in reading a recent issue of Hifi World (England) the point that naim amps, while formidable, have a damping factor of 14 whilst American amps are usually known for highish damping factors. what are the implications of such?
damping factor low vs high
- Thread starter hifitommy
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Low damping means high output impedance so the sound is more influenced by the load (speaker). I remember reading that over about 20 or so it may not matter but it depends upon the speaker, of course.
The other player is controlling the speaker cones or panels; low damping/high amplifier output impedance means more potential ringing or worse transient (time domain) response.
Post here showing the impact of amplifier interaction with loudspeakers: http://www.whatsbestforum.com/showt...ponses-into-Speaker-Loads&p=139289#post139289
Audibility is in the ears of the listener. Some may like the sound of less (or more) control, and in some systems in may not matter.
IME/IMO/etc. - Don
- With a high-impedance speaker it probably does not matter.
- With a lower-impedance speaker but one that has relatively flat impedance over frequency it should not matter much, just a gain loss.
- With a speaker that has fairly wide impedance variation, which describes many if not most speakers, the frequency response is now a function of the amplifier's ability to drive it.
The other player is controlling the speaker cones or panels; low damping/high amplifier output impedance means more potential ringing or worse transient (time domain) response.
Post here showing the impact of amplifier interaction with loudspeakers: http://www.whatsbestforum.com/showt...ponses-into-Speaker-Loads&p=139289#post139289
Audibility is in the ears of the listener. Some may like the sound of less (or more) control, and in some systems in may not matter.
IME/IMO/etc. - Don
Not sure why a company would choose to build such an amplifier unless they also built speakers of their own which would then be matched to the amps operational limitations.
Those Naim amps tend to be very picky about wire capacitance as well if I remember correctly?
Those Naim amps tend to be very picky about wire capacitance as well if I remember correctly?
That makes no sense to me... I prefer lower output impedance because my measurements showed lower distortion and my ears say bass is tighter and deeper with my Maggies. My ears could be fooled, natch, but a lot of time it seems like people prefer a little more ringing and distortion because it sounds "richer" or "fuller". Preference is OK, of course.
VTL's larger amplifiers allow the user to adjust output impedance. So preference is definitely part of the equation.
Don,
Although the variation of frequency response versus output impedance is well understood and documented, the "controlling the speaker cones or panels" should be considered with some caution, as referred by some authors - see this excerpt of the Audio Power Amplifier Design Handbook by Douglas Self. I read the Moir paper "Transients and damping in amplifiers" in Wireless World long ago, but unfortunately do not have easy access to it anymore.
Attachments
In order to do it they change the feedback ratio - we can't know exactly why it is changing the sound. It can be either due to frequency response or changes in the amplifier distortion and other parameters. I know that some DIY people implemented it in older VTL designs and considered it, but access to the feedback components in the MB750 was not easy.
Hi microstrip,
Not sure if you are implying I am wrong or they are. In my case, and this a memory of a test, FR changes were not real clear (and we did not have the nice DSP-based AP test equipment we have now; it was HP sweep generators and tracking detectors) but you could see some "ripples" decrease that we attributed to panel modes. In the time domain much more ringing was evident after an input step or impulse. The test was performed in an anechoic chamber but similar results were recorded in or showroom with the back wall well-damped and the mic fairly close to the panel. (Aside: panel modes were much more obvious in planar speakers, dynamic or ESL, than the modes in conventional drivers). For this test, if memory serves, I drove the panels from a big Krell or Levinson amp (do not remember which), short jumper to a big terminal block, then short cable to the speaker. The amp was on the floor behind the speaker so the total wire run was about a foot to 18" (say 0.5 m). The wires were some Fulton provided, doubled-up Fulton Brown for each link (each + and - wire was a pair of Fulton Brown, net AWG was about 8 or so IIRC). The terminal block used either a short heavy Cu jumper to hook two adjacent terminals, or I inserted a non-inductive power resistor to increase the effective output impedance.
HTH - Don
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