Highly Sensitive Speakers?

I suppose it’s only to be expected. Still, its a bit disconcerting. Another system? Already?

I mean, WTF, seriously? The last bits of my current system aren’t even in and yet, here I am, actively hoovering the Internets for info about another approach to high end audio: high sensitivity speakers. Egads.

My current system, built around a Plinius amp and pre, driving Magnepan speakers, is absolutely incredible. Best I’ve heard here at Chez Moi — and by a country mile. My new Berkeley Audio Series 2 Alpha DAC with it’s attendant Alpha USB is, likewise, the best digital front end I’ve ever heard here — and may well be the best I’ve ever heard anywhere. With that said, I fully expect that my digital front end will be utterly destroyed by the analog rig that is supposed to be showing up this week from Deutschland.

So, what gives?

Nothing, really. I really love that system. Love love love it, in fact. But you know what would be fun? A highly sensitive speaker with a low-output SET amp to drive them.

I know! I know. Believe me, I know — I have problems.

My Magnepan 3.7, love them though I do, can hardly be called anything other than low-sensitivity. I think Magnepan rates them at 86dB (@ 1w/m), but this might be a stretch. All I know is that no one runs these speakers without a giant amplifier — and I don’t either. My Plinius SA-Reference cranks out 450wpc into 4ohms, and the speakers pack a hefty whomp! because of it. But is that all there is, power?

Tackling that question requires a sidebar.

Now, everyone knows that to get another 3dB out of your speakers requires a doubling of power going in. To go from 86dB @ 1w, if we added a watt — using a 2w amp instead of a 1w amp — we’d have a max volume of 89dB (at one meter). Adding 3dB requires another doubling — so, now we need a 4w amp. 8w gets us another 3dB for a total of an extra 9dB over the baseline, or 95dB of speaker output. Keep doubling, and we’ll quickly get to 512w, which nets us a total of 27dB over baseline. 512w is a bit more than my Plinius amp can do (without clipping), but it’s close enough — so, say we shave 1dB off that number and call it even 26dB. With that extra 26dB that amplification provides, my Maggies can swing about 112dB of total output, max.

Is that good? Well, as the Bob Katz discussion tells us, we need no more than 20dB of headroom above (and below) a given average listening volume in order to allow for the full dynamic swings we might possibly find in our recorded music. So, assuming that the max average volume I play my music at is 92dB, I’m good to go. And luckily, 92dB is on the loud side of my comfortable listening window.

Of course, this isn’t to say that my speakers can’t play loud. They most certainly can — but the louder I turn them up, the less headroom I have available. As long as the music is compressed, the amps and speakers won’t clip, and as Bob tells us, most music is heavily compressed, so I think a good rule of thumb would be to shoot for at least 12dB of headroom in your system. That should make you right with the vast majority of music out there today.

But when it comes to headroom, the more the merrier. The more headroom, the more the speaker/amp combo can operate in their comfort zones, which ought to result in better quality sound. Interestingly, if you have a speaker that actually starts a bit higher on the sensitivity scale than my Maggies (which isn’t hard), you can get gobs and gobs of headroom pretty quick and pretty much painlessly.

Looking at a horn speaker like a Nano from Avant Garde, we’re looking at 110dB of efficiency right off the bat. Add a 2 watt amp and you have the same output as my Maggie+Plinius setup — going all out! Add an 8wpc amplifier to that horn and you have system that can push nearly 120dB. Yikes! Anyway, that’s dynamic headroom. The more of it, the better.

The last bit here is a tube-thing. Now, I’m not really a fan of tubes for the obvious reason — they’re either breaking in or breaking down. Owning a piece of tube audiophile gear is a commitment — and that’s before you go hog wild with swapping out (“rolling”) the tubes for ones that sound (usually, only slightly) different. And, of course, you need back up tubes. And with many tube amps, you will need to manually bias the circuit yourself, which means delays during warm up, continually fiddling with adjustments … and then there’s the whole voltmeter thing. Audiophile … turned electrician? It’s all kind of annoying and quite frankly gets in the way of the music. That’s why I hate tubes and after a harrowing experience with Joule-Electra OTL amps, have completely banished them from my big rig.


But there’s just something about the sound that you get with tubes that’s really and truly different than what you get without them. It’s not better — and in most measurable ways, quite the opposite. But as my experience having both the tubed Lampizator DAC and the non-tubed Playback Designs MPS-5 here taught me quite painfully is that sometimes great specs and measurements and control … well, it just isn’t all that fun to listen to.

So, where does that leave me? Well, color me curious about a more “fun” system. With a highly sensitive speaker, I can get away with getting a flea-powered amp to drive them. Why a flea-powered amp? Well, why the hell not? Honestly, there’s something about a single-ended triode system that I find magnetic. Perhaps it’s the insane immediacy of the mid range. Perhaps it’s those crystalline highs. I’m pretty sure it’s not the lumpy, bloated or slow bass, but then I guess you can’t have everything. I kinda want a 45-based amp. Or a 2a3. Or even a 300b. Heh. Ahem.

But to be able to get away with an amp less than 16wpc, I will absolutely need to make that extra volume up with the speaker. So, I’ll be looking at something with a sensitivity rating of around 100dB — much less, and I think I’ll be starving the speakers or continuously punishing the amp. Not that an 3.5 wpc amp can’t drive a 88dB speaker (I have a Miniwatt N3 feeding some 88dB Audioengine P4 speakers here on my desk, after all) — the speakers just won’t sound as good as a 60wpc amp will (bass will be weak, highs may seem blunted — and there’s just no cranking the sound to 11).

The question I’m wrestling with is “how low do I go?”.

In the wide-bander (single-driver) category, I’ll admit that I’ve never been a huge fan of Fostex-based speakers or of Lowther-based designs. Now, don’t get uppity there, settle down! — yes, both of those august drivers can be made to sound excellent, sure. It’s just that those are rare [ducking]. A slightly different approach would be to use an Eminence driver (or some other, similar, widebander). Going that route, I can get a 98dB Tekton Lore for about $1000 new. Similarly, Zu Audio makes a the 101dB Soul Superfly, for $3k that has gotten some very public raves. The Superfly is a 16ohm speaker, though, so finding a good SET integrated to drive it might be a bit of a challenge as most (‘most’, when qualified with ‘affordable’) seem to only come with 4 and/or 8-ohm taps. No, this mismatch is not fatal, it’s just not perfect. Doubling the speaker impedance (going from 4 to 8, or from 8 to 16) halves the power delivery of the amps attached — never a good idea — and this might rule out some of the more entertaining low-power triodes.

Another approach would be something like an integrated bass boost. Vaughn Loudspeakers makes a series of speakers with reasonably high sensitivities (93-99dB) and adds just that, a powered bass subsystem, which helpfully eliminates many of the objections that people have with SETs (that is, it has weak bass). They’re priced from $6500 to $9k.

And (yes,) there are a ton of other options besides. Ocellia, Tonian, and a host of others have offerings that can and do fall in the intersection of “reasonably priced” and “high sensitivity”. There’s too many to choose from, actually, though, affordably-priced horn speakers are difficult to find or just wildly colored (“cupped-hands”, “horn-honk”, &c), which rules out the favorite recommendation of the Internets, a classic Klipsch. Volti might work, but they’re not cheap and ….

Sheesh. This is hard.

More soon.

About Scot Hull 1039 Articles
Scot started all this back in 2009. He is currently the Publisher here at PTA, the Publisher at The Occasional Magazine, and the Executive Producer at The Occasional Podcast. There are way too many words about him over on the Contributors page.


  1. Malachi Kenney said it best with the — what was I supposed to be doing? and “loosing track of time” comments. THAT’S what I’m looking for in a system. I want to get curious about an old album about 6:25 and then say “WTF!” it’s 12:20 (am) and I work in the the morning.”

    That’s how it was back in the day listening with the Koss Pro4AA head phones. I want that in a system. To get lost.

    Can’t spend a life’s fortune either. There is other life going on. The Tektons seem to push the thought and I’m also looking at the RSL monitors. No comparison at all–I know.

    But I’ll sure read anyone’s thoughts.


  2. I stumbled on this blog in my search for a good amp for my Zu speakers and wanted to share my experience. I don’t have deep pockets, but I got lucky and bought a review pair of Zu Soul Superflys after the T.H.E. show in Newport Beach, CA. I was speaking with Shawn Casey at the show and told him that it had always been a dream to own a pair of Zu’s because of the “fun” factor. He surprised me by offering me a pair he just happened to have sitting in the hallway. I could pick them up after the show. I will say that Shawn is a real stand-up guy – he doesn’t buy into the hi fi hype and really wants to make his customers happy – I didn’t get that kind of down-to-earth feeling from many other vendors at the show.

    Now I’m a Maggie guy myself. I have a MG12/MC1/MMGW/MMGC 7.1 home theater setup that I power with class-D amps. This is not the last word in sound quality, but with Maggies, what else is there for someone on a budget? Anyhow, when I got the Zu’s home, I really didn’t have anything to power them with. I tried them in the HT room with my class-D amps, but that was an excruciating experience I would not ever repeat. So what to do?

    I had some decent gear in storage, namely an Odyssey pre and a NuForce-upgraded Oppo player, but no power amp. The only thing I had was a bottom-of-the-line, $80, Qinpu Q-2 hybrid headphone amp that has a pair of small speaker posts for powering cheap desktop/computer speakers. It puts out a measly 2.5W into 8 ohms, with a single diminutive 6N3 tube straddling the inputs – certainly not a good match for a $3200 16 ohm speaker… Mathematically, I’d be getting 1.25W into each speaker. Ouch!

    Well, surprisingly, it didn’t sound awful. Now this isn’t high quality sound, or anything. The frequency was limited both at the top and the bottom, but the imaging, the tube sound, and the great midrange the Zu’s are known for was all there. Granted, this is only temporary until I can get a suitable amp. I’m currently using solid state and still looking for a good tube amp, but it certainly makes for a fun conversation starter during parties. Anyhow, if you don’t want to spend a fortune right away, at $80 for the Q2, it’s about the most inexpensive way to start having some “fun” with those Soul Superflys without too much guilt.

  3. I’ve split the difference between “highly sensitive” and “pretty sensitive” by going with Tannoys in my main rig. Yes, they’re huge, ugly, and imperfect, but they tend to work well for me. They are not sensitive *enough* for the real flea watt amps, but my miniwatt does a fairly credible job of driving them well enough to fill a 15’x26′ room. In fact, the miniwatt (until it keels over) has done the best job I’ve heard next to a set of Snappers.

    If you don’t need real bass, but you do need that “what the hell was I supposed to be doing?” feeling, the best experience I’ve had has been with Lamhorn loaded with AER drivers. If you can find a way to audition them, well, that’s something you should do.

    My experiences with the Zu stuff have been very mixed. They’re usually as dynamic as all get out, but I never seem to lose track of time when I hear them. Since I’ve only heard them under show conditions or equally strange circumstances, I’ve reserved judgment. That Superfly *is* tempting.

    If you’re looking for amps with a 16-ohm tap just to mate with the Zu’s, you might want to look into some other options before you drop the three grand. Drag your miniwatt to the auditions.

    • Zu is definitely more in the “fun” category than in the “analysis” category. I’ve actually never heard a Lamhorn, but those single driver speakers make me nervous. Dunno why, but I might have to get over it. LOL.

      But you know what I want? I want something I can run a 2a3 with and not feel like I was killing either. That’d be fun. 102dB on a Lamhorn would do that quite nicely. Shame it’s $10k. 😉

  4. Not hard at all. The Tektons are getting rave reviews from owners and even now the pros.

    Opt for a Pendragon, Uruz or Katz Meow and you wont have to shell out more than $3K at the max.
    $5K gets you the OB Sigma!

3 Trackbacks / Pingbacks

  1. Now Drinking Heavily: Previewing the Red Wine Audio Signature 15 | Confessions Of A Part-Time Audiophile
  2. SET Blues | Confessions of a Part-Time Audiophile
  3. System Two: BorderPatrol Arrives | Confessions of a Part-Time Audiophile

Comments are closed.