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Thread: JAVA LDR passive pre-amp: Live now on Kickstarter

  1. #11
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 866
    I'm Chris.

    Default

    Quote Originally Posted by lurcher View Post
    Yep, but passive potentiometer don’t have "THD: 0.03 % @ 1.8V"
    Hi Nick
    LDR's indeed can be made to behave as a passive potentiometer when arranged
    the same, ie both devices as a passive L Pad circuit.

    Your comments have combined what has been used as the DC measurements via the anode and cathode
    to achieve low THD, and you have correctly pointed out fundamental differences in design to switches
    with mechanical wiping contacts.

    LDR's are a four terminal device, on one side a anode and cathode,
    with the form of a very small red wavelength LED having a forward voltage
    with resistance ON of 1.8v and Resistance off approx 1.32v

    On their other side a variable resistor, varied by more or less
    light intensity. They are an opto coupler, possessing excellent
    attributes for audio.
    LDR internal.jpeg

    Cheers / Chris

  2. #12
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 866
    I'm Chris.

    Default

    Quote Originally Posted by Arkless Electronics View Post
    That'll be yer cadmium sulphide innit....
    Hi Jez
    The signal side variable resistor also has selenium , the combination of
    these two elements forms a photo conductive variable resistor, posessing
    unique and excellent audio properties.

    Cheers / Chris

  3. #13
    Join Date: Mar 2008

    Location: Halifax, UK

    Posts: 1,416
    I'm Nick.

    Default

    Quote Originally Posted by Light Dependant Resistor View Post
    Hi Nick
    LDR's indeed can be made to behave as a passive potentiometer when arranged
    the same, ie both devices as a passive L Pad circuit.

    Your comments have combined what has been used as the DC measurements via the anode and cathode
    to achieve low THD, and you have correctly pointed out fundamental differences in design to switches
    with mechanical wiping contacts.

    LDR's are a four terminal device, on one side a anode and cathode,
    with the form of a very small red wavelength LED having a forward voltage
    with resistance ON of 1.8v and Resistance off approx 1.32v

    On their other side a variable resistor, varied by more or less
    light intensity. They are an opto coupler, possessing excellent
    attributes for audio.
    LDR internal.jpeg

    Cheers / Chris
    Bullshit.

    passive potentiometer don’t have "THD: 0.03 % @ 1.8V"

    0.03% is not low THD for what is claiming to be a passive device.
    Nick.

  4. #14
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,643
    I'm Jez.

    Default

    Quote Originally Posted by lurcher View Post
    Bullshit.

    passive potentiometer don’t have "THD: 0.03 % @ 1.8V"

    0.03% is not low THD for what is claiming to be a passive device.
    This is indeed VERY high distortion for a passive device! The distortion for a decent switched attenuator will be below measurement threshold as voltage coefficient of resistance can be very low indeed.

    "with resistance ON of 1.8v and Resistance off approx 1.32v" Oh dear.....

  5. #15
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 866
    I'm Chris.

    Default Other Forums differ in opinion

    Hi
    Discussion about pots vs LDR's on another forum is here:

    http://www.pinkfishmedia.net/forum/s...ad.php?t=68076

    Cheers / Chris

  6. #16
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

    Default JAVA - less than 48 hrs to go on Kickstarter

    For those that might be interested, the JAVA Kickstarter campaign has just under 48hrs left to run and closes early Saturday morning (GMT). So if you were considering making the JAVA plunge, now is the moment!

    We’re within spitting distance of our funding goal and earlybird pricing is only available via Kickstarter. Once the campaign is over, prices will increase.

    I hadn't made mention of it before, but we’re offering a 30-day no-risk trial on every JAVA pledge. Try the JAVA out in your system and if you decide for any reason that the JAVA doesn't suit you, then simply return it to us within 30 days of delivery for a full refund (minus freight).

    Two days ago we took delivery of the latest production sample of the JAVA, which incorporates a couple of minor refinements to the circuit design. Oh my! The sound is now even more holographic, the perceived noise floor has gone from vanishingly low to non-existent and bass performance has reached new heights (or should that be new depths?).

    The earlier pre-production samples already sounded impressive, but the sound quality of the final production version of the JAVA is going to be utterly incredible – it really has to be heard to be believed! I also took the opportunity to A/B the new sample against Chris's original Stereo Coffee kit (which I still own) and there's no doubt that the JAVA is in another league. And I say that as a massive fan of the Stereo Coffee.

    For your viewing pleasure, pics of the latest JAVA samples below. Thanks for your interest!

    Cheers
    Martin
    e: martin@javahifi.com
    Attached Images Attached Images

  7. #17
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

    Default Javatastic!

    We did it! A massive thank you to everyone that has helped make the JAVA a reality. Your enthusiasm, support and pledges saw the JAVA smash through its Kickstarter funding goal of NZ$40,000 with 24 hours to spare. Now, with 11 hours until the campaign closes, our pledge total is more than NZ$46,000. That's amazing!

    There's still time to pledge for JAVA and take advantage of the Earlybird pricing that is available during the Kickstarter campaign period. You can save up to $1000 - but only for another 11 hours! Once the campaign finishes, prices will increase.

    https://www.kickstarter.com/projects...-pre-amplifier

    A huge thanks again to all our backers – we can't wait to commence production and begin delivery of the JAVA to audio aficionados and music lovers worldwide.

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