Volca Nervous System (mixer + midi splitter + power bank)

[bogdanr]

Hello,

I started working on a Volca mixer product for my self and I wondered if maybe someone else would be interested in this, especially since it evolved a bit from the initial plan.

Meet the Volca Nervous System!

Currently planned features:

1. Mixer

- 6 stereo inputs (12 channels)
- standard 3.5mm jack stereo connectors
- no level adjust on the input since those are already available on the outputs
- panning pots on all the inputs
- Two outputs (headphones and line out) with individual volume controls

2. Midi spliter

- one input -> 5 outputs
- full size MIDI connectors (DIN5)
- LED for monitoring the MIDI signal is present

3. Power bank

- clean and rechargeable power supply for Volcas
- power 4 Volcas for at least 4 hours
- replaceable 18650 batters
- external charger would not be included


Since I was making this for myself, the initial though was that I could also sell it as a kit. For me it is hugely relaxing to solder for an hour or so and I think it might be rewarding for the users also. This kit would probably cost 200€.

If nobody would be interested in doing the soldering, perhaps at some point I could also sell a kit with all the components soldered so it could be built faster. This option would likely cost 50€ more.

For the case I was thinking of making it from dark plexiglass and it would be the same size as a Volca.

Currently the board looks like this but I will be making some changes to the layout because the case would not look too good:




So, what do you guys think?

[jreign]

Wow, thats awesome work! Great job in making the layout Volca-ish. I'd be interested in picking one up.

[eowyn]

That's pretty sweet! I defintely would buy a kit version if it gets released. I especially like the midi splitter!

I got one question: How would I connect an insert fx like a kaoss pad for lets say a couple 2 or 3 volcas on this nifty gadget?

[Koekepan]

I really like the looks of this.

I don't know how much the parameters are up for discussion, but here's a short version of my situation:

I have a live rig that consists of six volcas and a Blofeld. One Keys, one Bass, and four FMs. Obviously, I have cables going everywhere, and a couple of MIDI thru devices just to keep everything fed from my master keyboard/sequencer.

Your tool would be great for simplifying what I have, both in terms of what I do with my mixer, as well as what I do with my MIDI management.

I realise that this is probably fantasy, but any chance of capacity for six? If not, no biggie, I can definitely use what you have here.

I'd also like to suggest that you add pots for volume, if you can find any way of doing so, just in case people want to use other devices next to their Volcas. It just adds a little flexibility that may be valuable.

[bogdanr]

So, the main thing is that although there is a bit of space left in there, it is definitely not enough for everything and still have this as a kit. Also, I would like to actually finish this project and not add features to eternity

@eowyn: I also have a Mini KP2 unit and I normally connect it to only one of the synths by putting it between the synth and the mixer. It would also be possible to put it at the output so it would apply effect to everything. The Volca Nervous System doesn't have a dedicated FX send bus and I don't plan to add one because I am not sure that is a critically important feature.

@Koekepan: Nice rig! Adding another MIDI out would require an extra IC and an extra connector. I don't think we can find the extra space on the board.
There are a few reasons why I left individual volume controls out: less noise, cheaper, limited space on the board. Again, if people think this would be really valuable perhaps I could scrap the power bank feature, use a much smaller battery and add those pots.

A major change I was thinking of doing is a complete redesign of the layout. After a little doodling this is what I came up with:

• The circle part in the bottom central area is where the electronics would go.
  The rectangle in the left part is where the battery would go.
  In the center of it all there are the pan pots.
  In the top central part there are the input jack connectors.
  Instead of two slider pots, perhaps it should be only one for the master volume and a rotary pot for the headphones.

I am very open for suggestions of a better layout and a picture is worth 1000 words
Also, did any of you build electronics kits before or would this one be your first?

[bogdanr]

And just so you understand why I want to completely remake the layout, here is how the actual box could look with this layout:
https://drive.google.com/open?id=0B6iKR ... Xh4ZFhJOEU
You have to actually open it in acrobat reader because it's a 3D PDF.

[eowyn]

I soldered a small simple beginner synthesizer, but nothing serious so far. sooo yes this would be my first real kit!

yeah you're right, fx sends are not really necessary. I would use it to feed my microsampler anyway.

[Koekepan]

Purely my take on this:

The battery bank is not crucial.

a) The volcas take batteries already, and last quite a while on them.

b) The volcas can do the power cable thing themselves.

If you have a power source, you might as well plug your volcas into that (I use the powersquid style of powerstrip) as well as the nervous system device, or the nervous system could just run off its own batteries like the Volcas, and you're just as battery-dependent as ever.

To me, the biggest need and/or lack in the Volca world is MIDI management and sound management. With your MIDI Thru approach, you solve the MIDI thing nicely. You arrange it so that one could run a few Volcas off a Squarp Pyramid, or Social Entropy Engine, or whatever. (I use the sequencer in my Casio XW-P1). The rest is basically a mixing task.

I absolutely take your point on each Volca already having a volume knob. After panning and EQ, the other nice mixer feature would in fact be some kind of FX feature. Insert/AUX just makes a lot of sense there.

Here's what I propose then:

a) reduce the battery bank to just what the nervous system requires, and let the Volcas solve their own lust for power.

b) Keep the panning pots, but use the saved space to add an FX bus and an AUX plug so that one can add a guitar pedal or similar for sonic flexibility. Don't add volume pots, but rely on the Volcas for that.

c) Consider replacing the faders on the output with pots, to save a little more space.

d) (Vanity request) see if you can rescue some of the space for a sixth MIDI/panning/AUX knob.

I think that those suggestions make for a more powerful setup, because they address the strong and weak points in the whole Volca ecosystem a bit better. I agree with Eowyn that the addition of an FX bus would be a huge extension of the sonic power in this thing.

[bogdanr]

@Koekepan: I looked at how other sub 200€ mixers are doing it and it is not very good because they are sacrificing stereo on the FX bus. In order not to sacrifice stereo it should be two buses, which means significantly more traces on the board, double potentiates and and at least an extra chip. As much as I want to do it, I will have to pass on this one unless there are going to be at least 1000 people that would buy the nervous system.

Also, I am hoping to get some feedback from at least 10-20 people because I would like to base some of the decisions on crowd wisdom. Where else should I go for feedback?

I want to determine what would be a better layout and if this should be a kit or partially build kit with at least the resistors soldered?

[Koekepan]

You could consider a couple of options.

For pure feedback, consider going somewhere like muffwiggler.com as well as here.

For feedback on how popular an idea this might be, consider a kickstarter campaign, and try bringing it to the attention of someone like Sonicstate and Synthtopia for comment and support.

[Volca22]

What about adding a master sequencer for all your analog gear? Like the Korg SQ-1? I was thinking of adding this to my 4 volcas and the Korg Kaoss DJ.

[bogdanr]

@Volca22 That would significantly change the scope of this project and it would significantly increase the price.
SQ-1 is already good at what it does and it's also very cheap so I don't see a point of replicating that functionality.

Honestly, right now we need to find someone that can design a front panel with the current features and I would be willing to work some more on implementing it. I did a second design but it also didn't turn out very nice so it is time to try again

[Volca22]

Check this one out. Only 5 stereo inputs but what you are looking for.

https://www.amazon.com/gp/product/B01M6 ... UTF8&psc=1

[bogdanr]

Since nobody proposed a design, I wend ahead and did 2 designs:

1. This one has two larger speakers:


2. This one has a single smaller speaker:


So, which one do you prefer from a design point of view?

[Koekepan]

I like the one with two speakers more.

However, I would put the input jacks so that cables don't lie over buttons.