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chuck

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Posts posted by chuck

  1. The definitive MB-6582 PCB/kit thread

    in MIDIbox User Projects

    Posted

    Smashtv, thanks.

    I missed this thread and was hanging around at SmashTV's site and saw the boards and ordered.  It part of the horder/impulse buyer in me.  Anyway, I guess I'm going to have to go it alone on the parts.

    I had some questions and I searched all the threads and could not answer them.

    1.  Are the SmashTV boards a newer version, with no known errors?

    2.  Do the face plate files on the WIKI, line up with the control board from SmashTV?

    3.  Are the SmashTV boards red like the Wilba pictures?

    4.  Are there schematics to go with the SmashTV boards?

    Thanks to everyone who helped make this happen.

  7. DIY audio patchbay with digital routing....How hard?

    in Design Concepts

    Posted

    The first thing to do is to go through this thread, and make a list of all of the supported functions we have discussed (such as the 'inserts' for example). While you're there, it makes sense to get a list of practical usage too, such as for an analog modular synth, or a guitar switcher, or big studio patchbay, or SID synth internal routing.

    I think it will pay to consider the devices that are being used to send the controls. For example you mentioned that guitar pedal boards send CC's, maybe they can send notes too, I dunno...

    Then, we can make a list of the functions and their required input ranges.

    Then we can think about how to handle them.

    I thought about how to go about this -- and I felt I didn't want to embark n this only to have someone else do the same thing...  Seemed like too much repeating the same work.

    So can I suggest this work be done in a wiki page?  So that it can be added to or organized more as a groupware then a single thread?

    Is this cool?

  12. DIY audio patchbay with digital routing....How hard?

    in Design Concepts

    Posted

    What the hell? I wrote a big long reply, and it's gone... damn!

    Why not switch fx with notes instead of CC's? (it's binary, makes sense)

    This brings up something we haven't contemplated much - MIDI implementation. Any volunteers? That work will be a matter of talking a lot and typing up lots of pretty documents.

    Jacks should not be part of the design, so that anyone can use whatever they choose.

    1RU is 1.75"

    Personally I don't care if we switch FX with Notes, but CC messages are easier for guitar players and most pedal systems send CC messages.

    I didn't mean to make Jacks part of the design, just showing off some cool jacks.

    1U Face Plate is 1.75"  1U chassis is varies by manufacture.

    I know I need spell check.

    Sorry you lost your message.

    I'm not sure where chat is.

    I'm not sure what you mean by Midi Implementation.  The code or the specification?

  13. DIY audio patchbay with digital routing....How hard?

    in Design Concepts

    Posted

    And what about switching the patches themselves?

    I assumed that was a given.  :)

    tilted:  Are you as still doing the 48 I/O version?  How many cross-point chips does that take now?

    I have a ton of the MT8816 DIP chips, but I'm considering ordering some AD 75019 chips.

    Since you're going with the buffers -- unity gain did you consider adjustable gain controls so input and output gain can be mixed properly?

    Maybe using DACs or digital pots for the control?  So chains of patches can be mixed and saved?

    Back to the core interface....

    I implore you to look at http://www.soundsculpture.com/support/files/Sbgl_user_guide.pdf

    I have two of these Switchblades, a GL and an 8B.  I was looking to "mimicking" the setup used for these.  (Not steal directly although I'm not talking about marketing a product but making a DIY audio router.)

    If you look at Page 7, PROGRAM THE PATCH AND GAIN.  You'll see what I mean.

    You create a patch record, which patches an input to an output.

    This record also allows adjusting the gain of the patch.

    You can create patch records with duplicate inputs or outputs.  This allows for multiple inputs to multiple outputs.

    Example Patch Records.

    SOURCE        DESTINATION        GAIN

    instrument    distortion              0dB

    instrument    delay                    0dB

    distortion      amplifier                0dB

    delay            amplifier            -12dB

    Get the picture?

    A collection of patch records is a single preset.

    Presets are saved and recalled as program changes.

    Earlier in the document, you'll also see that each input and each output has a record.

    You name the input or output and you can assign a midi channel.

    Inputs and outputs with the same name are considered a loop, which can be switched in an out with a CC command.

    These records are global to the system.

    Inputs

    Jack        Device

    01          GUITAR

    02          DISTORTION

    03          DELAY

    Outputs

    Jack        Device             

    01          AMP

    02          DISTORTION       

    03          DELAY               

    04          AMP2

    There are also some setup/maintenance records.

    If you look in http://www.soundsculpture.com/support/files/Smart_Insert_Upgrade.pdf

    You'll see how the CC commands are setup and handled.

    The switchblades also have a PC based setup/configuration with a graphical environment.  I wasn't going down that road.

    The trouble I had, that let me get distracted to another project was that I'm used to programming C for very large system where memory is no issue at all and strings are handled with ease.  I had trouble stuffing this all into the limited capacity of the PIC.  Before you guys started this thread I was considering abandoning the core module and going to another processor -- like an AVR.  But now that real PIC programmers are involved maybe this project can fly.

    Speaking of I/O -- While researching my other project I came accross these.

    http://www.neutrik.com/us/en/audio/210_2146034064/NSJ12HF-1_detail.aspx

    Mouser had them for $2.42 us.  WHich is for two jacks.

    Trouble is they do not fit in any 1U case I found.  I actually purchased 4 separate vendor cases and couldn't find one that had enough space.  Even though the specs say 1.250" that doesn't include the pcb terminals.  You need one with slightly more then 1.50" space.

    If anyone knows of a 1U case where the case itself is nearly the full 1U of height let me know as I really want to use 16 I/Os in a 1U case.

    Have you discussed the control panel at all?

    Chuck

  14. Schematic's made by TK

    in Design Concepts

    Posted

    As far as I know, TK's using XC still. He doesn't build PCBs from a schematic... I think you already know this though, going from what you said.

    This is slightly off-topic, but as a preference to stealing eagle (which sadly a lot of people do), I'm pimping kicad these days ;)

    Not to offtopic the thread, but I'm using the non profit version of eagle now.  Doesn't really cost much and I actually am not making a profit.

  16. DIY audio patchbay with digital routing....How hard?

    in Design Concepts

    Posted

    Ok, I just read this entire thread.

    However the distortion figures are high, and that is a knockout blow for some projects, leading to the AD75019. These two chips compare the way they do for good reason - the Zarlink is intended for telephony systems, and you don't want people overhearing neighbouring phonecalls, so crosstalk is critical - but frequency content is not so important, whereas the AD is made for analog audio routing in studio or equipment's internal routings, so the distortion is low as heck, but that comes at the expense of slightly higher crosstalk figures. The catch is, they use a very different method of loading the crosspoints, specifically that the whole chip (or all chips) must be loaded at once.

    Beware of the zipper.  If you're not carefull, when you load the matrix you'll get ziiippppppp.

    Also, does it load fast enough to switch in a single guitar effect while playing?

    in my other design with the MT8816, I was trying to be able to set up a patch series, then switch in and out any single effect with CC Commands.  So you could set up Guitar -> Distortion->Delay->amp and switch the Delay in and out on command.

    I was modeling my design off of this.  http://www.soundsculpture.com/products/switchblade_models.htm

    Curious,

    Are the schematics that /tilted/ has done available for viewing?

  18. MT8816 based effects router

    in Design Concepts

    Posted

    Using the MT8816 switch matrix chip is very interesting. I have been looking at it for a while already.

    Did you need an (opamp) buffer for every input and output or was that not needed?

    How did you experience the cross-talk and harmonic distortion of that chip?

    Any troubles in separating the digital part steering the switches and the analog signals going through the switches, any noise or digital "bleed-trough"?

    Perhaps, if you are willing, you can already post the hardware circuit part of interfacing the MT8816 chip with the MidiBox core and some code snippets for addressing / programming it?

    I would be interested in it in order to build or try-out a (much) reduced / simplified 8x8 matrix version of it with a very primitive (if any) user interface. It would make a nice variant on a 8 looper version with relais that I'm trying to build using the MidiBox.

    First I made a simple router, using a MT8816 and only 4 jacks.

    http://www.voodooengineering.com/release/lab1.jpg

    I didn't get any crosstalk, not even a pop or anything when switching.

    So I decided not to use any OPAMPs.

    But I never went to a full scale 8 in/8 out test.

    Here is the schematic for the one pictured.

    http://www.voodooengineering.com/switcher/Effects%20Router%20v01r.jpg

    It is actually very simple.

    I used 74HC595 shift registers to switch the MT8816, and connected them just like the DOUT module.

    This was a mistake, I should have interfaced the 8816 better to the PIC, but I afraid of having to write a driver since I don't know assembler well enough to do so.  It really needs a parallel interface because the commands needed for the "serial control" just get too long.

    Options?

    The best is to redesign how the Pic controls the MT8816.

    Now that I'm building a Pico, I'd also probably try a -15v reference voltage.  This current design is using -5v.

    As for the Pico, we should start another thread on that.  I was going to try and control it with digital pots/ L2C interface.....  I'm still collecting parts.

  20. MT8816 based effects router

    in Design Concepts

    Posted

    Hey Chuck! This project looks fantastic! I hope you'll share the details when it's "street-ready"!

    Silly question, as I'm new to routers....

    Is it possible to route more than one source to a single destination (ie. summing sources)?

    Keep up the great work, Chuck, and keep us posted!!

    Gav

    Sorry, the project is on hold as I exceeded the memory in the Pic.....  I'm considering options.

    In the meantime I've been working on a Pico Compressor.

    But yes, you can use it as a mixer.  Many to one,  one to many, any input to any output.

    It is a full matrix.

  24. MT8816 based effects router

    in Design Concepts

    Posted

    Yes, but it will be the next version.

    I wouldn't recommend building this one.

    It uses serial based logic to control the MT8816.

    The next version uses a parallel control bus and two MT8816 chips to handle 15 audio inputs and outputs pairs.

    You can see the design talk in this thread here.

    http://www.diystompboxes.com/smfforum/index.php?topic=43104.40

    I wanted to finish this one though because I'm learning the best way to fit it all in a 1RU case.

  25. MT8816 based effects router

    in Design Concepts

    Posted

    I just thought I'd show you all a guitar effects router I've been working on some.

    It uses the MT8816 matrix switch to build patches of guitar effects in any order.

    As you can see it has a SmashTV core module and a DIN and DOUT module.  So it pertains here.

    This is a work in progress.  This is for my use, its not for sale.  But you can build your own.

    earlyrouter.jpg

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