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KIH #5: Power Over Sensibility

POS? To play with our ongoing 3-letter thematic, let this one momentarily mean power over sensibility to set the scene for today’s movie concept of Jane Austin meets Wladimir Klitschko. How much power must our amplifiers really deliver? Is the SET crowd off their collective rocker claiming a fistful of watts sufficient? How about shoppers of Musical Fidelity’s Tri-Vista kW monos of yore? According to Michael Fremer’s Stereophile review those were “rated at 1000W into 8 ohms, 1800 into 4 ohms and a speaker-boggling 3000W into 2 ohms. Instantaneous peak output is claimed to be a frightening 5000W, with a peak current potential of ±200 amps and output voltage of around 130 amps.” Did those amps embody the real truth to render their owners enlightened and in the full know?

Michael Fremer’s earlier review of MuFi’s 550K Supercharger monos explained that “how much power you need depends on how much realism you seek. If you want only background music or a pleasant but subdued version of the real thing, perhaps you don’t need that much power. However if you want a high degree of fidelity to the original event and the ability to reproduce the full dynamic majesty of a symphony orchestra, the concert SPLs of your favorite rock band or even the visceral drive of as expressive a solo pianist as Keith Jarrett, you may need more power than you think even in a room of small to medium size…The transient peaks in live music can reach high sound pressure levels. For example, John Atkinson sitting in a mid-hall seat in London’s Royal Festival Hal measured timpani thwacks at +106dB peak back in the early 1980s. Reproducing those peaks without clipping and thus generating ‘slam factor’ is what can make the difference between a system sounding ‘blah’ or ‘wow’, between ‘canned’ or ‘real’.”

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Let’s disregard the stretch of equating playback of full symphonic forces in your living room with realism and doing it at concert-hall SPL desirable. Let’s first get a handle on actual figures. Owners of iDevices have a number of SPL meter apps at their disposal. I use Mint Muse’s Sound Level Meter Pro. It offers 5 different weighting schemes. I’m no android but such devices will have similar apps. There are always the Radio Shack types too.

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On Kevin Seddiki & Bijan Chemirani’s Imaginarium album of intermingling guitar and zarb with some hand percussion at levels I’d run whilst writing a feature like this, I hit a ±50dB average with 58dB peaks. For serious sessions of the same purely acoustical very simple material in the hot seat I’d move the average up by about 6dB. If I wait long enough I’ll hit peaks of 70dB. With my 92.5dB speakers a good 3 meters from the seat and sound losing 6dB with each doubling of distance, let’s add 8dB to my peak figure. That still puts us about 15dB below the rating of my speakers to net <0.1 watts of listening power during peaks. Does that make me a bad audiophile and sissy listener? Nothing like a reality check to squash one’s macho notions of self worth.

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From our trusty decibel chart we know that 20dB equal a 1:100 power ratio. Conveniently 20dB of dynamic range as measured by PureMusic’s peak-hold meter right inside my iMac’s playback software turns out to be high dynamic range for 95% of all my music. Most tunes show rather less. If I were to listen loud enough to make my speaker rating of 1 watt @ 1 meter = 92.5dB the very quietest level and thus 112.5dB the max peak figure, I’d need a 100-watt amplifier. But do I ever listen that loud?

Never! A constant 70dB level is about as loud as it gets before room pressurization turns ridiculous. Let’s build in an allowance of 20dB peaks above such an average rather than minimum figure to call it properly manly. On my soundkaos Wave 40 speakers I then really don’t ever move out of the 1st-watt gear. Pathetic, huh? Humiliating.

But it does mean that my posh $10.000/pr FirstWatt SIT-1 monos of 10/8w into 8/4Ω are perfectly suitable for my needs. They might well be underpowered for yours though. Take the Finnish Prime Loudspeakers Tone monitor I expected for delivery within a week of penning this. It would arrive with an 81dB sensitivity rating in tow. For proper headroom and the same 90dB peak figures at the same 3-meter ear distance, I now would want a 100-watt amplifier. Pursuing such painfully inefficient boxes comes at a price.

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With that covered—you’ll do your own SPL metering to verify your situation—let’s lasso in a related argument I’m fond of. Low-power amplifiers can exploit single-ended operation and do so without paralleled output devices. With always-on outputs as is the case for class A operation there’s no zero-crossing distortion. One reason why low-power amps can sound so good is circuit simplicity. Fewer gain stages mean lower high-order distortion. Lower intrinsic distortion allows for zero or very low feedback. Non-paralleled output devices don’t muddy the picture with uneven behaviour between devices. That’s not trash-talking muscle amps. Excellent ones exist. It would simply seem to get disproportionately more expensive to do them right. The smart money might prefer not to go there.

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The mantra of easy does it describes a playing field where the opposing players are team SPL and team speaker sensitivity. Core members of team SPL are room size and listening distance. The other team includes players like speaker impedance and amplifier ratings into lower impedances for the full picture. One you know your actual listening SPL– not imaginary figures, not hyped-up values proposed by pushers of muscle amps but actual in-seat measurements—you can quite easily figure out what your power needs are. If your room is of average size and you don’t listen unnaturally loud, chances are quite good that you’ll get by with a lot less than assumed. And that could open doors to amplifiers you never considered before. Having more rather than less options is a good thing…


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Comments
  1. Frederick Crane

    Hi Srajan,

    Great points all. Volume, though measurable, is still only one factor in what’s ‘real’ to any given person. If sounding real hurts your ears, that’s something to consider. I know a few drummers that wish they hadn’t heard so much real-ness. Mixed into the discussion of power, I always felt as though the poor little damping factor gets left out-something you always talk about in your reviews…In other words, we’re dealing with voltage, current, and resistance. So it’s not just how many watts, (watts are voltage multiplied by current) but what your watts are comprised of.(10 amps and 10 volts should be 100 watts, but so are 20 amps and 5 volts) There’s a pretty good and easily understood explanation here:

    http://science.howstuffworks.com/environmental/energy/question501.htm

    I suppose there’s room for everyone.
    EMM Labs just came out with 1500 watt monoblocks, and Emia has a headphone amp (The Miniformer) that matches impedance to the driver from the source…so there is plenty of room, from zero watts to billions and billions.

  2. Srajan Ebaen
    Srajan Ebaen

    Clearly there’s room for it all. My point was simply that end users ought to know their actual needs so they can make more informed decisions. A free or cheap SPL app on a smartphone or iDevice is plenty accurate for these purposes and lays to rest once and for all what volumes one listens to. Perhaps some folks really do need 1’000 watts. My bet is though, most people think they need or are using far more when in reality they’re not. And that would be good to know just to keep it honest -:)

    • Frederick Crane

      True dat : )

  3. John H. Darko
    John H. Darko

    @Fred – Your point re. damping factor is a salient one. Muscle amps do more than provide greater potential for higher SPLs. They often bring greater bass driver control to the party – essential if you’re afraid of loosey-goosey bass.

    • RCD

      Let us also remember that some speakers are designed specifically for amplifiers with relatively high output impedance. I am listening to Apparat’s Duplex through a pair as I type. The “control” of muscle amps can be problematic for these types of speakers, contributing to a lean, stilted and almost overtly dynamic presentation of music… often exacerbating the inherent sound of said amplifier.

  4. Srajan Ebaen
    Srajan Ebaen

    But damping factor aka low output impedance isn’t exclusive to muscle amps, John -:)

    The way damping factor is promoted in figures is very misleading as it doesn’t account for the resistance of the connections, speaker cable, crossover parts and voice-coil inductance. By the time you add those, the 4-digit damping factor values that’s actually seen by the driver shrink dramatically. Which doesn’t invalidate low output impedance, just that the *effective* damping factor figure your woofers actually see is a lot lower than claimed.

    Also, not all speakers respond to ultra-low output impedance the same. Very light-coned widebanders with low moving mass and very powerful motor systems have good self damping and can suffer very premature bass roll-off with too high of a damping factor (overdamped). That’s why such speakers can sound better with valve amps (and make lower bass) which have a far higher output impedance = low damping factor.

    One must also consider how amplifiers arrive at such low output impedances. Very often it involves copious amounts of negative feedback which might have its own influence on the sound.

    In the end my conclusion is simple. Get easy-drive speakers so you can buy a simple good-sounding amp that needn’t be expensive nor bench-press unreasonable loads. If you want really low bass, get a powered subwoofer or two where cheap class D amp modules will do a most excellent job.

    One last point on Fred’s post. Realism. Musicians adapt to their surroundings. If I had a wind quintet playing in my digs, they’d adjust their loudness to my space to not overload it. In my friend’s far bigger room they’d play louder. And they wouldn’t perform in a symphony hall because a wind quintet can’t play loud enough to fill it properly – unless they had some sound reinforcement. With a recording of course you can play as loud as you want. But that doesn’t necessarily equate realism. By the time we get to arena-style rock concerts, attempting such SPL realism in an average living room has obvious consequences.

    I think the notion of live concert, home-based playback and *realism* is skewed. I’d personally not invoke realism and deal with each experience on its own merit. But that’s just me -:)

  5. D.Ryan

    On audiophiliacs: “They spend all that money trying to get the exact effect of an orchestra actually playing in their sitting room. Personally I can’t think of anything I should hate more than to have an orchestra actually playing in my sitting room!”

    Michael Flanders (of Flanders & Swann) intro to “A Song of Reproduction” (“At the Drop of a Hat” Angel 65042)

    • Dave the OzPom from Hell

      An orchestra in my living room?
      I couldn’t even cope with the beer and toilet paper.

  6. Srajan Ebaen
    Srajan Ebaen

    Thanks, D.Ryan. This is one of my pet peeves – people who use orchestral music to determine playback realism. I’ve played in a symphony orchestra. The sheer number of players involved wouldn’t even fit into the average mansion. I’ve measured SPL during symphonic or operatic performances which didn’t exceed 90dB peaks in my (definitely *not* front-row) seats. When I read people talking of 110dB in-room peaks playing Bruckner, Mahler and Strauss and calling it realistic… it just doesn’t add up on so many levels. That doesn’t mean they shouldn’t do it or not enjoy it. This is a hobby. Anything goes. My problem is solely with the *realistic* tag -:)

  7. D.Ryan

    Srajan, exactly: I have no problem with someone who wants to blast Wagner at AC/DC levels since what’s wrong with that? Not my style, but who am I to say you’re not enjoying yourself? What I don’t like is being told that this or that recording or piece of equipment fails some kind of test because it can’t follow suit. The music I like sounds best on low-power amps and full-range drivers, but I think all music sounds best on such systems, especially since any tradeoffs at the extremes are more than offset by the lack of crossovers and delicate handling of the signal. But not everyone shares my tastes, to put it mildly!

    A system that can place a convincing (even exaggerated) symphony orchestra in your listening room is an awesome possession, no doubt. But unless you actually enjoy a steady diet of musical sturm und drang, how it sounds with your actual music should be the first consideration. Many an audiophile has laid out serious cash, only to find out that the speakers that sounded so awesome playing the famous demo disk at the dealer’s (or did you buy them online and unheard, based on — gulp — reputation??) give him a headache after ten minutes. And he paid HOW much?

    But that’s the thing: No one who has laid out $100,000 or more for a stereo (that’s what it is, isn’t it?) is ever going to hear less than perfection, is he? Whatever’s coming out of the speakers.

    Chances are he’s getting pretty good sound since most gear is pretty good these days, especially at the high end. It’s hard to go disastrously wrong.

    But hi-fi (and especially analog) is one of those hobbies where real improvements are possible: We’ve all heard them, and the big ones make you grin involuntarily. Achieving that next level is what drives the gearhead in us all, sure. After several decades of listening, I have decent grasp of hifi. Obviously, I like audio equipment. A lot. But to what end? In my daily life, it’s playing music I enjoy.

    I should have let Flanders & Swann say it more briefly:
    With a tone control and a single touch
    I can make Caruso sound like Hutch
    Then I never did care for music much
    It’s the high fidelity!

  8. Srajan Ebaen
    Srajan Ebaen

    Well put. I can’t disagree with a thing you said. Here are a few more of them things. Unplugged vs. amplified bass. Classical and purely acoustical music relies on upright bass and bass drums which in a live venue sound big, round, redolent and a bit bloomy. Electric/synth bass on the other hand tends to be far more damped, hard, incisive and sharp. Voice a system to sound great with techno and Rock and there’s a good chance it won’t sound quite right on purely unplugged stuff. And vice versa.

    To me then it’s a bit theoretical or idealized to claim that a good system will play all music equally well.

    Something similar is true for quiet/loud. High-eff minimalist systems tend to excel at low levels but unless they’re multi-driver horns and not Lowther-type widebanders, they get flustered at high levels. Inefficient complex multi-ways with big woofers can play very loud but tend to move up the minimum level at which they ‘kick in’.

    Omni and di/bipole speakers energize a room differently and as a result produce tone (direct + reflected sound) closer to live than ‘direct’ radiators but also tend to image less specific and sorted.

    And so forth. Depending on the type of music we listen to most, our levels and our sonic hot buttons (soundstaging, dynamics, timing, tone, energetic or laid back etc.), we assemble a system to cater to all of it. But a system that does AC/DC at very high levels and sound good doing it nearly predictably won’t be as convincing with a string quartet.

    We’re the architects of our systems and most of us don’t look for ‘truth’ or ‘fidelity’ or some idealized ‘right’ but for very personal mental/emotional satisfaction. And many of us insist that we also like what the stuff looks like and perhaps some of our purchases even cater to certain ideologies or beliefs we fancy over others.

    To account for all of it, have a clear-cut personal goal and opinion and work against that backdrop doing reviews is, I think, the major learning curve all of us commenting on hifi undergo, be it as formal reviewers or enthusiast bloggers and posters.

  9. D.Ryan

    “And many of us insist that we also like what the stuff looks like and perhaps some of our purchases even cater to certain ideologies or beliefs we fancy over others.”

    -(laughs) what a nice way to put it! Yes, looks (and buttons) matter (just ask your wife!) and hifi is definitely a hobby, though I’m not the only one who thinks music is more like daily exercise than, say, collecting figurines, and hifi more like HVAC than an overgrown (and idiotically expensive) boombox.

    Music comes first, but yes I’m a gear geek too. Am I troubled by $100,000 pricetags for what amounts to OTT luxury goods (even toys)? Well, sure, but super-high-end audio is a proving ground of sorts in which few units are ever sold. Is it a good thing that the music lover and/or audiophile can keep ascending a ladder of genuine (if ever-diminishing) sonic ROI? Absolutely! There must always be benchmarks, a cutting edge, technological leaps, etc. Some sonic differences are obvious, whether it’s lute music or AC/DC!

    To come full circle, I agree it’s frustrating to have a standard of “realism” that few can attain to (and, as you note, isn’t even realistic) and is so unmusical, despite ever-climbing cost and specs; not because it leads to unattainable (to me) gear but because it skews the market (from R&D to reviews) away from methods and technologies that could provide better, cheaper, and even “greener” sound.

    • John H. Darko
      John H. Darko

      I kinda agree. I rarely call being into hifi ‘a hobby’. Similarly, I don’t see cooking as a hobby. For me, hifi gear anchors aural and emotional nourishment just as ovens and organic ingredients assist with making healthier, more nourishing food.