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Multichannel Audio DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

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Multichannel Professional Balanced Audio IO and Digital 196khz 24bit Field Recorder fully, waterproof & Backpackable!

https://www.youtube.com/watch?time_continue=20&v=jfS_0wlP3sM


It will include balanced audio IO on XLR and miniXLR with phantom power.
flexible routing from 8 or more pre-amp inputs
Digital Audio IO

4 channel Balanced Master outputs
2 x Stereo Headphone outputs ( individual mix bus )

The mixer will have no screen or knobs.
USB midi knob controller interface.
Bluetooth controlls preamp gains DSP fx mixing ( routing )

Record individual ISO tracks and mixed tracks.
VU / ppm meters of each track and mix on low power screen or glasses??
EPROM to store learned control suface maps / templates
GPS UTC time and LTC timecode share over wifi
SDR multichannel radio mic reciever and uplink t

OLDER PROTOTYPE  NEWS , see logs for latest updates :)

NEW DIGI board in the box and running.

NEW DIGI BOARD , dual uSD cards :) 1" OLED for debugging.

Its Alive !!! here's the 1st test recording :) 

https://soundcloud.com/benbiles/bbbox-proto1-recording-48khz16bitwav

here's a realtime audio meter input demo.


Its just 48khz 16bit stereo WAV. There are jumps from incorrect clock timing and there is noise !!

BUT its the 1st recording :):):)

Soon it will be 8 channel WAV poly and 4 stereo mix tracks recording !!!

The bluetooth App does a lot more now also.

Need to get the LIBltc in there soon and try and add timecode.

rev 1


messy box of wires !

rev 1power use for 6 channels , don't forget its +/5v so double this figure

8 channel differntial analogue IO

16 digital audio channel serial I2S TDM IO

ADC - DSP - DAC

8 channel digitally controlled Pre Amp with Phantom power

2 x high end headphone monitoring outputs on individual mix bus.

DSP mixing, mix routing and soft knee compression filters EQ filters and effects etc.

All pre and post mix faders controlled over Arduino USB midi and blutooth app.

Shared Master clock over fanout buffer ( low jitter )

Its working :)

VERY EARLY DAYS ! I can't believe this ever worked !!!! :)

Testing here the 4 channel digital controlled preamp pcb with Arduino USB midi control.

VERY EARLY DAYS :)

Testing of:

8 channel DAC controlled with the Novation Lauch Control USBmidi control surface.

code is here https://github.com/benbiles/usbmidi_multichannel_audio_mixer/blob/master/USBmidi_control_CS4385_DAC

I used the example software controled wiring diagram in the CS4385 datasheet and the DAC is very quiet adter boot. I need to figure out mutec pins etc ..

I use digital PIN 2 on arduino to make RST pin high to initialize the DAC.

the DAC takes the 5v from arduino or 3.3v from DUE etc just supply correct voltage to digital interface power on DAC.

I used these libraryss for USBhost and USBmidi.

the required USBhost version 2.0 library
https://github.com/felis/USB_Host_Shield_2.0

the required USBH_midi library by Yuuichi

https://github.com/YuuichiAkagawa/USBH_MIDI

  • 1 × ADAU1467 Semiconductors and Integrated Circuits / Misc. Semiconductors and Integrated Circuits
  • 1 × ARM STM32F7
  • 1 × Fan out Buffer
  • 1 × 24.576mhz oscilator
  • 1 × CS4385 Audio ICs / Audio Digital to Analog Converters (DACs)

View all 9 components

  • work on new backplane

    ben biles11/21/2019 at 07:31 0 comments

    new backplane nearly finished ! 8 preamp cards fit into a smaller space.

    I am using a shocking amount of SSR's ( solid state relays ) 2 for each preamp channel.

    8 on top and 8 on the bottom of the board. Yuk !! Why ? because I there cheap and I know they work.

    I will run wires direct to the micro controller breakout connectors on my main mixer board so I don't

    need to go to 4 layer board. Its a prototype and the price difference is large.

    The max 4mA required for each optoMos SSR pair ( +/- 5v ) can deliver 120mA per channel which

    allows plenty of headroom to fire up the PGA2500's 

    The ADC_DAC card will plug directly onto the analouge board and bridge to the main Digi board that has the ARM and DSP.

    I have a separate connector card and power card that will supply the analogue power.

    Also new and really exciting is the OVR connector. This will send over level signals from the individual cards 

    to the micro that will be the hardware limiter. The micro can trim back the gain in an instant. hopefully within 20ms or so.

    Lastly rail Voltage sense setup with divider resistors and a reference 3.3v. This will be so I can monitor the voltages

    of both the +/-5v and +/-10v or whatever I set the higher rails to for Headphone and driver cards.

    Theoretically I can shutoff all the preamp cards if there is to much difference in the +/-5v rails as protection !!

    Eventually I'd like to experiment with making a tracking dual rail supply MC controlled !!

    I'll have to see how accurate my voltage divider setup is 1st !

    I found much smaller smd SSR's by Toshiba but at 2$ a go that makes 32$ just to switch the preamps on/off with

    isolation. mmmm a bit to pricey for a prototype :)


  • new smaller cards

    ben biles11/03/2019 at 16:15 0 comments

    excited about my new smaller thinner preamp cards using 1.27mm headers.
    so far they seam to work as before. I kept some space by the optical relay as I expect there to be more front end circuitry. I hope to find a smaller 1 form c opto relay to use. found a toshiba that looks promising that's 1/4 of the size. The 60v 1Amp clamping protection diodes have started to loo very large so working on finding some smaller diodes to.  the gold caps to the right are DC blocking caps before the ADC. The PGA2500's output some DC which needs filtering out.


    The dual rail cards are quite long at 80mm but output +/- 1 amp at incredible low noise using lm43602's and TI ultra low noise regulators.
    I have 1 card for +/-5v and one for +/-15v ( or I might use +/- 9v )  depending
    on how much power I want on the master outputs of the line drivers.
    I should change the conductors for +/- 15v setup from 6.8uH to 15uH.
    The negative rails needs a lower in series resistance inductor 150megOhms. the + rail works with 75megOhms.
    both cards are set to  run at 1mhz switch frequency but are not running in sync yet.
    I'm interested in knowing how you can use an ADC on say the ARM micro to monitor the DCV of each power channel and then even using a digipot fine tune the accuracy of each rail. fine tuning the Voltage is perhaps overkill but monitoring the rails could be good way to self test the power is healthy before potentially frying amp chips in case a power card went down. maybe i'd need to use a higher voltage capable adc to feed the results to the micro ? and how about the negative voltages? would I need an ADC capable of neg voltage ? or use a voltage buffer for each channel and invert the neg rail?

    Although I was fairly happy with the shrinking down of the 1st cards ( still more to do ) the 3.3v 2amp power card was a complete fail!!!

    1st I messed up the voltage divider traces. I tried adding the correct resistor to ground to set the TI tpsm84209 output voltage to 3.3v

    Without the regulator IC in circuit the output fluctuates all over the place.

    I'm thinking so far using the through hole resistor made the voltage divider loop to large. ( the datasheet warns against making that loop large ! )

    Although the caps are within voltage spec I'm not sure about the in series resistance. This is were to be honest I'm entering a new area. I don't have a LCR meter and I don't even know if there is LCR mode on my keysight 34461A bench meter. ( better check the manual but dont think so ) 

    maybe if I generate 100khz square wave with the mixer recorder I could get the in series resistance of the capacitors I used that way ( the old mixer recorder prototype is still working ) . never used an LCR , no idea yet how it works. looks like I'll need one eventually.

    Even the picture I took of this little 1 x 1 cm board failed. it came out upside down and blurred. it cost 1$ , so I think the best thing is to make a better effort with the pcb design and start from there!

    These 4 cards will slot into a backplane to make

    +/-15v(+/-1A) line drivers and headphone

    +/-5v(+/-1A) preamps and adc + dacs

    48v(135mA) phantom power

    3.3v(2A) digital power

  • smaller phantom power module

    ben biles10/12/2019 at 09:05 0 comments

    I just finished soldering up a smaller modular phantom power board.

    I did look into making the 12v -> 48v boost converter side without IC's ( discrete components ) but it would have been to large for what I need. I tested on a dummy load and can produce 134mA 47.5V without the board warming up over long periods.

    I've started to use thinner circuit boards now to to reduce weight. I should have used 1.27mm headers for this board. I went against it thinking its a power board but at maximum 134mA a smaller header would have been fine.

    This is just the start of shrinking all my proto boards down !

    Next is the dual +/-5v and +/-15v boards and new smaller preamp boards with end cutouts for the DC blocking caps :)

  • DMA memory-> uSD working

    ben biles05/24/2019 at 15:51 0 comments

    DMA is working from SAI interfaces -> memory & memory -> uSD cards for recording and playback.

    I have UART / bluetooth RX TX working over DMA to.

    I'm not using DMA for SPI or both I2C1 and I2C2 buses.

    I might need to for the I2C readback from DSP if I start reading a lot of meters and LTC timecode etc.

    I'm thinking I will make one large packet from all meter data. its 1 byte per meter with a few bytes for header info for each meter type. I think I can get all the useful data back to the android app in approx 45bytes per packet streaming at about 1kbps. 

  • gain peek metering working with the odd glitch :)

    ben biles05/20/2019 at 15:30 0 comments

    The main problem seams to be the app inventor app can't keep up with the speed of the packets being sent from the field recorder. I did slow down the TX rate so it could also be the way the individual screens are cleared.

    I have to say a massive thanks to ABG on the MIT app inventor forum for helping me figure out a fast way to receive the 10 byte packets. My caveman code in app inventor was just not working quick enough :)

    https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/mitappinventortest/C2KYLiD1k0g/w_nyJ6OLAgAJ

    I thought my adaption of ABG 's example code was working at the end of the thread but I was wrong. I had to slow down the packet stream from the ARM since it was just way to fast.

    I'll hopefully be able to clean up the glitches and move on from android app designer. Not my thing !!! If the gain peek metering works I will add metering to main faders and mix faders. There will also be a screen with all faders working at once!! if its fast enough !

    I think I need to switch my BT dongle to BTLE 4. I read its better at streaming data.

  • Progress on the audio metering :)

    ben biles05/15/2019 at 16:07 0 comments


    I'm getting some great help on the MIT app inventor forum on the basic BT RX and drawing the meter levels.

    I'm streaming 1 byte value per meter and a 2 byte header over BT to the android app. The 2 bytes just mark the beginning of a packet the 8 bytes meter values.

    since I'm using every possible value of a byte for the meter value I had to go for a 2 byte header to mark the start of the packet.

    As i'm typing this I've just realized I should maybe use meter values between values 0x00 and say 0xF9 and use the remaining values 0xFA , 0xFB up to 0xFF to mark the beginning of a packet / code for what kind of meter packets they are !

    the bunch of numbers by GAIN are meter values just for debug.
     

     

  • more work on the app..

    ben biles04/23/2019 at 14:56 2 comments

    need to start on the realtime audio meters soon...

  • 24bit and 16bit switching playing and recording / different channel counts

    ben biles04/18/2019 at 10:26 0 comments

    24bit and 16bit switching playing and recording / different channel counts.

    I think I need to freeze the DSP while changing these rates but working well without !! 

    no clicking noise on change over either :)

  • 1" oled debug screen working :)

    ben biles04/12/2019 at 05:32 0 comments

    Maybe a bit pointless but it helps a little bit with knowing if i'm record or playback mode and I can report what bit depth / FS audio

    mode i'm in when I get that working :) but this is a BT only field recorder !!! :)

  • hardware startup GOOD !

    ben biles03/16/2019 at 04:23 0 comments

    OK starting properly now.

    The CS4385 has to get going within 10ms so I start this 1st after reset high , rather than having it wait around for the ADC

    to initialize. I'd set rest high on ADC DAC then DSP and left the DAC waiting or the ADC to startup.

    THINGS TO DO LIST...

    check over SAI configs and DMA for playback / record slots and make sure recording / playback works on both hardware slots

    dual recording to cards , have set up DMA but how to write to both card at same time.

    recording armed tracks from TDM8 from BT app  ( not changing TDM mode , just recording slots from it ! ? )

    recording both ADC DAC cards at the same time ? up to 16 channels wav poly or separate mono !!

    playback of different track count from wav poly? just assign to playback slots in order recorder ? 

    LTC timecode intergration into file recording. LTC timecode at start into wav header ?

    NEW analouge board with OVR lines for analogue limiter on front end needed. ( old 4 channel analouge board needs updating ) 

    power cards , dual +-5v , dual +-12v, phantom pwr to slot into new analouge board.

    some kind of master 12v reg isolation eventually.

View all 69 project logs

  • 1
    Step 1

    THESE ARE OLD INSTRUCTIONS FOR AN 

    ARDUINO / NOVATION LanchControl midi knob controller that I found useful earlier on in the development of this mixer. I could control the ADC and DAC chips via midi / usb with the arduino and it helped me learn about I2C SPI UART bus etc

    Instructions to hook up an arduino to Novation LaunchControl and get midi messages into your arduino.

    you will need

    1 x LaunchControl
    1 x Arduino UNO R3
    1 x USBhost shield v2
    1 x USB hub with enough power to power the LaunchControl
    relevant usb cables

    1/ connect the USBhost shield to the Arduino UNO R3

    I found these 2 but there are others to
    https://www.circuitsathome.com/products-page/arduino-shields/usb-host-sh...
    https://www.sparkfun.com/products/9947

    2/ download each zip folder from the 2 librarys linked below on GitHub
    uncompress each zip file and put each individual folder with contents
    into the Arduino IDE Library folder.

    the required USBhost version 2.0 library
    https://github.com/felis/USB_Host_Shield_2.0

    the required USBH_midi library by Yuuichi
    https://github.com/YuuichiAkagawa/USBH_MIDI

    3/ Download my Arduino project file below.
    http://www.benbiles.com/sites/default/files/LAUNCHcontrolBB_0.ino

    4/ compile / upload to Arduino UNO with Arduino IDE.

    5/ connect all usb leads making sure you have the usb hub between the arduino and the LaunchControl

    6 /open serial console in arduino IDE and set the baudrate to 115200

    press keys and turn knobs on the LaunchControl and you should see the relevent midi values 0-127 for faders

    EDIT THE CODE AND GET THE NUMBERS TO DO THINGS FROM THE ARDUINO :) !!!!

    comment below if you got this working or NOT ?

    I'll make a video of this working soon and post it here..

    I'm sure most types of Arduino will work as long as it supports the host shield but I have only tested arduino UNO as of yet..

    upload:

    LAUNCHcontrolBB.ino

    As of now the codec is noisey since I should have seperate ground planes from analouge / digital .. I'm not bothered with noise for now since I'm upgrading to an 8 channel DAC so I can mix 8 channels. the AIC3101 codec wa just a test to see how well the USBhost - midi cointroler would work..

    I remaped the numbers from the other way around since the codec volume was in reverse!

    mute was 127 and 0 was full volume 0db in the I2C register programming of the codec. so this arduino instruction helped me out..

    = map(volume1, 0, 127, 127, 0);

    not sure remaped is the correct description for map function in arduino code.. anway , it might be useful if you want to reverse the values of the faders etc.

    I used a midi dump example to find the values of each midi knob etc.. its in the examples that come with the midi usb library.

    here is the arduino code for controling the TI AIC3101 audio codec. Its setup to output incoming audio from I2S to Left and Right Line output.

    knob 1 & 2 contol L&R volume level output of codec

    https://github.com/benbiles/novation_launchcontrol_usbmidi_arduino/blob/master/AIC3101_codec_control

    I now have the 8 channel DAC CS4385 hooked and working , code available on github.

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Discussions

jackiredale wrote 03/23/2019 at 01:08 point

This project is amazing , I would love to have a go at making one myself , are you going to sell diy kits or the pcbs ?

  Are you sure? yes | no

ben biles wrote 04/08/2019 at 17:22 point

Hi jackiredale, sorry for the late reply. 

I was thinking of selling the 4 layer digital main board and ADC-DAC card modules with the firmware / android app already populated later when I've properly got everything working and tested. I don't really want to sell a board with problems :) so far I only found one error and there was an easy work around on this revision of the 4 layer digi main board but there are loads of gremlins on the other 10 or so module boards!

I am also working towards a final bluetooth only field recorder in a waterproof box that I want to give away to sound recordist friends that work in TV film etc. Idea being they could help me fine tune the thing and eventually get some kind of useful thing to sell ! no idea of the channel count or anything yet until I get the timecode / realtime metering working on the app. I got the test tone and test sweep 20hz -> 20khz working today :) pretty cool !

The sound quality is awsome from the preamps / headphone combination. better than my sound devices mixer. One thing though. I'm not using differential op amp buffer between ADC and PGA2500's ( just Panasonic FC DC blocking caps as in datasheet ) but this might not suite other preamp designs. usually you would have the op amp buffer to protect you ADC inputs from DC bias. So that might be annoying for people that want to add there own analogue hardware. 

on a plus side the ADC/DAC cards have split ground plane and there is really no noise coming across into the analogue from digital which I'm really happy about.

If I sell the mainboards I suppose I'll just do that here though hackaday but no idea how that works :)

have you seen this site ? http://www.freedsp.cc/ I think they have some pretty cool DSP boards that are open source and one that works with rasbery pi ? that might also work as an audio recorder although i'm not sure.

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Ulysse wrote 04/22/2017 at 16:16 point

I like. Of course. Music !

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Craig Hissett wrote 04/22/2017 at 15:56 point

This is great matey!

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Yann Guidon / YGDES wrote 04/22/2017 at 13:38 point

Impressive development !

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Francesco wrote 02/21/2017 at 13:44 point

Hi Ben, i have a question for you. I'm working on a similar project, taking a lot of inspiration from yours. You say you're controlling the ADAU1446 with arduino via i2c. I didn't find any specification about it, the datasheet only says "program it with sigmastudio" without giving any information about i2c via an external controller. Did you found some more information? Or do you have any tip for me, how to do it?

Many, many thanks... and again, your project is awesome!

Francesco

  Are you sure? yes | no

ben biles wrote 02/21/2017 at 14:09 point

https://ez.analog.com/servlet/JiveServlet/download/1806-3-5949/SigmaStudio Basic uC Integration Tutorial.pdf

You create files from sigmastudio when you have made your design. you need to add macros to SigmaStudioFW.h so that that the code can write / read to I2C depending on the platform you are using. So in arduino that would be  Wire.beginTransmission(44); // transmit to device #44 (0x2c)// device address is specified in datasheet
  
  Wire.write(val);             // sends value byte

  Wire.endTransmission();     // stop transmitting

sorry , I have no idea how hackaday does the formating , if I try and paste code into this box I get some rediculas things happening including user names poping up ?

I switched to intel edison recently and so I'm adding mraa I2C macros to SigmaStudioFW.h now since I need a micro that can record / playback TDM 8 channel audio. I could not find any way to record high quality multichannel audio in arduino. Not to say there is'nt a way. everyone points to teensy but I am interested in 24bit 96khz 8 channel audio etc..In fact I never added the macros for arduino athough I did get arduino & bluetooth controlling the preamp with SPI and of course controlled the DSP basic initialize power on to get the board working with I2C. I had some confussion with I2C in the begining but it turned out to be a faulty board ( heat damaged by myself ) . I have the board working in selfboot mode also now with eprom :)

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ben biles wrote 02/21/2017 at 14:12 point

Also I don't see your project on hackaday , can I take a look anywhere ? sounds cool ! what ADC / DAC 's are you using ? 

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Francesco wrote 02/21/2017 at 22:50 point

First of all, many many thanks for your answer, that's exactly what i was looking for and i simply missed it. Now everything is much more clear for me :)

My project is very similar to yours, i'm not interested in recording but in general my goal is to build a digital audio mixer. At the moment, it's only theoretical, i'm waiting for the components i ordered some weeks ago from china. My choices are an ADAU1442 (pretty much the same as your 1446) and your same ADC/DAC. I was interested in 8 ch TDM converters and this two are the most common. For example, the "behringher x32" mixer uses those converters as well, they are perfect for the purpose. But I use self puilt preamps, from old projects of analog mixers.
My project is different from yours because i will use rotary encoders, motorized faders, screens and so on.... like i said, the intention is to build my own digital mixing consolle. 
When i'll begin to build things i will create a project page somewhere :) Maybe i will find something usefull to you too :D
Again, thanks for your advices and your help! Will keep you updated.
- Francesco

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ben biles wrote 02/21/2017 at 23:28 point

interesting to know behringher x32 uses the same convertors. I would say that if your going for the highest dynamic range possible there are better ADC's. but I think you would need to use more chips and expense goes up dramitically. I also got my chips from china and managed to keep the cost down a bit. You will need to buffer your preamps with opamps to remove the 2.5v bias on the ADC or use AC coupling capacitors to remove ADC DC bias. There is an APP note from cirrus logic with 50khz corner freqnency filter and DC bias removal. I'm using PGA2500 so had to use AC coupling caps for increased dynamic range. PGA2500 only +-5v swing. anyway , if you get stuck your welcome to ask questions here. the shared clock and fanout buffer is working well for me. keep the clock line traces short and try to keep them equal leaghth. use split ground planes to sepperate analouge and digital ground return paths. I'm using I2C logic level translator as isolator to help keep noise away from preamp / analouge parts of the board. you could quite easily add 2 or more CS5386 ADC's by setting unique I2C addresses. ADAU1442 has 8 stereo asynchronous sample rate converters where the ADAU1446 does not. I did'nt need sample rate convertion and the adau1446 uses less power. same pinouts so you can change between them I think. I put ground pad on the pcb in case i wanted to use ADAU1442. I bought the cirrus logic programmer but I think there is a cheaper one out there.. might be an idea to build the programmer into your board? that way you could just plug your desk into sigmastudio and do realtime DSP from there software also. or just makes it look tidy. 

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Francesco wrote 02/22/2017 at 08:48 point

Cirrus logic programmer? you meant the analog devices one, right? I'm building the freeusbi programmer designed by freedsp.cc, total cost is about 6$ so it's much, much cheaper. I'm really trying to keep the cost as low as possible. Build the programmer into the board? Yes, it's one of my goals, it would be a very good thing.

I will for sure follow your advices about the wiring, at the moment de "pcb design" part is far away, i will first try things in some "breadbord version". At the moment one  of my biggest concerns (like yours, i read) is if i will be able to solder the ICs, i'm not an expert with that kind of "small" soldering. Hopefully.......

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ben biles wrote 02/22/2017 at 14:02 point

wooops !!! yer , I should say usbi programmer ! only 6$ thats pretty cool .. I'll build the programmer into my next board I think. I first used ic adapter boards to test things out , but to be honest I think you might be better just going for it and drawing a pcb. even if you make a mistake on the pcb you could run a bodge wire or 5 !! I managed to fit ADC DAC and DSP on one 10cm x 10cm board and when I drew that board I did'nt even know how to make ground planes !! just a 4 layer board routed badly and it works really well. 

you can get the ADC DAC and DSP working on adpater boards / bread boards, sort of. but it will be noisey and will probebly crash quite a bit. decoupling caps will be far away from pins on chip, ground plane will probebly be shared with digital etc.. you can download the Eval board guides for each IC and take a look at there schematics to get the idea of how to make the board.

I should'nt advise you to use naked DAC audio pins without buffering IC's, but I have to say I just hooked them up to my powered speekers for testing directly.. use some large 47uf 60WV electro AC coupling capacitors though if your going to do that since there is 2.5v bias ! don't blame me if you blow the IC's doing that also ;)

I found the ADC more tricky to get working than the DAC. theres a few traps in there , so ask me questions if you get stuck !! also I'm sure I could get ideas from your project to ! so would be great if you document it somewhere !

  Are you sure? yes | no

ben biles wrote 06/05/2017 at 11:20 point

Hi Francesco , could you ask me the question about the DAC buffer stage again here? sorry , I tried looking for your comment somewhere in the logs and couldn't find it. In the mean time the output bias of the DAC is 2.5v which is incorrectly labeled VQ? instead of the normal Vcom ! you can AC couple the outputs to your buffer line driver or use an opamp.  you can bias the OpAamp inputs so that the audio swings around the 2.5v on the buffer input and outputs the audio swinging around 0v, essentially removing the bias and protecting you DAC from unwanted current etc

I'm using a OPA1632 balanced op-amp which outputs the differential channel swinging around 0v to an audio line driver. you could just use AC caps maybe but you can add some filtering to the DAC output if you need it with an opamp. I'm running the DAC at 24.576mhz rather 12.288mhz so filtering is'nt really necessary as far as I can tell but I thought its good protection for the DAC since no nasty current can pass through the OpAmp. Personally if I did the design again I would go for a more basic OpAmp package that the OPA1632. something like the OPA4134 that I'm using on my headphone drivers as the buffer now maybe. Anyway , I'm no expert at opAmps but will try answer your question if you post it here..  I got My ADC DSP and DAC all working together really nicely with an ARM micro. started working on multi-channel recording and playback over 8 chnannel TDM. Looking hopeful :)

  Are you sure? yes | no

Francesco wrote 06/05/2017 at 16:07 point

Hi Ben! Yesterday i wrote the comment, then had dinner, came back to pc and... "oh, that's how it works, what a stupid question" :D I figured out the answer, I only had some issues understanding the datasheet. Of course it works like you are saying here!! You didn't reply yet, the question was usefull, i simply removed the comment, that's why you can't find it :P

Let me use this comment to congrat again... This project looks amazing to me, I check this page almost everyday hoping for news. Can not wait to see how well this works once finished :D

P.S. I decided to follow your suggestion and go directly with pcbs... as you know, now seeedstudio offers 10pcbs 10x10 cm for less than 5$... it's not worth it to do tests via breadbords :D At the moment I have almost the whole project designed, only some parts already printed, thanks to your advices it works like a charm :)

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ben biles wrote 06/05/2017 at 17:53 point

OK  ,  good to know your not wasting time with to much soldering :) take your time checking the circuits before you order boards. I usually leave it a day and check over again before ordering. I put a new pic up in the log of my 1st test backplane.. its only 4 channel. I'll make the final one and 8 channel :)  

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john.loftus wrote 08/03/2015 at 09:24 point

Thanks Ben. Glad you like it. We have a programmers reference guide here that may help with the LEDs http://d19ulaff0trnck.cloudfront.net/sites/default/files/novation/downloads/6958/launch-control-programmers-reference-guide.pdf

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ben biles wrote 08/03/2015 at 09:34 point

amazing thanks!  looks like all the info is there!  I Will code in some lights on / off after my holiday,  off to see if I can stand on a surf board for more than 3 seconds in hawaii without midi assistance :) 

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john.loftus wrote 08/03/2015 at 09:36 point

Lucky guy. That sounds like paradise.  Have fun.

Let me know how this project develops.

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john.loftus wrote 08/03/2015 at 08:18 point

Cool project Ben. We like seeing new uses for Launch Control.

Launch Control XL can also be used 'standalone' as shown below (no Arduino required)

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ben biles wrote 08/03/2015 at 09:16 point

great!  Did'nt know you could get usbmidi - midi boxes!  Just did a search and found midi - dmx controllers too for lighting! Awesome :)

Love the way 80's simple solid midi hardware lives on!
Going to try and trigger the lights on the launch control next when you press the buttons.. Any idea where I download the midi map to trigger the lights?  
Oh, also love your use of the phone charger to power the launch control XL :)

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