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Impedance measurement of Bass Shakers?

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  • Impedance measurement of Bass Shakers?

    I haven't been able to find anything here on PETT nor from a broader internet search. Has anyone measured the impedance curve of a bass shaker/transducer? I'm more specifically curious about the $25-50 Dayton models, but I'm pretty sure a rough generalization from ANY shaker would give me more information than I currently have.
    I'm assuming the weight and floor coupling of whatever the shaker/s are mounted against probably changes things kind of like how different cabinet size and tuning changes a regular woofer's impedance...so maybe free air measurement makes the most sense.?

    I'm trying to figure out if a somewhat traditional passive LowPass filter at the "driver" could be used alone or maybe added to assist along with an amplifier input LowPass.

    Also overall curious since I couldn't find ANYTHING about them and I'm guessing there are at least a few folks with measuring gear who also own some shakers.


    EDIT: I'm assuming this is mostly a dumb question because the shakers typically need their own amplifier for tuning (so using them as the bottom of a 2-3way isn't a common thing) and their ideal LowPass target would be pretty low and likely prohibitively expensive compared to a small/cheap filter at the amplifier's input.
    I have some of the newer Dayton 35watt versions heading my way, but I don't have an amp with built-in LP nor was I thinking straight enough to also order some tiny capacitors and high-ohm resistors....so I might need a temporary workaround.
    My first 2way build

  • #2
    They may naturally roll off rapidly due to motor design, not sure a low pass is really required.
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music
    Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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    • #3
      You'll find it to be roughly like an exciter, roughly 4 ohms, and every sweep is different.
      Wolf
      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

      *InDIYana event website*

      Photobucket pages:
      https://app.photobucket.com/u/wolf_teeth_speaker

      My blog/writeups/thoughts here at PE:
      http://techtalk.parts-express.com/blog.php?u=4102

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      • #4
        Originally posted by wogg View Post
        They may naturally roll off rapidly due to motor design, not sure a low pass is really required.
        I hadn't considered that because at least some models seem to recommend a HP[EDIT: LowPass...whoops] to avoid higher-frequency vibration, but maybe these newer versions aren't as noticeable about that. Would certainly make things a lot more carefree.
        Last edited by LOUT; 06-05-2021, 09:52 AM.
        My first 2way build

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        • AEIOU
          AEIOU commented
          Editing a comment
          If you want to block higher frequencies, you would use an LP (Low Pass) filter, not an HP (High Pass) filter.

      • #5
        Originally posted by LOUT View Post
        I hadn't considered that because at least some models seem to recommend a HP to avoid higher-frequency vibration, but maybe these newer versions aren't as noticeable about that. Would certainly make things a lot more carefree.
        I think I'm wrong though. The manual recommends an 80Hz low pass on the 50W models so I'd go with that. Active would be best, maybe one of those quick passive line level low passes?
        Electronics engineer, woofer enthusiast, and musician.
        Wogg Music
        Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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        • #6
          I posted quite a bit of stuff in the flat panel love thread that UB apparently ... loves. Never did an impedance sweep, but like you, assume it depends on whatever is attached to the exciter and how it is attached/mounted. It seemed like just about anything I did made a difference to the sound.

          After going through too many of the exciters (some never made it past the initial listen), I also wondered if, unlike advertised, they needed a crossover similar to a conventional speaker. My experiments lead me to believe that in the lower frequencies the size of panel in use (mass?) could become so excited by bass frequencies that it quickly overloaded the excursion of the exciter driving the exciter into failure.

          Somewhere along that overly bloated thread, I may have hypothesized a more conventional approach of the exciters by using smaller better suited exciters/panels for the high end, and large bass shakers attached to something large, like a 4x8 sheet of plexiglass, for the bass. In theory it seems plausible.

          Anyhow, no longer have any functioning exciters to measure as PE eventually said enough is enough and refused to warranty any more of them.
          http://techtalk.parts-express.com/fo...khanspires-but
          http://techtalk.parts-express.com/fo...pico-neo-build
          http://techtalk.parts-express.com/fo...ensation-build

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          • #7
            I have the Dayton mini puck bass shaker. Its basically full range but its dependent on what type of material you attach it to. Most bass shakers are attached to hard heavly damped wood so the high frequencies are muffled. If you want to completely take away the mid to highs a low pass is required. Easiest way is to just use a sub amp.

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            • #8
              I ordered a few high-value resistors and low-value caps aiming to cheaply DIY a passive ~80hz LP input filter. They'll arrive later than the shakers, but it's not like I wouldn't have tried them full-range first either way. :D

              Although I'm planning on the more traditional under-seat approach, curiosity demands I'll have to see what these sound like attached to some different panels too. I really hope they're frequency accurate/precise enough for that to make some semblance of 20-80hz bass sound instead of just an awkward rattling.
              I want to say the actual movie theater experience/s I've had with buttkickers (AMC theaters, I think) had their shakers feeling more like one-note-wonders which could vary in strength/output but not really in frequency. I think a more frequency-accurate shaker should blend a lot more smoothly between speakers and tactile bass. Less gimicky?

              I'm doing a terrible job of holding back my enthusiasm and expectation the longer I think about these. Quick, someone tell me they're terrible, lol.
              My first 2way build

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              • #9
                Wow these shipped a LOT faster than I though they would. I got a quartet of Dayton BST-2's. They're interesting, mostly in positive ways. Their bass IS noticeably frequency sensitive/accurate where the shaking is NOT just a "one-note-wonder" that changes with volume...instead, they do what I'd expected/hoped and behave like an extra beefy transducer.

                From the online images (my fault for not reading) I thought they'd be a thick plastic shell around 3.5inches diameter...instead they look/feel like cast iron and are roughly 5inch diameter. I'm currently just testing them with the little KAB230 (I'm think this peaks around 25-30watts/each, should be nicely safe) and I'm guessing the amp has a drop-off below 25-35hz because the output right now drops off down there while the BST-2 are rated to 10hz. They have been totally fine without any LowPass so far, and I haven't run into any problems yet while giving them a fullrange signal.

                They feel kind of subtle in a way that says "I'm not going to rattle or draw attention to myself" while at the same time their weight and bass depth makes them still feel effective for their job. Hopefully they'll keep impressing after being properly mounted to some seats, and I'll also have to see what kind of sound they make when attached to some large panels.

                EDIT: Listening to them alone without any other speakers running, you definitely CAN hear them playing fullrange music when given a fullrange signal. It's probably quiet enough to be mostly hidden by mains and it doesn't rattle or do anything weird/ugly so I'll probably just leave them fullrange unless it bothers me later.
                My first 2way build

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                • #10
                  Voices from your caboose should concern you....
                  Wolf
                  "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                  "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                  "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                  "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                  *InDIYana event website*

                  Photobucket pages:
                  https://app.photobucket.com/u/wolf_teeth_speaker

                  My blog/writeups/thoughts here at PE:
                  http://techtalk.parts-express.com/blog.php?u=4102

                  Comment


                  • LOUT
                    LOUT commented
                    Editing a comment
                    :D that was my first thought after realizing they can hit all the notes. I'm still hoping it won't be too noticeable, but I have some high-ohm resistors and low-uF capacitors on the way for a LP at the input if the voices-from-below make themselves heard.

                • #11
                  Well, have you measured their RESISTANCE? That would get you into the ballpark. Typically with woofers the nominal impedance is only slightly more than the resistance, it might just be the same with Bass Shakers.

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                  • LOUT
                    LOUT commented
                    Editing a comment
                    Not a bad place to start, but it doesn't seem like it should matter now that I've tried them and they don't appear to do anything too loud nor awful when played fullrange along with some tiny speakers.

                    I'm assuming their resistance is somewhere around 3.3-3.9ohm because they're listed as 4ohm versions. I was more curious if there was a typical pattern for the impedance slope that would have an effect on a driver-level LowPass...like a woofer+cabinet's impedance spike/s.
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