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  • Any interest in miniDSP controller?

    I've got some basic software (and hardware) working to control the miniDSP. It lets me directly control the miniDSP board from my own loudspeaker design tools. Except in reality, I'm just using the ADAU1701 chip and analog circuitry that is on the miniDSP board. I'm bypassing the controller that is on the miniDSP board and I'm not using their "plug-ins".

    I can set up a DSP program in the ADAU1701 (cells) and directly control the Parameter memory (data for the cells). My Windows program calculates the filter coefficients and sends the data via USB to the microprocessor board you see humping the miniDSP in the picture. The data sent to the micro is all text. This data could also come from Excel, since the microprocessor uses an FTDI chip and there is a VB.NET FTDI driver that can be invoked from Excel.

    So even though I've got a lot of refinement to do, I've got to start thinking about what's next. I could make a piggy-back board for the miniDSP. Or I could make my own miniDSP (there isn't anything really too complicated about the miniDSP--it's pretty much the Analog Devices reference schematic). Or I could do something else with the ADAU1701 chip--maybe a cool plate amp with an LCD display.

    Just looking for ideas and interest. ...And kind of excited about getting this stuff working.



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    Last edited by neildavis; 08-09-2012, 09:03 PM.
    Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

  • #2
    Re: Any interest in miniDSP controller?

    There's plenty of DSP development boards to do what you want I think...The minidsp I thought was meant to be a drop in solution where you didn't have to know much of anything of dsp operation, it is prepackaged and controlled via software.
    "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
    exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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    • #3
      Re: Any interest in miniDSP controller?

      I have been thinking about a minidsp for dual subs. Any chance?
      " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

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      • #4
        Re: Any interest in miniDSP controller?

        Some competition for those folks would be good. I think if others were doing similar stuff with decent economies of scale, prices would drop a lot.

        John

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        • #5
          Re: Any interest in miniDSP controller?

          The loudspeaker design software that I have will import FRD files, configure the drivers and amps, do baffle step calculations, model the cabinet, and apply filters to model the response. All of the DSP implementation details are totally hidden--the designer just sees a set of filter tools that they can use to apply as needed to achieve their desired response. It's like miniDSP software combined with an active version of PCD, WBCD and RM. And it goes beyond miniDSP by providing real-time control: it writes to the ADAU1701 rather than programming the EEPROM. As far as I know, there is nothing comparable.
          Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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          • #6
            Re: Any interest in miniDSP controller?

            A better product is the best kind of competition.

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            • #7
              Re: Any interest in miniDSP controller?

              I've thought about a sub amp. Right now the high-powered class-D amps with DSP are pricey, so there is an opportunity for competing in that marketspace. It would be very easy to implement an ADAU1701 DSP with a simple LCD display to set the crossover frequency, boost and volume. It could be added to an existing plate amp or paired with an IRS2902-based amp.
              Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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              • #8
                Re: Any interest in miniDSP controller?

                +1 on the subwoofer application. To start I'd say 2 filters for high and low pass, one peq and volume
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                • #9
                  Re: Any interest in miniDSP controller?

                  If you could implement UE's HBT stuff (excuse my ignorance) on a 2- or 3-channel ClassD plate amp, for less than Digmoda, that'd be insane.

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                  • #10
                    Re: Any interest in miniDSP controller?

                    Originally posted by neildavis View Post
                    And it goes beyond miniDSP by providing real-time control: it writes to the ADAU1701 rather than programming the EEPROM. As far as I know, there is nothing comparable.
                    Interesting. In bypassing the EEPROM, what's the volatility of the data download?

                    dlr
                    WinPCD - Windows .NET Passive Crossover Designer

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                    • #11
                      Re: Any interest in miniDSP controller?

                      I haven't addressed that yet, but it's not hard. Right now my micro waits for the ADAU1701 to self-load from the EEPROM and then it totally reprograms the ADAU1701 from a table stored inside the micro. I used SigmaStudio to generate the program and parameter RAM image. So basically I'm throwing away the miniDSP code and data.

                      I created my own chip configuration using SigmaStudio. It is just a series of biquads with some volume controls for each channel. SigmaStudio generates the program RAM and parameter RAM images, and I just format that data as data constants for the micro. So the program and initial load is stored in the micro in its Flash EEPROM.

                      My .NET program on the PC side is basically a math model of this program. SigmaStudio creates a file that shows the mapping of the program cells to the parameter RAM, so it is easy to figure out which data you need to change when the user specifies a change to the filters. But right now the updated parameter data isn't stored in the micro's memory or in the EEPROM. I could do either--I just haven't decided how I want to do it yet.

                      But all of the hard stuff: writing to the ADAU1701, using SigmaStudio, getting the data formats correct, getting the communications between the micro and .NET, and creating a math model--all of that is working. There is a lot of code that still needs refinement, but right now I can change a biquad spec from the PC and immediately hear the change in the audio going through the miniDSP board. So I'm feeling relieved. And I'm also starting to think about "what's next", which is why I posted about interest in this.
                      Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                      • #12
                        Re: Any interest in miniDSP controller?

                        Actually, that's where I was headed several years ago. I've made a number of 2-5 channel plate amps, but the software to control them was always a problem. I think I'm getting there. I haven't used UE, but from my limited understanding I think I've got most of the functionality addressed in my code. But my code doesn't require a PC to execute the filters--it is intended to control DSP chips or boxes. I can control the TAS3004 chip, the ST DSP cores (STA32X and STA308a) and now the ADAU1701. These are all small low-cost chips that can be embedded with amps.

                        I'm a bit gun-shy about stuff with power cords, though...not sure I want to go through UL approvals and with high power you need to worry about FCC regulations. But it's something I'm looking at.
                        Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                        • #13
                          Re: Any interest in miniDSP controller?

                          I don't know how this would fit into what you've done (which I think sounds really cool), but what I'd like to see is a minidsp type of thing that was a netduino compatible shield. Though I'm not sure the netduino would have enough horsepower to manage such a shield. If all it's doing is loading filters into the dsp for it to run, perhaps it could.

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                          • #14
                            Re: Any interest in miniDSP controller?

                            There really isn't any reason why the Arduino CPU couldn't directly control the miniDSP board. Unfortunately, the miniDSP board doesn't comply with the "shield" standard, but all you need to connect the CPU to the miniDSP board is power, ground, and the two I2C signals.

                            Once the miniDSP board "boots up" from the EEPROM, the I2C bus is available so that you can directly talk to the ADAU1701 chip using the I2C. The miniDSP board has a PIC controller onboard, but it doesn't do anything unless there is a command from the USB interface. So, sure, the Arduino board could control the ADAU1701 the same way my micro does.

                            I'm using a lowly Freescale micro--the MC9S08QG8. It's got an I2C port, but I don't use it--the I2C signals are all generated with software primitives that I wrote for the micro. Speed isn't an issue. I've thought about switching to Arduino, but I'm comfortable with writing the assembly code for the MC9S08QG8, and I've never felt a burning need to switch to something else. But it probably wouldn't take an enormous amount of effort to use an Arduino board instead of my micro. The biggest issue is whether there is a .NET USB driver for it, because you need to send commands from the PC to the micro. If there is, then it would be relatively easy.

                            In order to use my front-end loudspeaker design tools, you would need to implement the interface that I have for my microprocessor board. The micro uses a simple command interpreter that would have to be moved to the Arduino board. It uses messages that are formatted as strings on the PC side and converted to Hex in the micro. They are simple messages--for example, to set the I2C address you just send an "A" followed by two ASCII characters that represent the Hex data. To program the Parameter RAM in the ADAU1701, you send an "M" command (multiple), a string for the I2C subaddress, the length of the command ("4" for 32bit data), and the 8 characters that are needed to send the 32-bit data as a sequence of ASCII characters. It's pretty simple. Because the data is sent at 19.2KBaud, the response is a bit sluggish, but the micro has absolutely no problem keeping up.
                            Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                            • #15
                              Re: Any interest in miniDSP controller?

                              I believe this board (http://netduino.com/) should be compatible with .NET
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