What is damping factor relating to my Yamaha receiver?

twoengine

Active Member
I was looking at my old Yamaha AV receiver owner's manual and one of the specs listed was for damping factor. It stated that the damping factor was 80 or more for 20 hz to 20 khz at 8 ohms.

Therefore, my question exactly what is damping factor? I'm assuming a higher number is better.

Thanks in advance.
 
Damping factor is just a ratio between the impedance of a speaker and the output impedance of the amp driving it. The higher the figure the more control the amp can exert on the speakers drivers. Theoretically the higher the number the better defined the bass is and the cleaner the sound is. Solid state amps always have higher numbers, tube amps low. Personally I prefer just about all aspects of the sound of a good tube amp over a solid state amp so.... (cc
russk)
 
In the OP's case it is (no more, and no less) than 8 [ohms] divided by the output impedance of the amplifier in question -- the output impedance is thus, nominally, 0.1 ohms.

A DF "spec" is next to meaningless as far as I am concerned, at least in terms of its "absolute value", since it would only be accurate for a purely resistive 8 ohm load. Most loudspeakers (virtually all loudspeakers) are not resistive loads, but are instead complex reactive loads (with frequency dependent changes in capacitance and inductance).

An amplifer with a "low" output impedance will "feel" its load less than one with a higher output impedance.

The problem, howeverl is that the cure can be is worse than the disease. Especially in the spec-crazy 1970s into early 1980s, gobs of negative feedback were used to broaden/flatten frequency response, lower THD levels and reduce output impedance. These are all nominally laudable goals, but... too much NFB can result a loss of "immediacy" in the sound of an amp, and, poorly implemented NFB can cause "out of band" (ultrasonic) amplifier instability that can destroy such an amplifier when it is connected to a "difficult" (reactive) load. Polk Audio, in the 1970s, for example, sold a very reactive speaker cable ("Cobra Cable") which was a well known amplifier destroyer.

There have also been numerous loudspeakers with impedance curves that make them hard on amplifiers in general, and potentially fatal to some amps (the big Infinity IRS Beta system and the Quad ESL-57 are a couple of well-known examples).


DF of 80 is on the high side of "reasonable", I'd opine... but I use an vacuum tube amp with no added NFB and concomittantly low DF (output impedance ca. 1 ohm).

It's just not something I get too worked up about -- I am way more interested in how components sound than the numbers associated with them nowadays.

YMMV, though, of course.
 
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If customers were at all interested, I described damping factor as an "electronic brake" that controlled unnecessary cone motion. I would explain that the benefit was tighter, more accurate bass reproduction.

This tactic was to encourage prospective buyers to justify their spending a bit more for Yamaha than they would for say, Sony. To reinforce my claim, I would produce brochures for both, drawing attention to the spec section. Yamaha's published specs were usually more extensive than others then and did include damping factor. My intended point was that Yamaha catered to a more discriminating buyer therefore offered such information whereas other manufacturers didn't bother.

I didn't consider it a ploy necessarily, but it did often result in a larger sale than would have occurred had I mearly sold what was asked for.

I have always believed in the benefit of high damping factor and currently own an amp with a number of >1000. As far as I'm concerned, my system, which was not hugely expensive by many other's standards, has absolutely masterful bass reproduction.

I am a former bass guitar player and listen for such things.
 
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I am also into objective accuracy and find that such amps produce tight controlled bass with string and membrane harmonics preserved. IME, amps with minimum 200 are reasonably capable while amps rated 400 and higher are very capable.

BTW, the OP's AV receiver rating of 80 is not particularly good.
 
If you are fortunate to be able to bi-amp your speakers using an electronic crossover and throw away the passive crossover section for the woofer and the lower section for the midrange then having amplifiers with a high damping factor can really change the sound and performance of your loudspeakers in some instances. But if you are pushing speakers with high order crossovers using passive components from cost effective engineering bin then high damping factor really doesn't make that much difference. The topology of the amplifier will be more important. That said the over all frequency response of the system will be less compromised using an amp with a high damping factor than with a lower damping factor. In that respect your Yamaha is pretty much the middle of the road and should yield good performance if performing as it should.
 
All the folks responding have provided good information. Damping Factor (DF) is one of those specs that are useful to sell equipment, imho. Higher is better, in theory.

In practice, DF values in an amplifier specification may not be achieved at the speaker terminals due to the resistance added by the speaker wire and the speaker crossovers (if any).

An ideal speaker of pure resistance at 8 ohms attached to an amplifier of 0.01 ohms output impedance would have a DF of 800. Insert a speaker wire of 0.5 ohm plus the crossover coil of 0.8 ohms, for example, then the speaker "sees" an equivalent amplifier of 0.01+0.5+0.8 = 1.31 ohms. That gives you a damping factor of DF = 8/1.31 = 6.11 from an amplifier specified with DF of 800.

The DF can be increased somewhat with very low resistance wire (lower AWG number, or shorter cable length), which affects the 0.5 ohm part of the equation in the example. If the speaker wire is zero ohms, the DF only goes up to 8/0.81 = 9.88.
 
ThATS WHY TRUE BI-AMPING WITH SHORT WIRES AND NO PASSIVE CROSSOVER WORKS. Of course if you have critically damped drivers physically, it doesn't matter because the cones are controlled by the suspensions and enclosures.
 
ThATS WHY TRUE BI-AMPING WITH SHORT WIRES AND NO PASSIVE CROSSOVER WORKS. Of course if you have critically damped drivers physically, it doesn't matter because the cones are controlled by the suspensions and enclosures.

Sort-of. There's still other factors like time-alignment, speaker directivity changes in various directions and frequency, waveform accuracy of the drivers etc.
 
Some numbers, chosen at random:

Crown DC300A, >750 DC-400 Hz, 8 ohms
NAD 7175pe, >50 50 Hz, 8 ohms
Crown PS-200/400 >500 1-1000 Hz, 8 ohms
Marantz 2230, >45, 8 ohms
Marantz 250, >100, 8 ohms
Sansui 9090, ~10, 8 ohms
Dynaco Stereo 70, 15

IMO, damping factor doesn't seem tightly connected to sound quality or much of anything else. Crown is the only one that supplies a graph of DF vs frequency, so it's hard to compare others.
 
What are some examples of these amps with a damping spec of 200 and 400 because Ive never noticed a Damping spec that high? My Sansui AU-11000 has a Damping spec of 80, would that be considered low end?
The new Parasound JC5 amplifier has a damping factor of 1000 at 20khz for example. So a damping factor of 80 could be seen as on the low end.
 
Damping Factor basically controls cone movement. The lower output impedence of the amplifier acts like a short to the speaker, just like if you were to short the speaker terminals with a jumper and tap on the cone you would hear the cabinet ring go to a dull thud and the cone would be stiff. Some speakers will respond better than others to damping factor and damping factor will not affect the mid and hi frequency of speakers with passive crossovers.
 
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