Audio Transformer As Signal Processor

Sometime in the past couple of years, Tape Op ran a short piece by Allen Farmelo titled “Using Transformers to Transform Audio.” (EDITOR: the original Farmelo article is no longer available as far as we can determine – link removed) My reaction at the time was ‘it’s about time!’  Audio transformers are a crucial part of what we think of as an ‘old-school’ or ‘vintage’ sound.  My clients at the studio often ask me what makes tube-audio gear desirable, or ‘better,’ and I am always quick to relate that when vacuum tubes are operating in a linear (IE., not-distorting) way, you shouldn’t really ‘hear’ the tube – it should be amplifying, nothing more, nothing less.  Of course once you push a tube into breakup the effect can be quite different than a distorted FET or transistor but you get the idea.  A clean tube signal should sound… clean!  So, anyhow, the next point that I will make is that tubes are rarely very far from audio transformers, at least in pro-audio equipment, owing to the usefulness of ‘free-gain’ at input stages and the necessity of plate-or-cathode-matching at output stages (if this sounds like jargon to you/// basically/// tubes need transformers in order to play-nice with other pieces of gear).   The point: what we think of as ‘that tube equipment sound’ is really due to the transformers as much as the tubes themselves.

I won’t go into all the various effects that transformers create, as Farmelo does a very good job of explaining it in his piece.  Suffice to say: it is a very real, and very subtle effect.  Audio is a game of inches, though, ain’t it.  So when a regular customer of mine recently ordered a custom piece to allow him to use some high-quality transformers as a subtle signal processor in his studio, I was ready to go.   Here’s what I whipped up:

A single-rackspace unit – two 4PDT toggle switches on the front offer clickless true-bypass for each channel.  The switches are beautiful Japanese made units; each can handle 12,000 (yes twelve thousand) watts of electricity.  They should last…

On the rear we see Neutrik XLRs (my price/performance favorite) and…  a pair of 600:600 FREED output transformers pulled from some Scully 280 electronics that were too far gone to rebuild.  The transformers themselves are flawless, though, and they sound great; I have many of them at use in my own studio for various tasks.

Inside it’s just a buncha wire… Belden 9451… and at the rear you can see the heavy copper ground buss with a single chassis-contact point on the left.

Overall the transformers introduce a 1db loss in level to the program.  The effect is certainly subtle at reasonable levels, but I notice a more ‘organized’ sound to the extreme low end – it seems less vague while still retaining the full extension in the subwoofer.