iPhone audio input using hacked D.I. Box

If I designed the iphone, I would have included a line-in jack. If you’re a musician that is live streaming video right now and you’re lucky enough to own an iphone that has a headphone jack, here’s a pretty cheap ($20) and easy DIY project that I came up with to turn a DI box and a microphone cord into a device that will let you take stereo line-level audio and feed it directly into your iphone so your live video streams can sound as good as possible.

I built this device last year for Signal Exchange, our Windsor-Detroit synthesizer collective and have used it with my iPhone SE to live stream and capture video of performances. I would have named it something better than “STLN2IPOO” if I knew I would be sharing it publicly, but I’ve been asked a lot about this project and I know a lot of people are wanting to live stream right now – hopefully this will come in handy for some people.

Here is the full size instruction sheet

parts

instructions

Open the PDC21, cut the traces shown and test to make sure they are cut with a multimeter if you can. Wire up the resistors and potentiometers, drill a hole in the chassis for the potentiometer. Reassemble and attach knob. For the cable, you can either attach the adafruit 3.5mm TRRS plug onto a regular microphone cable by cutting off the female end and wiring as shown, or you can cut the female end off of a TRRS extension cable and add the XLR Male connector.

how it works

This hack rewires the “input” and “output” 1/4″ jacks of the DI for our stereo inputs, the line-level signal gets summed into a mono signal through the two resistors before going into the potentiometer. The potentiometer acts as an attenuator, so you can turn down a loud signal to avoid clipping. The signal then goes into the DI’s transformer that converts it to microphone level and impedance. The 3k resistor lets the iphone know a microphone is plugged in and our special cable gets the microphone signal and ground to the right pins on the 3.5mm TRRS jack.

using it

Take line-level audio out from a mixer or musical instrument into your STLN2IPOO into one (mono) or two (stereo) 1/4″ inputs and run the mic cord into your iphone. Run the “voice memo” program and start recording to get a visual representation of the signal levels, if it is clipping turn the volume knob down. The DI box’s ground lift switch still functions if you find that you have a ground loop somehow between your gear and phone. That’s it! Now stream some video with good audio!

New Shop

After quite a few months of renovating, we finally moved into the new shop. This building was once a welding shop and a pinball repair shop before it sat empty for several years. Here are some before and after photos.

Making of the Reclaimed Wood Therevox

I’ll admit that I’m a bit of a pack-rat, especially when it comes to nice pieces of wood. When I’m milling the rough Walnut to make a Therevox ET-4, I’m often left with an assortment of small pieces and I keep every single one of them. After four years of saving these pieces, I thought it was fitting to build a new Therevox ET-4 out of the wood left from construction of all the previous instruments.

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Hundreds of small strips were rounded up, measured, graded and then milled to proper dimensions. The order of the strips and grain direction were decided on and then the strips were laminated together.

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Each side of the instrument is made with a six-layer lamination. It wasn’t intentional, but I like the coincidence that this instrument is also the first of our sixth production run.

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Wiping on the first coat of Tung Oil is always the most anticipated part of building these instruments, and I was especially pleased with how this special instrument turned out. I was honoured when the guys at reverb.com showed off the final product at MoogFest in Durham, North Carolina.

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To be honest, this was an instrument I wanted to keep for myself but I already own one of the first ET-4’s (serial number 1 – 12). It was listed on reverb.com for only several hours before it found a good home at The Loft Recording Studio in Chicago.

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From our facebook page

If you aren’t following our facebook page, here are some photos that we’ve recently posted from the shop.

sanding

inspecting boards

expression pedal name plate

Prototyping New Versions

We’ve been prototyping and testing a few new versions of the ET-4 over the last few months. We’ve been adding features that customers have requested and some other interesting things. Last week we also filmed some new videos and we’re looking forward to getting those up soon.

Here’s a sneak peek from the testing bench:

testing effects loop

prototyping usb interface