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

  1. #1
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

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

    Greetings denizens of The Art of Sound!

    I'm very pleased to introduce the JAVA LDR passive pre-amp, which has just launched on Kickstarter.

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



    The JAVA is available in three strengths to suit the differing needs of the discerning audiophile:

    JAVA Single Shot

    • 3 x pairs of unbalanced (RCA) inputs
    • 1 x pair of unbalanced (RCA) outputs


    JAVA Double Shot


    • 5 x pairs of unbalanced (RCA) inputs
    • 2 x pairs of unbalanced (RCA) outputs
    • Remote volume control
    • High quality headphone output


    JAVA Triple Shot

    • 3 x pairs of unbalanced (RCA) inputs
    • 2 x pairs of balanced (XLR) inputs
    • 1 x pair of unbalanced (RCA) outputs
    • 1 x pair of balanced (XLR) inputs
    • Remote volume control
    • High-quality headphone output


    Developed exclusively for the JAVA by Chris Daly, the unique JAVA circuit and LDR control board are significant developments of those found in Chrisís original Stereo Coffee kit, which I know has garnered some favourable comments and interest on AoS. Chris's original Stereo Coffee kits are very highly regarded (and for good reason), but the JAVA circuit takes sound quality to another level again, as well as adding additional features such as a switchable 110-240 V 50Hz / 60Hz power supply, up to 5 x inputs and 2 x outputs, quality Neutrik connectors, a vibration-damped circuit board and feet, remote volume control and a high-quality headphone stage.



    Featuring a mixture of premium materials and with an organic, almost sculptural aesthetic, the JAVA is housed in exquisite luxury birch ply casework, with all models featuring a sumptuous copper JAVA logo inlay. Taking its cues from the mid-century design movement and inspiration from hi-fiís golden age in the 1950's Ė 1960's, the JAVA is a piece of audio furniture to covet ó one that would sit comfortably in the pages of the finest home interior magazines. The 4mm acrylic front panel is available in one of three high-gloss colours - there's even a numbered 'Founder's Edition' with a 4mm solid copper fascia (limited to only 10 units worldwide).



    In sound quality, construction and looks, The JAVA is an 'end-game' pre-amp available at a real world price - even more so with our special Kickstarter earlybird pricing, with savings of up to $1000 off the RRP.

    You can read more about the JAVA here.



    I'm genuinely interested to get some feedback from AoSers and and would love to hear from you. What do you think of the JAVA design? The features? The pricing? Any technical questions? All feedback welcome -- either here or in the Kickstarter comments section.

    Thanks for your interest!

    Martin Bell
    Founder, JAVA Hi-Fi
    www.javahifi.com
    E: martin@javahifi.com

  2. #2
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 5,880
    I'm Alan.

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    Fabulous looks, hats off to Shane Inder

  3. #3
    Join Date: Mar 2008

    Location: Halifax, UK

    Posts: 1,411
    I'm Nick.

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    What do you think of the JAVA design?
    I would love to see some measurements of the thing, when you use words like "Transparency". But that just me.
    Nick.

  4. #4
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

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    Thanks Alan - will be sure to pass on your kind words to Shane.

  5. #5
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

    Default

    Quote Originally Posted by lurcher View Post
    I would love to see some measurements of the thing, when you use words like "Transparency". But that just me.
    Hi Nick

    We will shortly be conducting some independent testing - our own measurements are as follows:
    Bandwidth: 20 Hz to 100 kHz
    Output Impedance: 100 ohms @ 1kHz at full volume
    THD: 0.03 % @ 1.8V
    SNR: average 120dB @ 1KHz

    A few additional points worth noting:
    The JAVA is suitable for use with all source components with low output impedance and an output of 500mv or more. It is important to note that the JAVA may not perform optimally with source components that are specified with rated output below 500mv into loads of 3000 ohms or higher.

    The vast majority of equipment today delivers rated output into 600 ohms or less. For example, modern DACs feature 70 ohm capability with over 1V output (most are 2V - 4V). You would have to search hard to find a source component that wasn't compatible with the JAVA! Likewise, nearly all power amplifiers will match well. The figure to note is the lower sensitivity vs the higher input resistance at power amp input. A figure of 1.5V sensitivity with 10k loading would be difficult (and an unlikely real world scenario).

    LDRs behave as a passive potentiometer, or voltage divider, not as an active device that has current and voltage derived from power supplies to provide stated outputs into low impedance loads. Output impedance is not meaningful with a passive circuit. But at full volume output impedance is slightly higher than 100 ohms. At other points it is as high as 20,000 ohms.

    Cheers
    Martin

  6. #6
    Join Date: Mar 2008

    Location: Halifax, UK

    Posts: 1,411
    I'm Nick.

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    LDRs behave as a passive potentiometer
    Yep, but passive potentiometer donít have "THD: 0.03 % @ 1.8V"
    Nick.

  7. #7
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,174
    I'm Jez.

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    That'll be yer cadmium sulphide innit....

  8. #8
    Join Date: Feb 2013

    Location: Switerland

    Posts: 1,202
    I'm rupert.

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    In sound quality, construction and looks, The JAVA is an 'end-game' pre-amp available at a real world price - even more so with our special Kickstarter earlybird pricing, with savings of up to $1000 off the RRP.
    Very nice looking device, congrats.

    Chris's circuits sound very good and are very cheap (compared to other technology like the Tortuga Audio) which makes them particularly interesting for DIY's.

    The slight drawback is that they don't offer calibration circuitry / software, updatability, etc. found in the Tortuga Audio LDR. Does the Java have similar circuitry or some sort of provision to compensate for LDR drifting over time ? What will approx. pricing be for the base model ?

    Thank's

    All the best with this project

  9. #9
    Join Date: Apr 2016

    Location: Auckland, New Zealand

    Posts: 8
    I'm Martin.

    Smile

    Quote Originally Posted by r100 View Post
    Very nice looking device, congrats.

    Chris's circuits sound very good and are very cheap (compared to other technology like the Tortuga Audio) which makes them particularly interesting for DIY's.

    The slight drawback is that they don't offer calibration circuitry / software, updatability, etc. found in the Tortuga Audio LDR. Does the Java have similar circuitry or some sort of provision to compensate for LDR drifting over time ? What will approx. pricing be for the base model ?

    Thank's

    All the best with this project
    Thanks for your kind words! In answer to your questions, accurate channel matching (caused by LDR "drift") and achieving a linear response across the audio band has long been a bugbear of LDR-based passive designs. The historical approach to dealing with this problem is to painstakingly and time-consumingly select components that match within a close tolerance Ė and even that doesn't effectively deal with inevitable drift in component performance characteristics over time.

    The JAVA approach differs to other designs currently available (including those from Tortuga and Lightspeed). To start with, the JAVA uses high-quality NSL32SR3 LDRs, manufactured by Advanced Photonix Canada. Extensive testing and trial and error has shown these to be the best quality LDRs available for audio applications, the electrical characteristics and reliability of these LDRs being very consistent compared to alternatives.

    But the real innovation is in the JAVA circuit, which then uses current trimming to further balance each channel, resulting in outstanding channel matching between L/R channels (typically less than a 1% variation). This "current trimming" implementation is unique to the design of the JAVA, with the anode and cathode of the LED of the LDR employed in a closed high-impedance circuit, separate from earth. In comparison most other LDR products have a resistor and capacitor in parallel to earth, resulting in those components always competing with each other. In essence, the self-regulating JAVA circuit detects differences between and changes in electrical characteristics of the LDRs of each channel and corrects.

    With the JAVA, Chris has made a number of incremental improvements from his original Stereo Coffee DIY kit (one of which I still own). The cumulative impact of these developments is significant. A/B testing of the JAVA and the Stereo Coffee kit show that sound quality has been taken to a new level with the JAVA and long term reliability is assured.

    Earlybird pricing for the entry-level Single Shot is NZ$1799 (approx 1080 Euro). Pricing details and specifications for different models can be found here: https://www.kickstarter.com/projects...er/description

    Cheers!

  10. #10
    Join Date: Feb 2013

    Location: Switerland

    Posts: 1,202
    I'm rupert.

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    Thank's for your detailed reply ! Very encouraging it is !

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