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Damping Factor - Interesting article

Benchmark Media published interesting article on Damping Factor.  I already knew that it does not make much difference for the damping of the membrane, but low output impedance is necessary to drive changing impedance ot the speaker (ideal voltage source).  According to this article DF=100 produces about 0.5dB variations typically, while DF=200 reduces it to 0.1dB.  DF above 200 is inaudible.

https://benchmarkmedia.com/blogs/application_notes/audio-myth-damping-factor-isnt-much-of-a-factor?omnisendAttributionID=email_campaign_5eda3b728a48f72deaf34bf2&omnisendContactID=5cf9266b15b61cc5a2a4dee7&utm_campaign=campaign%3A+AUDIO+MYTH+-+%22DAMPING+FACTOR+ISN%27T+MUCH+OF+A+FACTOR%22+%285eda3b728a48f72deaf34bf2%29&utm_medium=email&utm_source=omnisend

128x128kijanki

Showing 2 responses by bifwynne

bifwynne
2,206 posts
 
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
bifwynne
2,206 posts
 
General observation:  much of the discussion above focuses on high DFs of 20, 200 or 2000.  I surmise that most amps that fall into those DF categories are solid state amps that are constant (or near constant) voltage sources.  

I was hoping Atmosphere (Ralph) would have chimed in because he manufacturers very fine tube amps that probably have output impedances in the single digits. 

Anyone have any thoughts about the db spread on tube amps, even those that use NF??

BIF
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