3x3 Matrix Mixer Project

Would anyone be interested in this project?
For some reason I’m really into mixers lately.

3x3 layout … it will be a large project if I decide to do this. 5x LM6172
and I have 1 stage left, maybe an inverted input but that would mean 3 more pots. and there are already 12 :upside_down_face:

Destinations:

  • feedback routing
  • color mixing.

features: (for now)

  • 3x input with 3x pots per channel - so 9 pots
  • 3x output with 1x gain pot per channel

Things that might change:

  • gain pots: they can be in the feedback loop ? for better amplification / soft keying?
  • inverted inputs without pots. IDK if that is useful, but it would save panel space
  • SMD? maybe?

I’m open for idea’s!

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well I was just thinking about buying a doepfer matrix mixer - as there were no diy ones I could find that I liked

so why not

conditional add to group buy - if you do this I need 5 more

cheers
Jim

Yep definitely interested in this!

Schematic looks OK – but make sure you ground the noninverting input on the unused opamp, and connect a 1K resistor from inverting node to output. That way you won’t get any potential ringing or oscillation from the floating terminals.

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I might want to use that last opamp for something more useful, that is why it is still floating :slight_smile:
Maybe I’ll add a inverted input, or at least a mod input for expansion possibilities. to keep the DIY blood flowing!

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I can definitely see me wanting at least one of these please yes

Also Interested! Nice work @reverselandfill

Thanks!

These modules are not the most exiting things you could think up (as opposed to filters, effects and oscillators) but it is where I am right now in my personal electronics development. I’m mostly building on opensource schematics by LZX and others, adding some features I think might be useful. The help from @creatorlars is invaluable!

And I do think it is cool to have more DIY video projects in the ever expanding universe of modular !

3 Likes

Hey, what’s up? I have been working on something like this too. I was doing a 4x3 matrix. I just got access to a desktop milling machine, so I was going to prototype it.

I have another surface mount variation using a max4392. I’m willing to distribute whatever and collab if anyone is interested!

5 Likes

As mentioned in the previous 2x2 mixer thread, I am now finding that yes…buffers are our friends. Rev 2 Doh!

this sounds useful and great!

if I can get one built then I’d be in!

I’m back from Italy, so this project will continue this month.
I’ll keep you updated!

3 Likes

question:

There are 12 pots right now and there might be more, so I’m wondering how I will do the panel spacing.
Personally I’m not fond of trimmer pots and small knobs, but this can keep the panel small.
This will be a performance module, so I’d prefer space over size

so what to do?

1: use 9mm vertical pots - larger panel with enough space to wiggle
2: use 9mm trimmer pots - smaller panel with little room
3: 9mm pots with small knobs - inbetween solution. medium panel size

I think I’d prefer option 1, but any is fine

I just built an audio matrix mixer from york modular - which is 4 channel 20 pots and 14 hp - the designer recommends alphas - mainly as they are bolted to the panel and therefore offer a bit more support to the pcb - but I used short trimmers instead and it’s ok - the same trimmers will take the small knobs (from thonk for example) - but that has 8 jacks total and not 6 for support

yes, I also prefer the bolted ones. else I will need to add screws to the panel. or place the jacks on to and bottom for stability

I saw those small knobs at thonk , this was the reason for this question :slight_smile:

it’s only really the kits that are the issue (other than size - and that’s easily solved - the inevitable bigger/new case)

the pcb and panel holes are the same size - so builder’s discretion for supplying parts if they don’t buy a kit

same red panel colour as the function generators?

Yes, I was thinking of a red panel with geometrical shapes such as the TFG.

trimmers are cheaper. but I don’t like them much.
I think I’ll stay with the 9mm alpha pots bolted to the panel., as design
I might consider those small knobs and thighter positions

I’d prefer option 1 but 3 is okay as well. I regularly use NLC’s Cluster Mixer so I can deal with a little bit of cramped space. :slight_smile:

I’ve been using these for my mixer. It has 12 pots, and fits on a 4" x 4.6" board. They’re pc mount, so the panel can mount directly to them & the board. Seems like there’s enough space to get your fingers in there. That’s also with using BNC connectors, so it could be even smaller.

https://www.mouser.com/ProductDetail/652-PDB12-H4201103BF