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Thread: Moving Coil Cartridge loading

  1. #11
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

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    Quote Originally Posted by Firebottle View Post
    Hi Steve, there is another option, that is to get the internal resistors changed to 100 ohms.

    I could do this for you if you cover postage both ways, it's a small job to do.
    Thanks very much for the offer, sounds like the only and best option, PM me with your details.
    Cheers
    Steve


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  2. #12
    Join Date: Dec 2015

    Location: Alicante. Spain.

    Posts: 1,885
    I'm Adrian.

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    I bought them from a fellow member, this is the original thread. Not sure if I'm breaking rules.

    https://r.tapatalk.com/shareLink?url...7&share_type=t

    [IC]: RTJ Phono equalisers - experimental resistance/capacitance sets
    Technics SP10 mk2
    Jan Allaerts MC 1 Boron mk1 cart
    Miyajima Shilabe cart
    Hashimoto HM-X SUT
    Siggwan (gimballed not unipivot) Cocobola 12"
    Aurorasound Vida LCR Phonostage
    The Truth linestage
    Dave Slagle Autoformer Volume Controller
    Cary 805c SET amps
    Audio Note ANe-SPX speakers
    Townshend Isolda speaker cables
    Cardas Golden Presence interconnects

  3. #13
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

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    Quote Originally Posted by farflungstar View Post
    I bought them from a fellow member, this is the original thread. Not sure if I'm breaking rules.

    https://r.tapatalk.com/shareLink?url...7&share_type=t

    [IC]: RTJ Phono equalisers - experimental resistance/capacitance sets
    Do they add series resistance? as another member suggested adding resistance in parallel will reduce the value not increase it. 50-100 ohms extra would be ideal, are any of the set suitable ?


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  4. #14
    Join Date: Dec 2015

    Location: Alicante. Spain.

    Posts: 1,885
    I'm Adrian.

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    I'm not sure whether it's series or parallel to be honest - but I noticed no degradation in quality when I played with them and the Vida/Hashimoto.

    Will check values and get back.
    Technics SP10 mk2
    Jan Allaerts MC 1 Boron mk1 cart
    Miyajima Shilabe cart
    Hashimoto HM-X SUT
    Siggwan (gimballed not unipivot) Cocobola 12"
    Aurorasound Vida LCR Phonostage
    The Truth linestage
    Dave Slagle Autoformer Volume Controller
    Cary 805c SET amps
    Audio Note ANe-SPX speakers
    Townshend Isolda speaker cables
    Cardas Golden Presence interconnects

  5. #15
    Join Date: Dec 2015

    Location: Alicante. Spain.

    Posts: 1,885
    I'm Adrian.

    Default

    The 3 pairs add, 30k, 75k, 150k - with combinations as per the chart.
    Technics SP10 mk2
    Jan Allaerts MC 1 Boron mk1 cart
    Miyajima Shilabe cart
    Hashimoto HM-X SUT
    Siggwan (gimballed not unipivot) Cocobola 12"
    Aurorasound Vida LCR Phonostage
    The Truth linestage
    Dave Slagle Autoformer Volume Controller
    Cary 805c SET amps
    Audio Note ANe-SPX speakers
    Townshend Isolda speaker cables
    Cardas Golden Presence interconnects

  6. #16
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default

    Quote Originally Posted by farflungstar View Post
    The 3 pairs add, 30k, 75k, 150k - with combinations as per the chart.
    Doesn't look like they will work for me as the values are much too high, but thanks anyhow :-)


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  7. #17
    RothwellAudio Guest

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    Firstly, putting resistance in parallel with the input can only reduce the input impedance. You can raise the input impedance with a series resistor but I wouldn't recommend that because you will be attenuating the signal going into the phonostage and degrading the signal-to-noise ratio.

    Secondly, having a low input impedance is unlikely to make the cartridge sound shrill. If anything, it's more likely to make it sound dull. More likely still is that the sound will be fine at 47 ohms. Yes, it's a bit lower than is common but it will be fine with many LOMCs. Just choose a cartridge with a source impedance less than 12 ohms and you will be ok, and there are lots to choose from.

    BTW, the idea of changing an internal resistor might work, but that will depend on the circuit. With simple op-amp circuits it probably would work, but it might be a completely different type of circuit. Also, if it uses surface mount components it could be an extremely fiddly job. Some surface mount components are hardly any bigger than a grain of sand!

  8. #18
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default Moving Coil Cartridge loading

    Quote Originally Posted by RothwellAudio View Post
    Firstly, putting resistance in parallel with the input can only reduce the input impedance. You can raise the input impedance with a series resistor but I wouldn't recommend that because you will be attenuating the signal going into the phonostage and degrading the signal-to-noise ratio.

    Secondly, having a low input impedance is unlikely to make the cartridge sound shrill. If anything, it's more likely to make it sound dull. More likely still is that the sound will be fine at 47 ohms. Yes, it's a bit lower than is common but it will be fine with many LOMCs. Just choose a cartridge with a source impedance less than 12 ohms and you will be ok, and there are lots to choose from.

    BTW, the idea of changing an internal resistor might work, but that will depend on the circuit. With simple op-amp circuits it probably would work, but it might be a completely different type of circuit. Also, if it uses surface mount components it could be an extremely fiddly job. Some surface mount components are hardly any bigger than a grain of sand!
    Thanks for the info, I'm just puzzled why Schiit have set their input impedance lower than everyone else. The one review of the Mani on YouTube I've seen concluded that the MC performance of the Mani was inferior to its performance on MM which they rate very highly, my worry is that changing to a cartridge which is not optimal on MC will actually give me worse performance than my Nagaoka MP110. Both AT cartridges I'm considering are 12ohm coil impedance.


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  9. #19
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

    Default

    Quote Originally Posted by RothwellAudio View Post
    BTW, the idea of changing an internal resistor might work, but that will depend on the circuit. With simple op-amp circuits it probably would work, but it might be a completely different type of circuit. Also, if it uses surface mount components it could be an extremely fiddly job. Some surface mount components are hardly any bigger than a grain of sand!
    Andrew I'm familiar with the build and circuit (not exact details) and I am sure it would be a straight swap out of surface mount resistors.
    I have a good stock of these.

    Steve, pm sent.

  10. #20
    RothwellAudio Guest

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    Quote Originally Posted by steve-z View Post
    Thanks for the info, I'm just puzzled why Schiit have set their input impedance lower than everyone else.
    There's an almost trivially simple way to "design" a preamp for a LOMC, and that's to use an opamp. The resistor which defines the load impedance in such a circuit can be almost anything, and it's often set at about 100 ohms.
    However, if you design a circuit using discrete transistors it isn't so simple and the available range for the input impedance could be constrained by other elements of the circuit such as resistors used to bias the transistors. I don't know the details of the Schiit circuit so can't offer a more detailed explanation.

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