Horn-loaded speakers

Any truth to these statements ? They're part of a post on another forum (but from '05) :

For an actual technical reason, consider that a horn loaded speaker achieves its high sensitivity by directing more sound forward and less to the side. In traditional dome tweeters, you are radiating some extra sound to the sides such that in a reflective room, you might hear more overall sound in the midrange and the low range because what you hear for highs isn't projected so widely and thus its less efficient, especially at the high range, overall.

A horn loader speaker will sound similiarly between different rooms because its allowing less of its sound to radiate in an extremely wide pattern in the first place. This is not a bad thing if extreme room renovation is not a possibility.

Because the horn loaded speaker is sending ALL of its sound forward, you're actually getting a relatively equal mix of lows, mids, and highs, as opposed to wide dispersion dome-tweeter type speakers that send about equal balance forward, but also significant midrange to the sides.

A general rule that you could follow is that for a similiar overall performance class of speaker, the horn loaded one will probably sound better in a poorly treated enviroment but a wide dispersion speaker will probably sound better in a well-treated room. It is a tradeoff, but because of the relatively low wasted power in horn loaded tweeters and the less effect a bad listening enviroment has on them, they do remain quite popular.

Obviously, there may be exceptions to this generality, but the point is its a decent thing to keep in mind when comparing speakers. If you can't budget for a true 500WPC amp and all sorts of room treatment, horn loaded speakers may be an excellent choice.

 

Horns are acoustic transformers, their efficiency is not a result of narrow dispersion.
A horn-loaded speaker does not only radiate to the front, not in the bass at least.
Compared to a now-common narrow baffle direct radiating speaker, something like the Avantgarde horns are basically cardioid from the midrange and up which helps in tough rooms.

 

Not much.

 

Actually it's more right then wrong. Just over simplified. All speakers produce some sound in all directions though some designs very minimally. The horn is not the transducer. The actually speaker driver is. The horn is a coupler. And yes basically the horn increases efficiency by channeling and amplifying the sound. A driver coupled to a horn has to move less to create the same sound volume then a driver not coupled to a horn.

Two things to put this in perspective that are often discussed are old fashioned bullhorns and near field listening. Take an old bullhorn talk at a normal volume and then put the bullhorn to your mouth while talking. The horn now amplifies and directs your voice allowing you to do the same amount of work while being heard further away. Of course this introduces new problems with distortion which is why horned loudspeakers are harder to design than ordinary dynamic speakers.

People like near field listening because all the sound waves that hit your ears first are coming from your speakers. They are beating the room reflections to you.

 

I think you guys need to do a little reading: Horn Theory »

jeff

 

Read most of that 5 or 6 years ago when I decided to go with horn based designs. I've still got PDFs of the math on an old laptop from longer ago than that when I was going for an Applied Mathematics Degree

 

Did you build or buy?

jeff

 

I tried a Tang Band kit but suck at wood work and could never veener for **** so I bought. Though at some point I plan on breaking out the router and replacing the mid horn of my Cornwall with a Fastlane tractrix horn.

Had a lot of fun with DIY audio stuff though. When I have more time I totally want to try to build my own Edgar Horn speakers and tube amp and pre.

 

Matter of fact the poster IS talking about tweeters.

 

I haven't tried veneering yet, but I'm going to give it a go with some small boxes first. It will be the "iron on" stuff for sure.

jeff

 

ANY truth? Well, SOME, but not much.

...a horn loaded speaker achieves its high sensitivity by directing more sound forward and less to the side...
@ Actually the horn kinda sorta lets the driver "grab the air" better so more of the energy transfers from the driver into the air as sound. Kind like (this is a bad analogy, but here goes) using the correct transformer tap on a tube amp-all the taps will drive your speaker, but one is more optimum.
@ The directivity of a horn is not perfect, they all spread the low frequencies as noted above

...A horn loader speaker will sound similiarly between different rooms because its allowing less of its sound to radiate in an extremely wide pattern in the first place.
@ That's only true for horns designed for narrow dispersion, which is far from all horns, and it's not true in the bass.

...horn...relatively equal mix of lows, mids, and highs, as opposed to...dome-tweeter type speakers...
@ WAY too big of a generalization, often not true

...A general rule...horn loaded one will probably sound better in a poorly treated enviroment but a wide dispersion speaker will probably sound better in a well-treated room...
@ Not necessarily at all. Because first off, not all horns are narrow dispersion, and not all cone speakers have wide dispersion. And they ALL vary dispersion with frequency.

@ The thing about horn design is that there has been a fair bit of math developed around this over the years, and sophisticated simulation tools for horn design, but it seems like many horns are still designed from old 1940s formulas which, like Thiele-Small parameters for woofers, grossly oversimplify what is really going on.

@ And the vast majority of horns are still rectangle mouthed, which some research back when seemed to indicate is bad for internal reflection, causing the peculiarities of "horn sound." That research was perhaps not followed up so well, but I firmly believe many horn designs are still dominated by aesthetics and not acoustics. For instance, those PA horns that are rectangular on top and sides, but droop down to wrap around the woofer. No acoustical purpose is served by that, yet those designs persist.

 

I've been thinking of giving it another go and getting the cabinets professionally finished. A good well built horn design is really hard to beat. Hell the pair of Cornwall 1s I'm running now are hard to beat and can do things that ordinary speakers can't come near to doing.

Good luck

 

Is the human mouth an adjustable horn? Just a thought

 

Most but not all horn designs are compression drivers, not just an ordinary speaker with a horn stuck on the front.

The compression driver is designed to mate the sound to the air, acoustic impedance, coupling.

If you listen to just the driver and then, mount it to the horn body, it will get louder, that is the efficiency of horns.

However, just like a light bulb, if it is a bare bulb, the light will radiate in all directions. Place a reflector on it and direct the light on one direction and it will be brighter and cast all of its light in that direction.

If you are speaking of pure horn designs like those used in a pro-sound environment, yes those horns are designed, as most horns are, to control the direction of the sound as it exits the horn into the room. The term that is used is a constant directivity horn, for that exact reason.

The quoted post makes many general assumptions about horns as well as conventional tweeters, which takes away from some of the points that are trying to be made.

But, yes, horns do control direction and will sound more or less the same (as compared to a conventional direct radiator speaker design), from room to room because the sound reaches you before it reflects off of the different surfaces in the room.

Horn systems are more complex in their designs than most people realize. and they do more than just amplify and direct the sound coming from them. The higher frequency the band is, the more energy that is contained in the band. All I mean by this that, the higher the frequency the less power is needed. The job of an exponential horn is to amplify the lower frequencies so that all the sound is at the same sound pressure level. As the frequency gets lower.



Here is an Altec Lansing A7-500 style cabinet with the Altec 511B horn on top, which, in theory goes from 500-20,000 cycles (I said, in theory).

Now, it is not exactly correct that bass horns do not control the direction of the sound, they do.

Shown here is the Altec 828 bass cabinet, when combined with the 511B horn, a 500-cycle driver (such as a 908-A), and a 500-cycle frequency dividing network (crossover), make the A7-500 Voice of the Theater system (VOTT).

The 828 cabinet features a front loaded horn/ bass reflex cabinet . The purpose of the horn part is to acoustically couple the LF bass driver of conventional design to the surrounding air. This is effective from 500-cycles down to about 120-cycles, after that the bass reflex part takes over down to about 40-50 cycles.

Where, the higher the frequency is, the more it has a tendency to beam and it is the job of the HF horn to spread out the high frequencies evenly.

Similarly, bass frequencies spread out more and more the lower you go. By the time you get down to 40-cycles, it is almost impossible to control the direction and it is almost impossible to localize the source.

In the case of the 828 cabinet, it does a nice job of controlling the direction of the LF sounds by restricting their dispersal down to about 120-cycles. Below 120-cycles, where the bass reflex part of the cabinet kicks in. From that point, the cabinet is not very effective in controlling the direction of the bass.

In speaking of the cabinet design, there is one critical point the has not been covered, that being time alignment.

If a speaker is time aligned, then all the frequencies, will reach the listener at the same time, which means, being in phase. This is what gives a loudspeaker its imaging, the ability to preserve the placement of instruments throughout the perceived sound stage. Thiel loudspeakers are known for their excellent imaging due to being time aligned.

The 828 cabinet is 24" deep and notice that the bass speaker is not mounted on the front of the cabinet, but the speaker itself is mounted at a depth of 15" inside of the cabinet. While that part is obvious due to the horn part of the cabinet, what is important about this design is that the position of the bass speakers voice coil is along the same vertical plane as the voice coil on the HF driver.

The sound originates from the same plane in space, therefore all frequencies reach the listener's ear at the same precise time and in correct phase.

This is precisely why MGM get with James B. Lansing (and partner) and the original Voice of the Theater design was born. Movie theaters were using Western Electric horn speakers that, while efficient, were not time aligned.

In keeping with this thought, you can see why it is desirable to have the sound reach the listener directly, without reflecting of walls or other surfaces first.

So... The 828 cabinet design, does an excellent job of controlling the directional aspect of the sound, therefore eliminating primary room interactions, thus they are not really that dependent of the environment of a particular room.

In that regard, the OP's quoted post is entirely correct.

BTW... Currently, I have two A7-500 cabinets sitting across from me directing their music to my listening position.

 

Nice. The only other speakers on my to own list are Tannoy and some classic Altec speakers. If I had the room or/and a sufficiently tolerant woman I'd go for a pair VOTT speakers or some Model 19s but sadly for Altecs i think I will be stuck with some 604s or maybe GPA 604s in some very attractively finished custom 620 cabinets

Great post.

 

I built a pair of 'Avebury' back loaded horns from plans:
Woden Design | Mark Audio »

One of the first things I noticed (after switching from Parts Express TriTrix) was that for a given perceived volume, the sound level disturbing my wife on the upper floor was decreased. I attribute this to the speaker having a more direct and tighter sound projection than other speakers. I think some people call this 'Beaming'. So I think some aspects of the OP's question have merit.

 

Directivity. Beaming is a bad thing that corresponds with frequency response of horn and driver being pushed to far. At least that is how I've always heard it.

 

I tend to avoid horns, not because of the way the sound radiates, but because they can be a bit peaky and hard on my ears. I'm not trying to knock them. There are some fantastic horn-loaded speakers out there (Wharfedale even made a few nice ones for a while). They're just not for me more or less. Honestly, I like cone drivers best. With the right application, they can be open, spacious, and airy, with excellent efficiency, not to mention the sweetest sound I've ever heard, but this is also my personal preference.

Here's a picture of the tweeter that's used in my main speakers (Wharfedale W90's). It's Gilbert Briggs' famous Super 3, first introduced in 1955 (The one shown here is from the early '60's when my W90's were made). This simple cone-type tweeter has a very-large alnico magnet, and a "very-high flux" (Still not 100% sure what that means), and it produces some very-sweet, very-silky highs (It was also used to great effect in the SFB3 open-baffle model).


First off, each W90 cab has two of these tweeters, mounted on the far-left and far-right of the cab, which produces a very-wide soundstage. I mount the cabs up in the air, about 10" off the ground, and that puts the image right where it should be, at least for this room and the speakers' proximity from my listening spot. Here is the speaker in question (Mine look just like these except without the overhanging tabletops... Built in late 1963).


This picture shows the upper section where the two midwoofers (5" cone drivers) and two Super 3 tweets are housed, free-air-mounted inside that open area. The two 12" woofers (with very-large alnico magnets) have their own isolated, front-ported enclosures, both of which have a sand-filled rear panel (Fighting resonances was high priority at Wharfedale back in those days). The whole thing creates a very-rich, very-natural, very-sweet sound. For music made prior to, say, 1975, I couldn't imagine using anything else. The sound draws you in and engages you like nothing else I've heard. You find yourself totally-digging the kind of run-of-the-mill music that never got your attention in the past,and that's the sort of thing I wanted. It was all about becoming re-involved, re-engaged with all that stuff I heard as a kid.


Jensen had a cool, little speaker, the AS-10, which had two cone tweeters up top connected to each other via an angled mounting plate,, and one tweeter was angled left while the other was angled right, and this worked very-well to create an airy, widespread soundstage. Cone drivers can also work wonders in an open-baffle application when done right. From what I've experienced, you just have to be Johnny-on-the-spot with the placement. Without that, a cone-based system can sound as two-dimensional as anything you've ever heard. But when it's right, it can be truly-mesmerizing. I'm home today, and having to do some serious reorganizing of a bunch of things I had to pull out of storage before a repairman gets here to work on something, so I have the music going right now. John Lee Hooker's "Booogie Chillun'" is playing at the moment.

 

So, the 828 is merely the bass cabinet part of the A7 (or more-specifically, the A7-500)? I ask because I always found it somewhat difficult to dissect the VOTT lineage/history.

I really like to hear horn INSTRUMENTS sounding right (the trumpet, tenor sax and baritone sax, trombones, etc.), and both horn drivers AND cone drivers excel at this. Horn drivers have a definite immediacy, not to mention a focus that is difficult to beat, even with today's high-tech, purpose-built drivers. My only issue is that sometimes they can be TOO much, although I guess I'm referring to the big VOTT models (I'm jealous of folks who are able to comfortably-implement an A7 setup... The earliest ones must be the perfect thing for old blues 78's and classic jazz, or Lalo Shifrin m
soundtrack music from movies like "Bullitt" and "Dirty Harry"... Or you could use the A7's for the audio while watching the blu-rays... Over at Trinity College, they have a theater with some VOTT's and the original Altec tube amps to go with it, and they show lots of the old, analog-recorded flicks from back in the day... Pretty-cool... I heard "Woodstock" was amazing... THAT'S the way to do it).

 

Triple like

 

Horn geometry can be configured to give any number of dispersion patterns depending on the desired application. As per the OP's question, it is possible to limit dispersion for use in poorly treated rooms but there are trade-offs that will have to be made. The most common complaint for horns of this nature is the so called "horn sound" usually characterized as a deviation from linear frequency response with an emphasis on the mid to upper treble(This can be compensated in the crossover network, but often it is not). This is often exacerbated by the construction of the horn itself which often times is not dampened enough and will add its own sound depending on which frequencies the horn structure resonates at. A knuckle wrap on the VOTT horn will expose this weakness, as an example. Another problem with narrow dispersion horns is diffraction. Every horn in existence will diffract the waves emanating from the horn throat. The sound waves will bounce off the walls of the horn internally resulting in diffusion. The horn geometry with the least amount of diffraction is an oblate spheroid, but it is not a narrow dispersion horn.

 

How about MY horns ? (Klipsch F2 tractix square, CDirectivity ?)

 

I have no experience with tractrix horns. But I did find this:

The Art of Speaker Design »

An excerpt:

The best solution is to eliminate the mouth reflection entirely. This has already been done with the Tractrix horn profile, invented by P.G.A.H. Voight in the late Twenties!

The Tractrix still has a sharp edge at the horn mouth, but the horn wall has already curved through 90 degrees before the sound hits the boundary. The reflected sound then has the difficult task of curving backthrough that 90 degree curve before it can strike the phase plug. Therefore ... no standing wave, only one modest reflection, and very little of the "horn sound" if the compression driver is correctly designed.

(Note: there are rectangular horns on the market that are Tractrix-profile in only one dimension; since the reflection is still an unresolved problem on two of the mouth edges, most of the benefit of the Tractrix profile is lost.)

 

You can view photos from different audio forums all over the world, and view different exotic speaker systems and you will see how many of real custom high end systems use some type styling from the A7. It is typical to see 828 style bass horn cabinets that are not the original Altec but ones that borrow from their design.

I purchased a First Watt D.I.Y. amp, an Aleph J from someone on eBay who builds an $80K version of his own patterned after the A7. I will note, for those who are interested. This individual does not rip-off Nelson Pass designs to build for profit, he was selling his high quality personal custom built Aleph J because he bought a First Watt M2 from Nelson Pass. I don't doubt that the Alepj J build cost was as much or more than I paid for it on eBay. Since then, I have acquired a pre-loved First Watt M2.

Others use different Altec exponential horns and drivers. And similar styled horns from other companies.

There are similar photos to be found from the SHF members, check out some system photos.



This is the larger pair of A4 cabinets that you might have been speaking about. The bass cabinet, with two 15" speakers, stands 7" high, plus the HF horns.

Best have some extra high ceilings for these babies. Here is a link to a current eBay listing, you can check out the description of the cabinets and horns

A4-Pair eBay listing.

Even with high ceilings, these speakers were designed for long projection and I would not recommend these for home use. I did see photos of one installation where a stage had been built and and they had two of these bass bins lying on their sides with a plywood stage covering the top and the main speakers were sitting on this stage. The photos that I saw showed a view of the stage with the A4's below, but I have no idea just how large the room size was.

I have one A4 cabinet, but my bass bin is only 10 1/2" tall.

I was fortunate to come across an original Altec salesman's model on eBay. The salesman, who called on movie theaters that are newly built or remodeling, would take along these models when on a sales call to better explain their product. The guy who refurbished my A7's, did the restoration on my A4 model.

There is another cabinet that resembles the A7, it is called the A5 and it has the large horn like the A4 on top of a smaller A7 styled bass bin.



Here are a pair of A5 speakers. This pair has "wings", plywood sheets on each side of the front of the cabinets. These are somewhat hard to find and are more pricey than the A7 model.

There is a great altec information reference web site, LANSING HERITAGE ». This site contains information from the three business that James B. Lansing was involved with, Lansing Manufacturing Company, Altec Lansing and JBL. Archived information, system photos and a forum. Everything that you may want to reference and read about Altec is here (well almost everything).

Here is a photo from the Forum's member photos:


Notice that basic bass bin cabinet, looks familiar (well sort of).

This one seems to have incorporated a sub into the lower bass reflex part of the bass bin and what looks like a newer generation of horns on top.

A7's like tube amplification for a more relaxed natural sound in the home, SS amps are for commercial PA applications where you are looking for plenty of slam. And they don't get upset when you connect them with 16-gauge RCA Speaker Wire from Amazon.

I would bet that most if not all VOTT you have heard, with the exception of the ones powered by the original Altec tube amplifiers at the school, have been powered by SS amps. And most of these are dry, sterile sounding amps intended for PA applications.

The weakest link on the Altec's are the crossovers, they are perfectly good passive commercial crossovers tht are OK with the PA applications for which they are intended.

You can have the finest equipment upstream, but, at the end of the day, before the audio signal can reach the speakers, it slams directly into the crossover. For home use, ALK crossovers are the best and they are affordable, about $500/pair for their universal, soft slope (about 12dB per-octave). I felt that using a passive crossover in my home audio environment would be preferred over an active electronic passover (better used in commercial applications). ALK designs their crossovers as custom (not factory) upgrades for Klipsch products and they work for Altec products, crossing over from 500-700 cycles.

There are many versions of Altec horns and drivers, but none that I have heard, I would consider as sounding harsh. Klipsch drivers (and I have a couple of pairs of Klipsch speakers) do not have the sound quality that Altec has. Altec drivers simple sound better all the way around, they have better sound and are not harsh. Kplipsh used to source their drivers from Electro-Voice and University Sound, whose drivers are better suited for PA applications.

The Altec horns are better than Klipsch, less harsh and less directional beaming of the high frequencies.

Properly upgraded and correctly set up, in the home, they sound much better than what you are familiar with in PA applications.

Most have not heard products in the VOTT class as they should be heard. The most popular home Altec product seems to be the model 19's. I had a pair and I liked them, but, they are no A7's I did, many years back, have a pair of the A7-500W's which are VOTT speakers covered in walnut cabinets, quite nice.

Altec had a nice home division, with the more upscale products using actual components and technology that had come from their pro-audio side. You can find many of these legacy products on eBay at decent prices. The model 14's are quite nice and have an excellent WAF.

I have listened to many music soundtracks on the A7's, growing up, I initially had more soundtracks in my collection than rock music. Have a lot today still.

The issues with the speakers being TOO much is more of them not having good source material and having a pair set up correctly in the first place.

Yesterday and today, I have been listening to a lot of female vocalists, and that is where they really shine. For people like James Lansing and Paul Klipsch, sound was really about the details in the middle, because that is where we live.

People will say that legacy speakers, like the A7 don't do what a modern design speaker can do and they are right. I find many modern speakers to have a deep thumpy, pistonic, bass that seems to be highly unnatural, but perhaps well suited for EDM. Of course, there is not much to be said for the mid's, sometimes sounding flat and lifeless.

My approach, it to take something that already excels in the midrange and add a super tweeter to the top and a commercial subwoofer for the deeper base regions.

Works for me!

 

I am curious, I do know the sound of a knuckle rap on a 511B horn, to me, it is a pretty solid sounding piece of aluminum. But every horn that I would knock on would have a similar sound, wouldn't it? They would sound different from one another, due to being different shapes and sizes, etc.

Everything has a resonate frequency, tuning forks, bells, glassware (think - opera singer breaking the glass). That does not mean, that in ordinary applications, the horn will be resonating. Here I am speaking of something in the audible range. I have heard one of my own pairs resonate "honk", and that was back some 45-years ago when I was sixteen, and I was miking vocals through it at the time (my bad).

Engineer's that design these things and they have withstood the test of time, they are much smarter than I will ever be. I'm here to see what I can do to maximize their designs.

In the over four decades since, I have not had any of my A7's honk, ever. The pair that I am sitting in front of right now, have Emminance base speaker which have twice the power handling that the Altec's do. It has the 908 series drivers with greater power handling than drivers like the 902, no resonance at any volume. The A7 is rated at 103dB as measured to 4'.

Some people will never care for the sound of horn speakers, oh well...
(The only pity here, is that most of those have never listened to what horn speakers could sound like).

I'm OK with how they sound, you just don't get this kink of sound out of a non-efficient regular speaker design. I have many nice pairs of regular speakers, they sound nice too, but they ain't A7's