Introduction: The Ultimate Audio Converter

I always find myself wanting to convert between mono and stereo and 1/8" and 1/4" jacks and never seem to have the right adapter on hand. The other day I was making two separate adapters for two separate conversion tasks when I had the sudden brainstorm to make a panel with every single mono to stereo and 1/8" to 1/4" conversion path I could reasonably think of. And with that in mind I bring you the ultimate audio converter.

It can convert from 1/8" or 1/4" stereo to either 1/8" or 1/4" mono (with the option to change jack sizes between channels). It can do simple conversion from 1/8" to 1/4" in mono and stereo. It can even split a mono signal into a stereo signal (again, with fully selectable 1/8" and 1/4" conversion options).

It is my hope that I will never need to make another converter again!

Well... until I need two of the same kind.

Step 1: Go Get Stuff

You will need:

A 14" x 12" sheet of white acrylic.
An awesome Epilog laser cutter
Red and blue acrylic paint
A paintbrush, water cup and palette
A heat gun
Heat protective work gloves
An 18" metal extrusion
Table clamps
A ruler
A drill with a 1/4" bit
(x2) 3" carriage bolts
(x2) 1/4" nuts
(x2) rubber stoppers
(x6) 1/4" mono jacks
(x3) 1/4" stereo jacks
(x6) 1/8" mono jacks
(x3) 1/8" stereo jacks
(x4) SPDT rocker switches
A DPDT slide switch
Hookup wire
A soldering setup

If you don't have a laser cutter, you can use a service like Ponoko

Step 2: Laser Cutter - the Tool of the Future

First you will need to cut up your acrylic.

Using the files below, first make a raster cut with the following settings:
Speed: 100
Power: 100
DPI: 600

Then make a vector cut with the following settings:
Speed: 10
Power: 100
Frequency: 5000

Step 3: Paint

Neatly paint in the part that was etched away with dark purple paint. For an added touch of class, also paint around the outside edge.

Place it elevated and flat so that the edges don't touch anything and you can pick it up from underneath if need be. I balanced mine on top of my water cup.

Wait for it to fully dry and then peel away the protective coating.

Step 4: Bend

Using your table clamps and the piece of metal extrusion, clamp the board to your heat resistant table such that 6" of the board is sticking off the end as shown. Make sure that measurement is even on both sides.

Put on your work gloves. Heat up across the joint (where the board is clamped) until it starts to visibly start to droop a little. Hold the part of the acrylic farthest from the heated edge (the coolest part) and gently and evenly start to bend the entire panel down. Continue bending until the panel is at around 45 to 60 degrees.

Hold it in place until it starts to cool and stiffen and then unfasten it.

Step 5: Install a Stand

Clamp the rubber stoppers in place and then drill a 1/4" hole into the top of the stopper such that it goes most of the way through.

Install your carriage bolts into the top corners of the board, fasten them tightly with 1/4" nuts and then screw the rubber stoppers onto the bottom.

Step 6: Jack It

Install all of your jacks as they are labeled on the front side of the board.

This means, removing the nut from the threading, pushing the threading through from the backside and then refastening the nut. Easy!

Step 7: Wire It Up

Place your board face down on a piece of felt or an unloved t-shirt.

Wire it up using the following schematic.

Unlike me, be careful to pay attention while you do it so that you don't wire everything wrong and realize halfway that you have to redo all your work.

One you are done soldering, you are ready to start converting.


n0ukf made it! (author)2009-06-27

Isn't it nice how some projects specify tools that the average hacker can't afford? :P Laser cutter? Come on!

randofo made it! (author)randofo2009-06-27

Or, you could possibly hack this with a power drill, a dremel and some screen printing.

clazman made it! (author)clazman2012-08-12

I don't mind using laser printing on decal material or maybe a clear label if you don't mind the edge. My way of hiding the edge of a stencil or label is to utilize a border of some color for the cut line.

phant0m_sp00f3ra made it! (author)phant0m_sp00f3ra2009-07-14

dude i thinkg the average hacker would HACK not just follow

KaydenST made it! (author)2012-06-09

I like this! I've been in so many situations where I needed a converter, and I just mostly electrical taped together different adapters to solve my issues. This will come in handy.

deafmonkey made it! (author)2011-11-25

4.7k in line on every out screw terminals are very good for this as you can
feed a thin copper wire across the terminal to form a bridge to tie in your resistors assuming you are staying passive

interactive3 made it! (author)2009-07-22

How much is a a basic Epilog laser cutter/engraver?

randofo made it! (author)randofo2009-07-22

I think the cheapest model is somewhere around 8K

hintss made it! (author)hintss2011-03-24

plus shipping :P

jakebaldwin made it! (author)jakebaldwin2011-09-27

and handling.

building_boy made it! (author)building_boy2011-11-13

and supplies! :-)

ARJOON made it! (author)2011-08-22

lol. you seem to be very rich. epilog cutter is stupidly very expensive.

mattthegamer463 made it! (author)2009-06-25

Does your board convert from stereo to mono? I've been trying to find a way to do this. Apparently it isn't as easy as putting the L and R channels together, you need to actually combine them with a mixer chip or something, or else you can burn out your amplifier. Did you do this and if so, how?

dragonfly_blue made it! (author)dragonfly_blue2010-10-18

Yes, does it do anything really or is it just a theatrical guise? Not that there is anything wrong with that! tro lo lo!

woodswalker77 made it! (author)woodswalker772010-06-16

The quick and dirty way to go from stereo to mono is to use a 4.7K build out resistor on the hot of each outputs before tying them together. I've done this hudreds of times with no ill effects.

randofo made it! (author)randofo2009-06-25

I just wired the two channels together. I'm only ever going to really use this to listen to audio playback on my cheap ol' headphones. I can't stand hearing something in one ear.

Sound Guy Andy made it! (author)Sound Guy Andy2009-07-14

Wiring two sources together to mono without any summing circuitry is very bad to the signal and both source and receiving devices. By wiring directly, you're wiring two low impedance outputs together to a single high impedance input, and the outputs try to drive each other, which can be VERY bad depending on the device. At a minimum, it's doing nasty things to your audio signal.

The circuitry need not be complex, an appropriately rated resistor (470-600 R or so works nicely) ) in line with each channel before they're tied together is all you really need (if you want to get fancy, a 10k shunt from the summed point to signal ground is nice, but not strictly necessary).

See this article for a more detailed explanation and example circuits:

spytech128 made it! (author)2009-12-30

 Wow! I love the look of this! I agree, the addition of RCA would really top it off. Now, what I am trying to do is get stereo audio from 3.5mm to feed into my RJ11 cordless phone system. Now, I'd love to find a way to make that conversion, too! Any possibility of how I could do that?

Steven's workstation 2009-07-21 003.JPG
clintsmithgsm made it! (author)2009-09-19

lasers have been around for a long time and have been used in industrial apps for a long time

3BlindMice made it! (author)2009-07-16

Would be nice to also have RCA line level jacks. I find myself spending quite a bit of time to hunt down my RCA to 1/8" TRS line adaptor when I need to supply mp3 tracks through a mixer "tape in" or 1/4 adaptors for two channels if there is no "tape in". Not the best way to attach one to a mixer, but quick for no more times than I have to do it.

Davidl3 made it! (author)2009-07-15

How did you aford that laser cutter? It costs about $8000!

InfamousKirch made it! (author)2009-07-08

Excellent design... I really like the curved front & bolt-leg back, it's somehow very MOD, or at least Swiss.

bananafred made it! (author)2009-06-24

You forgot to add a line-to-mic level signal attentuator! Just two resistors.

n0ukf made it! (author)n0ukf2009-06-27

...per channel.

randofo made it! (author)randofo2009-06-24

Oh. That is a good one. Maybe I will have to make an ultimate-er one.

66411 made it! (author)2009-06-26

Could also add in like a headphone amp and/or variable resistor for simply volume control or to balance channels. Very nice and neat design.

martins999 made it! (author)2009-06-26

To make a Mono conversion, you can't just connect R and L channels together, you can burn the outputs if they are not exactly in phase, that is to say if they are not sending out the same waveform. You have to use a resistor net to avoid short circuits. Nice and useful instructables though.

Hatredman made it! (author)2009-06-25

How about some RCA (phono) connectors?

tudgeanator made it! (author)2009-06-25

Awesome. So useful. I need one!!!!!

pstretz made it! (author)2009-06-25

really like this a lot. They'll make great Christmas or birthday presents. I really need a laser cutter!

pestan made it! (author)2009-06-25

you got my vote

pestan made it! (author)2009-06-25

So cool

SPGWhistler made it! (author)2009-06-25

When I worked with audio on a daily basis - this would have come in very handy. I love that it is analog. It's very simple and gets the job done. I think this is so simple in fact, that someone could build it with a completely different case design (or no case at all) and still make it easily work. Very good 'ible.

N1CK4ND0 made it! (author)2009-06-24

Very thin!

caitlinsdad made it! (author)2009-06-24

I think now you will have to put up an ible on how to make patch cords. If you take a 1/8" earbud headset to convert to use with a 1/4" headphone jack or vice versa, and you use this converter, you are still stuck with a regendered jack. You then need a male-male cable to plug into the device.

marc92 made it! (author)2009-06-24

This is awesome, but I would have included RCA conversions as well... Even more ultimate!

gmjhowe made it! (author)2009-06-24

This is, Most Ultimate! I love the simple case designs you use. Simple piece of metal with a slight bend. Keep them coming! (im glad i never challenged you to a 5 ibles in 5 days)

baggot made it! (author)baggot2009-06-24


pyrohaz made it! (author)2009-06-24

It looks extremely stylish!

clickmatch made it! (author)2009-06-24

Really? An $8000 laser? More like a $3 drill bit and instead of using square toggles, hit radio shack for some "round hole" toggle switches.

duck_tape_ made it! (author)2009-06-24

I was thinking of making one of these, but i never got around to it, maybe with these instructions i will!

mattthegamer463 made it! (author)2009-06-24

I'm fairly certain you're a robot. You just can't stop making perfect things every 3 days. Good luck to you in the Art of Sound competition, you've got all my votes.

fwjs28 made it! (author)2009-06-24

oooo...pretty...i like the stylish curve...always one for details..

Bongmaster made it! (author)2009-06-24

nicely done :)

About This Instructable




Bio: My name is Randy and I founded the Instructables Design Studio. I'm also the author of the books 'Simple Bots,' and '62 Projects to ... More »
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