Manufacturers of expensive microphone preamps usually write a lot about transformers and how good they are. I know transformers have been used often in the past, but with modern electronics, this is somewhat unusual and typical budget preamps do not use them.

If I buy a microphone preamp with a transformer in the circuitry, under what circumstances would I expect it to sound better than a cheaper, transformer less design? Would a high quality microphone be required to notice the difference?

1 Answer 1


sound different


Mic preamps with transformers tend to color the sound more than their transformer-less counterparts. Mic preamps utilizing transformers tend to have:

  • lower sensitivity
  • higher distortion
  • less precise low end reproduction

These are not necessarily bad things BTW!

Different circuits sound different, just as different microphones sound different.

sound better

How it sounds will be subjective. If you want color, than in most instances, transformer based designs will sound 'better', while transformer-less designs tend to be 'cleaner'.

When I record my vocals, I want color. Lots of color, because my voice is not all that pleasing. When I record nice vocals, sometimes cleaner is the better choice because the truth is ultimately more pleasing than the color.

That is not to say transformer based designs can't be clean, but they do tend to color. Every circuit is different, try before you buy!

  • 1
    There is one area in which a good transformer-balanced input will usually be objectively better than the best differential op-amp input, and that's common mode rejection ratio. Basically, transformers are excellent at rejecting hum and buzz in balanced cabling. Nov 10, 2015 at 15:40

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