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  1. #11
    Senior Member
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    The result surprised me. With a 47k input resistance that level of capacitance actually extends the HF response in a pretty flat manner. Much more and we get a characteristic overshoot at HF - which, I guess, would contribute 'brightness'. Increasing the input resistance (reducing the damping) also results in overshoot.

    So choice of cable is clearly quite significant.
    That makes sense, given the recommendations back in the CD-4 days. Those records had a 30kHz carrier and were the inspiration for the half-speed mastering craze.

    I've attached a (pdf) plot, capturing my earlier comments and this one. It may be of interest. I've also attached the 'gnuplot' script which I used to generate it, should you be minded to tinker for yourself.
    This is amazing, thank you!

  2. #12
    Senior Member Jeff07971's Avatar
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    Quote Originally Posted by mrw View Post
    I haven't, other than the electrical characteristic of the pick up coil itself (Lo and Ro), which is what I am trying to say by my comment (in the title) "Assumes negligible electrical loading on hardware".

    I have no experience of these things, nor any feel of what the magnitude would be.

    I guess the equivalent circuit might be something like adding inductance (mass), capacitance (spring), and resistance (friction), all in series with the coil. The gnuplot script as drafted does not cater for the capacitative element, although it would be easy to add. The inductive and resistive elements could be done by simply increasing the existing values for the coil.

    But, as I say, I am clueless on what those values should be. Perhaps a full technical specification of the cartridge might give us the real model to be used. This model is really only a 'toy', perhaps helpful in determining the direction of things but certainly not definitive as regards values.

    The manufacturers seem to have had a 47k input resistance in mind, and must have had an idea about typical cable/device capacitance, and designed accordingly. Possibly this model isn't too far from reality, but I don't have the knowledge to be able make a judgement.
    Theres some info here regarding simulating the equivalent circuit if th OP wants to !

    http://sound.whsites.net/articles/ca...e-loading.html

    Though it would appear that most cartridge manufacturers give the loading which achieves the flattest response

    Of course the C of the cable must be included

    Jeff
    Players: SliMP3,Squeezebox3 x3,Receiver,SqueezeLite-X,PiCorePlayer x3
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  3. #13
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    Quote Originally Posted by atrocity View Post
    That makes sense, given the recommendations back in the CD-4 days. Those records had a 30kHz carrier and were the inspiration for the half-speed mastering craze.
    I never came across those. Based on this model, it's difficult to see how that would work very well with this cartridge, given the roll off. Which said, I guess that 20dB+ of equalization might cater for it ? I have no idea how it was actually implemented.

  4. #14
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    Quote Originally Posted by Jeff07971 View Post
    Theres some info here regarding simulating the equivalent circuit if th OP wants to !

    http://sound.whsites.net/articles/ca...e-loading.html
    An excellent web-site, I have never encountered this particular page. He looks to have done the work.

    It seems that I have missed the possible influence of any core losses arising in the magnetic material around which the coil would be wound. But, then, how can one determine it, other than by measurement... so I don't know what one would actually put in the model.

    I note no apparent attempt to model the mechanical side of life. Perhaps, in practice, its behaviour is not significantly influenced by the attached electrical network.

  5. #15
    Senior Member kappclark's Avatar
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    Glad to see there are still vinyl lovers out there !

    May be old news, but I guess we can no longer ask Shure Electronics to weigh in on phono cartridges -

    http://www.shure.com/americas/news-e...phono-products

  6. #16
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    Despite Shure pulling out there are still a few around - such as Audio Technica, Goldring, Nagaoka, Ortofon, Rega, Roksan
    Paul Webster
    http://dabdig.blogspot.com
    Author Radio France (FIP etc) plugin

  7. #17
    Senior Member w3wilkes's Avatar
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    Quote Originally Posted by kappclark View Post
    May be old news, but I guess we can no longer ask Shure Electronics to weigh in on phono cartridges -

    http://www.shure.com/americas/news-e...phono-products
    Years ago I switched from Shure to Ortofon, never looked back, so no great loss in my book.
    Main system - Rock Solid with LMS 7.9.1 Official on WHS 2011 - 2 Duets and Squeeseslave
    Cabin system - Rock solid with LMS 7.9.1 Official on Win10 Pro - 1 RPi 3 Model B/Hifiberry DAC+ Pro/PiCorePlayer and Squeezeslave

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