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Thread: Moving Coil Cartridge loading

  1. #1
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default Moving Coil Cartridge loading

    I’m currently using a Nagaoka MP110 on my 2016 Rega Planar 3, the output is then fed to a Schiit Mani phono stage, the combination considering the relatively modest cost gives a pretty decent sound quality. Having been a previous user, over a period of 30+ years, of moving coil cartridges I am hankering after getting another. The Mani has gain settings to accommodate MM and MC cartridges but I’m a little concerned over MC compatibility as the input impedance on the MC input is only 47ohms, considerably lower than the norm used by other manufacturers of 100-200ohms. From what I’ve read online the load impedance for a good match should be 10-20x the cartridges coil impedance, as most MCs coil impedance is around 10-12ohms 47ohms is too low, enough to mess up the frequency response at HF making for a sharp or brittle sound. I emailed Schiit with my concerns and tbh they could not give me any constructive help at all particularly when I asked why they set the value so low. If I get a moving coil I do not want to change the phono stage again. What I really want to know, is it possible to add some extra impedance to the preamp without going into the preamp circuitry. I remember some time ago seeing some loading plugs but I think they were to add capacitance loading not impedance, is there anything similar to add impedance ?


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  2. #2
    Join Date: Dec 2015

    Location: Alicante. Spain.

    Posts: 1,885
    I'm Adrian.

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    I have some beautifully made plugs for resistance should you be interested..

    Adey
    Technics SP10 mk2
    Jan Allaerts MC 1 Boron mk1 cart
    Miyajima Shilabe cart
    Hashimoto HM-X SUT
    Siggwan (gimballed not unipivot) Cocobola 12"
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    The Truth linestage
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    Townshend Isolda speaker cables
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  3. #3
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

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    Quote Originally Posted by farflungstar View Post
    I have some beautifully made plugs for resistance should you be interested..

    Adey
    Sounds good, any idea what I’d need to raise 47ohms to 100-150, is it just a question of adding 50-100ohms more ?


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  4. #4
    Join Date: Dec 2015

    Location: Alicante. Spain.

    Posts: 1,885
    I'm Adrian.

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    I'm at work at the minute but will check the plugs for you in the morning. They can be piggybacked to give many different values and are exceptional quality.

    Adey
    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. #5
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default

    Quote Originally Posted by farflungstar View Post
    I'm at work at the minute but will check the plugs for you in the morning. They can be piggybacked to give many different values and are exceptional quality.

    Adey
    Thanks that would be great.


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  6. #6
    Join Date: Apr 2012

    Location: London

    Posts: 685
    I'm James.

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    Quote Originally Posted by steve-z View Post
    Thanks that would be great.


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    There's a lot of MC carts that prefer low impedance loading. What are you considering?
    My limited experience suggests to me that a low input impedance to the phono stage should reduce the HF rise rather than the opposite, so I'd be inclined to try before you buy any loading plugs: they may not be necessary.

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  7. #7
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default Moving Coil Cartridge loading

    I’m looking at the Audio Technica ATF2 or ATF7, AT state a minimum of 100ohms input impedance in their spec sheet. According to some articles I’ve read online the low impedance does cause a droop in upper mid to lower treble but then a large rise at HF causing a sharp or brittle sound.


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  8. #8
    Join Date: Mar 2015

    Location: Finland

    Posts: 237
    I'm Kai.

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    You can't rise the impedance with plugs. So if your preamp has 47 ohms, that's the highest you can get without going inside. Plugs will only lower it.

    I think 5x cart impedance is usually still fine, but going lower from that it starts to go downhill. But only way to really know for sure is to try, and some people seem to prefer the sound you get running the cartridge into "too low" impedance. At some point you start to loose output because more current is flowing through the cartridge and that will also affect it in other ways, IME soundstage starts to collapse among other things.

  9. #9
    Join Date: May 2013

    Location: Rotherham

    Posts: 693
    I'm steve.

    Default Moving Coil Cartridge loading

    Quote Originally Posted by helma View Post
    You can't rise the impedance with plugs. So if your preamp has 47 ohms, that's the highest you can get without going inside. Plugs will only lower it.

    I think 5x cart impedance is usually still fine, but going lower from that it starts to go downhill. But only way to really know for sure is to try, and some people seem to prefer the sound you get running the cartridge into "too low" impedance. At some point you start to loose output because more current is flowing through the cartridge and that will also affect it in other ways, IME soundstage starts to collapse among other things.
    Sounds like I’m screwed then :-( Can’t understand why Schiit have to be different from Project, Cambridge Audio etc that all load at 100ohms. Even at 5x the coil impedance (12ohms) it’s still on the low side and the last thing I want is a droop in the mid treble.
    Can’t really afford to spend £200 and it possibly be a waste just to try it and see if it works.

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  10. #10
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

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    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.

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