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 .
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 .
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.
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.
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.
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.
Invitation to a Hype-Fest
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
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
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
Speakers where as the midrange driver begins to become directive, the crossover hands off to an EQUALLY directive tweeter.
What's easier to design, build, and sell, this:
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or this:
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?
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.
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A large number of users have found compression drivers to be perfectly appropriate to music listening.
It depends on the expectations
I believe that living in large rooms ( as most americans seem to have )
would require some 'long throw' devices for keeping the levels right .
But the sound exiting from a mouth after being bounced many times it is not
what I would properly call Hi-Fi ...or is it a bad world ??
I believe that living in large rooms ( as most americans seem to have )
would require some 'long throw' devices for keeping the levels right .
But the sound exiting from a mouth after being bounced many times it is not
what I would properly call Hi-Fi ...or is it a bad world ??
You bring up some interesting points, RockLeeEV.
In my opinion there is definitely merit in using waveguides, primarily for matching directivity at the crossover frequency. The extra dynamic headroom that comes with WG's in most domestic situation isn't necessary, but it's definitely a plus.
I don't think that larger diaphragms can't handle low crossover points. I've done it and my measurements didn't indicate anything strange going on in terms of distortion at high sound levels. Perhaps it would matter if the speakers were used for sound reinforcement where much higher sound levels are demanded, but for home use I strongly doubt it's an issue.
The main reason for me to use a waveguide was because of its directivity. For little over a year I've been using a speaker with pretty high and constant directivity from the low midrange up and I definitely like it a lot. Also there is acoustic treatment in the room, with wide-band damping panels for the ipsilateral, contralateral and rear-wall reflections. As such the direct sound is very strong in comparison to reverberation and there aren't any significant early reflections. The system sounds different than conventional setups. It can be cranked to high volumes without causing listener fatigue, imaging is razor sharp and there's hardly any noticeable coloration. For some time I thought I'd found the holy grail. However, though you definitely hear what's in the recording, it's not always the most natural or realistic sound. With dry recordings, it lacks spaciousness and envelopment.
Last month I moved and I am currently using relatively inexpensive conventional box speakers again (Infinity Beta 40's, WITH a small waveguide ) and they're in a room that's currently still untreated. I'll be adding some wide-band damping, but I think I might keep these speakers for a while. The speakers don't really do anything wrong in my opinion: they needed just a little EQ'ing to get a ruler-flat response and the directivity is also pretty good. I'm sure that in my current room I can get these speakers to really sing.
You say 'debatable' is the keyword. I concur. Last year I started a topic called What is the ideal directivity pattern for stereo speakers?. I now think I asked the wrong question. Although at the time I did realize the simplicity of the question, I was still focusing too much on speakers. I now have a more holistic perspective. Directivity is just one part of the puzzle. The question should have been, what is the ideal reflection pattern.
I guess the answer is 'it depends'.
In my opinion there is definitely merit in using waveguides, primarily for matching directivity at the crossover frequency. The extra dynamic headroom that comes with WG's in most domestic situation isn't necessary, but it's definitely a plus.
I don't think that larger diaphragms can't handle low crossover points. I've done it and my measurements didn't indicate anything strange going on in terms of distortion at high sound levels. Perhaps it would matter if the speakers were used for sound reinforcement where much higher sound levels are demanded, but for home use I strongly doubt it's an issue.
The main reason for me to use a waveguide was because of its directivity. For little over a year I've been using a speaker with pretty high and constant directivity from the low midrange up and I definitely like it a lot. Also there is acoustic treatment in the room, with wide-band damping panels for the ipsilateral, contralateral and rear-wall reflections. As such the direct sound is very strong in comparison to reverberation and there aren't any significant early reflections. The system sounds different than conventional setups. It can be cranked to high volumes without causing listener fatigue, imaging is razor sharp and there's hardly any noticeable coloration. For some time I thought I'd found the holy grail. However, though you definitely hear what's in the recording, it's not always the most natural or realistic sound. With dry recordings, it lacks spaciousness and envelopment.
Last month I moved and I am currently using relatively inexpensive conventional box speakers again (Infinity Beta 40's, WITH a small waveguide
) and they're in a room that's currently still untreated. I'll be adding some wide-band damping, but I think I might keep these speakers for a while. The speakers don't really do anything wrong in my opinion: they needed just a little EQ'ing to get a ruler-flat response and the directivity is also pretty good. I'm sure that in my current room I can get these speakers to really sing. You say 'debatable' is the keyword. I concur. Last year I started a topic called What is the ideal directivity pattern for stereo speakers?. I now think I asked the wrong question. Although at the time I did realize the simplicity of the question, I was still focusing too much on speakers. I now have a more holistic perspective. Directivity is just one part of the puzzle. The question should have been, what is the ideal reflection pattern.
I guess the answer is 'it depends'.
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"Waveguide loudspeakers", IMHO, are a subset of horn-loaded loudspeakers, implying that some sort of controlled directivity is taking place in the frequency bands of interest to human hearing. It also means that the waveguide is shaped in a certain fashion which is conducive to controlled directivity over its designed bandpass notably using conical expansion profiles and a carefully designed throat geometry, with some attention to the effects of mouth bounce (impedance mismatch) and other higher order modes of internal waveguide reflections.
1) They are usually large devices,
2) the cabinets are more complex to build than reflex or suspension-type direct radiating speakers,
3) the higher-freqnecy drivers are usually compressions drivers, for which many manufacturers lack expertise in design and technology, and
4) there seems to be a cultural "vaccime" against equating waveguide spakers to hi-fi (especially in the U.K. and related hi-fi industries). There is a contingent of "audiophiles" that believe that they don't exhibit their favorite characteristics of hi-fi loudspeakers (i.e., un-EQed flat FR on-axis).
However, these same audiophiles do not equate the loudspeaker's ability to faithfully reproduce the original dynamic range of source material in-room without adding objectionable amounts of AM and FM distortion and direct-radiator driver compression and Ohmic heating issues in voice coils, driver magnetic circuit, and crossover circuit associated with low-efficiency speakers trying to reproduce the original dynamic range performance.
I agree with Dr. Geddes above: waveguides, when properly designed, implemented, and placed in-room are unsurpassed in their measurable and subjective listening performance.
You might find the JAES papers on AM and FM distortion of loudspeakers of some interest when considering the reasons why I can make the above statement. Also note that controlled directivity is a very large component of waveguide (horn) loudspeaker performance, as Dr. Geddes has written at length on. Splashing acoustic energy around the room without regard for the effects on imaging and fidelity of early acoustic reflectors is the issue with direct radiating loudspeakers of almost any variety.
Chris
It depends on the expectations
I believe that living in large rooms ( as most americans seem to have )
would require some 'long throw' devices for keeping the levels right .
But the sound exiting from a mouth after being bounced many times it is not
what I would properly call Hi-Fi ...or is it a bad world ??
Could you elaborate what "bouncing" you're referring to and why this is not HiFi?
There's nothing less suitable about a compression driver than a small format wideband driver - and DIYA people seem to love those. However like those drivers you're possibly trading great pistonic operation if you want to play low (which is what I was refering to when I pointed out the large diaphragms). The subjective consequences are tough to judge. Soft dome tweeters are hardly pistons themselves. But the better hard domes (IE the ceramic Transducer Labs N26C) or planar tweeters (Beyma TPL-150) or ribbons (RAAL 70-20XR) may still be better. Personally I'm pretty convinced a good compression driver is at least as good as a good soft dome. I'm just not convinced yet either is as good as it gets. In a few months i'll have an opportunity to compare this tweeter:
Soon I expect a chance to compare a RAAL 70-10D + BG Neo 8 handling ~600hz on up, vs this tweeter in a SEOS-15 handling ~900hz on up, and hopefully with some of Dr. Geddes' foam in it.
Did you try the narrow directivity speakers in a more live room?
im in the UK. So apparently in backward and stuck in some seventies limbo...as some wise one commented the listening room makes all the difference. It changes WHAT exactly the listener can live with. Most houses here are modestly sized, those in the US are huge! Omni behavior, or MORE omni, optimised for flat on axis resp, works in a victorian terrace since youd be lucky to have space to have 4 cuft 'toed in' cabs. Throw in the sofa, and some dodgy velour curtains, and you find the room is rather dead and NEEDS some off axis output. If u got oodles of space and hardflooring and plenty of glass then the degree of dispersion control must increase, unless the listener enjoys the muddle of swimming bath reverb... This affects what is really compatible with the room. Put it this way, i have lived with a pair of 5ft tall boxes, twin 15s plus quad horns IN ONE BOX, all in a 13ft square room. In a Yanks house id love these, but it doesnt sound good in such a cosy room. Same goes for Oz, with many, or at least more, timber homes the requirements for good sound change again.
To be clear i like WGs and a controlled DI approach, but without meaning offence, it simply doesnt offer a universal solution, in every listening room. Maybe in an American house...thats WITHOUT going into audio trends, like the US sound, UK or Japanese sounds.
To be clear i like WGs and a controlled DI approach, but without meaning offence, it simply doesnt offer a universal solution, in every listening room. Maybe in an American house...thats WITHOUT going into audio trends, like the US sound, UK or Japanese sounds.
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I didn't write this book, but this fellow is the source of the negative comments that I referred to above:
Amazon.com: High Performance Loudspeakers (9780470094303): Martin Colloms: Books
Does anyone here actually respond to the OP comments, or did I forget my secret handshake...?
Chris
The room actually was still quite live. This was a dedicated audio room of about 100 m3 with in it just the speakers, a couple subs, a sofa, the damping panels, a couple QRD-type diffusers and some other audio junk. RT was about 0.55 and quite uniform with frequency.
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