to use two Eminence Alpha(lite) 6As in parallel for the midrange (low 100s through about 2kHz) and a fairly cheap compression driver above that. Sensitivity should be at least 100dB at 2.83V, though each individual box doesn't need a huge amount of power handling.

Here's a rough sketchup of what I am thinking
Click the image to open in full size.

Outer dimensions are 20cm high x 60cm wide x 40cm deep (8x24x16 inches)

My thought was that the paraline + horn shape should make for a fairly wide horizontal dispersion pattern, with a narrow vertical dispersion. However in light of what I've read here I'm concerned about diffraction at the long edges and pattern flip from the quite small vertical dimensions when used as a single box instead of a line array. Unfortunately I'm very inexperienced when it comes to horn directivity issues, and my simulations in hornresp only go so far (Only allows a single segment horn, only considers midrange, only allows for symmetrical horns, etc) - I've tried using multiple simulations, one with a 90 degree expanding conical horn, and one with 0 expansion parallel tube, in order to judge the directivity response in both axes seperately, but again, I still have no idea what the tweeter is doing here.

Any thoughts on this build concept? Oh yeah, this is paraline related, probably going to use 4mm or 5mm thick material for that, to allow wave lengths up to 20k to pass through, assuming that doesnt constrict too much. But I'm a bit more concerned how the directivity of a final unit is going to wind up.
Some thoughts:

1) What's the application?
2) Personally, I am not as concerned about the dips and peaks in the frequency response as most people are. For instance, if you make a call on your phone, the frequency response is far from flat. But the sound is not offensive. Now try making the phone call on a VOIP service like Skype. Even the smallest 'blip', a fraction of a second, is audible and offensive. That's how our hearing mechanism works; it's very sensitive to timing.
3) Pattern flip makes horns sound 'wonky' it's true. But there's an easy solution to pattern flip with the VTC boxes; just array them like they're supposed to be used. In your application that may be an acceptable solution.
4) Instead of investing a lot of time with Akabak and Hornresp, I'd simply download the dimensions of the VTC boxes and start from there. They've published all of the data in CLF format, so you can see *exactly* what the frequency response and directivity is like.

Having said all that, the main reason I like Paralines is that it allows you to package the horn in some very odd shapes. For instance, under the dash of a car, or have the horn fire one direction while the driver points another. In your app, a plain ol' Synergy horn might give you better results. I don't see that a Paraline would offer any efficiency advantage, as a fair amount of output is lost on the high end due to imperfect combining of the high frequencies. You'll notice this in the spec sheets of the Genesis boxes too; basically the more drivers you combine, the less efficient the combination is overall. (IE, four compression drivers on a layered combiner *aren't* 6dB more efficient than one driver.)
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Old 23rd June 2013, 05:42 PM   #508
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Quote:
Originally Posted by jwmbro View Post
My idea is to use two Eminence Alpha(lite) 6As in parallel for the midrange (low 100s through about 2kHz) and a fairly cheap compression driver above that. Sensitivity should be at least 100dB at 2.83V, though each individual box doesn't need a huge amount of power handling.

Here's a rough sketchup of what I am thinking
Click the image to open in full size.

Outer dimensions are 20cm high x 60cm wide x 40cm deep (8x24x16 inches)

But I'm a bit more concerned how the directivity of a final unit is going to wind up.
My Paralines are similarly sized, 16.5 x 11.25 x 15 inches using Alpha 8s.
I did not port them, as LF in multiples is OK.
They work well in multiples, but the EQ required singly is quite different.

They can be used singly, but the vertical dispersion being very narrow at HF going to near omni at 1K is not very useful.

Art
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Old 23rd June 2013, 06:01 PM   #509
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by Patrick Bateman View Post
Some thoughts:

1) What's the application?
2) Personally, I am not as concerned about the dips and peaks in the frequency response as most people are. For instance, if you make a call on your phone, the frequency response is far from flat. But the sound is not offensive. Now try making the phone call on a VOIP service like Skype. Even the smallest 'blip', a fraction of a second, is audible and offensive. That's how our hearing mechanism works; it's very sensitive to timing.
3) Pattern flip makes horns sound 'wonky' it's true. But there's an easy solution to pattern flip with the VTC boxes; just array them like they're supposed to be used. In your application that may be an acceptable solution.
4) Instead of investing a lot of time with Akabak and Hornresp, I'd simply download the dimensions of the VTC boxes and start from there. They've published all of the data in CLF format, so you can see *exactly* what the frequency response and directivity is like.

Thanks for your thoughts, John.

1) Basically the thought is a modular, mobile PA system. The basic item I want from a single box is a "boombox", high efficiency, no bass, battery powerable - but ideally I'd like to be able to combine a few to make a full-fangled PA setup (stack of 5 perhaps).

The whole project grew out of optimizing my previous boombox setup, so this is still the primary goal. However I discovered that in order to get >100dB sensitivity, I will pretty much automatically get about 100W worth of power handling, so might as well allow the system to make use of that if need be.

2) I have a psychoacoustics background, so I know a fair amount about the human hearing system - unfortunately my knowledge is rather lacking in terms of electro-acoustics and just general acoustics in air and horns. I've listened to some pretty wavy sounding FR speakers and still enjoyed the music, and particularly for this sort of application, hifi takes the backseat to SPL. But I'm a perfectionist like that, I'd still like it to be accurate (on paper at least).

3) well unfortunately my box is a bit smaller in each dimension than the VTC box, most noticeably in height, because it uses 1 tweeter instead of 2, and therefore 6.5" instead of 10" woofers. I feel that this is just about the biggest I can go for a single box, and when not arrayed, the 20cm (8 inch) vertical height is simply quite worryingly small for a horn mouth. I guess I might just have to build and measure and see how it turns out, practice is often the better arbiter than theory, in Germany there is a saying "Probieren geht über Studieren," which means to try is better than to study.

4) Good idea, I'll definitely look into that. Some conclusions can definitely be drawn even from other dimensions, particularly accounting for the respective wavelengths


Quote:
Originally Posted by Patrick Bateman View Post
Having said all that, the main reason I like Paralines is that it allows you to package the horn in some very odd shapes. For instance, under the dash of a car, or have the horn fire one direction while the driver points another. In your app, a plain ol' Synergy horn might give you better results. I don't see that a Paraline would offer any efficiency advantage, as a fair amount of output is lost on the high end due to imperfect combining of the high frequencies.
Indeed, I don't expect an efficiency advantage, in fact I believe that my woofers and their corresponding low volume are likely to be the limiting factor in total efficiency. Rather what I expect from the paraline is idealy a narrow vertical dispersion pattern, so everything doesn't go up into the air / bounce into the ground. The logic of the coherent line source wave pattern emanating from the front of the paraline (the original style, not your square version) appeals to me (though again, my knowledge of wave acoustics outside of free field point sources is unfortunately rather limited, so I don't know how accurate this picture is), however I don't know how long that vertical line source wave front can hold up once it encounters the diffractive horn mouth edge. As I mention, my experiments towards this in the hornresp wavefront simulator have been rather inconclusive.

Quote:
Originally Posted by Patrick Bateman View Post
You'll notice this in the spec sheets of the Genesis boxes too; basically the more drivers you combine, the less efficient the combination is overall. (IE, four compression drivers on a layered combiner *aren't* 6dB more efficient than one driver.)
This is obvious, you're never going to get more than 1 Watt out of 1 Watt in, no matter how many drivers you combine. so 1 Watt electrical power will never give you more than 109dB @ 1 meter for a true point source radiating into 4 pi. But a great way to drive this figure up is to reduce the angle it's radiating into.

Half space allows 112dB from 1 Watt already, but if you're able to get down to a radiation angle of 90 x 25 degrees, this (by my quick arithmetic using a rectangular approximation of sphere surface area around 0.2pi steradians) should allow you to get 122dB from 1 Watt. Twice the loudness without breaking any physical laws of engery conservation.

I hope I've brought the point across why I am concerned about losing vertical directivity, for the pursuit of sensitivity / efficiency it is simply wasted energy. Oh and potential bothersome for neighbors. Wow I've blabbered on quite a bit now, I'll stop.



One other question though, the B&C DE 10-8 is the cheapest compression driver I can find, but it only claims 40W power handling from 2.5kHz up, so probably about half that if I crossover at 2kHz or slightly above, which at the nominal efficiency of 107dB would still allow for 120dB max, but I feel like that might be cutting it a bit close. Agreed? As an alternative the BMS 4538-8 seems like quite a good bargain, not much more expensive, made here in Germany and already offering a nominal 114dB sensitivity in a 90x75 horn (though the broadband sensitivity is less, judging from the graphs), it will handle 60W AES from 1.9kHz up, which should definitely keep up with the little Alpha 6's. Anybody have any experience with this driver? Forum search only turns up one hit. BMS in general seem to have a good name, but I guess that is quite an entry level product.
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Old 23rd June 2013, 06:41 PM   #510
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by weltersys View Post
My Paralines are similarly sized, 16.5 x 11.25 x 15 inches using Alpha 8s.
I did not port them, as LF in multiples is OK.
They work well in multiples, but the EQ required singly is quite different.

They can be used singly, but the vertical dispersion being very narrow at HF going to near omni at 1K is not very useful.

Art
Hi Art,
thanks for that. I thought I remembered you having a fairly similar setup, but since it's nearly a year since I looked into it I couldn't remember any details nor did I have any info bookmarked. I've learned from that - documenting my progress better this time to avoid doing things more than once!

Anyway, I suppose any object that small is going to get omni at a relatively high frequency, there is nothing I can do in terms of design to change that. Too bad, but still, an inherent limitation I will have to live with, and design around. My thought would have been to plug the ports for multiples, but I can play around with that.

I guess I'll just order the parts for one and do some measurements and see what I come up with. About 200 euros in parts and material for the whole shebang seems reasonable enough, though it does add up once you start stacking them in the dozens.
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