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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    Headphone Impedance Question

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    scrotuss


    Posts : 21
    Join date : 2012-12-16

    Headphone Impedance Question Empty Headphone Impedance Question

    Post by scrotuss Wed Apr 24, 2019 9:08 pm

    I have a couple of amazon cheapo devices (one d/a converter and one class D amp) that have headphone outputs.  Unfortunately, my headphones of choice are the good old Koss Pro4aa (despite the cauliflower ear and neckache, I love 'em) which have a 250 ohm impedance.  The headphone outputs of these devices are designed for low impedance phones and I can't get loud volume with my phones.  Does anyone know of a cheap and dirty inline audio transformer for headphone impedance matching?- a 10:1 ratio would probably be perfect.
    Peter W.
    Peter W.


    Posts : 1351
    Join date : 2016-08-07
    Location : Melrose Park, PA

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    Post by Peter W. Thu Apr 25, 2019 6:20 am

    You could probably make one - look for a 10:1 audio grade transformer (pair) from Hammond, Mouser or similar. But, better you should look into a pair of Grado low-impedance headphones - made in Brooklyn, NY - and go from there. They are open-air, over-the-ear devices and do very nicely.

    I am in training this week, and so have no time to hunt around, but I keep a pair of 4AAA and Grados for the varying needs.
    Peter W.
    Peter W.


    Posts : 1351
    Join date : 2016-08-07
    Location : Melrose Park, PA

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    Post by Peter W. Fri Apr 26, 2019 1:37 pm

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    scrotuss


    Posts : 21
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    Post by scrotuss Fri Apr 26, 2019 2:47 pm


    Thanks Peter. That is more than what I was looking to do. I guess that people with high impedance cans are expected to go out and get a fancy headphone amp.  I looked at the Grado site- Unfortunately, all open back phones... not what I need for my application.  I might spring $60 for a pair of Status headphones on Amazon- they seem to be well regarded, if flimsy.
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    scrotuss


    Posts : 21
    Join date : 2012-12-16

    Headphone Impedance Question Empty cMoy Headphone Amp Circuit

    Post by scrotuss Mon Apr 29, 2019 8:30 pm

    Does anyone have any experience with one of these?  It looks like the design has been around for a few years, and many have tweaked it.
    Seems the one design feature cast in concrete is that it must fit into an Altoids box.
    I was looking at a kit from JDS labs > https://jdslabs.com/product/cmoybb-diy-kit-standard/.  It looks like a fun kit and it can be tailored to high impedance headphones.
    Zimmer64
    Zimmer64


    Posts : 123
    Join date : 2013-01-29
    Age : 60
    Location : Switzerland

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    Post by Zimmer64 Tue Apr 30, 2019 2:42 pm

    What is your source? If from a computer or phone, maybe a Cyrus Soundkey or a AudioQuest Dragonfly or an Apogee Groove is an alternative. Or a full fledged headphone amp.
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    scrotuss


    Posts : 21
    Join date : 2012-12-16

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    Post by scrotuss Tue Apr 30, 2019 5:07 pm

    Zimmer64 wrote:What is your source? If from a computer or phone, maybe a Cyrus Soundkey or a AudioQuest Dragonfly or an Apogee Groove is an alternative. Or a full fledged headphone amp.
    I checked and it seems that those products are DACs. I don't need a DAC.  I've got a few devices (DAC, CD player, etc.) with earphone/headphone outs designed for low impedance phones, and I'd like to use my 250 ohm headphones- the low impedance outputs won't drive the phones sufficiently. Even the cMoy amp kit I'm looking at requires 18v ( pwr. supply or 2-9v batteries) in order to drive high impedance phones.  I was hoping that someone sold a cheap'n'dirty inline matching transformer, but no dice.

    The sources I'm talking about here are not what I'd consider to be HiFi, so I'm more interested in size and convenience here..

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