“Detroit Boxes”: Motown-style transformer DIs

Last year I found myself with an excess of nice vintage 1:10 and 1:12 audio transformers, so I figured I would make some “Motown”-style passive DI boxes and see how they sounded. I built all of these using genuine 1960s era transformers, NOS Allen Bradley carbon-comp resistors, and NOS vintage hardware components in order to make something that ‘looked and felt’ like the sort of thing that a studio custom-shop would have built in that era. These aren’t copies of the Motown box – that piece used a particular model of transformer which I did not use, and I had my own aesthetic directions to pursue – but like the original units, they have that higher 1:12 ratio, variable defeatable pad, bi-directional operation (for use as a ‘re-amp’) and ground lift switch.

In the past I generally built my DIs with 1:5 or 1:8 ratios, so I was curious to see if the higher ratio gave a more open, detailed sound while still allowing for a sufficiently good signal-to-noise ratio. After building a half dozen of these things, I can say that yes they sound great. Here are a few examples of the units I built.