Wayne Parham's H290C waveguide measurements - Page 3 - AVS Forum | Home Theater Discussions And Reviews
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post #61 of 196 Old 08-09-2012, 09:23 PM
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Originally Posted by zheka View Post

now this is clearly out of my depth.
i'll use the opportunity to ask a question I could not find a google answer to .This HOM thing, is there a way to measure it or not?

There is, but not "conventionally"

http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-243.html#post1776210
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post #62 of 196 Old 08-09-2012, 10:07 PM
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You see it in the off axis sometimes. Depending how bad it is. EV is right though, I imagine the SEOS profile is HOM free essentially. I was just wondering today if foam would be necessary. Sure doubt it would hurt.

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post #63 of 196 Old 08-09-2012, 10:16 PM
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Originally Posted by tuxedocivic View Post

You see it in the off axis sometimes. Depending how bad it is. EV is right though, I imagine the SEOS profile is HOM free essentially. I was just wondering today if foam would be necessary. Sure doubt it would hurt.

I don't think the SEOS is really too different from the Geddes guide (the mouth might be a bit different though).

While the Super-Ellipse doesn't create on-axis cancellations the way the axi-symmetric does, I don't think that would affect HOMs. The throat and transition/expansion into the 90 degree pattern etc is where we are concerned most with HOM.

If Geddes' guide benefits from the foam, then the SEOS should as well. Yes the super-ellipse doesn't create an on-axis null, but I wouldn't confuse that with less HOMs.

That said, Geddes' guides are still some of the finest without the throat. I think people confuse the fact that he uses foam with the idea that his guides alone "need" foam. If anything, his guides (and those based on it, like the SEOS) "least" need the foam, but the foam still has an effect evidenced in his testing.

All the above said, for all we talk about the horn, my biggest reservation with C.D. designs tends to be the use of a large format driver high in frequency. I'm a bit skeptical that 12" or 15" midwoofers could have the resolution of < 6.5" midwoofer in that 1khz - 2khz crossover region.
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post #64 of 196 Old 08-09-2012, 10:22 PM - Thread Starter
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Have the claims that HOMs have audible effect ever been proven? i can see how devising a test for this maybe difficult if not impossible but I'd be surprised it was not attempted.
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post #65 of 196 Old 08-09-2012, 10:28 PM
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All good points EV.

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post #66 of 196 Old 08-09-2012, 10:31 PM
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Quote:
Originally Posted by zheka View Post

Have the claims that HOMs have audible effect ever been proven?

Higher order modes, by design, are just a subset of group delay. Group delay itself has been shown to have an audible effect, hence why Geddes seeks to eliminate it in all its forms (Mouth / Edge diffraction and Higher Order Modes etc). Its audibility is not SPL-independant - in other words group delay becomes MORE audible at HIGH spls ( > 85db most likely) .

So some may say they're inaudible and not be wrong - HOMs etc may be inaudible if you listen at low volumes. But then why are you even using a C.D. design, when Toole's research shows that intelligibility at low SPLs is higher when you have similar, high amplitude lateral reflections than when you have the fruits of narrow directivity.
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i can see how devising a test for this maybe difficult if not impossible but I'd be surprised it was not attempted.

It requires different equipment from what DIYers (or Geddes for that matter) have on hand. Is it really worthwhile to spend all that money just to measure something that won't affect your crossover design?

If you want to fund it, we would be very supportive in our role. That being sitting here on our keyboards twiddling our thumbs.
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post #67 of 196 Old 08-09-2012, 11:03 PM - Thread Starter
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the keyword is audible. i am looking for a double blind test validation
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post #68 of 196 Old 08-10-2012, 09:13 AM
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Sounds like you're trying to justify your purchase by questioning the audibility. EV just said it's audible. Many blind tests have been done on group delay, I assume. < can't think of one off hand > You don't have to justify your purchase. Those are good speakers. We just wanted to correct what you were saying that the H290 measures better, when that's not really the case. It kind of depends how you go about it. They're both very very good.

I sometimes find these comments funny about audibility. I often see posted, and often say myself, "I doubt it's that audible, so who cares." When doing DIY hifi, we should get hung up on the last little bit of performance that is barely audible. Why not ring every last drop of performance out of our designs. Hopefully when all the hardly audible things add up, they'll be remarkably audible and sound amazing.

Sorry, just a side note that I always think about. I do it too, just find it kind of funny.

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post #69 of 196 Old 08-10-2012, 09:39 AM - Thread Starter
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Originally Posted by tuxedocivic View Post

Sounds like you're trying to justify your purchase by questioning the audibility. EV just said it's audible. Many blind tests have been done on group delay, I assume. < can't think of one off hand > You don't have to justify your purchase. Those are good speakers. We just wanted to correct what you were saying that the H290 measures better, when that's not really the case. It kind of depends how you go about it. They're both very very good.
I sometimes find these comments funny about audibility. I often see posted, and often say myself, "I doubt it's that audible, so who cares." When doing DIY hifi, we should get hung up on the last little bit of performance that is barely audible. Why not ring every last drop of performance out of our designs. Hopefully when all the hardly audible things add up, they'll be remarkably audible and sound amazing.
Sorry, just a side note that I always think about. I do it too, just find it kind of funny.

I do not want to argue about which WG measures better any more.
But I am genuinely curious about HOMs and double-blind testing. Perhaps this thread is the wrong place to ask because of all the baggage. If you can recall any tests specifically done for HOMs, not group delay in general, I'd greatly appreciate the pointer. Something like Summas with and without foam insert, EQed.
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post #70 of 196 Old 08-10-2012, 10:42 AM
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4pi speakers are very good, well designed, and extremely popular.

go make some dusts already. tongue.gif

are you still tossing/turning over a 0.5% audible difference?
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post #71 of 196 Old 08-10-2012, 11:16 AM
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Quote:
Originally Posted by zheka View Post

I do not want to argue about which WG measures better any more.
But I am genuinely curious about HOMs and double-blind testing. Perhaps this thread is the wrong place to ask because of all the baggage.


There's no baggage here at all. No one is putting down Wayne's horn or arguing, just giving answers about waveguide designs. You should get what you think you will like the best. Simple as that. You'll enjoy your speakers, they get great ratings and Wayne is a great guy. No one is going to argue that.

The issue was that you said you were a noob just learning and don't necessarily understand all the info given. But then came out and said:

"I always assumed that SEOS is the better waveguide. This apparently is not the case......" How did you come to that conclusion if you didn't understand all the aspects that went into the SEOS design?

"I do not mind paying a little extra for the peace of mind." I don't really understand that comment because you could always pay more for the SEOS if you wanted. wink.gif Peace of mind from what? The SEOS design has been tested, refined and worked on a LOT more than any other waveguide I know of. And by some extremely smart people in the USA, Canada, Germany, and Poland. It performs exactly how they wanted it. Every single angle was scrutinized over and over along with the depth, roundovers, throat angles, even the darn screw holes. The prototypes were created and shipped out to multiple people for testing. The graphs have been posted many times.

To me, this is peace of mind knowing they've not only been designed, but also tested by some of the best out there for over a year.

When someone posts why the SEOS might perform good or look good, you seem to go the other direction. You think they look good, but don't care "if it comes at cost of performance." But you don't realize that their look is tied directly to their performance. The first goal was not good looks. biggrin.gif


Both are going to be good. No reason to second guess anything or worry about anything. But trying to talk down about one without knowing all the details about why it was designed the way it was isn't going to float well with any product. My guess is that you intended to buy (or already bought) the Eminence clone from the beginning, or you would have ordered the SEOS at the same time with the compression drivers that are for the SEOS project.


In the end, it really doesn't matter at all. Enjoy your decision and be happy with it. Those will be nice speakers. Be confident in your choice.

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post #72 of 196 Old 08-10-2012, 12:51 PM - Thread Starter
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Erich,
since you brought up the SEOS again, maybe you can tell me if it was designed to be a 90 degree horn? and if so, are there any measurements that show it as such? I maybe a novice but it does not take much to read the graphs.
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post #73 of 196 Old 08-10-2012, 01:09 PM - Thread Starter
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Originally Posted by smokarz View Post

4pi speakers are very good, well designed, and extremely popular.
go make some dusts already. tongue.gif
are you still tossing/turning over a 0.5% audible difference?

No, I have committed to the 4pi, no turning back smile.gif

But, you are right of course, I should be spending my time on something more productive.
this thread is getting me nowhere.
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post #74 of 196 Old 08-10-2012, 01:28 PM
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If you REALLY want to hear the difference, get them both in your home.

Listen to them, and then decide which you like better.

Otherwise, pick a design/build and move on.
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post #75 of 196 Old 08-10-2012, 05:04 PM
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Originally Posted by zheka View Post

I'd like to offer one possible explanation as to why jzagaja's measurements show wider horizontal dispersion.
It turns out that he measured from 1 meter as opposed to 2 meters in bwaslo measurements. The logic is that the further off-axis the signal is the higher the rate of decay.
Jacek was kind enough to BEM model the likely response difference for 0.5 meter vs 5 meter distance

If you get different polars based on where you measure, then you're not rotating around the acoustic center....

This is why I typically measure at >30ft, since being off by 1ft can at most cause a 0.3dB difference. At 3ft you could be off as much as 3dB. The accuracy of the angle also gets better as you move further away (or it should if you're measuring your angles in a way to improve that accuracy).

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post #76 of 196 Old 08-10-2012, 05:25 PM
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Quote:
Originally Posted by zheka View Post

Erich,
since you brought up the SEOS again, maybe you can tell me if it was deigned as a 90 degree horn? and if so, are there any measurements that show it as such? I maybe a novice but it does not take much to read the graphs.

Yes.....yes......and yes. The third yes was in case anyone asked if they looked as good as they performed. biggrin.gif

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post #77 of 196 Old 08-10-2012, 05:38 PM - Thread Starter
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Why don't you share the measurements then? In case you did not follow this thread, the ones you and Bill took show at best 100 degrees horizontal dispersion.
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post #78 of 196 Old 08-10-2012, 06:20 PM
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How on earth did you conclude that?


Here they are again, perhaps a better print so the lines are clearer. 7.5 degrees per step, the dark blue trace is the 45 degree off-axis step. Note it is also the trace closest to being 6dB down from the on-axis trace -- indicating a 2*45degree = 90 degree horizontal waveguide. It isn't like it takes an engineering miracle to get that, it is also simply the angle between the walls in the straight portion of the side walls rolleyes.gif These are conical horns (in the main section), their horizontal radiation angle is the same as the wall angle.

Here 'tis in color map fomat, all traces normalized to the on-axis trace. The white line indicates the -6dB point.

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post #79 of 196 Old 08-10-2012, 06:40 PM
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Quote:
Originally Posted by zheka View Post

Why don't you share the measurements then? In case you did not follow this thread, the ones you and Bill took show at best 100 degrees horizontal dispersion.

I'm following the thread just fine. I said the measurements are out there.

I was not the first person to bring the SEOS design into this thread. Nor have I attempted to put down any other horn out there. Nor have I put down any other horn designer, manufacturer, or speaker designer. Actually, there's lots of things I haven't done yet in life. biggrin.gif

Again, enjoy your horn and the DNA-360's. I'm glad I could save you and other DIY guys lots of money on these designs.

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post #80 of 196 Old 08-10-2012, 07:19 PM
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Well said Erich.
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post #81 of 196 Old 08-10-2012, 09:06 PM
 
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Some clarifications are clearly in order here.

As I look at the first post in this thread, Жека introduced the H290C horn/waveguide I provide in my loudspeaker kits. I see that he showed the measurements, which are very good. He did not make them as a comparison to other horn designs, but rather an introduction of my product.

I appreciate that, Жека, by the way. I am very proud of the H290C horn/waveguide, and I am happy that you like it too. Many other people are also satisfied purchasers of this new waveguide, and I'd venture to say that the four Pi loudspeaker you are putting it in is the single most popular matched-directivity two-way loudspeaker on the market today, certainly with the DIY crowd. There are literally thousands of happy four Pi owners around the world.

The H290C horn/waveguide is not a "clone" of anything. It is a horn that I designed about ten years ago, one iteration of a handful of prototype designs for the H390C wood horn/waveguide that's been in constant production for nearly ten years now. I ended up making my wood horn/waveguide a larger device because I knew it would always be cradle mounted instead of baffle mounted. It is usually purchased for its aesthetic beauty as well as for its acoustic performance.

The design was influenced by several factors. One was a long-time realization that constant directivity was desirable, particularly in the horizontal, but that sharp edges in a horn usually made them sound "spitty" and harsh. So I had been using radial horns with smooth contours and good horizontal patterns instead.

I was also influenced by Geddes opinions about the catenary shape, which he likes to rotate on axis to form the now-famous oblate spheroidal horn that so many people talk about. There were other factors too, but I don't want to turn this into a waveguide history lesson. Anyone interested can search my forum and others for this kind of information. Frankly, I think most of you know it, at least in part.

I had spoken to Earl Geddes at one of the trade shows in some depth before I designed my H290C and H390C horn/waveguides. We continued our discussions, and at one point, I considered entering into an agreement with him to produce Prolate Spheroidal horns. Earl preferred the round OS horns, but I always prefered to limit the vertical beamwidth as well as the vertical distance between sound sources. So the PS horns were more attractive to me.


My H290C and H390C horn/waveguides use a pure catenary in both planes. The edges are also catenary flares, It is a smooth transition from round to rectangular, as is prescribed in the literature. They are mathematically pure.

The H390C has a larger section at the mouth to provide more mouth area. Since it is to be used off a baffle, I wanted more area and a widening section to counter waistbanding. The H290C has less of a roundover because it is designed to be used on a baffle, and doesn't need as much. I found this out when I built the first prototypes.

The reason I had molds made was that Eminence lost their source for the H290 horn. They did not make this horn, they bought it from a vendor. So when the vendor suddenly stopped making them, Eminence was caught with no inventory almost overnight. The Eminence H290 was a radial horn and did not use a catenary flare, but it performed well. In fact, it performed so well that I preferred it to most of the other waveguides on the market, which is why I did not switch. However, when my source dried up, I decided to "make lemonade."

I basically just dusted off the prototype I had made during H390C development, and sent the 3D model off to some plastic mold makers to get bids. I modified it first to add the bolt patterns, but kept it as much the same as possible in order to retain the same acoustic characteristics and performance. This allowed me to use the crossover designs I already had.

It's not exactly the same as the (Eminence) H290 crossover, but very close. Close enough to use it as bolt-on upgrade, which was one of my goals. All my crossover schematics have notes to show what components to use for various options. So this allowed me to leverage the design work I had already done.

This is not some hack job or clone of anything, and I resent that implication. My designs have been in production so long, it seems to me that the "other guys" would be the ones seen as making the clones. I did not copy anyone's compression driver. I did not copy anyone else's horn. I did not copy anyone else's loudspeaker design or methodology. I'm just making speakers that excite me, and hoping that others enjoy them too.

I always liked how the Econowave folks and Pi Speakers enthusiasts saw each other as "kindred spirits", and we always shared information and friendly conversation. But the SEOS crowd seems to be loaded for bear. So since you've thrown down the gauntlet, I have some comments for you.

First, you can't claim the SEOS device to be "Geddes approved". I'm not sure this is relevant, but you do seem to think it's a trump card or something. So if that's your goal, then let's get this part straight.

Geddes has said numerous times that he feels the OS shape is the best way to reduce internal reflections, the high-order modes. In his mind, the flare profile must be catenary, revolved to a minimum surface oblate spheroid. He doesn't want it truncated, elongated or squished.

Even though Geddes patented the PS waveguide, he seems to distance himself from it. In his patent, he declares that the ratio of "squish" can be only 2/3rds or so, basically a 90x60 beamwidth. Otherwise, he is concerned that the shape might fracture the expansion enough to increase high-order modes.

The flare profile also has to be a catenary. But a catenary is like conical, in that it forms a right triangle. For a 90 degree pattern, the mouth radius MUST be the same as the depth. You can't make it too shallow, or it isn't a catenary. This also increases high-order modes. For a given mouth size, throat size and wall angle, there is a given depth. It isn't a variable, it's fixed.


Now then, I do know that Geddes sees some deformations as "forgiveable". I think he sees it as a continuum of acceptable shapes. The more the horn is squished, the more compromised it becomes, in his eyes. But it is pretty evident, at least to me, that Geddes yardstick for HOM-friendly deformations is still a bit of a guess. Nobody really knows what is acceptable or not, or how much each modification from the basic revolved catenary does.

I think we all would agree that some mouth radiusing is desireable, even though that deviates from the basic catenary shape. But I think there is some question as to whether or not deep radiusing to reduce waistbanding is going to increase high-order modes or not. I've not seen that brought into question, but I do know that Geddes doesn't do it. That's a throwback from Mantaray and other diffraction horns, designed with pattern control as the primary (perhaps only) design goal.

So is it a problem or not to widen out the flare profile to counter waistbanding? What if it increases high-order modes? After all, it is not part of the catenary shape. It is not included in the OS flare profile, nor in the PS, for that matter. If it increases high-order modes a little bit but makes the beamwidth more consistent, is it a good thing?

Those are rhetorical questions. I'm not going to give any more of my opinions in this forum, but I am going to say that the SEOS cannot be a catenary flare because its geometry isn't right for that. At best, it is a catenary for the first couple of inches and then it flares wider, to counter waistbanding. That is what I assumed it was, anyway.

I do not want to go any further into a critique of the SEOS horns. As I said earlier, I wanted to see us as kindred spirits, much like the Econowave guys were. Maybe we can get back to that, I don't know. But I do know you have taken a position that the SEOS horn is superior, and I do not see it that way, not at all. It is a good horn, but it is not right for me or I would have used it. For now, I will leave it at that.
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post #82 of 196 Old 08-10-2012, 09:58 PM - Thread Starter
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Bill,


Having the dB scale in 6dB increments on the sonogram certainly helps to see it better (the one in the measurements post is in 5dB steps)

It is over the 45 degree mark for most of the 1.7kHz to 6kHz range, reaching approx 55 degrees around 3kHz. correct me if I am wrong.
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post #83 of 196 Old 08-10-2012, 10:44 PM
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Quote:
Originally Posted by Wayne Parham View Post

I always liked how the Econowave folks and Pi Speakers enthusiasts saw each other as "kindred spirits", and we always shared information and friendly conversation. But the SEOS crowd seems to be loaded for bear. So since you've thrown down the gauntlet, I have some comments for you.

That's not really fair to say. No one has 'thrown down the gauntlet'. No one is putting down your horn, your speakers, or anything else. Matter of fact, it's just the opposite and I don't recall anyone saying anything bad about your products. I've stated quite a few times that the OP will very much like his speakers, as have others. How can that be bad?

However I do recall you saying that your horn was "far superior" to the SEOS a while ago before anyone ever brought this up at all. And 'far superior' is simply not the case for either of these models, which has been stated multiple times in this thread. To argue that just doesn't hold water. And no one has........except your last post. wink.gif

No one is 'loaded for bear'. To say that the SEOS crowd is loaded to argue seems pretty much the opposite to me. A question was asked, graphs were posted without bad mouthing any other product. No put downs were started from the "SEOS crowd" besides someone saying they liked the look better.


I'm done posting graphs when forum members ask, or telling the OP that he will like your speakers and to start building so he can enjoy them. Guess them's fightin' words on other forums. biggrin.gif

Moving on.....

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post #84 of 196 Old 08-11-2012, 12:11 AM
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hi wayne. nice to see you drop by. i think the friendly spirit to which you are referring is alive and well around avs, at least in the diy section. there are many pi builds around and they have been "goto" speakers for many years.

"But I think there is some question as to whether or not deep radiusing to reduce waistbanding is going to increase high-order modes or not."

my impression was that hom's, to the extent that they exist, arise from internal reflections, primarily in the throat, but also present in horns with less than a 90 degree expansion rate, as in the picture below.

the foam in dr. g.'s designs reduces hom's because they have a longer distance to travel through the foam than the on-axis hom-free sound.

it is also the reason why he won't go less than 90 degrees in the vertical, even though that moves the two point sources further apart.

i'm not sure how a smoother transition from horn to baffle could ever create more hom's, it just requires a larger horn and enclosure. that is part of the reason why the summas are so large.

it seems that the jbl guys chose a very large radius horn for the everest and the k2, so it probably has some benefit and was one part of the seos design strategy.

anyways, it is good to see you (btw, i have posted in the econowave thread under the callsign publius and wrote the short article on controlled directivity).


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post #85 of 196 Old 08-11-2012, 12:31 AM - Thread Starter
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Quote:
Originally Posted by MBentz View Post

If you get different polars based on where you measure, then you're not rotating around the acoustic center....
This is why I typically measure at >30ft, since being off by 1ft can at most cause a 0.3dB difference. At 3ft you could be off as much as 3dB. The accuracy of the angle also gets better as you move further away (or it should if you're measuring your angles in a way to improve that accuracy).

This makes a lot of sense, thank you.
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post #86 of 196 Old 08-11-2012, 06:03 AM - Thread Starter
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Quote:
Originally Posted by Wayne Parham View Post

...the SEOS cannot be a catenary flare because its geometry isn't right for that. At best, it is a catenary for the first couple of inches and then it flares wider, to counter waistbanding.

BWaslo says SEOS is conical in it's main section before widening up.
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post #87 of 196 Old 08-11-2012, 08:58 AM
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I don't want to jump into what is amounting to a flame war, but I have to add something.

I looked hard at Pi, Ewave, and SEOS. There are all great approaches (very similar, btw) and in the end will sound far better than what can be bought in the stores for 3X.

Zheka, I think you are in the same spot as I am in that I'm wanting to upgrade my setup with the best "bang for buck", but are relative noobs. Somewhere in all of the threads I followed, it was put to me that it's like comparing a Ferrari to Lamborghini. Both will exceed 200 MPH. In our terms, whether we build a PI or and SEOS, they will blow away anything we can afford in our price range (and then some). Be happy. Make some dust. You'll love your PI. I'll love my SEOS.
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post #88 of 196 Old 08-11-2012, 09:50 AM - Thread Starter
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Quote:
Originally Posted by Java View Post

I don't want to jump into what is amounting to a flame war, but I have to add something.
I looked hard at Pi, Ewave, and SEOS. There are all great approaches (very similar, btw) and in the end will sound far better than what can be bought in the stores for 3X.
Zheka, I think you are in the same spot as I am in that I'm wanting to upgrade my setup with the best "bang for buck", but are relative noobs. Somewhere in all of the threads I followed, it was put to me that it's like comparing a Ferrari to Lamborghini. Both will exceed 200 MPH. In our terms, whether we build a PI or and SEOS, they will blow away anything we can afford in our price range (and then some). Be happy. Make some dust. You'll love your PI. I'll love my SEOS.

I agree with you fully. I have no doubt that both are great horns. It is unfortunate that this thread spiraled down the "which one is better" path. Believe it or not I never wanted this to happen.
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post #89 of 196 Old 08-11-2012, 09:59 AM
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Hi, Wayne, sorry for any misunderstandings. I think you and your designs are held in high esteem around here, any perceived slight was not intentional I'm sure. I don't recall seeing anyone slam your horn (man, that sounds odd eek.gif !). I've taken a lot of (what little) I know about constant directivity design from your postings.

The "SEOS crowd" is basically just an extension of the ewave crowd, started because for a while it didn't look like we'd be able to get the QSC waveguide of the Econowave Deluxe. No need for rancor. I don't know whether one horn is better than another (or what that even means). I do like the appearance of the SEOS better than the other waveguide designs, and I know it measures well, is well made, inexpensive, and I like the sound of it a lot. But I don't think anyone would regret going with one of your designs.

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post #90 of 196 Old 08-11-2012, 03:18 PM - Thread Starter
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Apparently Geddes has ABed the foam plug at some point and found the results conclusive
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-155.html#post1570584
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