KIH #37 – Big-driver sound

  • Funking hey. Check out the Heco Direkt Dreiklang (that’s German for tri-sound to point at being a scaled-up 3-way over the original 10” two-way Heco Direkt). Whatcha reckon its driver diameters are? Here’s a hint. The midrange is an 8-incher. That makes the about twice-as-wide woofer a—gasp—15” monster, baffle width a mega 70cm! Add claimed 98dB efficiency, 19Hz- 30kHz bandwidth and wallet pinch of €7’000/pr.

    Which segues neatly into today’s theme. Big-driver sound. Audiophilia has its own form of political correctness. Nowadays, big woofers seem associated mostly with boom and bestiality, testosterone poisoning and doped-up raves. Even big midranges have fallen out of favour. 5.25/6.5” two-ways are far more common than a Heco Direkt or Zu Druid V whose 10” mid/woofers mate to horn-loaded or compression tweeters to appear like last century’s big-bore Hemi throwbacks when gas was cheap.


    The most obvious reason against hifi hemis would seem to be a prevailing preference for smaller speakers; or at least smaller- looking boxes which disguise their cubic volumes behind narrow baffles. Essentially they rotate the Dreiklang/Druid concept by 90° on a lazy Susan. What was wide goes narrow, what was shallow goes deep. This rotation doesn’t eliminate the need for LF displacement. It simply multi-parallels small woofers which either fit the narrower baffles; or locates them in a force-cancelling array on either side as Joachim Gerhardt pioneered at Audio Physics.

    Taking that narrow multi-parallel concept to the extreme was Anthony Gallo’s spindly Reference 5ls of yore. That augmented its frontal artillery of 8 mids alternating with 7 tweeters with a clean dozen of 4-inch ceramic-coated aluminium woofers on the back. Just so, their official -3dB spec was 36Hz, not the 19Hz the triple-ported Dreiklang 15er promises. The rationale for multi-paralleled drivers is higher sensitivity, lower excursions for equivalent SPL, increased motor control and, from the last two items, greater speed and precision. Yet looking at the Gallo spec, we see a typical 90dB efficiency figure. Contrast that to the Dreiklang’s or Druid’s 98dB. Not everything is like its propaganda would have us believe.


    Having reviewed the 2-way Direkt floorstander and Aperture’s Kalya 8” two-way monitor whilst now owning and loving the Druid V, I do have an opinion on the difference which “unnecessarily” bigger drivers make. I wrote unnecessarily because it’s not about bandwidth. Today’s long-throw drivers optimized by software-modelled port loading needn’t be huge to go low and even loud. To repeat, to go low per se doesn’t require big diameters. Just so, there’s a difference in textures and sensation. Call it tone and shove. Increasing a mid’s diameter is ultimately limited by its need to meet a tweeter. Typically that’s a 1-inch dome which can’t reach too low before there’s a gap with the midrange. Still, any number of “vintage” 10-inch or even 12-inch two-way towers exist to demonstrate just how seamless a meet can be achieved, even if often not with run-of-the-mill drivers.

    Comparing our Druid’s 10.3” widebander to the 6” ceramic Accuton mid/woofer in our Albedo Audio Aptica two-way tower cleverly loaded by a transmission line modelled in custom software, bandwidth is surprisingly comparable. With tailwind from correct setup and proper amplification, it’s in fact the Aptica which can outreach the Zu on raw extension. But covering equivalent bandwidth with very different weaponry makes decisive differences to the listening experience. Here it even includes a big offset in efficiency (85dB vs. ~96dB). A big sonic offset is the behaviour in the power zone of the upper bass. It’s related to what musicians call the engine room of a band. It’s the beat’n’bass makers of percussion and stringed bass which generate a groove’s energy and propulsion above which harmonies and melody occur. Here the greater cone area of big woofers or mid/woofers moves more air and does so from a single point. That translates into greater visceral punch. And that runs our engine room at higher RPM as it were.


    That’s obviously less noted with string quartets which feature no percussion to begin with and which normally use their cello con arco (on the bow), not as a plucked shrunken Jazz upright. But play any modern music which assembles around and above a drum kit and electric bass and voilà – the difference of a bigger woofer is self-evident. Again, it’s not about reach but the element of shove, rhythmic vigour and more kinetic impact. The second element of the bigger-is-different recipe is tone density which figures all the way up throughout the midband until the tweeter takes over. An 8/10” mid/woofer simply sounds chunkier, chewier and more robust than a 5.25/6” or even smaller equivalent. Of course there’s a price to pay in trade. It’s in the wider presence region where most tweeters hand over that the advantages of smaller mids reaching up there assert themselves.

    The lucidity, resolution and in-sight into that range is where small drivers routinely pull ahead. It’s the tit-for-tat doctrine. Whilst I hear bigger mids as having the described advantages, I also notice this lesser side. As usual, it’s a matter of flavour, preference and what mix of qualities makes your kind of music most interesting and compelling to your ears. Higher sensitivity very often translates into an earlier wakeup call. If you don’t want to or simply can’t play loud enough (often enough?) to where the sound shows up in full without feeling pale or pinched, then a high-efficiency speaker tends to cross the line into fullness sooner on the dial.


    That’s where speakers like the two Hecos (I’ve thus only heard the smaller Direkt) and Zu cash in. They move more air to enhance tonal solidity; they can go very loud and shift rapidly for good dynamic contrast; and (to reach back to KIH #35) they give good tensegrity or musical charge because they’re strong in the power region. Having gone back and forth between our new Druid V and various other resident speakers of late, I noticed something I’ve long suspected. At least for me, speakers which excel in the upper bass and lower midrange with punch and impact and which on tone play it beefier… they are the bigger emotional triggers. Speakers that excel at air and maxed-out presence region detail with shiny treble put me in a more observational mood. Listening then becomes more of a seeing than feeling thing. That visual perspective revolves around soundstage precision, micro detail and top-down illumination. The feeling perspective is a bottom-up thing centred on punchy time keeping and big robust tone.

    Me, I like both perspectives. They’re different but both fun. Happily, being a reviewer justifies owning various speakers whose readings spread out into different schools. Alas, most regular listeners just want one pair to “do it all”. I happen to believe that no single pair can, completely. Instead, one must identify the qualities that are important to one’s own list, down the sequence of priority, then make sure that one’s pick crosses off all the cardinal points and however many extras are within the particular design’s reach and budget. If meatier chunkier tone and feistier punchier time keeping rank high on your list, you might consider the type described today. If low-volume happiness is important too, add 94dB+ sensitivity. Besides the Heco and Zu models discussed, there’s also Audio Note UK, the Orangutan models from DeVore Fidelity, various legacy-range Tannoy and so forth.


    Srajan Ebaen

    Written by Srajan Ebaen

    Srajan is the owner and publisher of 6moons. He used to play clarinet at the conservatory. Later he worked in audio retail, then marketing for three different hifi manufacturers. Writing about hifi and music came next, then launching his own mag. Today he lives with his wife Ivette and Nori and Chai the Bengal cats in a very small village on Ireland’s west coast, between the holy mountain Croagh Patrick and the Atlantic ocean of Clew Bay in County Mayo’s Westport area. Srajan derives his income from the ad revenues of 6moons but contributes to Darko.Audio pro bono.


    1. Great article Srajan! As they say – there is no replacement for displacement… The liveliness and timber correctness of the big drivers is intoxicating and in a proper system the detail and the finesse can handily outdo typical two way micro monitor simply because of higher sensitivity, faster transients and overall lucidity.
      My favorite system to date – Volti Speakers driven by Border Patrol as presented at several RMAF. Cheers!

    2. take a tip from one who’s tried.big drivers mean big space and (mostly)big money.
      best is subjective,better is unsurprisingly expensive.
      michele,from rome
      p.s. ever hear a patrician corner horn in mono?

    3. Great topic. I’m an audio note fan. I’ve been to rmaf several times making an effort to listen for detail and looking for a sound that was moving. Consistently I’ve prized what the audio note presentation. I do recognize that there is some “lesser detail”.. I’d like to know more about other brands than the few mentioned. It’s much slimmer pickings than what’s available from more typical contemporary designs. Thanks for taking the time to write the article!

    4. Enjoyable read and helpful. I don’t have much experience with large woofers and hadn’t read about these observations previously. Great that you don’t solely glorify big woofers but also clearly highlight the trade-offs. I have a popular amp that’s more top down, and I can’t use it in my main system. Feels lifeless. Bottom up amps add emotion I can’t live without.

    5. Ben:
      Fair request but I must admit I don’t have a more comprehensive list of such designs. You’re right, the pickings for this type are slimmer. It’s why I called them ‘retro’. They used to be common but the rise of long-throw small mid/woofers with low resonant frequencies has changed the scene. There are a number of 10/12-inch two-way boxeswith compression or rectangular horn speakers of the quasi pro persuasion I’ve come across but their names don’t come to mind right now. I guess Google will have to be your friend there -:)

      Michele – I specifically mentioned the Heco and Druid models for not being silly money (relatively speaking), with the Heco 10-inch 2-way being €3’000/pr. That’s far from a 17″ woofer, granted, but as a two-way, it does follow the ‘bigger than strictly necessary’ route to give the benefits I described -:)

    6. Haven’t heard the term “tensegrity” in a good while. Shades of Carlos Castaneda, old boy.

    7. This a formula that has worked well since the seventies. I personally have been happy with this combination for 28 years but I should point out it is not an automatic formula. I never liked the AR 3a with the music I listen to. But the Ar 3a is iconic with jazz and smaller classical arrangements.

      Thanks for the description and reasoning behind why smaller speakers sound a little off to me. It’s the music I listen to and the things I think are most important.

    8. Steve:
      You nailed it. Much depends on our majority musical diet. For example, someone who listens predominantly to string quartets, soprano lieder, violin sonatas and such might require maximal in-sight in the presence region to find a big mid/woofer reaching up into lower tweeter turf too opaque or thick. Conversely, someone who does lots of classic Rock and modern music could really surf on the wallop, crunch and shove of a bigger driver and perhaps even appreciate that the presence region isn’t ultimately lit up to be kinder to poor recordings.

      Pretending that one speaker type does everything equally well (from Hip Hop to large symphonic, from coloratura soprano to distorted e-guitar, synths, amplified bass vs. acoustic bass etc.) is, I think, unrealistic. Each tech (planarmagnetic, electrostatic, dynamic, AMT) has its own strengths. Then add cabinet construction, crossover design and dispersion pattern (omni, di/bipole, monopole, mixed) and the range of flavours and presentational styles really expands to, in each case, play more to certain things than others.

      Then there’s the question of whether the majority of one’s fave recordings are audiophile purist jobs, mass-market dreck, somewhere in the middle or what. That alone should have a big say on what type speaker is best suited to make that music sound most compelling….

      • somebody opened the big can of worms.what dealers don’t want you to know is that not every speaker is good for all kinds of music.for the life of me i can’t understand why house fans need anything more expensive than cerwin vega.on the oher hand the record attests that i enjoy listening to monteverdi through klipsch heresys.
        michele from rome,again

      • It’s the process I described in KIH #35 that gets you in the right place. A Harpist during the same period followed the same process with the additional help of her harp being in in the listening room. She was happy for a longtime with completely different equipment because the equipment was suited to her music. We would play each other’s music and laugh at how it sounded on the wrong equipment.

        For me the recording quality is a limiting factor in speaker selection. I currently own one audiophile recording unopened that I’m going to give to Lincoln Cheng. Most of rest of my music is from mainstream record companies and requires speakers to mask recording issues. The balance of my music is self-recorded or made in small quantities and the quality varies a lot. There are exceptions of course I have some very good recordings but Gordon Holt was generally right when he said the better the recording the worse the performance.

    9. Great insight, as usual. I wish I had a bigger space to work with but as Michele pointed out, you need a big space for a big speaker. Been there as well, done with it as well. My Clearwave Duet 6 monitors come across similar to how you describe the Apticas but I do wish for some more heightening in the upper bass/lower kids to complete the picture.

      What I may try next is the Spatial Audio line (open baffle, 12″ woofer, concentric horn loaded tweeter in another 12″ driver) to see if it can impart that missing element. Having tried sealed towers (with 2 10″ woofers) which overloaded my humble space, maybe the open baffle concept can correct most of the errors of the towers and still satisfy.

      • hello tim,may i suggest listening to a good british made tannoy(slated for extinction ,alas):the sterling he,for instance boasts an impressive p/q ratio.

    10. Tim:
      Based on my still limited experience with open baffles, their bass doesn’t go as low as woofer diameter would suggest if one comes from ported boxes. That’s due to front/back in/out-of-phase cancellation.
      It means lateral nulls so less bass reflections from the sidewalls, hence easier in-room behaviour. But with the Spatials, you still get the big midrange aspect so at least on paper, this really could give you what you’re looking for without overloading your space. If you do go that route, perhaps remember to post a follow-up here?

      • As someone who has spent significant time with the Spatial Hologram M4, I never noted a bass shortfall – just the right amount of low frequency wallop for my tastes and (then) room. Audiophile buddies dropping by enthused even more than I. Likely that I’ll be getting a pair of the M3 when time allows. I recall that Clayton Shaw has implemented the Hologram Series’ drivers in such a way that bass output isn’t overly compromised.

      • Srajan,
        Will do. I’m certain your right as I heard the Spatials at the Newport Audio Show in a room not much bigger than my living room and just standing in the doorway convinced me that this was something special. No boom or bloat, just wonderful, enveloping presence with an ease to it that drew me in.
        It’s going to be awhile before I get there so this may have to be on another post or you just may get there first with an upcoming review in your queue. 🙂

    11. My comment about bass was merely *relative* to cone surface. An open-baffle 12-inch driver not back-loaded by trapped air and isolated from its own rear wave behaves differently than a ported/sealed 12-inch driver including extension. It’s why you see dual 12″ or 15″ woofers on open baffles by Jamo or Kyron Audio whilst Martin Gateley’s soundkaos goes with an 18-incher. You could get the same extension from a ported box with an 8/10-incher -:)

      So a 12″ open-baffle woofer or even two of them wouldn’t overload a smaller space whilst the same artillery in a conventional speaker most likely would. That’s what I meant to say…

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