Faderbank Run: See top post for status

[taylor12k]

looking forward to these and officially registering my interest in one!

[joshhh]

I’m going to The Metal Store (it is actually called that) for aluminum sheet in a couple days and should have two smaller aluminum sheets with some slots and holes in them in the mail later that same day, en route to be tested. I’m only doing a small part to help, but can attest to things happening!

also, @shellfritsch and @infovore seem extremely thorough, so I think by the time this makes its way to the rest of us it will be ready.

[Fma]

Also jumping on the interest train, mainly for a DIY version. Also willing to build this for folks (or help the primary drivers of the project build them for people), since at this point it looks simpler than an O&C. Either way its super exciting.

[emiddio]

also interested in this:) diy especially - looks amazing

[grllpnd]

Super interested in a built version, these look great.

[barnaby]

Looks like a nice device! I’d be interested in a completely DIY PCB+Parts kit (pre-soldered SMD is not necessary or desirable for me!) with no case or front panel, if that ends up being a possibility.

[mlogger]

very interested in a built one or kit (if no SMD soldering because im hopeless)

[Ithacus]

Fantastic project!

I’d also be interested in a built unit or DIY kit (0805 rlc and SOIC IC sizes are about my limit of comfort for SMD soldering).

I’m in the EU as well (not sure if this adds complication?).

A quick question:

For the analogue interface side of the circuit, would it be possible to add input jacks for the faders (normalled to a reference voltage)?

That way the faders could also be used as attenuators when a signal is present at the input jack.

Apologies if I’ve asked something already covered in the thread!

[infovore]

For the analogue interface side of the circuit, would it be possible to add input jacks for the faders (normalled to a reference voltage)?

Not without significantly redesigning the electronics. Because, as it stands -

The faders are normalised to 5V on one side of the wiper; the output of the voltage divider the pot makes (the wiper) is buffered and spat out of the CV outputs. The wiper is also connected to a voltage divider and buffered: this is calculated to lower the 5V to ~3.3V for the Teensy’s input pins.

Because the positive rail of the ‘direct’ buffer is 5V, you’ll never be able to buffer more than 5V out of the pin. So if put 10V in one side, push the fader all the way up, you’ll still only get 5V out (which you’ll get from halfway along the fader’s throw to the end) and you’ll be sinking a lot of that excess voltage into the op-amp.

Secondly, if, after the secondary division described above, the voltage going into that buffer is still >= 5V, it will peg to 5V, which is the positive rail of the op-amp. If it’s below 0V, it’ll peg to 0V, the negative rail of the op-amp. And then it’ll run 5V straight into a microcontroller pin that really doesn’t want more than 3.3V and possibly fry an input on the Teensy microcontroller, or maybe the whole shebang. It is very challenging to remove a Teensy from a production 16n. You do not want to fry it.

Given the propensity of people who like gear that connects voltages on minijacks (eg Eurorack) to chuck around > 5V, I think the likelihood of damage without further protection is… high. And, given the described behaviour of the buffered outs, I don’t think that’s what you want.

If you’d like that feature, you’d be welcome to take the circuit designs when they’re available, and make your own version of the board. 16n is going to be open-source. The main problem to solve will be raising the power rail voltages (which will require different op-amps, I believe the MCP6004s we use don’t want a rail higher than 5V), and ensuring that 0-3.3V is always hitting the Teensy. These are not insignificant changes; just adding the jacks (and impedance resistors) is not enough.

[Ithacus]

No problem; not a show stopper at all for me to be honest.

Thank you for the detailed response and explanation (most appreciated)!

Making the project open source and adaptable sounds great. I guess in the future I might look at adapting something into a MI ‘Shades’ style control bank (ref voltage/attenuation/mixing).

[elil]

My Er301 needs a best friend.
Very interested in a diy kit! I’m in Europe btw.

[AlessandroBonino]

This is so freaking cool I can’t wait.

Tom Hall

[coreyr]

To weigh in, definitely interested in one of these! If the options for pcb and a bom/the teensy program or a full kit, etc. I would personally lean toward a pcb, faceplate, bom kind of thing. Pcb and resources would be second, full component kit would be third.

[barnaby]

No idea how easy/hard this would be to do, but: maybe it would be possible to have pad layouts for both horizontal and vertical 3.5mm jacks (e.g. thonkiconns) at the back? If the layouts can be made to overlap, the builder could choose whether to install vertical or horizontal jacks. Front panels could be left plain and drilled by the builder. I’d certainly prefer to stick patch cables into the front panel than the back.

If the board files were open source and made using KiCAD I would give this a go myself

[infovore]

The product will be open source. It’s not open source whilst we’re still working on it. I’m afraid I’ve done the electronics design in EAGLE rather than KiCad, though. (meant to be a reply to @barnaby)

[swhic]

ok…interested! .

[CryptocrustB]

Oh dear… I’m not a real gasser by any means but holy foggy shipyard.

[polyoptics]

Wow thats pretty awesome!

[jonl]

interest in built unit from me

[lag_progress]

also a build one for me