Tech talk

September 25, 2021
 by Paul McGowan

I am most comfortable in the company of engineers.

It’s more than just camaraderie.

To non-engineering folk, our conversations might sound like a different language what with all the terminology bandied about.

But more than terminology is the implied understanding of bigger concepts. Terms like -3dB, half power, slew rate, open loop, rise times, wave shapes, carry with them major implications. If our depth of understanding of terminology’s implications is shallow, we can often find ourselves either lost or worse, drawing incorrect conclusions.

In a recent forum post, PS engineer Chris Brunhaver was generously answering some questions about our upcoming speaker:

“We’re still preparing some marketing materials on the FR-30 but I can share that the low frequency cutoff is -6 db at 27 Hz. While a reflex/passive radiator enclosure, the roll-off below this is rather steep but you’ll see typically see extension from 20-25 Hz in-room. Still, as other mention, the benefit of multiple subs/ LF sources will help smooth the response wider listening area.

Please keep in mind that, if you listen to dynamic music in the bass and want a subwoofer that “keeps up” with the speaker, you’ll need something pretty potent. A pair of FR-30, with their 8 x 8″ woofers and 8 x 10″ passive radiators is capable of ~120 dB (in half space) from 25 hz and up with (when driven with 600 watts x 2) at the Klippel rated Xmax of the woofers. Of course, you won’t want to listen full range at that level, but the system is certainly capable of it in the low frequencies, so that it has very low distortion at more moderate levels and a feeling of effortless bass dynamics.”

I love that our engineering team reaches out to our HiFi Family.

Chris speaks in very dense terms even when he’s doing his best to keep it simple. Unpacking terms like “Klippel rated Xmax of the woofers” or even the innocent sounding “want a subwoofer that “keeps up” with the speaker” carry with them loads of implied understanding.

The challenge for any engineering-centric company is to figure out a way to effectively communicate complex concepts to a hungry audience and to do so without boring the crap out of people.

Chris does an amazing job and I love it when he talks like that. 🙂

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56 comments on “Tech talk”

  1. What I love from the engineering team‘s output, no matter if Chris, Ted or Darren is, that it has at least the necessary depth to put rather superficial marketing talk into perspective to an absolutely necessary degree to avoid false believes. For them it seems as important as for me, that misleading perceptions are avoided, not encouraged.

    Example here:

    Marketing talk:
    The FR 30 are full range, no need of separate subs, as they reach deep enough powerfully.

    Engineering correctness, shining through from Chris‘ words:
    In practice in a listening room and depending on the positioning of speakers, bass may even extend deeper or less deep due to room node behavior, but could (and usually will) also have serious dips or peaks way up in the frequency range. Separate subs will care for actually ensuring the desired depth of bass of the combined speaker/sub/room setup and its smoothed out frequency response. I would add, that this is not only reality for a wider listening area, but also for the sweet spot itself, as most would prefer to position the main speakers for optimal imaging or at most for a compromise of imaging vs. flattest bass, not flattest bass alone.

    I love correctness in non misleading statements from the team.

    Due to the bass potential of the FR30, it seems, for perfection, subs that are rather bigger than the speakers are needed to keep up with them, but there are some choices 😉

    http://audiopub.co.kr/2017/01/07/세상에서-가장-큰-미쓰비시-diaton-d-160/

  2. “generously answering some questions about our upcoming (loud)speaker:”
    Ok, so here’s the thing…
    If you are going to ask CB questions about loudspeakers then it is incumbent on you,
    the questioner, to either a) be familiar with the terminology or b) go & find out what the
    terminology means, so that said questioner can understand the answer to the question.
    If you are truly interested in a topic, hobby or pastime you should have a certain level of knowledge…especially these days where everything is ‘Googleable’.
    So, if you’re gonna ask tech question of a tech-head, be prepared or there’s a good
    chance that you’ll feel silly.

    I don’t bother asking technical questions, I leave that to the measurement
    (design & build) guys & gals.
    I let the CB’s of this world do their thing & then I listen to their completed project.
    All that I’m interested in is the end result.

  3. So it’s official: Paul likes it when Chris talks dirty.

    On the subject of talking dirty, I was listening to the radio in the car a few minutes ago and a 9 year old was reviewing a record from his parent’s collection: Kylie’s all time classic, Fever. When asked about “I Can’t Get You Out Of My Head”, he explained “bearable, but a bit repetitive”. When pushed, he added: “too many la la la’s”.

    When it comes to electronics, I think I operate at the la la level.

        1. Off topic : okay FR, while I keep watchin’ Kylie you have fun (?) with the locomotion. To each his own.
          Speaking of Kylie…I also like Naomi Watts and felt sorry for her when that big ape was so rude to her.

          On topic : Nice video from dr.goodears’ bear.
          It seems to me the bear has more knowledge of technique than a lot of us have 🙂

      1. I watched his “ill be gone awhile” video. I felt oddly close to and concerned for him. Also i may be sensitive because my friend and neighbor is dying early because of COVID. Oops sorry to be a bummer.

        1. Hi Phil,
          So sorry to here about your friend… I treat many people with COVID as an ICU RN here in Washington state. I have befriended many of my patients only to watch several of them die. It is heart wrenching. My prayers to your friend, their family and you and yours.

  4. I guess the simplest way to communicate the technical quality of the new speakers would be to publish the room response of the best set-up for some standard sized rooms and the step-response at the listening seat placed at the distance for which Chris had designed them. Of course a sketch of the recommended set-up would be most welcome! 🙂

    1. First thing i thought of was that i bet Paulsquirrel loves tech talk…and they should include something with the speakers at least as detailed as the audio guide and CD.

  5. Back in the 1970s, I was a loudspeaker geek, devouring every book, magazine and anything else I could get my hands on related to loudspeaker design, so I understand most of Chris’s speaker-speak. Back in 1974, I even spent 2 1/2 hours one on one with Amar Bose discussing sound, loudspeaker design, his research, etc., and understood every word out of his mouth. That was one of my favorite moments ever, even better than the 8-10 months I worked with Donna Karan, and celebrating her birthday with her at work back in October 1986.

  6. Good morning Paul!\
    Perhaps you can answer this tech question for me.
    I read this a few times before.
    But lets just say, that I wanted to buy a pare of PS Audio FR30 speakers.
    And I wanted to get everything that they have to offer.
    But looking at the 8 8inch woofers in each speaker, you start thinking about the impedance load that they’re gonna put on your amp.
    If your amp can’t handle too much of a low impedance load.
    How are those woofers wired up.
    And also, what is the load on each woofer driver?
    Thanks in advance!

              1. Best curves of impedance and phase vs. frequency that I am aware of are published by John Atkinson in Stereophile. Paul Miller publishes numerical minimum and maximum impedence and phase at their respective frequencies in Hi-Fi News & Record Review. Out here in the substrate, nominal impedance is usually good enough unless your amp(s) is prone to self-immolation. Just watch out when playing “Magic Fire Music” from Die Walkure and especially “Siegfried’s Funeral Music and Finale” from Gotterdammerung.

  7. Same thing with musicians having a conversation. Although a lot of people THINK they know what we’re saying.
    On another note….is it true that the FR part of FR30 means “Fat Rat”?

  8. “…..effectively communicate complex concepts to a hungry audience”

    The issue I see is that the audience for the audio world is as wide and diverse as society and music itself.

    The group who genuinely are interested in all design characteristics… and the why’s
    The group who are only interested in how it sounds to them…and not how that’s achieved
    A group in the middle who like to understand technical to a point and also want a sound pleasing to them.

    I guess the trick is trying to find the common ground between all the groups – thus the need for multiple forms of communication / marketing … forums, posts , pod cast, video’s etc.

    Yet in the end, all the words and video’s in the world won’t communicate how something will sound until you hear it in your set-up.

  9. I know how to connect more than one speaker per channel in series and how to calculate what it does to impedance.
    I know how to connect more than one speaker per channel in parallel and how to calculate what it does to
    impedance.
    But “…woofers wired in series parallel…” ?

    1. jb4,
      It means that some drivers are wired partly in parallel and partly in series, to keep the total impedance where it needs to be.
      For example; if you have 4 x 8″ drivers you can hook-up 2 lots of 2 in parallel & run the resulting 2 in parallel together in series…hence, “woofers wired in series parallel” to maintain the impedance of the individual drivers.

  10. This is so important I like to listen to music and I have invested more in the gear only exceeded by my house and car ie no small sum ( in my economic class). So I rely on internet reviews and gear statistics to make choices. Sadly there are no audio stores near me and those two hours away carry only a limited number of brands. So the language is an important ingredient in my decision-making but sadly hard to comprehend, for example, THD of .5 would be considered way too high compared to .005 or less and brings unwanted distortion yet some highly regarded manufacturers have high THD. So really what does that increase in distortion mean in the context of good sound? Tubes distort the heck out of a music signal and you choose the sound signature that pleases your ear but if you can’t listen to it then what? Internet marketed companies like PS audio, Tekton, emotive allow you to trial their products but that is time-consuming and a hassle. How many products do you listen to how do you make a choice to listen to what brands you select for trial and what a bummer for the companies getting returns, and don’t forget this factors into the price of their products. Sadly it is a flawed hassle ridden sales system. This is a long winded round about way of saying. What stats. and definitions really matter and how do they matter and interrelate to one another so the consumer knows when he sees that certain statistics /definitions when combined form that synergistic interaction resulting in good sound. my,my,my.
    To say nothing about, reliability, durability and customer support after purchase.

  11. I’m not an engineer, but perfectly understand Brunhaver’s explanation. The FR-30 “in room” should reach down to what most humans can hear, though not as low as we can feel. Octobass and organ lovers will need to have external subwoofers to get down to 16 Hz. Octobasses are rare. 32-foot pitch organ bass is common in larger pipe organs.

    https://metalinjection.net/video/the-octobass-is-the-most-metal-lowest-tuned-classical-instrument-ever

  12. Does a doctor give you all the technical data about a medicine he wants you to take?

    If it makes you well? We do not need all the technical information.

    If it goes down to twenty hertz? What good is it if your body still hurts?

    Does it sound good?

  13. hmmmm, -6db at 27Hz for the FR-30…. 1980’s prices for the Infinity IRS Beta (Arnie’s Nudel Infinity) was $12k and they quoted +/- 2db at 15Hz.

    I would have guessed a low freq being specified at a relatively flat point, so we, the possible consumer would know when the FR-30s start dropping off.

    Me, as a tech consumer, I try to find comparisons and understand the why’s. Does the FR-30 at say a +/- 2db is at 45 or 48 Hz. And what was the tradeoff why the –6db number is not much lower? If you/PS Audio would have multiple woofers stacked in a different sub box, could that be a add-on to the FR-30 and then used as a sub into a future ?FR-60?

    Also, I also always look at the space / square foot area where the speaker is placed. My assumption is that PS Audio didn’t target the bedroom (80 – 135 sq ft) space, but a larger 250 sq ft family room type space. And thus figure our the dbs in that space with how much suggested wattage.

    Just my two cents..

    1. The lowest note on a piano is 27.5 Hz. I wonder if the FR30 is -6db at 27 Hz, will a well recorded piano be faithfully rendered? Will “room” make enough of a difference to overcome the frequency non-linearity? Maybe some more Tech Talk can clarify.

      1. That’s a good question. A 20 Hz wave is ~55 ft long and so you are acoustically “near” most/all of your room boundaries and so you get “room gain” at very low frequencies. A common rule of thumb on this is ~12 dB/octave boost below the half wavelength of the longest dimension of your room. As such, you get around 10-15 dB at 20 Hz in most domestic sized rooms, depending on the size and construction.

        As such, you want to design the inverse response into a speaker so that you net a relatively flat response into the very deep bass. You don’t actually want perfectly flat anechoic response down super deep because the in-room response will be very tilted up down low and sound “slow” because the balance of deep bass versus mid and upper bass.

        Also, physics dictate that to add an octave deeper extension, you either sacrifice 3db of sensitivity or need to increase the enclosure volume by a factor of 8 (and excursion requirements quadruple), so you want to engineer the system correctly to balance all of these factors as well.

  14. While I don’t fully understand how an amplifier works I understand what the job of the installed parts are and I could probably build one. The same with a car. Don’t know everything about them there is to know but enough that I can carry on a conversation with an auto mechanic. I know enough about audio engineering terms to have a conversation with engineers but I would probably be asking questions along the way.

    Being an audiophile there are many engineers who I would probably not feel comfortable talking audiophile jargon with. There are not a whole lot of Paul McGowan type engineers out there. Not all audio engineers are audiophiles either.

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