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Old 17th April 2012, 04:21 AM   #1
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Default benefits and drawbacks of waveguides

so what are they in a nutshell? Why do so few high end companies use them?

Are they better than conventional flat baffle speakers?
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Old 17th April 2012, 09:23 AM   #2
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Oh no ! Not again ! Another question by professor Smith !! It's the same Smith from 'the Matrix' ?
You don't/can't believe in what you see , YES ! believe it ! No, there's an under world !!
So , what's the question ? waveguides...for tweeters ?
And ...high end ?
what about common people facing the problems when projecting speaker systems , or just mere hobbysts that have some speakers laying around ,or making them fit to
room acoustics in some elegant waY ?
Scarcely : directivity matching between a woofer and a tweeter ,non-dependance of the geometry of the box ( edge diffraction ) ; sensitivity matching...that is what the wg does ,even if it's not a horn , if you tabulate the FR with or without the wg , it gives certainly a 'boost' to the lower part of the spectrum , thus integrating better with the woofer .

And..it depends : flush mounting is another thing . Or the same, if you watch it from an acoustical (waves) point of view .
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Old 17th April 2012, 09:39 AM   #3
AllenB is offline AllenB  Australia
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Are they better? Sure, why not. I have three. The third one is the centrepiece of my interior illumination scheme in my office.
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Old 17th April 2012, 03:14 PM   #4
gedlee is offline gedlee  United States
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Theoretically the use of a waveguide does do a great deal to enhance the performance of a tweeter. But they can difficult to design and build and this is probably why you don't see them more often. They don't have flat responses and this makes for a very complex crossover. They add depth and cost to the design as well. They increase sensitivity in the critical Lower Frequency region which lowers cone excursion for equivalent output. Do them wrong and they can sound horrible, but done correctly and they will beat a direct radiator hands down.
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Old 17th April 2012, 04:05 PM   #5
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by Professor smith View Post
So what are they in a nutshell?
Why do so few high end companies use them?
Are they better than conventional flat baffle speakers?
Hi,

a) See Zaph|Audio

b) High end is fashion as well as engineering.
Zingali have ploughed a lonely furrow for years.
Stuff used at lot for PA systems has a hard time
entering the "high end" mainstream, if it ever does.

c) Done well they work very well, see : Zaph|Audio
They are better for the cases the other driver(s) and
x/o choices suit using them well. Horses for courses.
They are not a universal panacea.

rgds, sreten.
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Old 17th April 2012, 04:45 PM   #6
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Revel, Kef and YG acoustics use wave-guides to a certain extent.

As far as I'm concerned wave-guides don't have many drawbacks but this I suppose would depend on personal point of view.

The main disadvantage from my point of view is that if one is going with a directivity match set crossover frequency then the C2C spacing usually ends up a bit bigger then would be universally recommended.

Normally they do require a more complex crossover, but sometimes you can get away with a very simple affair, as Zaph's design shows. From a DIY point of view they do require more work if only for mounting the tweeter to the wave-guide.

As to why they aren't used more in the consumer market is anyones best guess. Usually they don't look particularly attractive, which is important in todays high end bling, but can easily be accommodated if the front baffle is moulded or machined from plastic/metal. Most baffles aren't done like this and the usually mounted tweeter is commonly accepted and often wanted, sticking a large plastic moulding into the nice veneer is not. To do this right would obviously add in extra costs and in an already quite competitive market they might be seen as ineffective costwise.
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Old 17th April 2012, 06:23 PM   #7
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Quote:
Originally Posted by Professor smith View Post
so what are they in a nutshell? Why do so few high end companies use them?

Are they better than conventional flat baffle speakers?


1) First preemptive issue: Define what constitutes a waveguide. It can be argued that a flat baffle is a waveguide variant, as well as a horn, or for that matter, a tube with parallel walls.

2) If you are trying to address the mitigation of HF beaming, use of an acoustic lens may be the preferred method although more costly.

3) Competitive advantage and Increasing Profit Margin are the motives that drive all High End Companies as well. (At least that is true for those that are still in business.) There is a distinct inverse relationship between Sales Volume and Profit Margin. With Volume Low comes a Margin High (End).

4) Not all questions posed have answers; and some that do, don't deserve them.

Regards,

WHG
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Old 19th June 2012, 12:15 PM   #8
Cask05 is offline Cask05  United States
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Quote:
Originally Posted by gedlee View Post
Theoretically the use of a waveguide does do a great deal to enhance the performance of a tweeter. But they can difficult to design and build and this is probably why you don't see them more often. They don't have flat responses and this makes for a very complex crossover. They add depth and cost to the design as well. They increase sensitivity in the critical Lower Frequency region which lowers cone excursion for equivalent output. Do them wrong and they can sound horrible, but done correctly and they will beat a direct radiator hands down.
This is where my audio excursions have taken me: a pair of Roy Delgado's/PWK's last design.

1) I think that most people here haven't heard a pair of well designed and executed "waveguide" speakers in a good room environment. It took me a while to get my audio environment up to speed. Now most people don't even notice the speakers when listening, rather, they are focused on the music/sound itself. The soundstage image is much larger than the speakers themselves--covering the whole front of the room.

2) Are there discussions on loudspeaker AM and FM distortion this forum? There are some older JAES papers on this subject of some interest, that explain "waveguide" loudspeaker advantages in this area.

3) I've found that room acoustics and placement of "waveguide" speakers in-room is a subject that most folks apparently know very little about. I've found that corner-horn speakers help you to learn some of those lessons.

Chris
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Old 19th June 2012, 03:08 PM   #9
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Quote:
Originally Posted by Professor smith View Post
so what are they in a nutshell?
Speakers where as the midrange driver begins to become directive, the crossover hands off to an EQUALLY directive tweeter.

Quote:
Why do so few high end companies use them?
What's easier to design, build, and sell, this:

Click the image to open in full size.

or this:

Click the image to open in full size.

?

Quote:
Are they better than conventional flat baffle speakers?
Better in terms of output, but otherwise just different assuming that flat baffle speaker had smooth off-axis response. What kind of apparent source width do you want? (large) Waveguide speakers will have less room interaction, but that's not necessarily everyone's goal / what subjectively sounds real in every width of room. Part of what gets a lot of us into hi fi is the ability of a speaker to have ASW that's well beyond anything we've heard, even in mono.... then you get "imaging" people talkin about how that's a coloration... even though it sounds real.

It's also debatable if larger (IE 1.75") non Be (IE Aluminum, Mylar) diaphragm compression drivers being pushed rather low (IE 900hz) and large soft cone (generally treated pulp) woofers being used less than an octave near their cone breakup modes (IE ~900hz for a 15 inch woofer, most that i've seen seem to start breaking up around 1.7khz or so... even with an LR4 crossover and notch that's only gonna be around 24db down in level), will have the same low level resolution as a 5" kevlar driver and a 1" dome in a more shallow 120 deg waveguide (for example, the JBL LSR6332)? And that's assuming domes are the last word in resolution.

Debatable is the key word. Unless you've got the resources to do the testing, it'll remain a question - and it'll still be questioned even if you did do the testing because there's always room for error.

As a DIYer, you can try it out yourself though. The SEOS-12 waveguides can be had for just $28, and you can add the Denovo DNA-350 compression tweeter for $56. Add in a good 12" woofer - maybe the Eminence 4012HO - that's under $570 in drivers/wg - and the rest is in the box (minimizing diffraction and vent resonance) and the crossover (smooth frequency response, smart control of vertical off-axis response, good phase-tracking, smoothly declining sound power) - which is all about the knowledge and application of the designer.

Last edited by RockLeeEV; 19th June 2012 at 03:23 PM.
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Old 19th June 2012, 04:16 PM   #10
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Sorry RockLeev , but I don't think that compression drivers are suitable
for listening to the music .
You are right about the materials used , because a dome tweeter would find a different habitat when mounted in a WG . More pressure in the vicinity , so it needs to be very stiff .
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