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

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  • #91
    Re: Hmm, Dayton RS28F - F??? What have we here?

    sub harmonics are produced by IM as well. 10KHz and 11KHz will produce a 1KHz sub harmonic.
    Of course, but please reread my post: "sub harmonics are never mentioned for one tone tests"

    The issue is sub harmonics with a single tone input.

    I think we all know the definition of IM distortion.

    Dave


    PS Just saw mark's post. I was working on the assumption dlr was asking about sub-harmonics with a one tone test based on his comment "there is a spike seen on all of the measurements that appears to be precisely at a subharmonic of 1/5 of the fundamental".

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    • #92
      Re: Hmm, Dayton RS28F - F??? What have we here?

      Originally posted by markk View Post
      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.
      Mark, thanks for clearing that up. I've grown attached to using multi tone tests too, they provide a good visual indication of the clutter from IM with real signals. I weight my tone inputs to be more representative of the spectral density of real music.

      Dave

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      • #93
        Re: Hmm, Dayton RS28F - F??? What have we here?

        Originally posted by Deward Hastings 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.
        MLSSA will measure uncorrelated Noise+distortion (and has for 20 years probably), so someone is listening. These plots can be very illustrative of issues localized over a frequency range by the presence spikes in the plot over f.

        I find them hard to interpret when low in level though. How bad is one smooth plot vs another and what is the threshold crossed where the illustrated performance is problematic?

        Klippel also provides a measure where he looks at the time variance of the non linearities by plotting rms and peak anomilies over frequency. This is especially helpful since most "meters" don't average sound over time the same way the ear does.

        Dave

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        • #94
          Re: What midbass used here?

          Originally posted by critofur View Post
          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
          That explains why it is rear mounted.

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