The Great Waveguide Shootout!!! - Page 4 - AVS Forum
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post #91 of 192 Old 07-31-2013, 06:58 AM
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I think most people that designed with the DNA-150 have it crossed over around 2khz or higher.
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post #92 of 192 Old 07-31-2013, 09:45 AM
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This is where some thought about what's happening is required. I personally crossed the DNA-150 at 1300hz once. But that was on a larger WG that boosted the low end better. You have to consider what gain you're getting out of the waveguide/horn. And also have to consider what the XO is doing to the response. I used the DNA-150 down to 1500hz with a fairly small waveguide, but the woofer was ineffecient at about 88db. After BSC and a -6db XO at 1500hz, the DNA-150 was way down in output and will hardly ever see 2.83V at 1500hz. And by then the woofer is struggling.

Gotta judge the driver according to the system it'll be used in.
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post #93 of 192 Old 07-31-2013, 06:11 PM
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Very true, the top end on both of those horns is about 10 db lower, so equalizing flat gives you a pretty decent amount of head room, and much lower distortion.
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post #94 of 192 Old 07-31-2013, 07:28 PM
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What I don't understand is how any measurement of these waveguides with the 150 CD can show the waveguides performance when we have no way to see how low in frequency these can go due to the CD being so limited? Is there something I am missing here? Or is Mat measuring the pattern, horizontal, vertical, of each waveguide? Don't we already know what the pattern throw is for these?
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post #95 of 192 Old 07-31-2013, 08:03 PM - Thread Starter
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Not all of the waveguide tests will be done with the DNA-150, only the threaded 1-3/8"-18 TPI waveguides and a few of the other small waveguides will use it. When it come to the bolt on waveguides those will be done with the DNA-360 and you will be able to use the distortion graphs to see how low they are usable. Actually you should use both the distortion and pattern control to see how low you would want to use them.

Many of the waveguides hear have not had any off axis measurements done before, that was one of the main reasons I wanted to do these tests in the first place.
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post #96 of 192 Old 08-01-2013, 06:36 AM
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Thanks for explaining that Matt. What measurement in REW will show the pattern output by the waveguide?
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post #97 of 192 Old 08-01-2013, 06:48 AM
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post #98 of 192 Old 08-02-2013, 01:10 AM
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Great project! I may be a bit late to the table, but Arta is good for this kind of thing, especially when you want to speed things up. There is a macro that allows you to press start, and then run all the sweeps out to 90 degrees with a brief delay. You can do each combination in about a minute.
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post #99 of 192 Old 08-02-2013, 07:09 AM
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Quote:
Originally Posted by mtg90 View Post

Not all of the waveguide tests will be done with the DNA-150, only the threaded 1-3/8"-18 TPI waveguides and a few of the other small waveguides will use it. When it come to the bolt on waveguides those will be done with the DNA-360 and you will be able to use the distortion graphs to see how low they are usable. Actually you should use both the distortion and pattern control to see how low you would want to use them.

Many of the waveguides hear have not had any off axis measurements done before, that was one of the main reasons I wanted to do these tests in the first place.

Another question....How can you get an accurate distortion measurement, and be able to get an idea how low each of these waveguides will reach down to when the DNA-360 will distort in frequencies below a certain point?

I mean, how do you know if waveguide "A" or waveguide "B" will go down to say....400hz or 700hz because the DNA-360 will not reach down that low without significant distortion?
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post #100 of 192 Old 08-02-2013, 07:53 AM
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He's using compatible CDs for each waveguide. I doubt he uses the 360 on a 6" wide waveguide or the SEOS 24. He'll use different CDs for the appropriate waveguide.
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post #101 of 192 Old 08-02-2013, 08:10 AM
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I think that the questions on how to interpret the results are good. That's because it is not so easy to do! First a compression driver/waveguide is a single system and it is not really possible to make judgments about one without the other. So one cannot look at waveguide X and know how it will work with driver Y when driver Z was used to take the data. Each combination is unique.

I offered to help because I think that the data should all be shown in a common format where one can readily compare two system against one another in an easy manner. That is why I did my Polar program because it is ideal for that kind of thing. And I already have a rather large array of systems being shown.

How one deals with EQ is a real issue because this is a key factor in how any of these systems will work in the end. Normalizing the axial response is not the way to do this because it will not optimize the response in the proper way. What one needs is to compare the waveguide/driver combination as it can be done in its optimal configuration. This is a big part of why waveguides/drivers can be so hard to work with.

Different drivers should be used and the results should be shown along different axes if the waveguide is not symmetric.

As to showing my own waveguides, this information is readily available now as are several other waveguides, on my website. This is where I would like to show all of the devices, although the software could also be posted elsewhere if that is an issue (but it cannot be readily distributed because there is no setup program for it).
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post #102 of 192 Old 08-02-2013, 08:57 AM
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Quote:
Originally Posted by gedlee View Post

How one deals with EQ is a real issue because this is a key factor in how any of these systems will work in the end. Normalizing the axial response is not the way to do this because it will not optimize the response in the proper way.

This subject comes up often and it's important because it does have a lot of pitfalls. But Where the axial response is uniform with the off axis responses, I don't see an issue with equalising the on axis response. Would you agree with that? I'm not considering the vertical direction for non-symmetrical waveguides when I say that, but if we leave that part of the problem out for now I don't see a problem with eq.
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Different drivers should be used and the results should be shown along different axes if the waveguide is not symmetric.

It would be nice to see the vertical response for these, although I think the more important result is the vertical response in the speaker system, which is dramatically altered based on the geometry of the driver layout and XO. Whereas the horizontal polar response is mostly preserved with the typical vertical TM (sure, there's some "combining" of the two drivers at the XO, but generally they're complimentary if done right). I wonder if Matt is setup to easily get the vertical responses. Maybe even just for a few of the really popular waveguides. We have a pretty good idea of the SEOS12, but not many others. The SEOS 12 does fairly poorly vertically in order to be a short waveguide.
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post #103 of 192 Old 08-02-2013, 11:34 AM - Thread Starter
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It is very easy to do the vertical axis, I just pop out the baffle and rotate it 90 degrees smile.gif

Those first two waveguides were symmetrical so there is only one axis.

Last night I just did the DW-7ES, DW-654S, EOS-6 and one of the ones Erich gave sent which I don't know if he has a name for. I did both horizontal and vertical for those first three the other is another symetical waveguide.

I planned on testing some of the waveguides with multiple CD's Something like the EOS-8 I will measure with the DNA-150, DNA-205(comparable to B&C DE10), and DNA-360(comparable to B&C DE250). Right now I am running through all the ones I am going to test with the DNA-150.

Quote:
Great project! I may be a bit late to the table, but Arta is good for this kind of thing, especially when you want to speed things up. There is a macro that allows you to press start, and then run all the sweeps out to 90 degrees with a brief delay. You can do each combination in about a minute.

It's not bad at all running REW right now, it only takes me around a minute to do a set of off axis measurements. But I do need to do a little formatting in order to import them into Omnimic for the Polar Sonograms.
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post #104 of 192 Old 08-02-2013, 11:47 AM
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Are you going test Erich's BA 750 with the SEOS 18?smile.gif
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post #105 of 192 Old 08-02-2013, 12:37 PM
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Quote:
Originally Posted by tuxedocivic View Post

This subject comes up often and it's important because it does have a lot of pitfalls. But Where the axial response is uniform with the off axis responses, I don't see an issue with equalising the on axis response. Would you agree with that?

I think he's talking about normalizing the axial response when making measurements to show for comparison purposes, like Matt is doing here. Right, Earl?
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post #106 of 192 Old 08-02-2013, 01:41 PM
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Ah ya, that might be what he meant.
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post #107 of 192 Old 08-05-2013, 07:45 PM - Thread Starter
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Updated original post and added index on 2nd post (also picture of the waveguide being tested in the posts with the results).

Results of the next 4 waveguides to come shortly.
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post #108 of 192 Old 08-05-2013, 07:50 PM - Thread Starter
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Smaller of the two round unnamed waveguides:




Distortion @ 2.83v/1m:


0-90 degrees off axis. Note that the measurements are not all that accurate out at 90 degrees, I think there is some sort of transition happening from 2pi to 4pi space out near 90 degrees when the baffle no longer acts like a baffle causing the broadband drop in SPL below 9k or so.


Polar Sonogram:
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post #109 of 192 Old 08-05-2013, 07:58 PM - Thread Starter
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DW-654S:




Distortion @ 2.83v/1m:


FR 0-90 degrees off axis vertical


FR 0-90 degrees off axis horizontal


Vertical Polar Sonogram:


Horizontal Polar Sonogram:
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post #110 of 192 Old 08-05-2013, 08:32 PM - Thread Starter
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DW-7ES:



Distortion:


Horizontal FR 0-90:


Vertical FR 0-90:


Horizontal Polar Sonogram:


Vertical Polar Sonogram, note there is an off axis peak or I should say a dip on axis near 18k that throws off the -6db line on the sonogram so I have included another one which is zoomed and better represents that point:


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post #111 of 192 Old 08-05-2013, 08:50 PM - Thread Starter
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EOS-6:



Distortion:


Horizontal FR 0-90:


Vertical FR 0-90



Same issue with off axis hot spot/on axis dip throwing off sonograms so I have included ones cut off at 17K also

Horizontal:



Vertical:

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post #112 of 192 Old 08-05-2013, 10:57 PM
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Two things sir:

Do you need a hand at all, and/or would you mind showing a newbie like myself exactly what you're doing and what it all means? I live in Plainfield and would love to leaRN.

Many of us are running SHO-10's yet I don't see its' waveguide in your group. Any chance I can add it to your testing group?
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post #113 of 192 Old 08-06-2013, 01:16 AM
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So much beaming and a collapsing polar.
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post #114 of 192 Old 08-06-2013, 07:36 AM
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Quote:
Originally Posted by omholt View Post

So much beaming and a collapsing polar.
.

These are pretty small waveguides. About 6".
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post #115 of 192 Old 08-06-2013, 08:20 AM
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Quote:
Originally Posted by tuxedocivic View Post

.

These are pretty small waveguides. About 6".
Ok. Understandable.
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post #116 of 192 Old 08-06-2013, 09:21 AM
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Wonderful project, watching closely.

Thanks for the effort, as it is much appreciated.

------------------------------------
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post #117 of 192 Old 08-06-2013, 12:06 PM
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^^ +1.

of course, when you get done measuring and posting, an index in the op would be VERY useful as I suspect this thread will be referenced 1000's of times...

Listen. It's All Good.
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post #118 of 192 Old 08-06-2013, 01:11 PM
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Not sure if you're interested in this or not, but when you're showing the frequency response at multiple angles (not the sonogram), it is possible to normalize the plots by telling REW that the first on-axis measurement is a calibration file...

I'm curious about your comments in regards to the "full space" thing dropping off the lower frequencies...could you post a picture of the mic position when you're at 90 degrees? Did you fall off the baffle or something? I wonder how much edge diffraction from the baffle might be affecting some of your numbers too?

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post #119 of 192 Old 08-06-2013, 05:35 PM - Thread Starter
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Quote:
Originally Posted by a|F View Post

Two things sir:

Do you need a hand at all, and/or would you mind showing a newbie like myself exactly what you're doing and what it all means? I live in Plainfield and would love to leaRN.

Many of us are running SHO-10's yet I don't see its' waveguide in your group. Any chance I can add it to your testing group?

If you can mount the SHO-10 waveguide/CD on a 12"x12" piece of 1/2" MDF then I will be happy to test it as well. I'll send you PM.




Quote:
Originally Posted by LTD02 View Post

^^ +1.

of course, when you get done measuring and posting, an index in the op would be VERY useful as I suspect this thread will be referenced 1000's of times...

Did you see the second post. smile.gif


Quote:
Originally Posted by MBentz View Post

Not sure if you're interested in this or not, but when you're showing the frequency response at multiple angles (not the sonogram), it is possible to normalize the plots by telling REW that the first on-axis measurement is a calibration file...

I'm curious about your comments in regards to the "full space" thing dropping off the lower frequencies...could you post a picture of the mic position when you're at 90 degrees? Did you fall off the baffle or something? I wonder how much edge diffraction from the baffle might be affecting some of your numbers too?

I never thought about doing that in REW, however I normalize in Omnimic for the Sonograms anyway. If anyone would like me to include the normalized plots as well just say so and I will add them to the posts.

I'll try to get a picture the next time I have the baffle setup. It is weird though as it happens really quick you see that 75 degrees still looks fine but after that the low end starts to drop. I may have to look into what diffraction effects the baffle has on the waveguides, I'll test a few unmounted on a rotatable stand to compare FR and directivity.
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post #120 of 192 Old 08-06-2013, 06:22 PM
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mtg,

Tremendous. This is great stuff.

JSS
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