brunoputzeys

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Ever since hearing, aged 16, two pairs of EL84's make short shrift of a shiny new solid state amplifier, Bruno wanted to know how and why things sounded the way they did instead of how they should. The ensuing expedition past all the stations of valves vs FETs vs transistors, analogue vs digital and their respective proponents gave him a keen eye for paradoxes, red herrings, logical fallacies, nonsequiturs and plain weirdness. In the meantime he graduated cum laude at the National Technical School for Radio and Film on the subject of power stages for switching audio amplifiers. He then went to work for Philips where he developed various digitally and analogue controlled class D amplifiers, noise shapers and modulation methods, and invented among others the "UcD" class D circuit. Since 2005 he divides his time between Grimm Audio and Hypex. Current activities include designing high-performance discrete AD/DA converters and analogue signal processing circuits, DSP algorithms, class D power amplifiers and active loudspeakers. What little time remains he devotes to writing and giving lectures in the hope of furthering rationality in audio. In these presentations and articles he shows skeptics what to measure before judging subjectivists to be wrong and demonstrates to audio mystics just how much of subjective audio experience is readily explained in ordinary physical, mathematical and psychoacoustical terms.


brunoputzeys

's contributions
  • 06.25.2014
  • The G word: Demo project - A balanced volume controller
  • It does. Carbon ink is notably nonlinear for instance. Other types may be better. At low frequencies the temperature dependence of the resistive material becomes noticeable. This circuit arrangement helps minimize the impact on distortion of these problems. After publishing the graphs I found that I'd inadvertently stuffed a logarithmic pot on the board (quite something after all that pontificating about it needing to be linear). Indeed, after I'd fixed that the distortion at LF went away too. Score for theory. I might put up the new measurement one day. It looks a sight better than the one in the article. The funny thing about ohm's law is that there are no resistors that follow it exactly. Every resistor data sheet gives an indication of the extent in which it deviates. If this info is not stated it just means that it's missing :)
  • 10.08.2013
  • Active noise cancellation: Trends, concepts, and technical challenges
  • Something worth adding about the feedback method is that (due to something called bode's inequality) you also get regions where noise gets boosted. One below the frequency range where the loop works and one above. The subsonic hump places extra strain on the power handling capability of the driver.
  • 04.22.2014
  • The G word: How to get your audio off the ground
  • Eh no. The Rane story goes that they originally had the wrong sort of wiring and earth lift switches etc and had a few guys employed full time to talk people through hum issues until someone finally plucked up the courage and nailed pin 1 to chassis. The phone calls stopped coming and the guys manning the phone could go back to engineering.
  • 04.22.2014
  • The G word: How to get your audio off the ground
  • This is the first part of the article as it appeared in LinearAudio. I agree it's hardly more than an introduction, dismembered as it is from the second half which will appear soon and will do exactly what you're asking.