Clock Select

Hey guys --

So I'm laying out yet another revision of WTPA2, and I need some advice.
The new design has independently clockable sample banks in caveman mode.
Here's how I'm thinking of doing it.

Bank 0 is clocked by the VCO. Bank 1 is clocked by a second relaxation oscillator (like the current WTPA). The VCO has a coarse and fine knob, the relaxation osc has only one knob.
With a jumper, you can slave both banks to the VCO, so the coarse and fine controls then control both banks simultaneously (like now).
When bank 1 is slaved to bank 0's clock, the relaxation oscillator does nothing.

That way you can decide whether you want to adjust samples independently or together.
Does this make sense? Is it overkill?



  • Yeah that sounds like a good way to do it. People who want it 'oldschool' can go that route too.

    The main reason I don't use the 2nd bank too often is that the pitch is tied together, so being able to control them separately will be slick.
  • sounds fine! so i could use a switch to change it.
  • Along those lines, I would make the jumper a switch, "officially."
  • Yeah, I know a switch is better than a jumper. If I can find one in the next couple days that doesn't jack the price up a ton I'll use it, but switches are expensive.
  • I think a jumper would be fine as people can wire that into a switch if they want to. Maybe have the switch only come when people buy the hardware/case bits and not just the done board/kit?
  • btw how will you do it? will there be kits only, with the option of an enclosure, or are you planning to offer say pcb + mcu + the encoder (ie custom items) also?
  • Good question!
    There will be 5 things you can buy:

    1.) The electronics kit. This is like the OG WTPA, it's everything for the sampler brain. Parts and PCB, pre-programmed MCU
    2.) The permanent memory daughterboard. This is separate because I have to make it since it's all small SMT stuff. It will be sold as a complete unit.
    3.) An enclosure. This comes with panels and hardware.
    4.) A jack/connector/IO motherboard. This is like the old hardware kit, except it mounts slickly into the above enclosure, and it also (hopefully) keeps you from wiring jacks backwards. Includes audio, midi, and DC jacks, and a switching jack for CV. Probably also the clock select switch.

    5.) There will be an option to buy WTPA2 with all the above, built and tested. It will be expensive but pretty.

    So, you can get whatever suits your build style.
    I'm afraid I won't sell a board/MCUs/Endcoder set because it would be a shipping nightmare to ship many small cheap things every week, I make no money on it, and it would screw up inventory really badly.

    Since the code for this will be on the site, so I see no reason to ship chips. I did it as a courtesy before, and I might do it once (and if) a firmware revision comes out.
    The encoders have a standard footprint, so you can always source one that's close.
    The PCBs I may ship individually since they are the only thing you really _need_ to make the kit. I'm still on the fence about that though. I hate doing it, but it is the responsible thing.

  • Is there a mockup of what the enclosure/panel look like? Or is that TBA?

    I forgot the perm memory was going to be a daughterboard. That works out well for those that don't use that kind of thing (me included).

    I'm loving all the new info/activity on here. Can't wait for this bad boy to come out.
  • oh i thought the encoder is a totally custom thing.
    yeah, flashing mcu is not a problem. SMT would be no problem too, unless it's that small that you'd need a microscope to do it.

    i'll get a kit first for sure, with or without panel+associates.

    but it would be super awesome if there was the possibility to build one (ie some) more after the kits are gone.
    so please do offer the bare pcb!
    i guess that would mean also bare daughterboards at some point, for fluxjunkies :)
  • If it gets that far (hopefully it will) I'll for sure keep the boards around. The plan lately has been for Olivier and I to use the same micro SD daughterboard if we can, so hopefully that will split up the annoying-ness of keeping them in stock. I sure hop that works out.
    Right now I'm having a blast working out the enclosure. It's not going to be just laser cut. There will be some cast parts, and also some anodizing....
  • Most interesting...
  • down for a kit inkl. enclosure + perma board! :D yeaahaw!
  • Jumper or switch? An extra setting available,
    extra fine!
    Escuza me for a not knowing..?
    Pre-programmed MCU but not chips?
    Does that I should be puttin' a little extra cashino (and brainspace)
    aside for (learning AVRdude) and some
    form of USB 6-pin ISP format AVR programmer
    for OSX?

    I've heard that it's really true - the WTPA-2 rapture is nigh?
  • sure, it's good to have a programmer ready. and it's not much cash. i bought an usbtiny from adafruit.
    and avrdude isn't that complicated to use, too. everything well explained.

    wrt daughterboard, good to hear you guys are teaming up hardware wise!
  • You'll only need an AVR programmer if you want to update firmware after your initial build, and yeah, @rosch is right, they come cheap and there are lots of tutorials.

    Time was, a long time ago, WTPA was designed to be pedagogical before it became the shameless grab for cash and nerd cred that it is today. The "users program their own chips" was part of that ideology, since it really is super handy for an electronics enthusiast to know how to do. You all are lucky I took out that part of the design where you had to match trace impedances using the network analyzer :-)

    FWIW, I worked clock select into a switch. The Jack Daughterboard will now have a switch to change between using the relaxation oscillator for the Bank1 clock and slaving Bank1 to the VCO. It adds a little cost but it rules more.

  • I am playing with an op-1 which has click switch encoders that have no code attached to that yet. I sure wish it did. But I'm patient. So rather than a jumper/switch an encoder/switch would deepen the density elegantly, but I recall you've been waiting on some fancy smshmanscy chinoise encoders already?

    Me buy one of everything to build.

    Partnering with Olivier on microsd, oh interesting... Also new batch of shruthi-1s online today, not gone yet...
  • That would be classy. But the encoders are already here in bulk, so that means they're the ones that have to get used.
    Also, to do that needs a latching SPDT switch (it's a signal routing change) and I'm not sure if they make encoder switches like that -- they're normally tact switches.
  • "FWIW, I worked clock select into a switch"

    You da man - thanks!!
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