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New Dayton Unshielded RS drivers - some measurements

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  • New Dayton Unshielded RS drivers - some measurements

    With the new Dayton unshielded drivers, there are two big issues to be answered for each driver:

    1. Does it measure closely to the original, shielded driver? (Does it measure closely to the mfr spec?)

    2. Will it work as a "drop-in replacement" for existing designs that called for the No Longer Available shielded woofers?


    I will answer these questions as I have each driver available to me.

    First up is the Dayton RS180, unshielded. Thanks to a generous lender here at Tech Talk for letting me measure it.

    So, for question #1: Here is the measured impedance of both drivers (unshielded in black, shielded in red)

    Seems very close. The unshielded driver has a slightly lower Fs.

    Here are the Thiele-Small parameters I measured for the new, unshielded Dayton RS180


    Here are the Thiele-Small paremeters I measured for the old, shielded Dayton RS180S

    Both measurements came very close to the Dayton spec sheet (though they obviously do differ from one another. How much that matters we'll have to plug in to our favorite box modeling programs and try them out)

    Finally, the Frequency Response of both drivers, measured on-axis from .5 meters in the Amiga cabinet. New, unshielded RS180 is in black; old, shielded RS180S is in red.
    First off, it appears as though the new unshielded RS180 is 1 dB or so more sensitive than the old, shielded driver through the passband. (How much of an issue is this? I'll have to try it in some designs to find out)
    Thankfully, it appears as though the cone breakup is pretty much exactly the same between the two drivers, so at this point it's reasonable to speculate that notch filters used in existing [shielded] designs won't have to change.

    That's all I got for now. Chew on that.
    Attached Files
    Isn't it about time we started answering rhetorical questions?

    Paul Carmody's DIY Audio Projects
    Twitter: @undefinition1

  • #2
    Re: New Dayton Unshielded RS drivers - some measurements

    Great to see the first of the new measurements showing up. Thanks for starting the process...

    So, inductance haven't changed much, while there are some shifts in the basic T/S... I do like how the FR looks. Very similar, with a very consistent difference in sensitivity. Interesting that the (WT3?) measurements say that the old '180 should be slightly more efficient, but the FR seems to show the opposite. Also nice that the new '180 has a smoother area from 2 - 4Khz... that dip-peak is no longer there. Wonder if they've changed the cone or surround any?

    All in all... looks like not a great difference, and possibly some improvement.

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    • #3
      Re: New Dayton Unshielded RS drivers - some measurements

      Paul, thanks for the effort. Very much appreciated.
      I was so much older then, I'm younger than that now.
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      • #4
        Re: New Dayton Unshielded RS drivers - some measurements

        Appreciate the effort. How much difference would you expect from driver to driver in the same series? In other words, are the differences between the shielded and unshielded versions larger than would be found in a batch of 10 from either version?
        It is estimated that one percent of the general population are psychopaths - New Criminologist: Understanding Psychopaths

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        • #5
          Re: New Dayton Unshielded RS drivers - some measurements

          Excellent report! Questions of drop-in replacement aside, for new designs the new unshielded RS180 might be a bit easier to work with. It does not appear to have the small peak at 3.5k in FR that the older version had.

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          • #6
            Re: New Dayton Unshielded RS drivers - some measurements

            Hi Paul,

            Thanks for the measurements. It reinforces that the new unshielded RS180-8's will be drop in replacements for any 3-way designs using RS180 shielded drivers as woofers. Two Statements designs done and one more to go. :D

            Good news!

            Great work!

            Jim

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            • #7
              Re: New Dayton Unshielded RS drivers - some measurements

              Thanks Paul I've got to say it looks good, I'm not sure how much that extra 1db in sensitivity will change a design, I would guess not much. It does look like that first 5db spike around 3.5k is gone, that seems like a nice improvement. All in all I'm optimistic about these new drivers now. We'll just have to see how all the different sizes compare. Also with the lower VAS it seems like box sizes should be able to decrease a bit, but I guess I'll just have to get out Unibox and see for myself? Btw I assume it was but you don't say; was the new RS180 unshielded broken in before these measurements were taken? I guess for that matter was the old?

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              • #8
                Re: New Dayton Unshielded RS drivers - some measurements

                My guess is that using these as a "drop in" will work in most existing designs if the tweeter padding is dropped a bit. The break up modes look about the same so I'll bet the notch filters will work just fine.
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                • #9
                  Re: New Dayton Unshielded RS drivers - some measurements

                  I think Curt C also came up with a smaller box size result for the 225-8.
                  Not sure how long break-in takes but Paul has only had the drivers a day. He has free rein to keep and test the drivers until he accomplishes every test and driver combination he can think of. At the very least his work will revive his "dead computer series" and even expand it.
                  Thanks Mr. C.
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                  • #10
                    Re: New Dayton Unshielded RS drivers - some measurements

                    Yeah, I was just curious, a lot of people debate whether woofer break in is real. Well I've seen people tests a large sample of woofers, "break them in" and then test them again. The TS parameters do change, sometimes significantly. Whether this actually changes they way they sound in any manner that is detectable is debated, but the empirical numbers do change. That is the only reason why I ask if broken in or not.

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                    • #11
                      Re: New Dayton Unshielded RS drivers - some measurements

                      Originally posted by evilskillit View Post
                      Btw I assume it was but you don't say; was the new RS180 unshielded broken in before these measurements were taken? I guess for that matter was the old?
                      I "broke in" the new driver by pushing down on the cone to flex the spider a few times (technically, the only part of the driver that needs to be broken in). I also played a few minutes of 25 Hz sine waves and program material just in case.

                      The old RS180S is my own; it's been playing music for years. I hope that's broken-in enough ;)
                      Isn't it about time we started answering rhetorical questions?

                      Paul Carmody's DIY Audio Projects
                      Twitter: @undefinition1

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                      • #12
                        Re: New Dayton Unshielded RS drivers - some measurements

                        Originally posted by jclin4 View Post
                        for new designs the new unshielded RS180 might be a bit easier to work with. It does not appear to have the small peak at 3.5k in FR that the older version had.
                        Anyone who tried to notch or contour the old peak at 3.5 KHz has too much time on their hands.
                        Isn't it about time we started answering rhetorical questions?

                        Paul Carmody's DIY Audio Projects
                        Twitter: @undefinition1

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                        • #13
                          Re: New Dayton Unshielded RS drivers - some measurements

                          Great work, Paul! Thank you, sir! ;)
                          Being defeated is often a temporary condition. Giving up is what makes it permanent.

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                          • #14
                            Re: New Dayton Unshielded RS drivers - some measurements

                            Originally posted by Paul Carmody View Post
                            Anyone who tried to notch or contour the old peak at 3.5 KHz has too much time on their hands.
                            Not that I know much about this but that peak looks like 5db? I take it if you're crossing at 1500-2000hz its contribution is insignificant? And lack there of doesn't really help with crossing any higher due to the larger distortion peaks afterwards? So while having that bump be gone it doesn't really help anything? Interesting to know.

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                            • #15
                              Re: New Dayton Unshielded RS drivers - some measurements

                              I'm sure it's broken in in you hit it with some Deftones...:D
                              You abuser, you!:rolleyes:
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