Help with A1 dreadnaught

Goth child
Goth child Posts: 38
edited July 2009 in Vintage Speakers
Im hoping one of the many experts out there can answer a question I have pertaining to the design of the A1 dreadnaught,in particular the transformer required.The person who is makung this for me has asked me what the primary and secondary impedence of the transformer needs to be.Ive re read Darque Knights excellent post on the A1 but cant find this piece of information.Is it important?
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  • F1nut
    F1nut Posts: 50,748
    edited July 2009
    All you need to know......
    A couple of years ago, Matthew Polk provided the following specifications for a toroidal transformer based AI-1:

    "1. DC Resistance of primary and secondary should be less than 0.8 ohms and preferably less than 0.5 ohms. The lower the better.

    2. Inductance of both primary and secondary should be at least 10mH. Ideal is around 14mH.

    3. Current capacity to saturation should be 5 Amps minimum.

    4. Of course the turns ratio is 1:1."

    I sent those specs to transformer manufacturer Avel-Lindberg and they recommended the following two toroidal transformers:

    Avel Part No: Y236856, 5.4" diameter, 2.6" high, 10.8 pounds weight.

    Avel Part No. Y236906, 6.3" diameter, 2.2" high, 13.2 pounds weight.

    I chose the Y236906 since it was the more robust of the two and its specifications exceeded the requirements. Listening evaluations confirmed that The Y236906 works exceptionally well.

    Y236906 Specs:

    DC Resistance: 0.275 ohms primary winding, 0.360 ohms secondary winding. The dual primary and secondary windings were wired in parallel as follows:

    Right Pin = Red/Yellow

    Right Blade (Negative Speaker Terminal) = Black/Orange

    Left Pin = Grey/Brown

    Left Blade (Negative Speaker Terminal) = Blue/Violet

    Inductance : 153.3 mH primary, 168.8 mH secondary.

    Output Current Capacity: 6.95 Amps

    Output Current Capacity To Saturation: 6.32 Amps.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • Goth child
    Goth child Posts: 38
    edited July 2009
    Thanks for the quick reply.I have already forwarded this information to the person making this for me.It mentions the inductance and the resitance but not the impedance which is the information he is after.Excuse my ignorance on the matter,its all beyond me,which is why I am getting some one else to make it!
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  • F1nut
    F1nut Posts: 50,748
    edited July 2009
    All you need to do is order the following, Avel Part No. Y236906 and have the person connect it up as posted above.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • george daniel
    george daniel Posts: 12,096
    edited July 2009
    +1 Been there done that,,Jesse won't steer you wrong,, just do it,it'll work just fine,good luck.:)
    JC approves....he told me so. (F-1 nut)
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  • Goth child
    Goth child Posts: 38
    edited July 2009
    Thanks guys.I think the problem is that I am in New Zealand and the company making it for me was trying to find an alternative transformer from another supplier that they already deal with.I will suggest that they just order the avel.
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  • Goth child
    Goth child Posts: 38
    edited July 2009
    OK so the avel transformer has been ordered and will soon be on its way to NZ.Once we are all done I will post some photos and comments on the results.My 2 channel system will consist off a Sony scdxa5400es cdp,audio Experience A2 special edition balanced tube pre,ATI At3000 350watt balanced power amp,wireworld eclipsemk3 balanced interconnects,wireworld eclipse mk3 bi wire cable,Polk srs1.2tls with rdo tweeters.All components use Belkin sd1000 high current power cables and evrything is protected by the Belkin pf60 console.Cant wait!
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  • bsoko2
    bsoko2 Posts: 1,449
    edited July 2009
    Goth child wrote: »
    OK so the avel transformer has been ordered and will soon be on its way to NZ.Once we are all done I will post some photos and comments on the results.My 2 channel system will consist off a Sony scdxa5400es cdp,audio Experience A2 special edition balanced tube pre,ATI At3000 350watt balanced power amp,wireworld eclipsemk3 balanced interconnects,wireworld eclipse mk3 bi wire cable,Polk srs1.2tls with rdo tweeters.All components use Belkin sd1000 high current power cables and evrything is protected by the Belkin pf60 console.Cant wait!

    I have had mine for several months now and you will notice the difference in the audio. The sound stage opens up like never before and you notice more subtle notes in the music.

    Bill
    My 2012 HT Room - http://www.avsforum.com/t/1416077/bsoko2-new-ht-june-2012
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  • Polkie2009
    Polkie2009 Posts: 3,834
    edited July 2009
    Sounds like a great idea,I'll see if I can buy a used one.
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