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Tang Band W5-1138SM (Voxel) driver higher than expected resonance

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  • Tang Band W5-1138SM (Voxel) driver higher than expected resonance

    I recently picked up my Voxel project which had been sitting idle for a couple of months.
    I felt the response seemed a bit boomy, so I wanted to check whether the tuning was off. I measured the impedance with REW, and got the minimum a bit higher than expected, at 43Hz, rather than the expected 38Hz. I decided to measure the driver alone in free air and the resonance peak is coming out at 56Hz, vs. 45Hz in the spec sheet. The driver has already had maybe 10hours of run time at fairly modest volume levels. Is this kind of deviation from spec normal? I'm not sure what to do now, any advice?


  • #2
    Not surprised. Mfg specs are rough guidelines. Measure your drivers. Do you find it odd drivers never have a lower Fs? It is called advertising my good sir.
    What you do is always prototype and tune to reality, not build blindly to a model with mfg. specs.

    Comment


    • #3
      I've had a higher Fs on the 1138, but the other parameters were shifted to compensate and still modeled well in the intended enclosure.

      Later,
      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:
      http://photobucket.com/Wolf-Speakers_and_more

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

      Comment


      • zx82net
        zx82net commented
        Editing a comment
        Did you adjust the port tuning frequency in proportion to the change in Fs, or just leave it as is?

    • #4
      Originally posted by tvrgeek View Post
      Not surprised. Mfg specs are rough guidelines. Measure your drivers. Do you find it odd drivers never have a lower Fs? It is called advertising my good sir.
      What you do is always prototype and tune to reality, not build blindly to a model with mfg. specs.
      Since you mention it, we bought a big batch of Peerless 830869s for arrays. They measured a couple Hz lower than the 30Hz spec. But yeah, typically they are high, at least until you break them in for a long time.
      Francis

      Comment


      • #5
        A whole stack of HDS woofers might be really sweet.

        First hint of advertising stretching's the truth is calling a 5 1/4 inch driver a subwoofer. I guess a market for those unencumbered by knowledge of the laws of physics or for that matter, the definition of "SUBwoofer" Sorry.

        Comment


        • #6
          Originally posted by tvrgeek View Post
          A whole stack of HDS woofers might be really sweet.

          First hint of advertising stretching's the truth is calling a 5 1/4 inch driver a subwoofer. I guess a market for those unencumbered by knowledge of the laws of physics or for that matter, the definition of "SUBwoofer" Sorry.
          They went in square quads below 511 horns, crossed at 800Hz. But yes; they do work well.
          Francis

          Comment


          • #7
            Originally posted by tvrgeek View Post
            First hint of advertising stretching's the truth is calling a 5 1/4 inch driver a subwoofer.
            Ah- you must be of the uninitiated. To experience the 1138 or 1139 is to change one's mind about smaller drivers being subwoofers. I see your point works better in the 3" and 4" sizes, as the mass has to be high enough to get the Fs low enough, and the xmax long enough; to be able to be used as such without having Pe too low and Sensitivity also too low.

            The 1138, 1139, and 1363 are venerable behemoths in their size classes.

            @zx82net-
            No, I left the alignment as it was as it worked as designed. I usually build to driver measured T/S and not spec sheets, so this is not usually a concern. There was just no reason to shift the model and retune fro mthe box sim as they were pretty close to an overlay.

            Later,
            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:
            http://photobucket.com/Wolf-Speakers_and_more

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

            Comment


            • #8
              Originally posted by tvrgeek View Post
              A whole stack of HDS woofers might be really sweet.

              First hint of advertising stretching's the truth is calling a 5 1/4 inch driver a subwoofer. I guess a market for those unencumbered by knowledge of the laws of physics or for that matter, the definition of "SUBwoofer" Sorry.
              Laws of physics suggest to me that 4x Voxels ~= one ten inch sub with the same tuning frequency and excursion. Not so?
              I like to teach physics by analogy, perhaps a comparison to a car engine:

              driver diameter ~ cylinder diameter
              xmax ~ stroke length
              number of drivers ~ number of cylinders

              More of any = more SPL

              No one defines what is or isn't a sports car on the basis of the cylinder diameter

              Comment


              • #9
                zx, you didn't tell us how your other parms measured ...
                BUT if Fs is high (by 10Hz, for instance), and Qts is (also) high by 0.10 (say it's "0.50" instead of a spec of "0.40"), AND if Vas is LOW (like, maybe half?), a sim will most likely guide you to the same box size and F3. FYI

                Comment


                • zx82net
                  zx82net commented
                  Editing a comment
                  I'm not set up to measure anything other than impedance at the moment. I intend to sometime, but busy with a load of stuff at the moment.

              • #10
                The little TB wonder may be the best 5 1/2 barely-a-woofer out there and make a nice low SPL desktop 2-way, but it is no sub. Remember: distortion and efficiency are inversely proportional.

                xz, "taint no replacement for displacement"

                Comment


                • #11
                  Originally posted by zx82net View Post
                  ... The driver has already had maybe 10hours of run time at fairly modest volume levels....
                  I think a proper break-in may help your issue. Running the sub at Fs, in free air, near it's xmax to exercise the suspension. See my post #4 in This Thread.

                  Comment


                  • #12
                    Originally posted by tvrgeek View Post
                    The little TB wonder may be the best 5 1/2 barely-a-woofer out there and make a nice low SPL desktop 2-way, but it is no sub. Remember: distortion and efficiency are inversely proportional.

                    xz, "taint no replacement for displacement"
                    Then you can remain ignorant. It's your fault alone if you don't give it a listen. It has displacement via long xmax, and is a very competent little beggar.
                    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:
                    http://photobucket.com/Wolf-Speakers_and_more

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

                    Comment


                    • #13
                      Originally posted by Wolf View Post
                      ... and is a very competent little beggar.
                      Wolf
                      It's F3 in a 10.6 L box is ~32 Hz. And it will do that at it's rated 40 W w/o breaching xmax.

                      Comment


                      • #14
                        Here is some guiding info on what is a subwoofer from the Parts Express resources page...

                        What's the difference between a woofer and a subwoofer?
                        These terms have become almost interchangeable, and there is definitely a gray area between the two. The difference can be in the woofer itself, or how the woofer is being used. A raw speaker or "driver" that we call a subwoofer generally has a limited frequency response range, often not extending above about 400 Hz. A standard "woofer" can have frequency response easily reaching 2500 Hz or higher. This upper limit is a function of electrical and mechanical characteristics; often the large voice coil inductances on high-excursion subwoofers limit their high-frequency capabilities. It is a matter of compromise in the design of the woofer: trying to achieve good high frequency performance generally will cause poor low frequency and power handling abilities, while producing a powerful subwoofer with ultra-low frequency abilities and high power handling will not be able to play well at higher frequencies. However, if a wider-range woofer is used only below 80 Hz or so it could be called a subwoofer due to how it is being implemented.

                        What does a subwoofer do?
                        A subwoofer is used to reproduce the lowest frequencies that other speakers in the system can't reach at full volume. In the most general application, the subwoofer will work with a pair of smaller speakers to produce the bass that the smaller drivers are not capable of reproducing faithfully. While some media may not contain much low bass information, many types of rock, hip-hop, jazz, classical, or electronica rely heavily on low frequency content. In these cases, using a subwoofer will help fill out the sound and produce a more realistic experience. In home theater systems, there is a specific channel of sound specifically designed for the subwoofer, including most bass effects such as explosions, gunshots, and rumbles. Most home theater processors also contain settings to divert all low frequency content to the subwoofer, which frees the satellite speakers to play much louder and with less distortion.
                        --------------------------------

                        Lots of words to say what we all know... subs cover only the low end of the music. No mention of driver size, output level, or even an exact number for low end extension to qualify... could be a woofer by name, as long as it's covering the low frequency range with a bit of authority...

                        I try not to chime in on subjects I don't have much knowledge on, but I've used the Tang Band w5 1138 in a bunch of projects, some mine, some others... and it is, as a matter of fact, a real subwoofer by any measure...

                        tvrgeek, have you actually heard this driver yet?

                        TomZ
                        Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                        *Part 2 *Gluing multiple curved laminations of HDF

                        Comment


                        • #15
                          Originally posted by tvrgeek View Post
                          The little TB wonder may be the best 5 1/2 barely-a-woofer out there and make a nice low SPL desktop 2-way, but it is no sub. Remember: distortion and efficiency are inversely proportional.

                          xz, "taint no replacement for displacement"
                          Tom is spot on.

                          Really the only thing that makes any driver a "sub" is the filter. Some tweeters could actually make good "subs" in a headphone type application if you only allow them to play low frequencies. Any speaker used strictly to extend low frequency capability is a subwoofer.
                          There is no qualification that says a "driver in X enclosure must be capable of Y SPL at Z Hz with less than 20% distortion" to be called a sub. The title "subwoofer" is all based on how you use a driver.

                          A driver is just called whatever it is originally designed for (or how it will usually be implemented into a design).
                          The Tang Band W5-1138 is a very capable compact subwoofer driver.

                          Please do not be so negative about other peoples' designs or plans. This forum is here to encourage and support people in this hobby we all enjoy so much. Not everyone is expecting the level of "perfection" you strive for. Most people are able to accept the compromises that we have to make when designing any speaker system.

                          -Chris P

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