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Jaycar Valve Amp

Discussion in 'Hobby Electronics' started by David L. Jones, Oct 29, 2008.

  1. Re. the Jaycar Valve amp that was mentioned on here a few weeks back.
    http://www.jaycar.com.au/productView.asp?ID=AA0474

    In this months SC ad Jaycar have printed an appology about the product being
    deceptive and are offering a refund to anyone who bought it. They are even
    offering a $30 gift voucher to people who still want to keep it.

    Dave.
     
  2. Why is it deceptive?
     
  3. Jasen Betts

    Jasen Betts Guest

    the advertising blurb nowhere says that the output stage is solid state.
    'hybrid' has many interpretations.

    Bye.
    Jasen
     
  4. Apparently because they didn't adequately tell people it used a solid state
    output stage. At least one aus.electronics member got duped and posted a
    rant here about it a few weeks back.
    At the time though the web page for the product is as you see it now, it
    clearly says it's solid state, so not deceptive at all as far as the web
    page goes.
    I don't know what the box or any other in-store or print advertising said
    though.

    Dave.
     
  5. Andy Wood

    Andy Wood Guest

    From that story:

    "They're using the 16V transformer winding in series with a diode to
    function as a dropper. Here is a 19V peak half wave rectified sine
    wave to feed the heaters. The idea is that by chopping off half the
    sine wave is that you feed half power into the load (valve heater).
    ...

    This is the waveform showing 5.72V DC on the DMM. The RMS value is
    closer to 8.5V. "

    I'm not sure where that peak value of 19V came from. I also don't know
    why I need to know the peak voltage, so perhaps it is not surprising
    that I don't know how to come up with a value of 8.5V for the RMS
    value.

    The diode halves the power. That is equivalent to reducing the voltage
    to 11.3V ( 16V divided by SQRT(2) ). The voltage drop across the
    diode is not going to make that much of a difference, is it?

    Andy Wood
     
  6. Oh well, if you are dumb enough to buy a valve amp for anything other
    than the eye candy value then you deserve what you get.
     
  7. ZACK

    ZACK Guest

    on the back of the amp reads tube or valve amp
    never ses hybrid or with solid state output.
    yes i fell into that trap.
    im now making a mod to fix the heater problem
    by useing a regulater to bring those heaters down
    where thay sould be.
    oh and theres another diode on the other side
    that powers the relay for the speakers dthump
    that diode has blown twise, im fixing that to.
    i hate it when i have to mod things to make them
    work properly.
     
  8. Why on earth don't you take it back and get a refund?

    Dave.
     
  9. ZACK

    ZACK Guest

    on the back of the amp reads tube or valve amp
    never ses hybrid or with solid state output.
    yes i fell into that trap.
    im now making a mod to fix the heater problem to bring those heaters down
    where thay sould be.
    oh and theres another diode on the other side
    that powers the relay for the speakers dthump
    that diode has blown twise, im fixing that to.
    i hate it when i have to mod things to make them
    work properly.
     
  10. ZACK

    ZACK Guest

    problem solved, heaters now at
    normal heat.
    mod has been made
     
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