Inspiring confidence

April 4, 2021
 by Paul McGowan

I don’t believe it comes as a surprise that at my core I am an engineering nerd. My internal fires light up when we start talking engineering-speak.

One of the real downsides to CoViD has been our separation. Before the pandemic, our engineering group was together and right outside my office door. When an interesting discussion would start my ears perked up and I joined into the fray—the classic water cooler conversation. That doesn’t happen much anymore.

So I was heartened when on our PS Audio forums, I read a long technical ramble from our speaker guru, Chris Brunhaver. Chris knows more about the technical aspects of loudspeakers than any human I have ever over the last 50 years. When we get talking tech, his depth of knowledge is so great it’s actually sport to egg him on into a  drill-down just to see how deep he can go.

If you are like me and enjoy getting deep into the technical nuts and bolts, head here and click on this link. https://forum.psaudio.com/t/high-efficiency-speakers-low-efficiency-speakers/22908

The whole conversation started in response to one of Steve Guttenberg’s questions about loudspeaker efficiency with one of the Zu Audio fellows.

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29 comments on “Inspiring confidence”

  1. So, you think you know a little something about The Allman Brothers and Rolling Stones!

    Well, this cat is a national treasure. With recent accolades for Nicky Hopkins and Nils Lofgren around these here parts i deemed it appropriate to share his story of music, friendship, love, forestry, environmentalism and the impact of global warming.

    Chuck Leavell: The Tree Man – now playing on Amazon Prime Video

    https://www.amazon.com/Chuck-Leavell-Tree-Keith-Richards/dp/B08P47JX6C

    Never an Amazon anything, i signed up for a free 30 day trial to view this documentary and Amazon was kind enough to gift a $6 Prime Video coupon to view. Then, upon cancellation provided an extra 30 days of basic viewing.

    Now thinking i might be warming up to the Massive Disruptive Amazon Universe. (Mda -u) Nah, not really. Am i the only one who thinks the Amazon logo on the side of their semi’s looks like a Nike inspired banana with a penis head on top? (insert smiley face)

    While you’re there, check out Gordon Lightfoot: If You Could Read My Mind and episode three of “A Long Strange Trip” to recall the days of American/Canadian & European Adventure.

    It’s all Good stuff!

    1. dr.goodears,
      Now that you’ve planted that idea in my head I guess it does, never to be unseen!
      They’ve recently changed the app logo because people complained the previous one, with the blue serrated panel, made it resemble Adolf Hitler.
      The imagination CAN BE a wonderful thing.

      1. Thank goodness that all-time / top-of-the-line wackadoodle Adolf didn’t have access to nuclear weapons. Otherwise, we might not be here.

        As far as Chuck Leavell is concerned, the only folks alive today who probably wouldn’t have a need for his talent are Paul McCartney, Stevie Wonder, Elton John, Bruce Hornsby, Alicia Keys and Billy Joel.

        Ironically when Chuck played with the Allman Brothers in the 70s (brothers and sisters & laid back) they featured two keyboard players along with two drummers.

  2. I just read his post and two things come to mind. Try selling a speaker with 15” drivers. They are just too big. Secondly, no mention of cone material. For most of the speakers I’ve used, the performance characteristics of the cone material is the number 1 critical ingredient.

    1. I had a look at the video afterwards and it was spectacularly superficial in relation both to loudspeakers and amplifiers.

      Speaker design is of more interest to me than any aspect of audio as: speakers are the most critical component because they produce the sound we hear, they have to look good to be domestically acceptable, they must take into account the cost of amplifiers needed to drive them, they must measure as accurate but also be subjectively pleasing to listen to and the options are almost endless.

      The proof of the pudding is in the eating and until there are successful products in the consumer and professional markets, preferably both, there is not a lot to talk about.

      The irony is that the two designers I do listen to are Peter Thomas (PMC) and Alan Shaw (Harbeth), who have both had continued success in professional and consumer markets for 30+ years each, and I’ve used products by both of the. However, many of Peter Thomas’ speakers employ a transmission line, a design which Alan Shaw considers fundamentally flawed. Trying to have a discussion with Alan Shaw about transmission lines is a bit like discussing the merits of mains conditioners with Paul.

      Hopefully one of Chris Brunhaver’s designs will finally be available later this year and the way things are going in the UK we may have an audio show around September/October. Vaccine passports anyone?

      1. Once you’ve had the Harbeth Loudspeaker experience, with a high quality source, the Law of diminishing returns for loudspeakers starts it’s incredibly steep exponential rise.
        The pressure is really on for CB & PSA to produce a truly magnificent loudspeaker.

        1. I imagine those Harbeths everyone speaks highly of sound amazing. They would have to in order to have any chance in hell of pushing my NHT 2.9’s into the closet. At the moment the only speakers I would consider replacing my NHT 2.9’s with are the NHT 3.3’s. Both sleepers and giant killers. But two speaker systems I do want to hear are the Harbeths and the upper priced Tekton’s. Still there’s little hope of anything replacing my 2.9. That’s how good they are. And they are sealed versus ported and for the most serious listening I prefer a sealed system. Just a preference of mine. I have heard and own some great ported speakers.

    2. No reason not to trust Chris for me (although my speaker design knowledge is far less than suitable to judge this 😉 )

      But the fact alone that his upcoming design is way off the time schedule and detail of the marketing approach, as well as the fact he thinks a lot about customized detail solutions makes it (and him) trustworthy.

      1. Chris explains and articulates questions about speakers with a great deal of expertise. I doubt there is anything he doesn’t know or understand about speaker design or how materials used effect the sound one way or another. Hes knows all about successful vintage speaker designs as well as newer designs. He understands all of the pros and cons and technical mumbo jumbo. What more can you ask for?

    3. Dear Bernd,

      I have been studying loudspeaker design starting with J. Robert Ashley’s Loudspeaker course in 1974 as part of my EE curriculum. I started building seriously in 1997, and have discussed speaker design issues with my favorite designers Siegfried Linkwitz, Charlie Hansen, Richard Modafferi, Richard Sequerra, John Dunlavy, and Alex Khenkhin who designed the Earthworks speakers with David Blackmer.

      I invested in Liberty Audiosuite and Lsp CAD 20 years ago, and built my own custom speaker test gear because MLS wasn’t good enough to measure all required parameters. The culmination of my research was the first speakers that sound like traditional orchestral instruments to the real golden ears, conservatory graduates, in side by side comparison with Guarneris and a Steinway Model D.

      From this perspective, I agree 100.00% with Chris’s description of the trade-offs. Although far from complete, it was an excellent extemporaneous overview.

      Let me put forward a theory of why you disagree:

      I have also researched human hearing extensively, especially from BEFORE audio because the results were different with acoustically trained ears; and MRI studies measuring musician’s hearing, instead of the hearing of audio consumers, which is always conditioned to universal audio deficiencies,if not bad audio design (which comes in some very expensive gear!)

      Speakers with ragged off-axis response enhance the delusion of imaging from 2 channel audio for “audiophiles”, those with the most ear training to their audio system. Therefore what Chris and I hear as a deficiency of 2 way speakers, you may well hear as a positive because of the perceived “soundstaging”.

      My theories explain the differences between audiophiles’ and musicians’ reactions to different aural stimuli, and also the arguments between audiophiles. I may be wrong, but it seems I am the only one who can match the data so far, including the objective brain scans.

      1. Dear Acuvox,
        I am not a HiFi professional but have always had a good stereo system since my early youth.
        As the eldest child from a working class family with four other siblings, I had to finance my university studies myself. I did that by repairing and selling equipment in a hi-fi and TV shop. In the shop there were products from the most well-known European, Japanese and American manufacturers at the time. I stayed connected to the hi-fi sector after my studies because music was and is an essential part of my life.
        Even taking into account all possible loudspeaker parameters, I have found that the listening room plays a much bigger role than the loudspeaker itself. Therefore, with one exception, there was never “the” loudspeaker for me, because the same loudspeaker in different surroundings leads to different results in music reproduction.
        The “one” speaker I mean was the Duntech SOVEREIGN.
        I’ve heard this loudspeaker in a wide variety of rooms, and it always played well, even in an almost near-field setup.
        I even had the opportunity to hear the SOVEREIGN in comparison to Paul’s favorite the Infinity IRS V. I preferred the Duntechs. The Duntechs simply played more “real”, which was confirmed by some musicians from the Radio Symphony Orchestra of the Hessischer Rundfunks and their chief conductor at the time, Eliahu Inbal. Maestro Inbal has therefore decided to acquire the SOVEREIGN.
        So let’s see what Chris delivers – the bar is set high.

        1. Dear Bernd,

          I mentioned that John Dunlavy was one of my favorite speaker designers, along with three other famous RF engineers. After careers in the no-excuses, no handwaving business of radio waves, Dunlavy, Linkwitz, Modefferi and Sequerra have unique insights into audio waves. Interestingly, Dunlavy sticks to first order crossovers, I believe Sequerra uses second, Linkwitz favors third or fourth order and Modafferi patented a 7th order crossover that uses two components.

          BUT, they all pay close attention to polar pattern, phase and diffraction. Speakers are supposed to produce waves, not just frequencies.

          I have a trio of Dunlavy SC-I in my living room, they are similar to the treble portion of the Duntech Sovereign and require a high pass filter (small mode) and a wideband subwoofer. Besides these two companies built around Dunlavy’s designs, I also recommend the Lipinskys which are an evolution of the two way Dunlavy models with bespoke drivers instead of stock drivers used in Duntech/Dunlavy.

          Happy Spring!

          1. Are you sure you meant MRI and not fMRI? I don’t know what you would “see” in a MRI related to hearing.

            fMRI or PET scans seem more appropriate (and more invasive). Injecting radioactive material is never fun (I mean for PETs).

  3. So Paul, what fires you up more?
    Talking engineering-speak with ‘the boys’ or listening to a
    brand new ‘Octave Records’ (DSD) CD in Music Room 2?
    😉

  4. Side question for today, since it deals with engineering the website!

    Do you all get email notices anymore when there is a reply to a comment on this blog? I no longer do and have tried everywhere to find a fix. I get the regular daily email of the post, but that is it.

    Perhaps still a work in progress I suppose.

    1. Larry,
      Correct; no-one is getting email notices like we were before.
      It is a waiting game, or as you suppose, “still a work in progress”.

  5. Over the years I’ve noticed that the really successful speaker designs are based on a passion for a particular sound. Vandersteen, Harbeth, Wilson, Magnapan, Rockport have evolved to deliver the goals of a particular designer. They sound different, they may use different drivers and different technologies to achieve their aims, they are not state of the art in all aspects, but they are true to the passion of the designer. Sometimes too much knowledge gets in the way of achieving a particular aim.

  6. “Chris knows more about the technical aspects of loudspeakers than any human I have ever over the last 50 years”
    Assuming the word “met” after the word “ever” is missing (?), that’s what I call a strong statement !
    And what does this tell us about the other employees ?
    Or maybe PmcG does not meet a lot of people.
    Anyway, IF all this technical knowledge really helps, then the upcoming PSA speakers must be the best in the world.
    But then again, PmcG says that about virtually every new PSA product 🙂

  7. To me, a simple layman, loudspeakers are like Boeing aircraft. After decades they look and work pretty much the same. They just get more efficient parts and materials, run less noisy, and get higher tech electronic innards. The ride hasn’t changed much.

  8. I’m reserving any judgement until I hear the new PSA speakers.
    A thought that pops into my mind is I think there is a difference between driver design and speaker design using drivers designed by someone else. Each approach can be equally valid with the sound that comes out. The “final presentation” as we all know depends on the speakers input, and how the output couples into the environment the speaker is placed in.

  9. Reading Chris’s response, what caught my attention immediately was the following:

    “That being said, I have been putting thought into doing a more budget larger format woofer and compression driver because performance versus cost can be quite good (a single larger woofer is less expensive than two smaller woofers of equivalent performance).”

    Correct me if I am wrong, but does not a “compression driver” require a horn?

    First PS abandons the idea of using a servo woofer….

    Now there is talk of PS Audio building a speaker with a horn driver?

    I liked reading that Chris is open minded to all configuration possibilities.

    Paul, please keep this in mind during Chris’s annual job review 😉

    1. I am generally against horns, but that appears to be a question of implementation. Almost all of them “honK”, which is narrow band resonances from reflection at the mouth; and all of them have issues at the bandwidth limits. The low end has a sharp cutoff with gobs of phase shift, and the high end loses efficiency as it separates from the horn wall unless you have a REALLY long taper – and that introduces too much time delay and accentuates the organ pipe resonances.

      The first horn I heard that really sounded good was a vintage Klangfilm with a mouth 180cm x 250cm – you could walk into it by mistake. The second was Tom Danley’s Unity horn, and I have three of them for LCR. Meyer Sound makes some good ones, and there is now a new horn profile available for OEM and DIY that theoretically has perfect impedance matching at the mouth: Tractrix.

      I am going to fire one up this Spring, in a 2 way with 2×12″ woofers.

  10. OK, I read down the comments and found this quoted by Mr. Brunhaver:

    ” Cleaner than large-cone short-stroke drivers: The combination of the above characteristics results in a compact long-stroke driver that delivers complex sound with a clarity and lack of effort that was previously the exclusive province of large-cone short-stroke drivers. Additionally, thanks to the small cone size, the driver has excellent midrange reproduction. It is highly suited for two-way systems.”

    There are three problems that large diaphragms solve:

    1. Moving more air (Vd, liters)
    2. Higher efficiency (Eff. dB/W/m)
    3. Lower Doppler Inter-Modulation Distortion (% or dB of spectral contamination, no established measurement protocol)

    When you move up from “polite” level audiophile listening sessions (95dB to 105dB peak) to balls-out live ACOUSTIC performance levels (about 20dB hotter), DIMD goes from un-noticeable to fatiguing on “acceptably small” speakers. In this case, long stroke is the enemy.

    Most consumers don’t notice this because they listen on tiny speakers (7″ woofers, 3″ midranges, and 1″ tweeters) and associate this distortion with loudness. They either enjoy it as a social signifier of celebration, or turn it down because wifey says it’s too loud.

    One simple test, is try to turn your system up until an averaging SPL meter is registering 110dB crescendos or higher at 1 meter. Try to hold a conversation with someone seated next to you. If you have to raise your voice, either the recording is distorted or your speakers are. If the amp is not clipping and your speakers are not hitting DUMax, then the culprit is DIMD.

  11. Chris’ comments seem really fin target. Which means that if you want good midrange, good high frequency and extended bass, you will need a three way speaker. And for the woofers to sound good, you will need a lot of amp power. Again, this suggests to me that PS should have gone active to manage better all the trade-offs discussed by Chris. Or, definitely, powered woofers.

    Very interesting set of exchanges by Chris.

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