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Thread: User programmable DSPs

  1. #1
    Senior Member Jan Daugaard's Avatar
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    User programmable DSPs

    There are some very nice DSPs that not only serve as electronic crossovers, but which, with the aid of a measuring microphone, are also capable of achieving a nearly perfect frequency and phase response.

    The DEQX DSP has been previously been mentioned
    http://www.deqx.com/
    and at a recent hi-fi exhibition here in Copenhagen I heard a demonstration of another DSP:
    http://www.holmacoustics.com/dspre1_introduction.php

    The problem is that they are so expensive. The 3-way stereo version of the Holm Acoustics DSP thus costs 40.000 DKK (approx. $6800).

    Being a computer scientist with some knowledge of DSP, I could programme a DSP myself. I just need a device with suitable analogue og digital inputs and outputs, and with a USB or similar port such that programmes can be transferred from my PC to the DSP.

    I would like to hear from members with a knowledge of user programmable DSPs.

  2. #2
    Senior Seņor boputnam's Avatar
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    Jan, there are many. Interfacing with a laptop is possible, with most.

    In relative order of increasing cost, worthy candidates include:

    dbx Driverack series
    Ashly Protea
    BSS Omni or Minidrive
    Klark Teknik DN9848
    xta DP4-series
    Meyer Galileo

    I've used all these. My favorite is xta - particularly with their AudioCore software. Slick...!
    bo

    "Indeed, not!!"

  3. #3
    Senior Member Jan Daugaard's Avatar
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    Are any of them user programmable? They all appear to be turnkey solutions, and I would also like to learn something about DSP by writing the programme.

  4. #4
    Senior Seņor boputnam's Avatar
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    I'm not sure I know what you mean.

    Many of the devices have library of "presets" - EQ tunings for specific cabinets. However, they do not need to be use only that way.

    I use them without presets, and make my own settings - from input to outputs, using Smaart measurements for time-algnment, phase and EQ.

  5. #5
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by Jan Daugaard View Post
    Are any of them user programmable? They all appear to be turnkey solutions, and I would also like to learn something about DSP by writing the programme.
    You can buy some really good software crossover engines.

    http://www.diyaudio.com/forums/showt...89#post1592689

  6. #6
    Senior Member Jan Daugaard's Avatar
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    Boputnam:

    Most of these devices are based on FIR filters:
    http://en.wikipedia.org/wiki/Finite_impulse_response

    I can, and would like, to write the software from scratch.

  7. #7
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Jan Daugaard View Post
    I can, and would like, to write the software from scratch.
    I don't think any of the available DSPs are designed with geeks of your magnitude in mind. There are so few people who are knowledgeable of audio and capable of programming at that level that there is virtually no market for such a product.

    You may find a manufacturer who would let you "crack" their box, but short of that I really doubt that the product you are looking for exists.


    Widget

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    Have you tried this ?

    http://drc-fir.sourceforge.net/

    It's free, it's open source, and (according to what a lot of user say) seems to be one of the best Software DSP.

    Michele

  9. #9
    Senior Member Jan Daugaard's Avatar
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    Mvaldes:
    The site you linked to contains some excellent suggestions. Thanks!

    I have also considered processing the digital signal once and for all, i.e. processing the signal from a CD and then burning the corrected signal onto another CD which is then played instead of the original.

  10. #10
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    Quote Originally Posted by Jan Daugaard View Post
    I have also considered processing the digital signal once and for all, i.e. processing the signal from a CD and then burning the corrected signal onto another CD which is then played instead of the original.
    What an interesting idea! Of course, then you're tied to the hardware, if I understand correctly, but it takes a complete layer of processing/reprocessing out as I see it. Or am I missing something?

    And before you go all detailed, no - I'm not a programmer of any sort, and wouldn't understand what you're talking about. But I *think* I understood that little nugget you just dropped...

    John

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    I'm sorry to hear you are not inclined to buy our DSPre unit, but as a fellow DIY i fully understand your eager to try on the task for yourself. The trick re-burning a CD with Digital Room correction is to be found somewhere on the internet - i though completely has forgotten the name of it and can't seem to find it again.. If you are not put off by having a PC running at all listening time and the constant hassel of computer breakdowns ect., i would recommend you getting a multiway soundcard and running BruteFIR on it, this way you can make crossover and correction filters from scratch.. Good luck on your filter coding! Remember you need a gain and phase calibrated microphone+hardware, before any of your filters make sense.

    http://www.ludd.luth.se/~torger/brutefir.html

  12. #12
    Senior Member Jan Daugaard's Avatar
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    HOLM Acoustics:
    There is a private message for you (you have to log in to read it).

  13. #13
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    I suggest waiting several months.

    ESS Sabre DAC chip ( read : best spec ever )

    new revision coming next year with independent FIR filters on each of its 8 outputs. You can use your class-a amps. Completely eliminates digital interfacing jitter. Close to theoretical max specification, thdn ranges from -112 to -116 . 50 step digital volume attenuator, isnt sacrificing much because it is right inside the dac chip.


    You wont need multiple digital outs with the new Sabre.


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    Jan,

    If you are serious about learning DSP programming for audio purposes probably the easiest path would be to buy one of the Analog Devices eval boards. They cost about $500 and include software development tools.
    _______________
    Best Regards,
    Carl Huff

  15. #15
    Senior Member Jan Daugaard's Avatar
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    Carl:

    I take it that you are referring to these products:
    http://www.analog.com/embedded-proce.../en/index.html

    Do you have personal experience with one or more of these products?

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