I see this mentioned and know my amps have very high damping factor but what is it, how's it achieved and why is it important?
I see this mentioned and know my amps have very high dampening factor but what is it, how's it achieved and why is it important?
Thanks, what's involved in designing a amp to have a high 'damping' factor.. The numbers relate to what precisely?It's actually damping factor, not dampening factor.
In simplistic terms, it's a measure of the ability of the amplifier to control overshoot, to stop a driver from moving and overcome back EMF.
An amp with low output impedance and high damping factor limits this kind of sloppy driver behavior.
It's sort of like engine-braking in a car.
Thanks, what's involved in designing a amp to have a high 'damping' factor.. The numbers relate to what precisely?
Thanks for your help, I was under the impression it was to do with controlling the bass drivers well but vague understanding to say the least.
Why the negative stance (some have) on high damping then? Is there a trade off somewhere?Also, the SET guys are also not believers in high damping factor.
Why the negative stance (some have) on high damping then? Is there a trade off somewhere?
That's great don thanks ..What watchnerd said: damping factor DF = Zload / Zamp
While massive damping factor was the range in the 70's and 80's studies showed the required factor was much less than thought (by marketing, probably); most people can't tell beyond a factor of 20 or so. Most SS amplifiers these days are probably around 100 or so at lower frequencies, tube amps around 10 or less. For both designs output impedance rises and DF drops as frequency increases due to both feedback and the characteristics of the output devices (gain falls and output impedance rises with frequency).
A low output impedance (high DF) will let the amp look more like an ideal voltage source, the reference for most audio amplifiers. That reduces sensitivity to the load, both its impedance and the reverse EMF speakers can generate that tries to modulate the output. If the amp's impedance is high, then impedance variations by the speaker will change the frequency response. If there is significant back-EMF, essentially the driver acting like a generator instead of a transducer or motor, then an amp with high output impedance (low DF) will let the driver ring more. These affects can be audible and are certainly measurable.
This is part of why some amp/speaker combinations do not work well, and is also at least partly responsible for the difference in sound among amplifiers. I love tubes on panels in the midrange, but most tube amps do not control the panels well in the bass, and the very low impedance (often 2-3 ohms or less for ESL's or ribbons) at high frequencies can make tube amps sound a bit harsh or going the other way a bit soft if they roll off the highs. A speaker with a big dip in impedance at low frequencies can lead to amp stress and muddy sound if the amp has high output impedance. And so forth. Of course, ringing in the bass can sound "richer" or "fuller" and so some people like that sound better, and if the tube amp rolls of the highs again people may appreciate the effect and call the upper end "smoother". The SS amp that provides such solid bass may sound "harsh" even though its distortion is lower; people simply do not like the extended high range it provides.
It gets waaay more complicated than this but hopefully that helps a bit. - Don
Ah, it's a can of worms
Just get active speakers so you can stop worrying about it.
A passive XO will always add (usually) undesirable impedance to that seen by the driver(s), the impedance is frequency dependent, and ranges from perhaps an ohm or so to almost infinite. The potential for uncontrolled cone movement, intermodulation distortion and loss of performance is so great that it is impossible to determine in advance, but it is all negated in one fell swoop by using a fully active system.
It's hard to interpret the conclusion in isolation...
I may not be understanding what he is supposed to be debunking here. Is he denying that amplifier output impedance leads to audible consequences?He explores the problem with some assumptions and formulae, and posts the theoretical results over a broad range of Damping Factors for an example resonance and power loss.
It's a quick read.