Damping Factor - Interesting article
Yep. This is why Stereophile tests with a simulated speaker load. Look at any amp review, and compare tube amps to SS in the measurements. For a counter point though, look at Nelson Pass. He wrote at least one article where he showed that with some speakers, low damping factor, not high, is ideal. Best,E |
kijanki ,... I am generally aware of the relationship between an amplifier's output impedance and a speaker's input impedance, the latter stat which varies as a function of frequency response. What I found surprising is that Benchmark writes that if an amp has an output impedance of 1 ohm, the output level of the speaker could vary by as much as 2 db. I own an ARC Ref 150 SE. Some years back, John Atkinson (JA) reviewed an earlier version of my amp and reported his bench test findings here: https://www.stereophile.com/content/audio-research-reference-150-power-amplifier-measurements JA's bench test findings report that the FR changes of Stereophile's hypothetical test speaker varied by only .8 db off the 8 ohm tap. Curiously, JA measured the Ref 150 as having an output impedance of 1 ohm. FWIW, ARC reports that the Ref 150 has a DF of 14, which permits the inference that the amp's output impedance is .57 ohms (or 8 divided by 14). I know you are a techie. Can you please explain why there appears to be a difference between JA's findings and the Benchmark report. Perhaps Atmasphere (Ralph) or Almarg (Al) can weigh in if they catch this thread. Thanks BIF |
Looking at the Sterephile simulated speaker load FR/Impedance diagram, you can see the lowest impedance is 6 ohm, vs the 2.6 ohm of the Focal. So their simulated speakers isn't as difficult to drive. WIth the Focal, the AR amp would have a higher variation, and you can figure out by how much using the equations from the Benchmark article. |
The Focal is an interesting speaker to chose, since I've analyzed at least one model in depth, and let me tell you, it deliberately dropped the impedance. No doubt in my mind that having a low impedance was a crossover design goal. Since then I've seen they have a remarkably similar profile in many of their speakers, and it does make a difference. It makes a speaker seem more "discerning" of amplifiers. "My Focal must be better because I can hear the difference in amps." is the message. Still, people don't want to chat about that, there are many other high end speakers which brush with low impedance. From B&W to your average ESL. The Stereophile simulated speaker load is more forgiving than some, but you can still see the impedance dependent effects there if you look at a tube amp review. The principle is the same, if not as large. Best, E |
