This page describes my ongoing development of a M/S Stereo headphone decoder for use with my Sound Devices MixPre.

This circuit (from Dave Latchaw) was initially going to be inserted into the headphone selector switch described on the Headwize website by my buddy, Rudy Trubitt.

Realizing that this was not a 45 minute project, I scaled back my initial project with plans to modify it in a series of steps.

The Circuit

The circuit was bread boarded using parts from Radio Shack (Hey, its walking distance from my house!). An IC socket was used so that the TL082 dual op amp could be removed and replaced at a later time with the better performing (but not available at Radio Shack) NE3352 dual op amp.

The Power Supply

The dual op amp requires a bipolar power supply, initially implemented with two 9 volt batteries.

The enclosure

The first prototype used an Altoids tin. Cinnamon Altoids.

The first mod - refining the power supply

This two battery power supply worked fine for the original prototype, but in an effort to shrink the size of the unit, the Maxtor 1044 was used to create a single battery bipolar power supply.

The second mod - A "mid-only" switch

Radio Shack push button SPST switch was added to send the "mid" signal to both channels.

The third mod - undoing the second mod

I installed the "mid only" switch for times when I was using the MS mic as a mono boom mic. The same function can be accomplished using the switches & pots on the MixPre.

The fourth mod - external power jack.

I can use the same external battery (a radio shack toy car battery) for both units.

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