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The Great Waveguide Shootout!!! - Page 2

post #31 of 190
Thread Starter 
I was not going to normalize distortion to SPL, it would be too much trouble to program a minidsp EQ setting for every horn/CD combo.

Does Omnimic let you do that? I know you can normalize SPL with it but I am not sure if that carries over to the distortion readings or not?
post #32 of 190
Quote:
Originally Posted by mtg90 View Post

I was not going to normalize distortion to SPL, it would be too much trouble to program a minidsp EQ setting for every horn/CD combo.

How about just adjusting to a particular level
post #33 of 190
Thread Starter 
Do you mean adjusting the voltage level of each so that the SPL is the same across the different waveguides at a chosen frequency? Say somewhere in the range of 2-5khz? That might be easy enough to do.
post #34 of 190
Maybe that, plus FR at a consistent voltage...2.83 or whatever.
post #35 of 190
I can supply a Faital Pro LTH142 if there's interest. I have two of these sitting around awaiting a project build, but am forever procrastinating. rolleyes.gif These will require a 1.4" CD.

http://www.faitalpro.com/products/HF_Horns/product_details/index.php?id=903020105

- Robert
post #36 of 190
Matt,

Are you concerned at all that the rotation axis will be on the baffle plane, not at the acoustic centers of the respective CD/WG combinations? do you think 2 meters mike distance is far enough to make the differences negligible?
post #37 of 190
Thread Starter 
I am figuring about a 5% error in angle if the AC of one is about 10cm behind another. I think when graphed that discrepancy will be pretty small (45 degrees is actually 42.75, 60 is 57). I may back the mic up to 3m for the off axis which should drop it to 3.33%.


I drove up to Seaton Sound yesterday and picked up the QSC 152i and SEOS-24 from Mark. Now just waiting for the last 4-5 from Erich.

Here is the current crop:
post #38 of 190
This is great! If you need any help actually executing the test (i.e. somebody to turn the crank while you take the measurements, somebody to help keep the dozens of measurement files organized while you swap waveguides/drivers, et cetera) let me know. I don't live too far from you.
post #39 of 190
Is there reason to add vertical dispersion to the tests, or can we infer everything you'd want to know that you wouldn't measure anyway when designing a speaker?
post #40 of 190
Quote:
Originally Posted by mtg90 View Post

Do you mean adjusting the voltage level of each so that the SPL is the same across the different waveguides at a chosen frequency? Say somewhere in the range of 2-5khz? That might be easy enough to do.

yep

Are you going to normalize the polars to flat on-axis response?

Personally I think this is the only way to go, since otherwise you have to try and eyeball out the differences in freq resp by focusing on the distance between curves at different angles.
post #41 of 190
Thread Starter 
Oh yeah polars will be normalized, well at least the sonograms will.
Quote:
Originally Posted by batdorf9 View Post

I can supply a Faital Pro LTH142 if there's interest. I have two of these sitting around awaiting a project build, but am forever procrastinating. rolleyes.gif These will require a 1.4" CD.

http://www.faitalpro.com/products/HF_Horns/product_details/index.php?id=903020105

- Robert

When it comes to the second round of waveguide testing I'll be sure to let you know.

Quote:
Originally Posted by pitviper33 View Post

This is great! If you need any help actually executing the test (i.e. somebody to turn the crank while you take the measurements, somebody to help keep the dozens of measurement files organized while you swap waveguides/drivers, et cetera) let me know. I don't live too far from you.

Thanks for the offer Pitviper, You may get a PM if I know specifically what day beforehand I might end up doing some of the testing. You could also have a listen to the some of the speakers that don't have their insides strewn about biggrin.gif, might be good to get an outside opinion on the voicing of some new ones in the works.

Quote:
Originally Posted by HopefulFred View Post

Is there reason to add vertical dispersion to the tests, or can we infer everything you'd want to know that you wouldn't measure anyway when designing a speaker?

You could get most everything you need to know from the horizontal pattern but verticals will be tested for good measure. A horn with less spill (tighter control) vertically is usually a good thing when trying to reduce floor/ceiling reflections.
post #42 of 190
Quote:
Originally Posted by mtg90 View Post

Oh yeah polars will be normalized, well at least the sonograms will.

xlnt, sonograms are even better
post #43 of 190
Quote:
Originally Posted by noah katz View Post

xlnt, sonograms are even better

Sonograms??? Who's pregnant?!?!
post #44 of 190
Subscribed. Gunna b great. Props for doing this!
post #45 of 190
Quote:
Originally Posted by mtg90 View Post

Thanks for the offer Pitviper, You may get a PM if I know specifically what day beforehand I might end up doing some of the testing. You could also have a listen to the some of the speakers that don't have their insides strewn about biggrin.gif, might be good to get an outside opinion on the voicing of some new ones in the works.
Sounds great! Just let me know.
post #46 of 190
Subscribed.

JSS
post #47 of 190






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post #48 of 190
Thread Starter 
What have I gotten myself into biggrin.gif




I am currently trying to cut baffles for each of these waveguides, unsure how I am going to mount the fiberglass ones without screw holes. Any suggestions?
post #49 of 190
This will be EPIC. eek.gif
post #50 of 190
Just a bead of silicone. That way when you're done they'll pop right out.
post #51 of 190
Thread Starter 
I'll try that, thanks Tux. smile.gif
post #52 of 190
or some sort of clamp jig.

post #53 of 190
WIth the weights of some of the CD's I would be concerned about silicone coming loose. I second the vote for a clamping system to secure them.
post #54 of 190
Padded, double sided tape would also work as well. cool.gif
post #55 of 190
As much scrutiny as these results are likely to get, they should be as close to a finished installation as possible - free of irregular diffractive surfaces and atypical resonances.
post #56 of 190
Quote:
Originally Posted by tsloms View Post

WIth the weights of some of the CD's I would be concerned about silicone coming loose. I second the vote for a clamping system to secure them.

With his setup, only an issue at around 90 degrees. Only has to last 5 minutes at most. And the larger heavier CDs are on the larger waveguides where the silicone seal will be bigger. I would think it works, but who knows. Cheap and easy to try.
post #57 of 190
Matt, how are the baffles coming? Which CD's will you be using for this test? Is this just going to be a measurement test of these particular waveguides or are you going to mount the baffles to a real enclosure and add a woofer to get a better idea of how they sound in a real world setup? (Sorry if these questions have been covered, I read back through the thread and didn't see the answers, but I could have likely missed it) smile.gif
post #58 of 190
Quote:
Originally Posted by Martycool007 View Post

Matt, how are the baffles coming? Which CD's will you be using for this test? Is this just going to be a measurement test of these particular waveguides or are you going to mount the baffles to a real enclosure and add a woofer to get a better idea of how they sound in a real world setup? (Sorry if these questions have been covered, I read back through the thread and didn't see the answers, but I could have likely missed it) smile.gif

It's all in post 1....
post #59 of 190
Hey Matt,

Rather than mount the waveguide to a rotating baffle, why not rotate the microphone around a fixed baffle. The mic is a lot lighter and you could let the waveguide rest in place facing upwards held by gravity alone.

Mike
post #60 of 190
Quote:
Originally Posted by mhutchins View Post

Hey Matt,

Rather than mount the waveguide to a rotating baffle, why not rotate the microphone around a fixed baffle. The mic is a lot lighter and you could let the waveguide rest in place facing upwards held by gravity alone.

Mike

That would work, but it will be hard to get the mic in exactly the same position every time.
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