Transformer question

Discussion in 'Hi-Fi and General Audio' started by anon_bb, Dec 30, 2006.

  1. anon_bb

    anon_bb Honey Badger

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    The stevens and billington stepup I am currently using has settings of 14, 20 and 26 db gain. Currently it is set to 20 and the phono stage is set to 46 db gain. Would I get better results turning the phono stage gain right down to 40 db and putting the stepup to 26db gain? In addition this would remove the need for the current resistive and capacitive loadings which might also improve matters further. Any ideas?
     
    anon_bb, Dec 30, 2006
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  2. anon_bb

    felix part-time Horta

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    If its relatively straightforward to do it could be worth trying. It will double the load (halve the impedance) seen by the cartridge if the phono stage input impedance remains unchanged though, and may do slightly strange things to frequency response due to the increased effects of the transformer's parasitics at the higher step-up ratio.

    Actually I think my inclination would be to use less step-up and more active gain, but this is rather outside my experience. There you are, no help at all really...
     
    felix, Dec 30, 2006
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  3. anon_bb

    anon_bb Honey Badger

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    The 26db setting should make the loading ideal for the cartridge (which is a brinkmann emt). Also the emt requires around 500 pF capacitive loading (cartridge to phono input buffer). Currently I use a 270 pf loading on the primary (and 10k resistive loading on the secondary) so I should be able to get rid of that too. The phono stage is an FM Research 122.
     
    anon_bb, Dec 30, 2006
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  4. anon_bb

    hifi addict

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    Your Just rubbing it in now about the FM 122.

    I would go for the highest step up ratio. But as we all know try it in all its settings to see what you prefer. I'm going to see Johnathan Billington On Tuesday. I will ask him and I will post his reply.
     
    hifi addict, Dec 30, 2006
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  5. anon_bb

    anon_bb Honey Badger

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    Thanks - I would appreciate that.
     
    anon_bb, Jan 1, 2007
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  6. anon_bb

    hifi addict

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    Right,

    I spoke to Johnathan Billington today and he made a few sketches and diagrams. i sort of understood but I have to say I am not qualified to decypher it all. However, on the Stevens and Billington Website he doeas have a graph showing what you need.

    If you have a ready built complete step up unit from Music First then you would just set it to what you need.

    Any how have a look at Stevens and Billington page on the Step up.

    http://www.stevens-billington.co.uk/page103.htm

    I hope this is of use to you.
     
    hifi addict, Jan 3, 2007
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  7. anon_bb

    hifi addict

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    Just to add I believe Thorston Did the graphs for Stevens and Billington.
     
    hifi addict, Jan 3, 2007
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  8. anon_bb

    anon_bb Honey Badger

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    Hi,

    I already have the info to make the conversion - my query more concerned wether it would be better to split the gain 26/40 or 20/46, putting more in the stepup and also removing the need for a loading capacitor and resistor.

    Regards,

    Nick.
     
    anon_bb, Jan 3, 2007
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  9. anon_bb

    hifi addict

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    Nick,

    I gave your question to Johnathan today and he will email me a response.

    PM me (don't worry I won't try to sell anything)

    regards

    Paul
     
    hifi addict, Jan 3, 2007
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  10. anon_bb

    anon_bb Honey Badger

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    Well I removed the loading resistors and caps and set to 26db - huge improvement!

    Effective loading is now just under 120 ohms instead of about 90 ohms but the FM MM module has options for 100k 47k 33k and 10k loading so I may try 33k to see how it sounds. The parisitic capacitance in the high gain mode must be just about right for the emt.
     
    anon_bb, Jan 31, 2007
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  11. anon_bb

    Tenson Moderator

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    Good news :) That bake-off will have to happen sooner or later! :D
     
    Tenson, Feb 1, 2007
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