Generalizations about horn systems tend to short-change models that are exceptions to the "rules", and in high-end audio it is the exceptions that are usually the most interesting.
I started out with as strong a prejudice against horns as you'd ever be likely to find. Over the years my perception has changed (with John Wolff's designs acting as the catalyst), and I now believe that the downsides can be overcome while the upsides offer worthwhile improvements, particularly in radiation pattern uniformity and dynamic contrast.
Recently I received an e-mail from a manufacturer of high-end solid state components, and referring to a horn system he said this: "I have not heard speakers that were more 'relaxing'. Honestly they were so damn smooth."
I have every reason to believe Macrojack's perception of his horn system, as I'm somewhat familiar with the work of its designer and he certainly qualifies as "exceptional".
Duke
dealer/manufacturer |
Unsound wrote:
"Macrojack, why would 'Horns have a greater potential than any other approach.'"?
Well I'm not Macrojack, but I did stay at a Holiday Inn last night...
Okay, my design experience is limited to systems that use a direct radiator woofer and a constant-directivity-horn (or waveguide)-loaded compression driver. Focusing on the horn section, here are a couple of inherent advantages as I see them:
1) Well-controlled radiation pattern, which results in a reverberant soundfield that has very nearly the same spectral balance as the first-arrival sound. Not all horns do this, but constant-directivity ones have this potential assuming you get a few other things right. Live sound sources usually result in very little spectral discrepancy between the first-arrival and reverberant energy, but most speakers fail to preserve this relationship. I think it matters because, in most listening situations, most of the energy that reaches our ears is reverberant energy.
2) Presevation of dynamic contrast due to negligible thermal compression at normal in-home listening levels. This can actually be detrimental if the horn is not paired up with a woofer that has similar characteristics; if the woofer compresses and the horn doesn't, then the system sounds brighter and brighter as the volume level goes up. But when the dynamic contrast in the recording is properly preserved (including correct tonal balance regardless of loudness level), the emotion that the musicians intended is more effectively conveyed because musicians often use dynamic rise and fall to convey emotion.
Disadvantages include:
1) Coloration. This is a complex subject, and briefly all horns produce coloration of some type, but not all horns are equally objectionable in this regard, and some types of coloration can be dealt with in the crossover. The best horns minimize those colorations that cannot be readily addressed by the crossover, and then the crossover does the rest. Unfortunately reduction of coloration to negligible levels by a properly designed and implemented horn cannot be proven in an internet forum post, so this subject is hotly debated. My comment here would be, just as not all cones or domes or ribbons are created equal, so too not all horns are created equal.
2. Challenging crossover design. With rare exception, horns call for fairly complex crossovers in order to minimize their colorations and provide a smooth transition to the woofer section. Those few horns that are exceptions are not constant-directivity types, and thus do not have the reverberant-field characteristics that matter in my opinion. Some people hold that complex crossovers in and of themselves are bad, and this I disagree with; as long as the crossover does its job unobtrusively, the component count has no audible consequence.
If horn colorations can be reduced below the audibility threshold, and if dynamic contrast and the reverberant field really do matter, then a good horn system offers worthwhile advantages over a conventional system. I think the colorations can be rendered insignificant with proper system and crossover design, to the point where a good horn system is quite competitive with conventional systems in the same price range. But I think one has to start with a very good horn to begin with, as most horns have audible problems that cannot be solved by the crossover.
In general smaller horn systems need less distance to "focus" than larger ones do; one of my customers was listening to one of my systems (10" woofer + 10" round waveguide) at slightly more than arm's length, with (to my surprise) no audible problems.
Now it might be possible for a conventional speaker to match the thermal compression charactics of a good horn system, but at a higher price. And I do not know of any low-cost techniques of radiation pattern control that are as precise as what a well-designed horn or waveguide can offer in this regard. That being said, I think a good planar system that inherently has good radiation pattern uniformity can also be pretty spectacular, but that's a different topic for a different thread.
Duke |
Unsound, thank you for YOUR thoughtful response. I'll try to answer some of your questions:
"Wouldn't such a controlled radiation pattern reduce the size of the sweet spot and reduce the sound-stage, especially for multiple listeners?"
On the contrary, my experience with 90-degree constant-directivity waveguide-style horns indicates that they will give you a much wider than normal sweet spot when set up correctly. I use about 45 degrees of toe-in, such that the axes criss-cross in front of the listening position. Now before I go on, note that the ear localizes a sound source by two mechanisms: Arrival time and intensity. With good pattern control and this strong toe-in, for the off-centerline listener the far speaker is actually louder (greater intensity) because the listener is on-axis relative to it and well off-axis relative to the near (first-arrival) speaker. The two localization mechanisms partially offset, and you still get an enjoyable (though not perfect) soundstage even when well off to one side. The key is the smooth, fairly rapid off-axis roll-off of the near speaker. The tonal balance holds up well throughout the room.
"Wouldn't the amount of reverberant sound be greater in most indoor live venues too?"
Absolutely. In fact, I believe that two key discrepancies between live and reproduced sound are the spectral balance of the reverberant field (addressed by radiation pattern control), and the relative lack of energy in the reverberant field of most home listening rooms as compared with a live indoor performance. The latter leads us towards wide-pattern speakers, or omnis, or "poly-directional" speakers (Richard Shahinian's word). The type of poly-directional speaker I embrace is the controlled-pattern offset bipole.
"So long as the reverberant sound is not too close in time, shouldn't we be able to hear this as a reverberant sound and not as distortion?"
Yes indeed. The concept of "reverberant sound = distortion" is flawed; the ear/brain system actually uses some types of reflections to improve speech intelligibility. Part of the reasoning behind the bipolar approach I prefer is maximizing the time interval between the first-arrival sound and the onset of increased reverberant energy.
"Furthermore, couldn't this reverberant energy be controlled via room treatment and/or room correction?"
In my opinion, control should start with the sound source - the loudspeaker. It is difficult to do frequency-specific room treatment, and room correction via signal processing is microphone-position-dependent. The less spectral variation from one location to another within the room, the greater the listening area in which room correction is clearly beneficial.
"If my budget permitted, I'd guess that I'd move from cones & domes 'n boxes to top quality omnis. Perhaps the antithesis of what you've described as an advantage."
Well, a good omni inherently excels at generating a reverberant field that has the same spectral balance as the first-arrival sound, which is one of my top priorities. The only conceptual problem I have with omnis is the large distance from sidewalls required to avoid a detrimental early sidewall reflection.
"Aren't there already existing remedies for such thermal compression in many cones & domes and not really much of an issue for alternative drivers?"
My understanding is that, in general, drivers have less than 1 dB of thermal compression when used at less than 10% of their RMS rated output. Of course there may well be exceptions to this rule, and it's always the exceptions that are the most interesting.
"Am I correct in assuming that the cross-overs you describe aren't digital and therefore are probably incapable of preserving correct time and phase?"
Yes, I'm talking about passive crossovers. I do not believe that waveform preservation is a top priority, because the ear does not hear waveforms as such. At a certain very high level of performance, where more audible problems have been resolved, then waveform fidelity would be a significant issue. In my opinion, from a perceptual standpoint the tonal balance is the most important issue, but the perceived tonal balance includes the reverberant energy as well as first-arrival sound.
"It would appear to me that this ideal matching of non-horn loaded woofers to the rest of the horn loaded drivers must be rare in deed, all the horn loaded systems I've heard are blaringly bright. I have still yet to hear a horn system that's colouration's are below audibility."
Understood! In my opinion as well, it is rare. I could of course suggest a horn system or two that pays attention to these issues [rolls eyes innocently], but I must also acknowledge that some people's ears are simply more sensitive to horn-type coloration than others. If by any chance you'll be at the Rocky Mountain Audio Fest, please come by and let me know how I'm doing.
Ralph, you are correct - I left out compression driver quality. The field coil Beryllium diaphragm units John Wolff uses are magnificent. I was thinking in terms of more modest price ranges, where diaphragm resonances have to be addressed in the crossover - admittedly less than ideal, but many direct-radiator domes have comparable issues.
I think there are probably size and price floors below which a horn system is unlikely to be competitive with a direct radiator system, but above those thresholds I think good horn systems generally become increasingly competitive. |
Johnk, you're more than welcome to disagree with me. If we always agreed, one of us would be redundant!
In my experience (which is of course limited), it simply isn't feasible to use a minimalist high-pass filter topology with a constant-directivity horn because of the equalization requirement imposed by such horns. A tractrix is not a constant-directivity horn so a minimalist crossover is more likely to be feasible with it, but even then it probably calls for just the right compression driver.
To get more specific regarding driver integration with horn speakers, in my experience problems can arise when you have a high crossover (3 kHz or higher) between midhorn and tweethorn, and the midhorn is large enough that there's a significant distance between the throats of the two horns. The ear's ability to judge the height of a sound source is pretty good at short wavelengths, but poor at long wavelengths. So driver vertical integration is a function of not only vertical separation, but also the crossover frequency (and maybe crossover slope, but I'm not sure about that). In many cases a two-way horn system has a definite advantage here.
Unsound, regarding waveform fidelity, that goes to the ever-present issue of juggling tradeoffs, and my understanding of human auditory perception places other things higher in priority. Our nerves simply cannot fire fast enough to trace out a waveform, so the ear de-constructs the incoming sound based on energy distrubutions rather than waveforms. On the other hand, the ear can readily detect a broad hump in frequency response even if the height of the hump is only 1/2 decibel. So I prefer to juggle tradeoffs in favor of what I believe to matter most, namely frequency response, with particular emphasis on the off-axis frequency response because that's where the most opportunity for improvement exists (in my opinion, anyway). Now I will readily admit that the ideal would be waveform fidelity without tradeoffs in the frequency response domain, in which case the tradeoffs shift into the monetary domain.
In his landmark book "Sound Reproduction", Floyd Toole lists five measurements that have been experimentally shown to correlate well with subjective preference. Four of the five have to do with off-axis frequency response, and the fifth is the on-axis frequency response. |
Weseixas wrote: "There is no such thing as a fast 15 inch woofer operating @ 400 Hz IMO ! Consider how directional the speaker will be @ 400 Hz and it's large mass ( relative ) with it's accompanying cone coloration ..."
Four hundred hertz is probably more than two octaves below that woofer's upper rolloff frequency, so it will be plenty "fast" enough to do its job. The radiation pattern will be fairly wide at that frequency, and the cone will probably still be pistonic.
Weseixas: "...based on what you have expressed so far, it would be baffling to not have a high degree of nasality."
It is quite possible to build a horn system that doesn't have a "nasal" or "horn-like" signature. Part of the solution lies in the design of the horn itself, and part lies in the crossover. Having heard several Bill Woods designs over the years, I have every reason to believe what Macrojack says about his speakers.
Duke
dealer/manufacturer |
Thanks, Macrojack.
In times past I misjudged your honest enthusiasm to have a commercial motivation, and gave you grief about it. I'm sorry about that. Nowadays I just enjoy your enthusiasm, especially when we agree!
Duke |
Weseixas, down at 400 Hz, a 15" woofer has a radiation pattern that's approximately 150 degrees wide.
As far as coloration goes, the larger the cone the more difficult it is to get it to behave well. But as long as the behavior isn't too bad, it's possible to correct it or compensate for it in the crossover. On the other hand the smaller the cone the more excursion is required and (in general) the more the voice coil heats up, and therefore the more coloration we get from the motor going non-linear and/or from thermal compression. These types of coloration cannot be corrected in the crossover.
You mentioned coloration from the backwave energy of a large cone. For a given SPL, a large cone and a small cone are moving essentially the same amount of air, so we have the same amount of backwave energy to deal with. A large cone has more area for reflected backwave energy to strike and re-radiate through, but it usually has a larger box which can make better use of damping material to attenuate that backwave energy. I can offer up a link to anecdotal evidence that a good large cone can be low enough in coloration to compete with a good planar.
The main reason I like large cones has to do with radiation pattern control, another topic for another thread.
Having worked with cones large and small for many years (started as an amateur in 1979, turned pro in 2005), in my opinion a good large cone usually has greater performance potential than a good small cone - BUT it is usually a lot harder to work with.
Duke |
Hi Weseixas,
"The published data including the response curve on both drivers will require eq-ing IMO for that speaker to be listenable..."
Quite right you are! Aggressive equalization is virtually always required with such systems, and it's the crossover designer's job to do it. The published curves for the drivers only indicate how they start out, not how they end up. If you were evaluating the system based on how the individual driver curves start out (which makes perfect sense until someone tells you otherwise), no wonder you were skeptical! The published "before crossover/EQ" curves for the drivers I use look pretty awful at first glance, and the curves I actually measure before starting on the crossover are even worse.
The most useful curve for evaluating a compression driver is the "plane wave tube" curve, which is supplied by some manufacturers. Ideally, this curve slopes down uniformly without significant peaks or dips. Any curve measured on a horn has that horn's characteristics superimposed on the compression driver's output, which complicates any attempt to evaluate the driver. |
Herman wrote: "Macro, you should look into getting a true horn for that compression driver. What you have looks more like a megaphone than a horn. I don't doubt you are pleased with the sound from it but I wonder what it would sound like with what I would call a true horn."
The horns Bill Woods makes are conicals, which are onstant-directivity type. Equalization is essential with a conical (or any other constant-directivity horn); if not equalized properly, it does indeed sound like a megaphone. But once equalized properly, they have a very desirable characteristic. Let me explain:
A compression driver all by itself (no horn) will have a very wide pattern at the lower end of its range and a narrow pattern at the upper end - just like any direct-radiator piston. When this output is forced into a constant angle by a conicial horn, the result is over-emphasis of the lower end of the driver's spectrum (megaphone effect). Without the horn, the response was good on-axis, but poor off-axis; now with the conical horn, it is equally bad both on-axis and off-axis. But this is actually a window of opportunity - when we fix one, we also fix the other! So we equalize in the crossover, and now not only is there no megaphone effect, but the sound is quite uniform across the entire angle that the horn covers. In my opinion this is very desirable and well worth all the trouble we just went through, as now the reverberant energy will have nearly the same spectral balance as the first-arrial sound (a characteristic of live voices and instruments that most speakers fail to emulate).
One very slight downside to a round horn is that the horn's mouth reflection is equidistant from the central axis, which results in an on-axis dip. The location of this dip varies with the diameter of the horn and the listening distance. But the fix is quite simple: Listen from about ten degrees off-axis, and the dip disappears.
Duke |
Macrojack I took at look at the spec sheet for the woofer in your speakers, and it's quite impressive. The response curve looks unusually good, and the parameters predict excellent bass power and extension in a suitable large cabinet (which is not always the case with 15" prosound woofers).
Also, sorry about the typo in my last post; "...which are onstant-directivity type" should read "...which are constant-directivity types".
Duke |
Before I completely lose my train of thought (again), let me do a quick tie-back-in: The conical horns Bill Woods (designer of Macrojacks's speakers) uses are arguably what might be called "waveguides". And when Bill Woods came by my room at RMAF several years ago, he subsequently referred to my waveguides as "conical horns". Maybe neither perfectly fits the defnintion of the other, but they are conceptually and sonically very close cousins.
Duke |
I use a Geddes-style waveguide on most of my designs, but it's not the same as the ones he uses. Nor am I using his patented refractive waveguide plug. In my more recent/less expensive models, I'm using what might be called a "waveguide-style horn", which is considerably more of a challenge to get good results from.
If either of you will be at RMAF, come on by my room if you get the chance.
Duke |
Several years ago I conducted a controlled blind listening test, administered under the guidance of a leading researcher in the field of psychoacoustics. In the questionaire that the listeners filled out, one very experienced listener wrote that he knew what kind of speakers we had behind the curtain: Electrostats. He owned electrostats and was sure he recoginzed their signature clarity, detail, and freedom from coloration. Just so you know, guessing what kind of speaker was behind the curtain was not part of the test.
Well, he was wrong. They were hornspeakers - rather unconventional ones, but still that's the category they'd fall in.
Fast-forward to a recent audio show. This was posted on another forum:
"As an audiophile for 40 years, and a high-end dealer for 15, I have my preferences of what works and what don't. When I first stuck my head in the room and saw the horns, I immediately judged the speaker and walked by the room. Every horn speaker I have ever heard always screamed at me one way or the other, I hate horns.
"But since I was there for a couple of days, I found myself back into this room. [They] sure made me eat those thoughts. Smooooooth, musical, and detail.....it was awesome. I went back more than a few listens, I knew they were going to start screaming at me eventually, I was wrong."
Those of you who, like this guy, hate horns, I'm not saying you haven't heard colorations. What I'm saying is, you may not have heard from among the best of the low-coloration hornspeakers yet.
Duke
dealer/manufacturer |
Prdprez, that guy who hated horns was talking about mine at Lone Star 2010. The speakers behind the curtain in the first example were GedLee Summas.
Until you've heard speakers designed or inspired by Earl Geddes, you haven't heard all there is to hear in the world of low-coloration hornspeakers. And at least one of his students got some press a couple of years ago: a Golden Ear Award from The Absolute Sound.
Duke |
Weseixas wrote: "Duke are you saying those that dislike horns cannot pick them out in a blind test?"
I'm saying that a high quality, low-coloration horn system doesn't sound like a horn system.
Duke |
Pdprez, good call - I hadn't made a mental distinction between "horn system top-to-bottom" and "horn system over part of the spectrum". And your understanding of my designs is correct; you also get extra points for coming up with the right name for one of them!
I have no hands-on design experience with top-to-bottom horn systems, and would think that they'd be far more difficult to do well. I'm too chicken to even try.
Weseixas, a waveguide (as Earl uses the term) is a type of horn optimized for low coloration and well-controlled off-axis radiation characteristics. If you're willing to distinguish a Geddes-style waveguide from the rest of the horn world, then you and I are quite likely to end up on the same side here. And what fun would that be??
Cheers,
Duke |
Weseixas asks: "What models are you displaying [at RMAF]?"
Duke replies: My current plan is to show a bipolar model called the Cloud Chaser. It's fairly new - not up on my website yet - but is described in my Audio Circle forum. |
JohnK, I think it's great that an offset bipolar type might find its way into your lineup! I consider it an honor that you see enough potential to give it a shot. Let me know what Joe thinks if you get a chance.
There's at least one other manufacturer, Jim Romeyn, doing his own variation on the theme, and here's a link in case you'd like to take a look at what he's doing:
http://jamesromeyn.com/home-audio-gear/jr-modular-pro-monitor-3kpr-usd/
Very best to you.
Duke |
Ralph wrote: "If you cannot get the [dipole] speaker far enough from the rear wall, the first comment [that dipoles create the required space and time of a recording more accurately than monopoles] is moot. Duke has built systems that are rear-firing and they seem to work fine..." Weseixas replied: "Atmasphere... You are comparing a monopole to a dipole, they cannot sound alike or have the same presentation and never will... Spare me the condescension of telling me about Duke's speakers, been there done that and a ball of wax..." Duke chimes in: I think Ralph was saying that if your dipoles are not far enough out into the room, the advantage of dipole radiation is lost. And I agree; in fact, I usually advise people who can't place speakers at least 3.5 feet out into the room to get monopoles instead. Without sufficient time-lag in between the first arrival sound and the arrival of the backwave energy, that strong early reflection is more likely to be a net detriment. I think Ralph referred to my bipolar horn-type speakers because they are an example of a horn speaker that has radiation characteristics similar to a dipole, and as a result when set up like a dipole, they tend to sound a lot like a dipole. These comments by an Audiogoner who has owned some rather nice dipole and omni speakers (as you will see) backs up this claim. Weseixas again: "Anyone who says a good planer sounds like a horn or vis a vie has never heard a good planer setup." What a good horn system and a good planar system have in common is this: They both generate a reverberant field that is spectrally correct (something few cone-n-dome systems accomplish). The relative level of that reverberant field different: With a correctly-setup planar, the reverberant field is considerably stronger relative to the first-arrival sound than for a monopole horn system. One could liken this to sitting in Row 15 versus Row 3. (A good omni is usually more like Row 25.) Weseixas, your "been there done that" remark about my speakers implies that you've heard them. Which ones, and where, if you don't mind my asking? Thanks, Duke |
Weseixas wrote: "I'm sure you are not comparing your bi-polar speaker polar plot to that of a Di-pole with it's figure 8 pattern ?.... I highly doubt the 2 will sound the same, the sonic characteristics are so completely different..." Duke replies: Indeed I am making precisely that comparison. My bipolars radiate into a constant 90 degree pattern, both front and back, over most of the spectrum. Few dipoles maintain their initial figure-8 once we get up into the midrange and treble region; their radiation patterns usually change significantly with frequency (SoundLabs being a notable exception). As we go down in frequency my pattern widens somewhat, but this is of less consequence down where the room dominates anyway. In the bass region I even manage to emulate much of the in-room smoothness of a good dipole system, and here's a recent article in a webzine that describes how I do so. A few years ago I had a longtime (decades long) SoundLab owner tell me that one of my bipolars came the closest to sounding like his speakers of anything he had ever heard, including monopoles, other dipoles, other bipoles, omnis, or anything eles. In fact he actually placed an order for a pair of my speakers, but later cancelled it after changing the setup of his SoundLabs to be more like how I set up my bipolars - apparently that made a significant improvement in his room. Since my intention was to emulate the radiation pattern characteristics of the SoundLabs (something I did with Roger West's full knowledge), the outcome there was still encouraging to me. I don't mind coming in a close second to SoundLab. Since you didn't reply to my inquiry about where you heard my speakers, now I'm thinking that maybe you didn't. Is that correct? Duke |
Weseixas, the reason few dipoles maintain their figure-8 up into the mid and treble region has to do with beaming and/or driver interference. For example, the horizontal pattern of Maggies changes due to horizontal comb filtering in the crossover region, and then they have a very wide pattern just above the crossover point, narrowing with increasing frequency (beaming) just like any direct radiator. It's still a dipolar pattern, but not the same neat figure-8 we had at low frequencies. Still, overall Maggies are better than most when it comes to radiation pattern uniformity.
Unfortunately electrostats tend to have patterns that narrow significantly at high frequencies because they are relatively wide in the horizontal plane; even the concentric-ring Quad 63 and its descendents beam severely in the top two octaves.
In contrast, my bipolars have a much more uniform pattern over most of the spectrum. From about 500 Hz on up, the faceted-curved SoundLabs are the only bi-directional speakers I can think of that have a more uniform radiation pattern in the horizontal plane than mine (and below 500 Hz is considerably less critical in most rooms, according to Dr. Earl Geddes). I happen to think radiation pattern uniformity matters a lot, because it largely determines what's happening in the reverberant field, and typically most of what we hear is reverberant energy. No doubt other designers place higher priority on other characteristics, which means that the industry offers a pretty good variety of choices for those who go digging for them.
Responding to your questions:
* The measurements I take which reveal radation patterns are always time-gated to exclude reflections.
* The rear-facing drivers on my bipoles are not in reverse polarity; if so, they would be dipoles.
* My first two bipolars use round waveguides based on Earl Geddes' work, but my most recent (and least expensive) one uses what I'd call a waveguide-style horn; that is, constant directivity with no diffraction slots, vanes, or other pattern-widening features.
I wasn't necessarily suggesting you take a look at any of my bipolars, beyond the links I've provided. Any of my three bipolar models would have room-interaction characteristics similar (but not identical) to a dipole. The article linked to in my last post offers a good introduction to the controlled-pattern offset bipole configuration I use.
One other thing you said that I would like to comment on:
"Look I can understand those that have migrated to the sound of horns, they do it for the power."
That wasn't my motivation. As a hard-core amateur in the late 80's (with two SpeakerBuilder Magazine articles to my credit), I came to believe that getting the reverberant field right was critical, but didn't know how to do it well. And I hated horns, so didn't consider them as a possible solution. Well in 2001 I heard a hornspeaker that didn't have the coloration I'd come to take for granted, and suddenly saw a window of opportunity to get the radiation pattern right. I won't bore you with the details of the journey, but it was the possibility of good radiation pattern control that attracted me to horns (or waveguides, to be specific... I'm still leery of most types of horns).
Duke |
Weseixas: "Which maggies are we discussing?"
Duke: I probably should have picked one model and stuck to it, which I didn't do.
Weseixas: "A speaker shoot out would be interesting!"
Duke: If a "shoot-out" could be arranged that was satisfactory to both, I'd put my $4k bipolar up against the Maggie 3.6. Shoot me an e-mail if you'd like to explore further.
Weseixas: "I also cannot agree that a horn speaker will sound like a planer."
Duke: I'm not expecting you to agree without an ears-on; just hoping to show enough evidence that you'll keep your mind open to the possibility.
Weseixas: [to Macrojack]"I'm sure Duke is proud to have... you for a customer!"
Duke: I wish!! But no, Macrojack isn't a customer of mine, and now that he has a pair of Bill Woods' speakers it is extremely unlikely that he ever will be. I think he's done. Macrojack is passionate, and so are you. If you two had met anywhere other than on the internet, I bet you'd focus on what you have in common rather than where you disagree, and very quickly become friends.
Weisaxas: "Duke, Ralph, I have enjoyed the discourse and wish you both the best in such a tough business...."
Duke: Thank you sir, and I wish you the best in such a tough hobby! |
Weseixas asked how Bills Woods' horns would compare with Avantgarde type horns. For one thing, Bill's horns are constant-directivity devices, so the off-axis energy will have nearly the same spectral balance as the on-axis energy. According to Floyd Toole and others, this is desirable. I don't understand all the implications of the dodecahedral geometry, but it might serve to somewhat de-correlate the reflections in the horn body and/or at the horn mouth.
On another subject, I don't think mocking someone's moniker is productive, especially coming from one who claims to have years of experience as an industry professional. This reflects poorly on industry professionals, and invites the sort of escalation that would get this thread shut down or removed. It would be a shame for that to happen, especially if instigated or enflamed by one of us.
Thank you.
Duke
industry professional |
Learsfool, I don't have first-hand experience with the A7, but it seems to me that there might be a step-down in response below the frequency were the short horn in front of the woofer un-loads, such that in the bass region the response might normally be down a few dB relative to the midrange and above. This may be compensated for in the crossover, or it could be offset by boundary reinforcement with appropriate placement. Lacking that short horn in front of the woofer, the Model 19 would probably be a bit lower in overall efficiency but would not have a potential step-down between the midrange and bass region. Perhaps the primary innovation of the Model 19 was moving the crossover frequency up to 1200 Hz. This seems rather counter-intuitive, but what it did was allow pattern-matching in the crossover region. At 1200 Hz the woofer's pattern had narrowed sufficiently to match that of the horn, so there was no discontinuity in the off-axis response. The "manta ray" horn had constant directivity in the horizontal plane above the crossover point. These are worthwhile characterisics because in many listening situations the off-axis response strongly influences or even dominates the perceived tonal balance, though I think horn design has advanced since then. Wayne Parham, Earl Geddes, and yours truly embrace constant directivity and pattern-matching in the crossover region. A few years after the Model 19 was introduced, JBL designed a studio monitor, the Model 4430, with strong emphasis on pattern-matching in the crossover region as well as constant-directivity above the crossover region. I would not be surprised if the Model 19 was one of their primary inspirations. While the horn geometry is quite a bit different, the basic concept is similar to that of the Model 19. Here's a link to an Audio Engineering Society paper written by the designers of this speaker: The landmark JBL Model 4430 studio monitorDuke |
Thanks, Macrojack. Since posting the link, I have "met" one of that paper's authors in another online forum (he and I are disagreeing about something... surprise surprise!). I don't have any experience with either the K-2 or Everest, but I'm sure they're awesome. The original Everest, circa 1985, used an asymmetrical horn to achieve the desired toe-in angle without having to actually toe the speakers inward: Original JBL EverestI borrowed the concept; one of my models uses asymmetrical enclosures to achieve the same end, but with a conventional symmetrical horn. Duke |
