You Cant Buy It but you Can Build It

@mijostyn --

"... put on anything with a little low bass in it and turn it up to your usual listening level. Put your hand on the bass horn say just inside the mouth. Feel that vibration? Any vibration you feel is audible distortion. Getting any large structure not to vibrate at bass frequencies is extraordinarily difficult. This is the problem with bass horns. They add way too much coloration."

This is grossly incorrect and an assertion that clearly doesn’t rest in experience - period. My counter reply here would apply even at SPL’s where most typical commercial subs would’ve left the building, but you’re talking "usual listening levels"? Come on. I’ve you have ever listened to a pair horn subs in a home environment, which VERY few people ever have, you would know that they - properly implemented (and this goes for any sub principle) - produce a smooth, effortless and enveloping bass, quite different even from direct radiating designs. They may be big structures, but made of high quality plywood or even MDF they're sufficiently sturdy as the internal horn path acts as effective bracing, which is furthermore reinforced with additional bracing to support the horn path itself. Moreover the horn acts as a low-pass filter and thus filters out harmonics and driver induced noise that would otherwise be readily exposed from direct radiators which are working much harder being much less sensitive. Horn subs produce "way too much coloration"? No, sir, it’s the other way ’round.

"You would literally have to make the horn out of concrete. Getting a small enclosure not to resonate is difficult enough but a horn is virtually impossible. There are very few horns that make it below 30 Hz. The K horn is already down 4 dB at 33 Hz. A horn that makes it down to 18 Hz would be huge and even more difficult to control. The driver is happy as a clam, the horn itself is an audiophile nightmare which is why you do not see or hear many of them."

The predominant reason you don’t see horn subs in home environments is because so very few are available and that they’re very big. Oh, and the few that are are typically very expensive. Please name me a couple of commercially available, non-DIY horn subs that not only you but audiophiles at large are actually aware of. Horn subs aren’t disregarded by audiophiles for some speculated flaws of theirs, but because by and large they’re simply not part of the audiophile narrative.

Great bass requires big size, and proper implementation here is automatically assumed. 20Hz honest reproduction from a horn sub necessitates roughly 20 cubic feet of enclosure volume. Sure, that’s a lot, but it is manageable if you set your mind to it. As Arnold (and Nike) would’ve said: Just do it!! ;)

@mijostyn --

"... sorry lad, it would appear your experience is lacking. I have heard and built Horn subwoofers. Mahlmans’s sense of vibration is not good. I hope he is not diabetic. The other answer would be that his horns do not go very low which is in keeping with his other posts. Yes, horns are very efficient but, bass is bass and it is very powerful and hard to contain. Any subwoofer, horn or otherwise putting out 20 Hz at 85 dB is going to shake and it is going to shake the entire house. Making one that does not vibrate with just the distortion produced by the driver is virtually impossible. There are examples that come close, Magico’s Q subs come to mind. I might be able to do better. We shall see. I have been designing and building subwoofers for almost 40 years."

Forest for the trees, as they say. Not to impugn your decades of experience, I hope they’ve done you some good, but it seems to me you’re chasing an aspect in subwoofer design that’s really the lesser evil compared to, in my mind, more primary goals. You’re a line source guy on the main speaker front, one terminated at both the floor and ceiling no less, so why haven’t you gone to length ensuring two bass columns, loosening a wee bit on the vibration control, placed in each corner behind the mains to meet the challenges faced here with both headroom and acoustic coupling? No, because you’re hellbent on killing vibrations as that which has precedence, thus limiting yourself to a smaller sub design. It’s all a matter of degree and measuring its importance relative to other aspects, and to you vibration/resonance control comes first with all that entails - fair enough. I’d have gone differently, as you imagine, letting physics more readily have their say - vibrations to some degree be damned.

@mahlman’s horn subs (yes, in my understanding of the correct use of the word ’sub’ they qualify, being they’re able to reach honest 30Hz without any issues) as a classic single-fold front loaded horn, very high efficiency at that, will most likely deliver some of the most effortless, smooth and nuanced bass out there. I’m sure there’re some cabinet vibrations at elevated levels, but do they really matter in the bigger scheme of things, not least outweighed by the qualities of a horn sub design that has the woofer cone moving close to zilch at anything but earsplitting levels sans mechanical driver noise, where a direct radiating sub design like yours, almost 20dB’s less sensitive, will necessitate up to 100x the amount of power and prodigious excursion for the same SPL?

Shelling out $40k for a single(!) sealed, 15" loaded Magico sub is just dumb, sorry. That’s $80k for a pair of them, and it’s not like they cured polio or other.

"As for horns being the best type of driver, they have their advantages. I am waiting to hear a horn system that is not colored. They also require crossovers. IMHO the best type of system is a one way driver crossed to a subwoofer below 125 Hz where digital bass management is easy to apply. The only one way driver that is truly one way is an ESL. With horns you are also stuck with a point source system. It does not matter how big they get. Line sources project power better particularly in the bass and are more capable of generating the visceral sensations of a live concert."

I have no issues with ESL’s, really, other than they need to be big to really be worthwhile (and usually lack macro dynamics), certainly compared to big horn setups. And yes, an advantage of theirs is not needing a cross-over in most of the audio band, except crossing over to a pair of subs and the challenges this presents. Point source(s) as a design characteristics is not necessarily a flawed approach. A single point per channel is desirable and to my ears is most favorably realized through the Tom Danley invented Synergy horns, but they also need to be fairly big to do their best and maintain directivity control down low to the subs. The dispersion characteristics of my horn hybrid main speakers is quite uniform through their audio band, not least at their single cross-over point, and this is achieved via the big midrange/tweeter horn and how it couples to the twin vertically mounted 15" woofers. In that regard they’re sonically not wholly unlike big panel speakers.

Interesting (and to me rather familiar) rundown on your audio setup, mahlman. All-horn, -active, DIY, inclusion of pro audio products, letting size have its say, PC-based source - hear you loud and clear. One senses the vitriol from some of the comments, because this - all of it, actually - rubs audiophilia quite the wrong way. And that’s how it should be, apparently.

It’s great that you’re able to maintain a 2-way speaker system running from ~25Hz to ~18kHz and a sensitivity across the board no lower than 105dB’s, it seems. Something tells though the bass horn is at its limits in the upper range crossing over to the K-402? The K-1132 apparently isn’t all too different compared to the EV DH1A (used in my main speakers).

My own speaker system is 3-way - that is, 2-way pro cinema Electro-Voice TS9040D LX speakers, run actively through a Xilica XP-3060 (same as yours) with a Belles SA-30 for the HP9040 horn + DH1A compression driver and a Lab.gruppen FP6400 for the ported dual 15" drivers. A Crown K2 runs a pair of DIY MicroWrecker 20 cf. tapped horns fitted with a 15" B&C unit in each, augmenting the EV’s from just below 85Hz down to 20-25Hz. Total output power sits at ~2.5kW per channel (the EV bass section sums into 4 ohm). Slopes across the range are 36dB/octave Linkwitz-Riley, though the high-pass on the MW subs at 20Hz uses a Butterworth slope style. I'm implementing 5 PEQ’s on the EV horn section (4 subtle notches and 1 peak suppression). The rest of the bandwidth is run sans PEQ.

What really makes a difference here, and where I find 3-way to be worthwhile, is high-passing the EV bass section at ~85Hz crossing over to the TH subs, which "sets them free" with a cleaner and more agile/expressive imprinting - it adds a bucket of headroom in this vital region. The DH1A is a monster, a sledgehammer in velvet gloves, and is crossed with the HP9040 at just over 600Hz. The TH subs are wholly effortless, smooth and quite visceral, and integrates tremendously well with the EV’s.

I use a PC source as well in the shape of a DIY music/HT server with a Marian Seraph D4 AES/EBU digital output interface to feed my DAC/preamp via a balanced Mundorf silver/gold digital cable.

I find it’s great that you’re using the system you do, actively and all and with the priorities you’ve made. I may end up with all-horn again (been there), but for now I’m very pleased with where I’m at. An important trait with the EV’s is their physical height of just over 6’ with the acoustic center sitting between the lower horn edge and upper edge of the EV bass cab. It’s an unrestricted sphere-like presentation that fills the room effortlessly, not unlike a large panel speaker (but with much better macro dynamics). A future upgrade may present itself with a pair of DIY high-order bandpass subs fitted with 21" pro neodymium woofers. They extend higher and cleaner in the upper band compared to my TH’s, and thus may further clean up the upper bass/lower midrange (the MW’s are run at their max upper ceiling). Fun stuff.

@mahlman --

"If pure sound quality was the metric they use I can only think they have not heard such a system. I suspect however that there is a lot of snobery involved and it is just "not possible" that serious hobbiests can build better than the high end audio store offerings."

"High-end" audio is a genre, even; it is as much defined by character and limitations as it cultivates certain virtues in reproduction, while not least being overly expensive. Our "playground" would seem to challenge the narrative of audiophiles-at-large that it’s moved outside their field of interest. Indeed, one can only do so much to get them to assess with an open mind, if they ever meet up.

"I find that when I have to put a lot of watts into a speaker to get decent volume I have also lost some fidelity. On a two way double 12" woofer + a horn top I have built the least I considered was 99db on the woofers. These things have great crsip sound and tremendous fidelity and even with Bach organ up pretty loud you have to put your hand on the cone to feel the excursion since visually it is almost imperceptible. I also prefer cloth accordian surrounds which only come with more efficient woofers.

I have about lost interest in 15" woofers which just don’t sound as tight to me as a good 12". Impacts on percussion are sharper and realistic acoustic string resonance is more defined for example."

I was at one point hellbent on all-horn, and while this is still largely where I’m coming from there are variations in design to attain an end goal that is hugely satisfying. A departure of sorts early on was choosing Tapped Horn subs instead of the more classical Front Loaded Horn dittos, which is really about maximizing the potential of a given cone size using both its front and back wave while attaining excursion minima at the tune (as opposed to a FLH that has the driver placed in a sealed chamber and excursion max. at tune). Then came the experiment choosing dual, vertically placed and direct radiating 15’s to closely mimic the dispersion pattern at the cross-over from the large HP9040 horn for a better uniformity and coherency of sound. High-passing those 15’s fairly high means movement is reduced to zilch, even at close to war volume, and the 15" drivers in the TH subs only vibrate at volumes that are physically overwhelming. Next may be trying out another variation on the 6th order BP that shaves off a wee bit size (from 20 to 16 cf.) but adds pro driver size from 15 to 21" and has a variable tune. They’re dynamite in a relatively limited package, and it pays off in dividends with regard to smooth, effortless and natural bass reproduction also due to a cleaner and more extended upper range.

My preferred surround types are cloth and foam. Foam is very low loss and more modern foams last up to about 25 years. Cloth is also very good, lasts longer, but is usually best at limited excursion (as in your case). Rubber I try to avoid, and has for some time now.

@mijostyn --

"... use a USB DAC or a USB to SPDIF converter to a DAC."

There are other ways, equally well or better sounding to my ears.

@mijostyn --

"... I did not say there were not other ways. They are generally a lot more expensive, not any better sounding and have limited functionality vs a full fledged computer. My system doubles as a theater. I can also stream videos and movies as well as any audio service. I can record records to the hard drive and AB various versions of ...you name it. IMHO music servers are an insane waste of money. It is like comparing the pricing of commercial vs consumer audio equipment. Hint, professionals are not as easily conned."

Can’t really say what you’re after here, but I’ll bite: pro digital output PCIe sound cards from RME, Lynx and Marian, not least Word clocked, to my ears are the easy and generally cheaper equivalent to USB or USB to S/PDIF offerings - the latter of which have been the hot cakes in computer audiophilia for several years now, and are a true PITA to be brought to their fuller potential (go figure). No indeed, pro’s aren’t easily conned; naturally they’re not going for the latter option.

And regarding PC’s/music servers: mine IS a fully fledged full ATX-sized DIY computer with care taken into a low ripple and powerful PSU, mobo choice, processor, RAM, etc. and overall implementation. A lot more could be done here, but it’s a balancing act with other areas that need attention as well.

"One last thing. The problem with ears is that they are connected to a brain and when brains are concerned all bets are off. Example. Have a dispute with your wife then go mow down 50 people with an SUV. Sometimes brains really s-ck."

Getting down to brass tacks: if one’s ears deems it’s worth going for, it is. If not.. And let me bring it to you - peoples brains seem to f*ck up their decision making perfectly well without the aid of hearing. Often it’s all about the proper narrative, and if it wasn’t as much about spousal-imposed restrictions, aesthetics, conjecture, prejudice, convention, snobbery etc. and a little more about what hits the ears only, well, that’d be something to cherish, I find.

"The material a surround it made from really does not matter. It is the design of the surround given the drivers intended use. Certain designs work best with certain materials. Subwoofers need a large X max and a long throw, low compliance suspension requiring large dual spiders and butyl surrounds. Foam surrounds are a poor choice for subwoofer drivers as the stress causes even the good foam to disintegrate. 25 years is not good enough. A suspension should never fail."

That a suspension material doesn’t fail for several decades is just a convenience. Foam surrounds allow for application in designs that otherwise wouldn’t be properly implemented, so yes you’re right; it’s what the design dictates. Subwoofers don’t necessarily need long throw drivers with butyl surrounds though, but more on that below.

"... unless you are using an insanely large driver (21") you are not going very low at all. In order to move the amount of air required to produce a 20 Hz note a 12 or 15" driver has to move quite a distance especially at volume. Even at moderate levels the excursions would be plainly noticeable. If they are not then your woofers are not doing anything below 40 Hz. It is simple physics and it does not matter what type of enclosure you are using. Distortion does increase with excursion distance after a point. Modern subwoofer drivers can easily do 1 cm excursions without distortion, some up to 2 cm. Down below 40 Hz it is not what you hear that counts. It is what you feel. A 20 Hz sine wave played at just 75 dB causes my entire house to rattle. I have four 12" subwoofers in a 16 foot wide room and you can see the excursions across the room."

You make absolutes from a local context - your own. No, a 12" or 15" driver doesn’t have to jump wildly about to make to some rumbling at 20Hz, but you’re right that they will in a sealed enclosure with max. excursion at the tune - that’s also physics. I can tell you for sure that a 15" B&C pro driver with accordion cloth surround and +/- 9mm Xmax in a pair of tapped horns like I’m using only vibrates at levels down to 20-ish Hz that shakes the air quite violently, because the horn enclosure and the specific loading of the driver does the heavy lifting with excursion minima at the tune. They’ll each do ~120dB’s at the LP @ 20-25Hz and stay within the B&C’s Xmax limits - that’s a damn fact. Actually, add a few dB’s because they’re corner loaded.

Where it does get hairy is sub 20Hz into the infrasonics. This is where you need a couple of big a** drivers to produce proper pressure to make these ultra low frequencies matter as something that reverberates your whole body. To some a subwoofer (for the term to be strict) should cover down to 10Hz, but mostly that’s fruitless unless you have the right floor and room construction and über displacement capacity plus -wattages at hand. Horns would be quite big indeed to do the honors down that low, but you’d get away with using fewer drivers.