Horns V. Vented Subwoofers


Everywhere I go I hear sound systems of dubious quality, I see people blowing woofers and drivers in large numbers and I see people working hard on audio jobs just to make enough to pay to keep their audio systems functioning rather than profiting from their labor and investment.  This doesn’t have to be the case.  I believe its possible to show people that buying a quality system package is ultimately not only less expensive but is, in fact, much more profitable than buying a pile of parts that sort of fit together.

During all my years in the business, I have been on a quest for the ultimate subwoofer. Horn-loaded subs were my preference and I started BASSBOSS essentially based on the performance of the B-One and B-Zero horns. We developed a lot of horns over the years, and continue to do so, because horns have a number of desirable and beneficial properties compared to vented boxes. There was, however, just one thing I was always missing from the horn-loaded subs: Really DEEP bass!

Other than building individual horns that are absolutely massive, or building a segmented horn comprised of many separate elements that combine to make one massive horn, there was not a practical way to build a portable horn-loaded bass cabinet that would reach a minimum frequency of 30Hz.   I had to look for a more practical way to deliver the deep bass I wanted to incorporate into the horns.

Eventually I designed a hybrid box that incorporated a vented section with a horn-loaded section and it produced massively low bass but even with the horn-loaded section, it lacked the impact of the purely horn-loaded cabinets. The box was also quite large and complicated. It was impractical, from a size and cost point of view, to build a cabinet that would combine the vented and horn-loaded segments in one construction.

What I then did was begin to develop a vented box to see what I could achieve with a highly optimized vented box. What I got was a really magnificent, musical and ruler-flat subwoofer with massive deep-bass output capabilities and virtually unlimited power handling, but it still lacked the impact I loved about the horn-loaded boxes.

In order to deliver both impact and depth I started combining the two types of boxes and found it to be problematic to integrate the two types. I could get the super-deep bass I wanted from the vented boxes and I could get the massive impact from the horns but getting them to line up and do it together took a great deal of time, measurement and experimentation.  I finally figured it out and it was magic!  Massive shock impact with body and depth I’d never heard or been able to achieve through any horn subs alone, especially since they had to at least fit through a door.

Not only do I understand and agree with the love for the impact of horns, I have improved upon it, to make it even more impactful.  Think of it this way, if an 80 kilogram man hit you in the chest with a solid punch, it would be a hard hit, but if that man was 160 kilograms, that hit would move you much further! Understand that to go an octave lower requires four times (4x) the power, and displaces four times the air for the same sound pressure level. If you can extend the power behind that initial hit by an octave, then it effectively hits four times harder because it literally is four times the mass of air behind the hit. This is effectively what I can do with the combination of the horns and vented boxes. The reason I do it with vented boxes is because to do it with horns would take up more than four times the space and that becomes impractical for both portability and for floor space in a nightclub.

Please understand that I am not suggesting using vented subs in the place of horn-loaded subs, I am suggesting using vented subs to extend and improve the impact of the horn-loaded subs.

Regarding the choice of amplifiers, I have heard opinions about all kinds of equipment, some of which are more extreme than others.  I’ve even heard it said that if the signal is ever converted from analog into digital it is un-recoverably compromised. This just proves that one can take anything beyond the realm of practicality.  I do my best to focus on the best practical solution.

The problem with anyone having an opinion about a piece of equipment is that in order for the opinion to be valid as anything more than an opinion, in other words for it to have value as a basis for making a decision, it must be derived from some form of test that eliminates any other variable from influencing the opinion.  Personally I have conducted and participated in double-blind tests between amplifiers where all other parts involved in the test were the same.  From these tests three things were evident:

1) Not everyone agrees on what “better” is.
2) There is very little difference between top-quality amplifiers and most people can’t tell one from another if they don’t know which one is playing.  (People hear with their eyes.)
3) One amplifier may be better suited to a particular speaker than another.

The conclusion to be drawn is that the only way to choose the best amplifier for a particular system is to choose based on its compatibility and perceived superiority for use with the specific loudspeaker components of the system. In other words, you must somehow choose the loudspeaker system you intend to use and then audition every possible amplifier in order to be assured that there isn’t a better choice somewhere in the world. Naturally this is impractical unless it is your full-time job to know these things.

So, since most people form their opinions based on limited experience, and based on experiences with too many variables to isolate a causal relationship, it is highly impractical to make a decision based on a number of peoples’ unverified opinions. I can tell you my opinions, which are based on over 20 years experience in the industry and hundreds of system installations and productions, tests and experiments, but they will still be just my opinions, based on my personal preferences, and not necessarily perfectly aligned with yours. In audio there is virtually never an objective opinion. Everyone’s ears are different. Everyone’s preferences are different.

The last time I was involved in a double-blind comparison of amplifiers, the one that was consistently loudest on subs was Powersoft. Which one was loudest was measured and was therefore an objective conclusion.

You can drive yourself crazy trying to figure out the minutia of which components will be the best in every single position in the signal chain.  You can also spend a great deal of money!

The third limitation is that a horn (or array of horns) must have a radiating area whose perimeter is at least one full wavelength of the lowest frequency to be reproduced.  For 30Hz that would require the perimeter of the frontal area of the horn array to be 11.43m.  That calculates to an array approximately 3m high by 3m wide or roughly 6 horn-loaded subs per side to deliver the performance my system design will achieve with just 3 subs per side.

The TRICK is combining the right horn with the right box in the right way.  The vented box you choose MUST offer low frequency extension well below the horn and must be capable of output sufficient to match that of the horn.  Horns are naturally more efficient than boxes, so they require less power.  They convert more of the electrical energy into acoustical energy.  Boxes are less efficient than horns, so in order to have a box (or boxes) able to match the output level of a horn an octave lower than the horn, that box must be able to handle a great deal of power.  In essence, the trade-off between horns and boxes is size and complexity versus power demand.  Vented boxes can invariably be built smaller and lighter than horns but they require more amplification to reach equivalent output.  Further, boxes can’t deliver the impact of horns due to the limitation of coil/cone inertia.  In most cases, the vented boxes can’t reach equivalency with horns before they reach either an excursion, thermal or distortion limit.  The answer has been to add more vented boxes until there are enough drivers to match or beat a horn-loaded array.  Unfortunately, all those vented boxes might be able to match the output LEVEL of a horn-loaded array but not the transient dynamic response and impact of the horn-loaded array.

From this information you can gather that in order to install a horn-only subwoofer system with flat frequency response to 30Hz would require a large amount of space, cabinets and money.  BUT low frequency response is NOT what people love about horns.  It’s the impact and immediacy of their delivery.  It’s the tight and punchy-ness and the tremendously dynamic transient response.  Therefore, if you use the horns for THAT function and use direct radiators for the extended low frequency response, you can use smaller horns that are specifically designed and perfectly suited to delivering the impact that people love about them.

If you asked me to design you a system for the ultimate in sound quality, I might make different choice than if you asked me to design you a system for ultimate reliability or ultimate SPL or ultimate simplicity.  Somewhere we must make choices and all choices involve compromises.

Horns have 3 factors that dictate their performance.

Their first limitation is the length of the horn.  The internal path length between the driver and the mouth must be long enough to support one-quarter wavelength of the lowest frequency that horn (or array of horns) needs to reproduce.   If the horn isn’t long enough the pressure wave will exit the mouth while the cone is still pushing forward and the “load” on the driver will fall off, losing efficiency and allowing the driver to hyperextend.  Therefor, a horn must be long enough to support the expansion of the wave to the lowest frequency you need it to play.  Assuming 30 Hz is your low frequency target, the horns you choose must be AT LEAST 2.85m long.

The second limitation is the flare constant.  This is how quickly or slowly the area of the horn increases down the path length. Low frequency horns require a slow flare, making their construction more complicated when folded into reasonably-sized cabinets. When designing a horn with a low frequency flare rate one must choose on a continuum between  efficiency and size.  Most horns that are made in a reasonable size are NOT built with a low flare constant AND a long enough path.  One, the other or both are compromised. This leads to peaky response and “horn honk” and a total lack of depth in their performance. These are compromises I’m not willing to live with.

While a single horn can’t achieve low frequency extension in a reasonable size due to the limitations of low frequency horn-loading, a single box can reproduce extremely low frequencies. Our SSP218 Subwoofer, with 6000W power handling can also reach output parity with a horn. Using 2 of the SSP218 Subwoofers allows for parity to be reached at half power, taking the strain off the system, lowering distortion and ensuring long service life. The combination allows the horn to deliver the impact they are known for and leaves the low frequencies to the slower cones for which they are better suited.

This solution takes advantage of both technologies’ strengths to create a system that offers the benefits of both with the weaknesses of neither. The combination overcomes the limitations of both the boxes and the horns. Provided the cabinets are properly aligned and integrated with each other, (which I do for you,) the shocking impact of the horn combines with the extended depth of the boxes while keeping the size and the power requirements reasonable and affordable.

If, however, you do insist on an all horn-loaded system, the B-Zero/D is the best single-box solution I’ve ever heard. The only thing you won’t have with 3 B-Zero/D per side is the super-low bass that nobody even knows is there until they hear it on a speaker like the SSP218 Subwoofer. (In my opinion, the combination is still better than either one alone!!)

Because I design boxes for a living I know the limitations of almost every loudspeaker design and configuration. The difficulty is in trying to explain the difference between competitor’s systems and what I can offer you.  Are you comparing an assortment of speakers and amps to a complete, integrated system? Do they have the necessary time/phase alignment correction in the processing?  Compared to any system I’ve ever heard, I can deliver deeper, louder, harder hitting, better sounding bass, and that is just the beginning.  Its difficult to understand without the experience.  The problem is explaining what “Oh My God!” feels like.

I know what bass is supposed to sound like.  I know what bass is supposed to feel like.  My subs were used on the main stage of the Ultra Music Festival year after year because nobody else could deliver what I can.  We delivered 120dB flat to 30Hz at 120′ (front of house mix position) for 20,000+ people with only 16 SSP218s.  In over 4 years in production, we have never lost a single voice coil in that box and we’ve had Bassnectar, Freq Nasty, Datsik, MSTRKRFT, Deadmaus, Black-Eyed Peas and so many others try to push our systems to the limit.  They still haven’t found the limit.

What is “Oh My God!”?   Its what happens when you hear a familiar song and realize there are layers in the music you’ve never heard before.  Frequencies below the capability of what you’ve heard before, dynamics above it, textures behind it and subtleties within it.  Its the experience of being immersed in the music, swimming in it, being a part of it.  Its beyond hearing it. It turns the air into a liquid.   Its the transcendence that happens when you fully integrate the senses of hearing and feeling into the experience of music and dancing.  For those who get it, its an instant addiction.   It takes your breath away, modulates your voice, caresses your skin, moves your clothes, blows you hair and gives you warm chills….

Such a system will allow you to listen at very high levels and not be in pain.  It sounds big and effortless and open.   From barely on to dangerously loud, it will be crystal clear at any level and will keep the same character no matter how high you turn it up.  It offers tremendous loudness with no compromise in quality.  Its intelligently designed so that you have enough headroom that you never force it to strain and distort and compromise the experience of the audience.

In what I am offering, there is no need for you to have to choose tight over deep or deep over tight or make any compromise.  I know how to set up subwoofer systems better than anyone.  I’ve been doing this continuously since I left the hi-fi business in 1987.  My companies have  done the sound for over 100 clubs and easily as many shows and festivals.  You will have tight, controlled, kicking bass that goes lower than any song you are ever likely to play on it.


  1. Leo R

    Awesome article. Well written. I would love to get my hands on some of those double 18 boxes. Probably out of my price range though.

  2. Tim

    Ever experimented with a ‘tapped horn’ design? I haven’t heard one but I’ve read about them, they are said to have the deepest high efficiency bass for their size and Danley Sound Labs uses them a lot in PA subwoofers.

    • morethanbass

      A tapped horn is an interesting idea, and seems impressive in some ways. I’ve never built one because it’s someone else’s technology but I’ve modeled them in software and heard the Danley TH115, TH412, TH812 and TH221. My software models indicated that they would have to be really big to gain any deep-bass advantage from the technology and I concluded I had more practical ways to achieve what I believe to be superior results.

      The claims about tapped horns are absolutely mind-boggling and at first exposure they are impressive. As good as they seem to be on paper, they do things I just don’t care for, particularly at high levels. During testing they have made noises and smells that would make me very reluctant to run them hard for long periods. Still, like anything else, if you have enough of them, you don’t have to run them as hard! In my opinion, they do upper bass really well but their capacity for deep bass is limited, particularly the smaller ones.

      The really big 12″ ones CAN do deep bass and they CAN go really loud but something happens when you try to do both at the same time. It’s appears to be a limitation of the technology related to the combined path lengths and driver limitations but it sounds odd when it happens. The average person might not notice it unless they had heard something play the same thing and NOT do it. Like I said, not my design. The (also) really big TH221 goes deep, but to me the size is totally impractical and the upper bass isn’t there any more. The coils also started to smell hot when tested at the same drive level that my 218s could handle for days… So, they are said to have the deepest high efficiency bass for their size. Interesting claim. Their size is enormous if you want them to go deep. And what does high efficiency really mean?
      Let’s look at the medium-sized TH412 tapped horn in comparison to a conventional vented dual 18”. The TH412 efficiency is quoted to be 110dB, that’s with 2.83 volts into “rated impedance” which is stated to be 2 ohms, which translates to 104dB at 1 watt. That’s only 3dB more than one of my SSP218s at 101dB at 1 watt, specifically 2V into 4 ohms. The TH412 weighs 357 pounds, 153 pounds more than the SSP218, and the TH412 doesn’t include an amplifier where the SSP218 does. The overall exterior volume of the SSP218 is 18 cubic feet, the TH412 is 31 cubic feet. The TH412 handles 4000W continuous, the SSP218 handles 3200W continuous. Two of the SSP218s will deliver higher output at lower frequencies for less money and in only 5 more cubic feet and at 50 more pounds. And, in a lot of venues, moving two lighter boxes is often a lot easier than moving one very heavy one. This point is more clearly made against the bigger tapped horns.
      They make a point to mention output at 200Hz that is 10dB higher than the rated output. A very impressive number but totally undesirable. An increase of 10dB/octave between 90 and 180Hz means that a 24dB/octave low-pass crossover slope will result in only 14dB/octave roll-off. Would you use a 14dB/octave crossover on your subwoofers? With the TH412 that’s the result unless you go with a steeper filter. The increased upper bass output from the TH412 may account for why they seem impressive at first listen because that range tends to give the impression that they are very loud. It’s just not loud where I want it to be loud.

      The Tapped Horn is different, but different isn’t necessarily better, it’s just different. A TH412 is bigger, heavier, more complicated, more expensive and louder than an SSP218 but in my opinion the SSP218 is a better, more practical choice if you’re looking for a real subwoofer that can be run at very high levels and deliver very low frequencies, trouble-free, with outstanding sound quality.

      So, the answer to your question is yes, I’ve experimented with the design and with existing products but I concluded they didn’t offer what I wanted.

  3. gjsanchezm

    David, this article was so good and answered so many questions, in such a clear and easy to understand way, that I can only thank you, not only for writing it, but for making it easy for anyone to grasp the basics of the somewhat complex to explain concepts you wrote about, while at the same time, eliminating so many misconceptions and myths on the subject. Thank you for sharing your experiences, opinions, knowledge and tips. Very appreciated. Can’t wait for more intelligent, interesting posts like this.

  4. gjsanchezm

    Hi David, I was thinking that linking your blog from Bassmaxx’s website would be a good idea. I don’t know, maybe there’s a link already, but I couldn’t find it. I mean, articles such as the above are a must read for anyone visiting the website / interested in Bassmaxx, not many people know what you state in the article, certainly not many clients (if any), and not even many who claim are knowledgeable, this would make them understand, and articles like this, linked from Bassmaxx’s website, would gain you (even more) credibility and respect from people who are not directly in the sound reinforcement world (those, already know you). It also would make you gain visitors to the blog (and the site if you link back from here), and even brand fans (most of which might never need / buy a Z-5/D, but would talk about Bassmaxx everywhere and in every forum).

    I’m just a guy who found this blog while researching folded horn / horn loaded subwoofer enclosures, I knew about Bassmaxx’s subs and their great reviews, since long ago, heard them at UMF and well, knew mostly what everybody knows about Bassmaxx’s subs, but I had no idea about this great blog. You can become the go-to resource for people who do not work in sound reinforcement but are just enthusiasts, amateur DJs / producers, hobbyists , grow the company’s reach, marketing and fan base, you never know what the future holds. Get everybody talking good things about Bassmaxx’s blog, the knowledge and associated brand. Just an idea.

  5. gjsanchezm

    Why tractrix instead of exponential or exponential / hyperbolic horn flare?, doesn’t the faster expansion rate of the tractrix horn make it less than ideal?, wouldn’t this mean a bigger horn mouth than with a hyperbolic horn flare?. Why do you prefer tractrix instead of hyperbolic?.

    • morethanbass

      You’re right about the bigger mouth but the mouth is bigger relative to the other horn types and that alone isn’t a bad thing… if you can make it fit. If the horn is long enough, the flare constant is low enough and the mouth is big enough, the result is better with Tractrix. (JMHO) The sound quality is the reason I prefer the Tractrix flare type. Listening to different horn types I’ve found that hyperbolic are very effective and efficient but the trade off is they are more honky. The L36 comes to mind. Comparing a Tractrix to an exponential, the sound is more similar, like an EAW KF940 or KF760 IIRC, and all other things being roughly equal, the exponential will be more efficient… But, in direct comparisons, to my ear the Tractrix has a more natural, dare I say un-horn-like sound. Yes, the down sides are that they tend to require slightly bigger boxes but the upside is that you can really enjoy listening to them.

      • gjsanchezm

        As always, VERY informational and straight to the point. Thank you!.

  6. acoustican

    A few Pictures of your endeavor would have been awesome.

    • morethanbass

      We’ve heard your request and added some photos of David’s designs in action at ULTRA Music Fest in Miami and on location in Bermuda. You can find more at https://www.bassboss.com Thanks!

  7. Anthony Rosa

    You know I really wish I had the money to even purchase 1 of the ssp218’s =( I have 2 peavey folded horn subs but the Xmax on them is only like 9mm and I don’t get the low end I want. I just went and saw hardwell in niagara falls new york on Monday and I know for a fact they were using these subs. I’ve never heard a sub reproduce low frequencies like bassmaxx!! I would probably do anything to get one of these subs!! wish there was a giveaway or something lol. I’d do anything =(

    • morethanbass

      Hey Anthony,

      So you’d do anything? That covers a lot of ground…

      I’m glad you liked the subs. You should check out the new ones… 🙂

      I realize that the products can seem expensive when compared box-to-box but when compared in terms of output-per-cost they are extremely competitive. Add in the reliability and life expectancy that comes with the bassboss build quality and the price looks even better. Then add in the number of hours you save on setup because you’re using less equipment to do the same shows. And then there’s the question of your reputation. What would being able to deliver the sound you love to your customers do for your business?

      I challenge you, and anyone in your field, to add up the total cost of your system, honestly, including amps, racks, processors, speaker wire, repair costs and anything else required to make your system work over the last 12 months. Then ask me for a quote on a system that would outperform yours. I think most people would be very surprised by how cost effective these systems are when compared to any other. Unfortunately, by the time most people figure this out they have already spent too much on something else that doesn’t work as well.

      So you’d do anything? Would you sell all your old gear and invest in a new system?

      • Anthony Rosa

        Oh yea definitely. I’d sell all of my old equipment and invest everything into bassboss! Just wish I had the money to invest more into it =/

  8. morethanbass

    I’d be curious to find out what your entire system consists of and whether I can be truly cost-competitive with it. Send me a list of all your gear and I’ll look into it. Not to try to sell you anything, just to validate my claim. Are you willing to do that?

    • Anthony Rosa

      Well my mixer is an American Audio vms4.1, which is the newer version of the vms4. So it has the updated sound card which is nice because everyone in my community that dj’s hears how loud and clear my set – up is and see that my gains on my powered speakers are barely touched. Not even a quarter of the way up. I’ve been waiting to go to the pioneer cdj’s but I just don’t have that kind of money. I don’t have any eq’s or sonic maximizer ‘ s which I wanted to get for my subs but there just not giving me what I want. For the low end I have two Peavey SPFHBX 18In Passive Folded Horn Subwoofer’s. They run off of an American Audio xlt 2500. Bridged at 4 ohms I believe putting out 2,000 watts. It was a cheap amp that I could am offers at the time. For my tops I have two
      Peavey PVX-P15 15 inch Powered Speaker’s. That’s pretty much all I have . It’s not much just because it was all I could afford but I would honestly give all of that up for just even 1 of the dual 18 inch bassboss cabinets =/.

      • morethanbass

        Since we don’t get into mixers and sound cards I considered your speakers and amp to figure out a budget. I came up with a rough estimate of $4000.00 to buy what you listed from internet retailers. You didn’t mention cost of cables, amp rack, tripod stands, etc. so I didn’t count anything like that in your budget but our systems include those types of items. You may not have bought the gear new but it’s a fair way to compare. In truth there isn’t a complete BASSBOSS system package I can provide for $4000.00 new but I will work on that for future product plans. We are working on a single 18″ subwoofer and satellite set that I believe will give you what you’re looking for in the low-end. As of this moment the price hasn’t been determined. It’s safe to say that the set of 4 boxes, (2 subs, 2 tops with 6000W of amplification, DSP, cables and speaker poles,) will sell for more than $4000.00 but it will kick serious butt and take up half the space of your current rig.

        It’s hard to fight a low-price war while using premium components so we focus on performance and value. Ultimately one of our systems might cost double what your system cost but every metric of performance is far better. From sound quality to reliability to ease of setup to appearance to electrical current draw to weight to size to longevity to customer service, you get that much more value for every dollar. It does take more dollars for us to deliver all that but we believe guys like you can appreciate that and will make the investment when the time comes. Does that sound right to you?

  9. Ian Lewis

    Hi David, almost a year ago I purchased 1 ssp218 sub(2000 Watt Version, I use it with 2 QSC KW153 tops), I have played with cerwin vega,QSC , yorkville ls801, ls2100 (2400 rms, 135spl) this box is loud, and highly regarded, but ssp218 does lower frequencies much smoother, this sub is in a different league, I have played that box with R&B, Reggae, Soca, Salsa,it hits those lows so much smoother, I will puchase another one. I am not a DJ, but Iam a sound enthusiast.Good job David. Iam the guy from Toronto Canada.

  10. January

    This was a fantastic article! I can tell that I am not even in the same league as you as far as experience and expertise go. I really appreciate you taking the time to put this together, I have never owned a horn loaded speaker before. I currently have a Peavey SP218 that seems to produce very low tones easily but I have not been able to get the “chest thumping” feel out of it. I was thinking about a horn loaded speaker because when I read articles it seems that this might be a good solution. I appreciate all the info you have given and the way that you made it understandable for a person like me, I have had a bit of schooling on this subject but most of what I know is self taught and yet I was able to follow what you said in the article. Thank you so VERY much for the info. God Bless!


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