transformer signal path distortions – part 1

transformer circuit symbol


“Audio-frequency transformers are used mainly for matching impedances and transmitting audio frequencies. They also provide isolation from direct currents and present balanced impedances to lines or circuits.” (cited from Reference Data for Engineers: Radio, Electronics, Computers and Communications from Wendy Middleton, Mac E. Van Valkenburg)

In other words, they are most commonly used for two purposes: One is the isolation between two sections of an electric system which have different ground levels and another one is to change voltage levels (as is typical for tube circuits for example).

But whats that special about those “simple” electrical components that some folks are linking almost mythical sonic abilities to them? Remember, a transformer is basically just a piece of iron with two wires winded around – so what makes that so special? Bill Whitlock (Jensen Transformers, Inc.) said in the Handbook For Sound Engineers: “Although a transformer is not a complex device, considerable explanation is required to properly understand how it operates.” and it even gets worse since not all effects can be explained just by looking at the transformer itself but this topic requires a deeper look into the circuits around which causes the load to the transformer.

As a matter of fact, audio distortion in transformer cores can really sound ugly and when an audio-frequency transformer has been built much efforts has been spent already into making it as linear as possible by the technical designer for sure. Already back in 1939 Norman Partridge (Partridge Transformers Ltd.) had published some great articles about the circumstances of transformer core distortion, their measurements and how to minimize such distortions by proper design. Such literature is a great resource to get a deeper understanding on what that distortion actually is and what is going on when current flows through such a device.

to be continued


  1. Awesome! Thanks for the info – I can’t wait for more

  2. This is why I love the stuff here.

    There’s so much resources spent on making boutique plug-in sound like bits of vintage iron rather than looking at those qualities (or unwanted aritfacts) that contribute to new and effective ways of producing DSP’s which lend themselves naturally to the digital domain.

    It always must be borne in mind that many of the ‘quirks’ in analogue circuits, tape saturation et. al. were not actually desired at the outset.

    So I guess the challenge is now becoming how to sweeten the clinical digital domain in new and creative ways.

    This site seems to be in the forefront of that quest.

  3. Nekro Dean says:

    Herbert and obviously everybody else intrested, I was having a look around for suitable transformer candidates for use in a possible audio gear build which would be 30% my usually silly idea from a non-electronics engineer fried brain and 70% my close friend, fellow audio engineer and electronics dude Paul that would/will build it up if it turns out viable/not a monster waste of money & time, Whom tells me often ‘no thats ridiculous because…’, ‘well it doesn’t work like that…’, Asks me “Why do you want just another glorified tubescreamer!!??” and so on 😳 whose blog dedicated to the dying art of the strip board layout and build, It and Paul can be found here: 🙂 So I came accross this downloadable PDF from Sowter Audio Transformers who need no introduction. Its a good read and goes really well to compliment this article in my very humble opinion. So without going on here is the link should your goodself see it fit for posting linkage here plus anybody else that isn’t aware of it and fancies giving it a read:
    All the best and I do hope it is some useful information. Hope everyone has a goodtime over the christmas period with your families and loved one’s 😀
    Dean and Family


  1. […] transformer signal path distortions – part 1 Share this:Like this:LikeBe the first to like this post. Filed Under: TechTalk Tagged With: Audio, core, current, distortion, frequency, ground level, impedance, input, stage, transformer, voltage level « a welcome surrounding […]

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