WTPA3 Advice



  • @sealion @Altitude
    Good advice all around.  I'll make sure it plays nicely with others.  And what WOULD Biggie do?
  • edited February 2015
    "Buy knobs that match Oliver"

    Oh God, please no.  Those Rogan parts require a rail spike driver to get on
  • loslos
    edited March 2015
    This may be a little late, but I've got my WTPA2 patched in to my eurorack rig.  Things that I would find nice:

    - The ability to trigger the sample via CV, so I can easily kick it off from a sequencer, or clock pulse.  If the sample is playing when triggered, it would restart.
    - A switch to toggle between single shot playback and repeat
    - The ability to trigger record start/stop via CV so I cut perfect length samples
    - Clock input that would that would somehow sync the sample to the beat, maybe by adjusting the sample length to match the length of a certain number of ticks of the clock.

    Anyways, not sure what you have in the works already, but those features would be pretty cool to me.

  • @los--
    -You'll be able to trigger samples via gates, so we're good there.
    -I think single shot and repeat will be based on how long the gate input stays high.  It it remains high at the end of a sample, the sample will loop.  Is that cool?
    -You'll be able to record with a gate, too.
    -There's no "beat sync" right now, although there could be.  I could add it as an "effect" perhaps.

  • edited March 2015
    Here's the first draft of the Eurorack's analog / controls PCB.  These are the gerbers.  They'll change some, but they're routed and the DRC is good on them.
    This panel is 4.8 inches wide, so 24HP.

    It's got knobs for days (12 of them).  5 gate inputs.  Analog modulation of the sample output.  See if you can make heads or tails of this; I explain technical details later; I'm crosseyed.
    But excited!

  • Hmm. Dont know about the controls on the bottom there, That's the "usually buried in wires" area, maybe turn the whole thing 90 degs clockwise?
  • I think that is cool for me.  Just to understand, if I got a cv trigger going in to the start jack and I leave it on, it'll loop, if I just send a short trigger, then it plays the sample once?  If I trigger it while it's in the middle of playing the sample would it start over, or ignore it?  The "Bank Select" would just toggle to the next sample when triggered?  I think this would work pretty well in my rig.  I like the LED placement, I've been a sucker for LED's since I left the womb.  
  • edited March 2015
    The distribution of controls and jacks seems a bit unconventional and potentially ergonomically problematic. Especially the jack inputs in the middle of the module.
    Most modules use either jack on the bottom of jacks on the sides.
    Some others have jacks on all sides and top and bottom and knobs in the middle (makenoise) .
    I guess it's mostly about being able to still reach the knobs with wires plugged in. And also somewhat have a logical distribution of knobs. 
    I think having a logical distribution of jacks is much less important.

    Maybe you should try if you could go and play with a modular somehwere for a few hours and you'll see how ergonomically difficult the euroack format in itself already is. 
    You can come over an play with my small rack albeit it's in the Netherlands. ;)
  • edited March 2015
    One suggestion...I'm sure you know but everyone can help if they see and post links to other modules that are similar in regards to using audio sampling and playback? I guess wavetable modules would also be included as related? sealion has already posted the Qubit Nebulae and there has to be at least 20-25 other new sampler type modules available in Euro these days. I would do research on the history of sampler "features" from the 8-bit age in the mid-80's thru to something like the Kurzweil K2000 (with its algebraic algorithms), to ssmplers like the Octatrak, and even what's cool in iPad apps and Max. I saw a build using hardware build of toy audio IC's with filter and mixers developed into an iPad app. So many possibilities with the the format and tech available today that I'd assume more you know about sampling- past present AND future -the more your own neuroplasticity is going to be able to thread the features needle by knowing the greater art concept of sampling and how far it's come in some respects and applying that to the devtech.
  • nice progress!

    +1 on what shifter said :)
    also what does "Analog modulation of the sample output" mean? what gets modulated -  the volume?
    are there analog vcas or is it done in digital before dac?
  • @loderblast --
    The output is generated by a multiplying DAC, which means you can multiply the digital output code by an analog voltage.

    In this application that comes across as amplitude modulation, so you could apply an envelope or tremolo similar to a VCA style effect, or you could use it as a ring modulator.
    The bandwidth of that MDAC is in the hundreds of kilohertz so it's plenty fine for audio.

  • @Altitude @shiftr @loderblast --
    Jeez.  You know it takes a long time to lay out a board like that, right?

    Seriously, thanks.  My fault for routing first and asking questions later.
    If any of you want to make a pencil drawing of a better (or different) layout, you should do it.  I mostly made this layout grouped by function, with corresponding jacks near their knobs.  Plus I wanted it to look cool.
    If you're like "THAT'S CRAY", hook me up.

    And just to be clearer than those Gerbers, here's a list of the controls:

    Input Gain
    Through Volume
    DAC Volume

    DAC Modulation Input Attenuator
    Audio Combination CV/Input Attenuator (how the various samples are combined)

    Sample 0 Frequency CV/Attenuator
    Sample 1 Frequency CV/Attenuator

    Sample Start Postion CV/Att
    Sample End Position CV/Att
    Sample Window Position CV/Att

    Effect Parameter CV/Att
    Effect Value CV/Att

    Audio In
    Audio Out

    Freq 0 CV
    Freq 1 CV
    Sample Start CV
    Sample End CV
    Sample Window CV
    Effect Parameter CV
    Effect Value CV
    Output Combination CV

    Effect Gate In (hits "go" / gates-in current effect CVs)
    Bank Select Gate In
    Play Gate In
    Record Gate In
    Overdub Gate In

    Effect Gate (hits "go" / gates-in current effect CVs)
    Bank Select
    Slave All Banks To Bank 0 Frequency

    So now you all are officially only allowed to complain about the layout in the final product if I don't get some crayon drawings.
    Thanks again!

  • Ok, firing up illustrator.

    For me, I lay out my panels with inputs on the lower left,  outputs lower right, non-patchable controls on top/upper of the panel, patchable controls (i.e. ones with an associated input) above the i/o jacks
  • Here is what I had in mind
  • @Todd,
    yeah sorry .. i see how much time you already put into this but i assumed you didn't want to be the guy who designed that great euro sampler know for it's impossible ergonomics.

    You do know modulargrid don't you? You can view nearly all euro modules over there.

    If i find some time i'd love to throw something together too... 
  • Oh and there are some people specialized in eurorack design...
    Hannes is a really nice guy on the MI forum and does the designs for Mutable Instruments and hexinverter.net modules.
  • i think my drawing would be a lot like what altitude posted.

    maybe you could use these kind of pots like here for example. for (some of) the cv attenuatiors and illuminated buttons instead of button + led for play/rec/overdub/bank to save some space.

  • Here's a simple layout .....for a simpler device. http://www.ginkosynthese.com/product/sampleslicer/
  • Thanks for the pointers. I really do appreciate you all helping out with stuff like this. I guess what seems intuitive to me is very much unlike what a normal modules look like. I checked out those links and I can see what you're getting at about standard form factors, etc.

    For the time being I will probably proceed with this pcb for the first prototype. There is bound to be something else wrong, and n when I fix that I'll do the layout changes as well.

    Anybody else who wants to chime in, I'm all ears. Thanks again.
  • Sampleslicr is the app that I mentioned that was initially all developed in hardware I referred to. Thanks for posting the link bcomnes. I'd add an effect wet/dry modulation unless its already above and I missed it. The CV ring-mod would lend itself to wavetables as a mod source as further dev and I would add that any sort of onboard input/output matrix would add more options?
    This tri-drone from Enrique Ochoa Gomez is sure different and the oms idea sounds positive- no?
  • so todd, any news?
  • Not much right now.  I'm moving labs so things are a mess.  Also half a mind to just redo the front panel again rather than getting used to it one way and then changing it.
    I did actually complete my first bare-metal ARM project (for work stuff) from the ground up since this post was started and it kinda ruled, so it's safe to say the processor on WTPA3 will be at least a Cortex M0 and more likely an M3.

    The M0 I like is 50MHz, the M3s are 100 or 120MHz, and both are 32-bit, so they basically stomp all over the AVR on the WTPA1 and WTPA2.  This means that signal processing is a lot simpler to code, and sample rates can be pretty arbitrarily high, more grains can be used, etc.
    WTPA2 jumped through a bunch of efficiency tricks to get the sample rate it has.

    So that's exciting.

    Thanks for checking in!
  • nice, STM32F4 seems to be the go to chip for music stuff these days for sure..  
  • quite forum is quiet.

  • Too true.  And I think I still owe you a t-shirt.
  • Dont worry about it.  Old Polish proverb says "Odrobisz na polu" which translates to "you'll make it up in the potato field" :P

    If you need some inspiration, check out Oliver's Clouds module.  Mind blowing module and hardware wise, looks like everything you would need for a WTPA 
  • It's pretty much potatoes from Krakow to Łódź up in the lab over here so I'll do my best. There'll be a wtpa3 this year and I'ma save my forum juice until then. The Clouds is definitely impressive but of course I'm all hard headed about hardware so you know how that goes.
  • Todd, are you still working on this?  The bigger my euro setup gets, the more I want a sampler module 
  • The plan is still to release it this year. It'll be good to have out there.
  • Here is another device (just built it myself) that is worth looking at architecture wise.  It runs on a teensy 3.1 but has a nice low part count and works great, the 4 pin OLED is also very nice and available through amazon

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