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Hmm, Dayton RS28F - F??? What have we here?

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  • #76
    Re: Hmm, Dayton RS28F - F??? What have we here?

    Originally posted by markk View Post
    Verrrrry interesting, Mark. The SB Acoustics blurb about better off-axis performance for the SB29 seems questionable. I suppose they're comparing to the SB25. The RS28F is clearly the winner and is overall more linear, though after equalization it's probably a wash.

    For practical applications it does look like the only real difference is the top end directivity, at least for me, since I almost always use tweeters in systems that requre they be padded anyway. The one other very slight quality difference is the very small one in faceplate diameter, not enough to matter in my book. That and $1.25 more for the SB.

    dlr
    WinPCD - Windows .NET Passive Crossover Designer

    Dave's Speaker Pages

    Comment


    • #77
      Re: Hmm, Dayton RS28F - F??? What have we here?

      Originally posted by markk View Post
      I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.

      Comment


      • #78
        Re: Hmm, Dayton RS28F - F??? What have we here?

        Originally posted by DDF View Post
        I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.
        It's the noise from all those silk fibers rubbing together. ;)

        Don't have the problem with 'luminum. :D
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

        Comment


        • #79
          Re: Hmm, Dayton RS28F - F??? What have we here?

          Originally posted by DDF View Post
          I wonder what the HF hash is all about on the RS28F at 2 kHz? Looks like something is buzzing but its way down in level.
          There are a few other of Mark's measurements with some HF hash, Test Group 5 for example. I attributed that to something minor in his test rig, thinking it might be reflections from the mic clamp. All three drivers in this test group have it. Now that you mention buzzing, it does appear to be more of a ringing/buzzing signal intruding since reflections from the stand/clamp wouldn't ring that way.

          What would be the influence of that on distortion measurements?

          In the distortion measurements, there is a spike seen on all of the measurements that appears to be precisely at a subharmonic of 1/5 of the fundamental. It's in all of them and relatively high in level and few if any others are prominent, maybe only one in the Tang-Band.

          Looking again, the relative level seems constant between all of them for the 1/5, the T-B the only one with any significant output in the other subharmonics. In Test Group 5, the LPG looks particularly bad, but the 1/5th is rather strong even in the SS6600.

          Interestingly, the North Creek D28 has little between fundamental and 1/5 and at 1/5 it's lower in level than any of the others. To what can this be attributed?

          What's the impact of the subharmonic as far as the relative ranking goes or is it simply to be ignored as an artifact of testing?

          dlr
          WinPCD - Windows .NET Passive Crossover Designer

          Dave's Speaker Pages

          Comment


          • #80
            Re: Hmm, Dayton RS28F - F??? What have we here?

            Originally posted by dlr View Post
            What would be the influence of that on distortion measurements?


            dlr
            Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

            If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.

            This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

            http://www.elec.qmul.ac.uk/people/jo...oudspeaker.pdf

            This one could shed light, but I don't have it:
            http://www.aes.org/e-lib/browse.cfm?elib=12584

            There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

            Dave

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            • #81
              Re: Hmm, Dayton RS28F - F??? What have we here?

              Originally posted by DDF View Post
              Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

              If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.

              This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

              http://www.elec.qmul.ac.uk/people/jo...oudspeaker.pdf

              This one could shed light, but I don't have it:
              http://www.aes.org/e-lib/browse.cfm?elib=12584

              There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

              Dave
              sub harmonics are produced by IM as well. 10KHz and 11KHz will produce a 1KHz sub harmonic.
              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

              95% of Climate Models Agree: The Observations Must be Wrong
              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

              Comment


              • #82
                Re: Hmm, Dayton RS28F - F??? What have we here?

                Hi guys,

                This is what to expect, courtesy of SL-there can be much more of course!



                The subharmonic is a pretty typical constant

                I'll have more to say about the hash later (work) but that is very important!
                audioheuristics isn't around right now...

                Comment


                • #83
                  Re: Hmm, Dayton RS28F - F??? What have we here?

                  I guess the F in RS28F stands for: Fantastic, or, Fabulous?

                  Mark, what do you think about the power response of your RS225-28 2-way design in terms of how it relates to the listening experience. Compared, say, to your more recent designs.

                  I have no idea if this applies to your RS 2-way - but some people have commented about other all metal RS designs they had, they enjoyed the clarity, and some other aspects, but in the end, found them a little too "harsh" and "fatiguing".

                  I do know that I have REALLY liked RS225 speakers in some that I have heard, including 2-ways (albeit with non-metal tweeters).

                  I had some paper woofer paper tweeter inexpensive 2-way bookshelf speakers from the 70's that I used to find really enjoyable for listening to pop + rock records, radio, mix tapes. Don't recall if they had any "imaging" and I never said "wow, they're so revealing, I never heard that part of the music on other stereos" :P
                  "...this is not a subwoofer" - Jeff Bagby ;)

                  Comment


                  • #84
                    Re: Hmm, Dayton RS28F - F??? What have we here?

                    So the 28F is not interchangeable with the 28A, correct?

                    Comment


                    • #85
                      Re: Hmm, Dayton RS28F - F??? What have we here?

                      Originally posted by DDF View Post
                      Mark would be the go-to guy to answer these, but other than the jammie chaffing raised by Pete, the usual cause of frequency dependant buzz in a good driver is driver mounting.

                      If it's truly a sub-harmonic, that's pretty rare. I read through Klippel's site again, and sub harmonics are never mentioned for one tone tests, just multi-tone (maybe there's hum in Mark's set up?). It would be odd to see it across a number of drivers with one tone present.
                      This paper predicts sub-harmonics as appearing just before the driver goes chaotic:

                      http://www.elec.qmul.ac.uk/people/jo...oudspeaker.pdf

                      This one could shed light, but I don't have it:
                      http://www.aes.org/e-lib/browse.cfm?elib=12584

                      There's also a mechanism which creates sub-harmonics in compression drivers (my guess is excessive throat velocity creating distortion in the air itself), but that wouldn't apply here.

                      Dave
                      Dave,

                      The stimulus is a 3 tone test. It's the same one SL uses. I've been using it so long it's just a convenient, well known and interpretable test for me. I know there are pros and cons to this three tone test, but I've developed a fondness to it that I don't have for simple HD testing.

                      http://www.linkwitzlab.com/frontiers.htm#G

                      So it's all HD+IM.
                      audioheuristics isn't around right now...

                      Comment


                      • #86
                        Re: Hmm, Dayton RS28F - F??? What have we here?

                        Originally posted by critofur View Post
                        I guess the F in RS28F stands for: Fantastic, or, Fabulous?

                        Mark, what do you think about the power response of your RS225-28 2-way design in terms of how it relates to the listening experience. Compared, say, to your more recent designs.

                        I have no idea if this applies to your RS 2-way - but some people have commented about other all metal RS designs they had, they enjoyed the clarity, and some other aspects, but in the end, found them a little too "harsh" and "fatiguing".

                        I do know that I have REALLY liked RS225 speakers in some that I have heard, including 2-ways (albeit with non-metal tweeters).

                        I had some paper woofer paper tweeter inexpensive 2-way bookshelf speakers from the 70's that I used to find really enjoyable for listening to pop + rock records, radio, mix tapes. Don't recall if they had any "imaging" and I never said "wow, they're so revealing, I never heard that part of the music on other stereos" :P
                        I don't think my RS22528A is in any way fatiguing. I think that many systems are a bit bright/forward. (see dBe's comments) If a metal coned system is slightly bright, the blame is laid on the cone material. If well designed, metal cones shouldn't sound bright/edgy/fatiguing. Lot's of paper cones sound bright and fatiguing... Still, it takes some effort to really tame metal cones.

                        The power response is a different question, and I do think that higher order xovers have a certain presentation. I'm loath to overgeneralize based on the N=1 study of my ER18DXT vs every other speaker I've designed which is 4LR or higher...

                        The problem with using a metal cone is that it's almost mandatory to use 4lr or higher to tame the metal, so clear comparisons can't be made. I do think that "fatiguing" is mostly in the crossover, then the source material.

                        Originally posted by Wushuliu View Post
                        So the 28F is not interchangeable with the 28A, correct?

                        You mean as a drop in replacement in a completed design? I don't think so, although I bet it's pretty close. You shouldn't have to make much more than some small changes to whatever xover you're using.
                        audioheuristics isn't around right now...

                        Comment


                        • #87
                          Re: Hmm, Dayton RS28F - F??? What have we here?

                          Originally posted by markk View Post
                          I'd go so far as to say forget the HD (except as an easily measured proxy for more audible distortion) . . . it's the IM and resonances and aliasing and noise that place signal at frequencies and times where they were not in the original (along with cone breakup and reflection and re-radiation in and from speaker boxes). And I'd be repeating what has been known, and said, and mostly ignored, for decades.
                          "It suggests that there is something that is happening in the real system that is not quite captured in the models."

                          Comment


                          • #88
                            Re: Hmm, Dayton RS28F - F??? What have we here?

                            Originally posted by Wushuliu View Post
                            So the 28F is not interchangeable with the 28A, correct?
                            Did you see this picture earlier in the thread?:



                            I've seen more variation between some tweeters of the same exact model, than between the RS28A and RS28F in the "crossover range" - I wouldn't worry so much about the high frequency variation (above 10Khz) other than to say the F will be a little flatter 15 - 30 degrees off axis than the A due to the slightly rising response on the top end.

                            If you do switch an F in place of an A, nothing more than an L-pad, or, half an L-pad should do the trick? I would listen without any changes first though.
                            "...this is not a subwoofer" - Jeff Bagby ;)

                            Comment


                            • #89
                              Re: Hmm, Dayton RS28F - F??? What have we here?

                              Originally posted by Jeff B. View Post
                              You heard it in my little speakers in Auburn, this past spring.

                              Jeff,

                              Just curious as to what midbass is being used here?

                              Comment


                              • #90
                                RE: What midbass used here?

                                Originally posted by KeithL View Post
                                Jeff,

                                Just curious as to what midbass is being used here?
                                He's using the Auram Cantus AC130F-1 : http://www.parts-express.com/pe/show...number=296-400

                                See a post of his about it here: http://techtalk.parts-express.com/sh...4&postcount=11
                                "...this is not a subwoofer" - Jeff Bagby ;)

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