gMIX Minimal 4-Channel Stereo Mixer


The gMIX is a minimal four-channel stereo mixer, designed for mixing the output of anything with a headphone jack.

It uses a passive design, so it can run without power or batteries. Here’s the official intro video:

The gMIX features four 3.5mm stereo jacks, which you can use to plug in just about any modern electronics with a headphone output, including Korg Volcas, iPads, iPods, KAOSS pads and many other devices. Each channel gets a volume control and that’s it.

The gMIX is being developed as a Kickstarter project and is available to backers, starting at US $35.

36 thoughts on “gMIX Minimal 4-Channel Stereo Mixer

  1. Nice but a simple passive summing mixer with no volume controls would be OK with me.
    This reminded me of the 9v Midiman 8X1 / 4X2 mixer I got for $10. I gotta go dig it out of the basement!

    1. Yes. I have a Rolls MX41b. Works great. Has both mini 3.5 mm jacks and 1/4″. You can use it for stereo unbal or mono balanced signals.

      I never noticed any noise issues with mine. Perhaps when folks were using low-level sources and feeding a pre-amp- but that isn’t noise from the unit, that’s just problematic gain structure.

      1. sounds great. thanks for sharing your experience. i am also worried a bit about the levels.
        the one little passive dual channel mixer i have, halves the signal and running two volcas makes them really quiet. does anything like this happen with rolls model?
        cheers for bringing some info to this topic all of you.

        1. Any passive mixer is going to come with a significant volume drop. There needs to be some resistance after the input stage to prevent the possibility of too much current being sucked out of the source, which would cause heavy distortion (and possibly mess up the output stage of whatever you have connected). Any increase in noise is going to come from having to crank up the other gain stages, so you need to rely more on your other equipment having good preamps.

          I found a good discussion:

          On a side note, I’d like to propose the term ‘kickbait’ apply to kickstarter campaigns for products where there are better commercial options already available.

          1. thanks for the link. i will look into it. i´ve actually pulled the trigger on a motu828 to work as a summing mixer in a standalone mode. should be good enough and older models are very affordable.

            1. I love interfaces that can do this! Switching from my M-Audio to a MOTU traveler was a major step forward in my setup – and I do largely the same thing with my MH2882 now. I can leave all the synths plugged in and just compose, and only worry about inviting a computer to the party when I need to record.

  2. i am just looking into that rolls model. some complain its noisy though.
    can it really be used as a sort of submixer for tha volcas in the studio?
    really interested in your experience with it if you catch this message.

  3. It’s a really simple schematic that one could build with minimal circuitry experience. I have an ART
    Electronics passive mixer that I bought new for less than this Kickstarter’s price. It even has the schematic printed on the bottom of the unit.

    A person could build this for 5 dollars.

  4. Nothing new about mini mixers, BUT this is the first to use mini jacks as far as I know.
    What would be cooler next step would be one that is active with multiple headphone jacks so you can have a jam out at Starbucks with your buddies and not annoy others

    1. Anything that delays my coffee purchase in Starbucks annoys me!!!!!!

      Especially people asking about the stupid Flat White.

  5. Best simple stereo mixer that can be had for a great price second hand is the Rolls RM203 – 10 channel stereo line mixer in a 1U rackmount format … I have 2 and love them

  6. The bad thing about passive mixer designs is that you end up with a really low output level and have to significantly crank the gain. That’s an issue when you’re mixing instruments that have a significant noise floor to begin with.

  7. I made a passive mixer once, but I wasn’t happy with the results (due to my lack of skills and very recycled mini-jacks!) so a well-made one is always welcome. Have to say this gets a little pricey once the case is included. For passive stuff I just use a Belkin Rockstar which can now be had for about £7, but obviously has no volume control on-board so relies on using the volume on my sources (mostly DSs, Monotrons, iPod etc.

  8. I know most people these days have a limited opinion about fidelity, but I would take a Radioshack active mixer over pretty much ANY passive mixer. Using it with low level outputs will result in unintelligible mush in the mix. For $35, haunt Ebay/pawn shops/yard sales for a used ACTIVE mixer.

    For the effort that went into the design/plus having it built, they could have designed this mixer to be active mixer (2 quad op amps, 1 dual op amp would do it), and maybe added $5 to the price but offered a product far more useful.

        1. Your reply to my comment was so full of meaning, I can’t even comprehend what you were trying to say, but thanks anyways. I suggest you immediately buy two of these passive mixers!

    1. What would be the point of them designing yet another active mixer though? Like, there are so many small active mixers from big companies already out there, they’d never be able to compete on price. I like this, especially in the PCB version, because it’s just SO compact and doesn’t demand power because so often you don’t need it. This is exactly what I’m looking for for my live volca setup.

      1. Putting Volcas (or anything else with a low level output) thru a passive mixer will work, but the sound quality will suffer. You could spend a little more for something active that reduces the noise floor, or something like a passive mixer that lowers the individual gear’s output.

  9. I feel this product wasn’t really thought thru. You can get plenty of mixers on the cheap by behringer or other brands for less than fifty bucks with twice the features. There’s also this thing by Belkin called the “rockstar” that’s only $15 bucks but lacks the volume control. That’s what I use With my volcas when just jamming in my kitchen with a cup of tea. I can see some uninformed kids purchasing this product but I don’t see it going too far.

  10. This is mostly designed for iPods and such.

    I would definitely use an active mixer with Volcas, Monotribes, etc.

  11. An active 8 port mixer with mini jacks would be a better idea I think. With all the Volcas, Monotrons etc makes you outgrow 4 channels pretty fast. Minijack mixers are hard to come by and active ones I’m not sure if they exists. All the converters and special cables cost nearly more than the mixer in the end and are a great pain to use.

  12. $80. People are pledging $80 for 4 stereo pots and 5 trs jacks in a case. Also a handful of diodes, I guess. I give up.

    This could be built on breadboard in an altoids tin for $20, max, with ten minutes of assembly.

  13. I made a 7 (Max number I could fit on the face plate) I/P with 1/8, 1/4 and banana jacks using a cct from Ray Wilsons MFOS for less than £10.

  14. I don’t like to be negative but this is truly uninspiring and not what I’d expect from a kickstarter campaign. the product is so simple to build and doesn’t need special/expensive components , correct me if I’m wrong but it doesn’t even come with an enclosure for $35? , that’s ‘taking the piss’

    pledge $10 and get a sticker? or just order the parts yourself for less than that

  15. The fact that it is passive is a deal-breaker for me. I’ve been hoping for someone to manufacture an active mixer along these lines.

  16. Some interesting discussions here. I always wanted a decent pocket mixer with 2 mini jacka and a cross fader. There was one once but I never found one for sale. I wonder what price you could sell an active (battery or mains) mini jack mixer with just volume and pan for and still make a profit? Now that would be a kickstarter I could get behind!

    1. keep in mind with simple designs can be problems.
      I remember someone show me multi passive and wonder why when one pot was adjusted other levels would change, told him that you circuits are needed between the pots to prevent

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