The 4-sum mono mixer is not much bigger than the 9v battery needed to power it

Syntherjack has designed a tiny portable mixer called the 4-sum, ideal for those diminutive noise-maker setups.

Featuring a four mono inputs and one headphone output, the mini-mixer boasts a very long battery-life of around 100 hours, which can be doubled with a lithium battery.

The unit comes unassembled, so will require you to flex the flux and warm-up the soldering iron. The upshot of being a DIY project is that costs are kept to a minimum. 

One caveat though is that the 4-sum looks like it won’t be much use for Eurorack, as it’s unable to handle such hot signals.

The 4-sum is available now and can be purchased from Patch Audio for 210zł, which works out around £43/€49/$56 and you can find out more about the project on the Syntherjack website.

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4-sum features

• 4x mono inputs
• 1x headphone (dual mono) output
• Long battery life – average 100 hours (up to 200 hours with lithium battery)
• Low noise
• Output in phase with input
• Highest quality components
• Designed for portability
• LED power indicator