Static THD measurements alone won't tell you how an amplifier will sounds when driving a loudspeaker. It's far more complex.
5% THD to .000 THD SOUND
I was searching the amplifiers available and noticed quite a big difference in THD specs from model to model. Example.. One of the best amplifiers Kondo Audio Note $150k Kagura has 5% THD and by reviewers definition sounds like an amazing amplifier. Now compare $ 30k Devialet with the lowest 0.000% THD on the planet. Both at the opposite end of design yet both sound amazing.. according to reviewers, I havn t heard either. SN/R 133 by Devialet and a lot less by Kagura. I realize an amplifiers sound can t be based by Specs alone. If the specifications are not that important to the sound, why list them? They must be a way of determining sound, quality, and system synergy of an amplifier? A whole lot of amplifiers purchased on the net haven t been heard before and I believe the decision to purchase is made by reviewers point of view, specifications and word of mouth of other owners and buyers pocket book. By looking at specs of Devialet and NOT knowing the prices of Kagura and Devialet I would of gone with the Devialet just based on specs alone for the impression of it being a great sounding amplifier. Ive read other discussions on forum and cant quite get a handle on why BOTH amplifiers sound great. I thought High THD was a bad thing..
Showing 3 responses by onhwy61
Atmasphere, I'd like your opinion on Bruno Putzey's latest class D amp design philosophy. I've read that he once held the same view as you do regarding negative feedback producing random upper order harmonics, but he's now broke with that orthodoxy. First, he claims that negative feedback needs to be evenly applied across the frequency spectrum and not disproportionately at lower frequencies. Second, Putzey claims that as you apply more and more negative feedback the odd harmonics disappear and distortion levels are low and smooth. I believe he is talking about 40 to 60 dB loop gain. Here's a link to Putzey's Kaluga amp's measurements. What you've written makes a lot of sense to me about why some amplifiers sound the way they do, but Putzey seems to be going in an opposite direction and his designs are said to be aurally excellent. |
Atmashpere, thanks for taking the time to reply. I misrepresented Putzkey when I said the distortion spectrum resulting from negative feedback was random. I should have said higher order harmonics instead of random. Whether is right or wrong in theory or in practice is being tested in the marketplace. Theta, Bel Canto, MBL, Jeff Rowland and others are using Putzkey's amplifiers in their products and they are getting positive reviews and user feedback. I guess only time can really sort these things out. |