A transformer is a device that transfers electrical energy from one circuit to another via inductively coupled conductors — coils of insulated wire wound (most often) around a ferromagnetic core. Transformers are useful in audio recording, as they can block DC voltage and facilitate electrical isolation between gear, but they also shape the sound of signals sent through them by introducing subtle, often very desirable "coloration." This may be a result of any combination of frequency response, time response, distortion or a number other factors for a particular transformer. These effects can be especially attractive when working in the digital realm, where sounds can be perceived as too "cold" or "digital."
We always hear how certain transformers in a piece of recording equipment add to the quality of its sound. If these transformers are so great, why not skip all the electronics and strap bare transformers into the audio path directly? The first time I heard and saw this done was at a mastering session with Nick Blagona in Toronto, when he ran a pretty crispy sounding master through a pair of vintage Marinar transformers that he had lifted from a Neve module. The sound was just right for this record — fat lows, punchy mids and a silky top. I personally hadn't had a chance to do much with this idea until I recently pillaged my repair guy's stock bins, and now I'm hooked on trying all kinds of transformers in all kinds of situations.
A Simple Transformer Explanation
A signal goes into one side of the transformer (usually the side driven is referred to as the primary), and the voltage that results on the output (secondary) is the input multiplied by the turns ratio (neglecting internal losses). The impedance ratio is the square of the turns ratio. Example: a 1:10 step-up transformer on a mic pre input would have a 1:100 impedance ratio — meaning the voltage gain is x10, at a cost of increasing the output impedance by x100. A DI box is an example of going the other way, stepping the voltage down to reduce the driving impedance. The lower the impedance a signal is being driven with, the less susceptible it is to noise. -SH
What you'll need are 600 ohm to 600 ohm "matching" transformers. These will generally work properly with the gear in our racks. Be careful of center-tapped transformers (center tap to ground). If these are exposed to +48 volts (from phantom power) in your system, they could easily be damaged. Simply wire your transformers up to cables that work with your gear or patchbay and you can insert them anywhere in your line-level signal path.
