How much does the damping factor matter?

[PENG]

So, if I'm to understand this correctly, what you all are saying then is that "resistance is futile".

DJ

I don't understand your question. I am saying there is no use to explain the math and why the so call high damping factor are not that high if you consider the effective (real) damping factor due to the "d.c." resistance of the speaker coil, the effect of the crossover, the cable resistance etc.

By the way, nice Denon universal player you have, I have the older 3910, they are built like a tank aren't they?

 

[djreef]

I don't understand your question. I am saying there is no use to explain the math and why the so call high damping factor are not that high if you consider the effective (real) damping factor due to the "d.c." resistance of the speaker coil, the effect of the crossover, the cable resistance etc.

By the way, nice Denon universal player you have, I have the older 3910, they are built like a tank aren't they?

I'm sorry Peng. It was bad pun reference to Star Trek, and the topic being discussed. When I saw it I just couldn't 'resist'.

Yes, I do love my Denons.

 

[PENG]

Really reading, yes. Really understanding, no.
I cannot say that I've read every bit of every linked document.



Thanks, while I don't fully understand, I suspect that almost any amp would have a value of 10 or higher, thus damping factor is effectively a useless rating.

Well, I wouldn't go as low as 10. Anyway, if you follow the links posted so far by some of us, and understand the math, you will see that the DF of your amps are only slightly lower than those with DF greater than 100 or even 1000. It is the overall/effective DF that matters. This is not to say your Sansui can control your bass driver as well as a Crown amp can (claimed DF>1000), but its DF=60 will get much closer to the Crown's 1000 or even 3000 once you factor in the resistance of the driver's coil and other resistance external to the driver coil. I know this may appear to be confusing but try reading the fine prints of those linked article. Here is another one:

http://www.classic-audio.com/marantz/mdampingfactor.html

 

[PENG]

I'm sorry Peng. It was bad pun reference to Star Trek, and the topic being discussed. When I saw it I just couldn't 'resist'.

Yes, I do love my Denons.

No problem, I own every single Star War DVDs but not Star Trek... LOL.

 

[Lordoftherings]

Bob, just in case you may have missed his point as he did not show the formula. For damping factor calculation purposes, the d.c. resistance of the voice coil (in fact even the resistance of the speaker wires) must be considered as part of the output impedance of the amp so no matter how low the output impedance the amp is, the "effective" damping factor cannot be anywhere near the theorectical damping factor of 1000 that Rotel may specify. Put it in another way, Rotel has no control over what kind of speaker you are going to use. So if your speaker has a d.c. resistance of even just 1 ohm, the damping factor will effectively (hence call effective damping factor) be brought down to a much lower level. The difference in effective damping factor between amps with damping factors of 1000 and 200 is not that much for reasons TLS Guys cited.

Hi PENG,

I did respond to your post (this one right here in the quote), but it was not registered, and some of my other posts were deleted. I'm sorry that I cannot pursue anyfurther this interesting and informative thread.

Regards,
Bob

 

[KEW]

The amps you referred to didn't have high damping factor but at the time, many were rated at more than 100. 60 wasn't state of the art at the time. However, damping factor was mentioned at sales training sessions as something we could use to sell what we had, over the other brands. We need to remember- here in America, more is better, regardless of whether it matters, or not. No offense, but Technics was known for their turntables, not their amplifiers and by the time Sansui was making their R series of receivers, their hey-day was over.

While the power ratings included 20-20KHz (or wider), both channels driven, the THD % with a frequency response tolerance, some companies still made some pretty gutless and fragile amps and receivers.

I guess the bottom line is, if it sounds good, use it.

Thanks for keeping me honest!
That is what I get for trying to remember that far back. Amps like the HK Citation 12 had DF=40 but there were certainly a good many that broke 100 and a few that broke 200.
My Sansui was state of the art for slew rate, TIM and, I believe, rise time. It also had a near perfect low frequency square wave (which may be common now, but was unusual back then). I thought wrongly that the damping factor was also especially high.
The Technics was never a favored piece of equipment, I just was using it (along with the Sansui) as an example of what common DFs used to run.

 

[KEW]

I really originated this thread out of curiosity as to how significant the DF is with my Marantz SR6001's amp section in mind.
Marantz seems to avoid revealing amp performance data aside from Watts@THD, S/N ratio, and FR.
As a rule of thumb, "buyer beware" dictates that if it is not published, it should be considered inadequate. However, it seems like I can reasonably assume the DF is not an issue.

 

[PENG]

I really originated this thread out of curiosity as to how significant the DF is with my Marantz SR6001's amp section in mind.
Marantz seems to avoid revealing amp performance data aside from Watts@THD, S/N ratio, and FR.
As a rule of thumb, "buyer beware" dictates that if it is not published, it should be considered inadequate. However, it seems like I can reasonably assume the DF is not an issue.

In the 2nd last paragraph of the last link I gave you under the heading Some Perspective, the guy wrote:

"In the old days, when hi-fi shops were easy to find, you could walk in and a good place would let you switch different speaker systems in and out, amps in and out, etc. You could always hear the difference in the speakers. It's a lot more difficult to hear differences between most decent or better amplifiers. You can, but you'd better have some pretty exceptional ears when you're auditioning the best that good manufacturers can put together."

I share the same experience of the writer (presumably one of the Marantz fanboys). I should add that in those old days, every time after I went to a live concert I could not stand my Stereo system for about a week, then I would get use to it and started to enjoy it again. Thanks to technological advances, nowadays I can almost enjoy my home system immediately without re-adjusting to the slightly inferior sound quality.

Like the writer said in his last paragraph, " Hey, enjoy your music. Don't sweat it. Play with the knobs, and if you like what you're hearing, the specs are probably pretty good." You've got that great Sansui fixed, right?

 

[Lordoftherings]

Is it or isn't?

Audioholics reviewers seem to favor a higher Damping Factor than a lower one.

Me too. And I thought that a Rotel RMB-1090, with a spec of 1,000 DF
would have better control on my so so front set of speaker's drivers,
compared to my Onkyo TX-SR876 with a spec of 60 DF.

And my ears seem to agree. And from what I've been reading...

So, I'm probably wrong again? (Story of my life!)
Ya, gimme a break.

 

[KEW]

In the 2nd last paragraph of the last link I gave you under the heading Some Perspective, the guy wrote:

"In the old days, when hi-fi shops were easy to find, you could walk in and a good place would let you switch different speaker systems in and out, amps in and out, etc. You could always hear the difference in the speakers. It's a lot more difficult to hear differences between most decent or better amplifiers. You can, but you'd better have some pretty exceptional ears when you're auditioning the best that good manufacturers can put together."

I share the same experience of the writer (presumably one of the Marantz fanboys).

Same here!

I should add that in those old days, every time after I went to a live concert I could not stand my Stereo system for about a week, then I would get use to it and started to enjoy it again. Thanks to technological advances, nowadays I can almost enjoy my home system immediately without re-adjusting to the slightly inferior sound quality.

Unfortunately, around here, the well known bands all get booked in the mega-size steel and concrete stadiums. The old boom box down in the garage sounds good in comparison!

Like the writer said in his last paragraph, " Hey, enjoy your music. Don't sweat it. Play with the knobs, and if you like what you're hearing, the specs are probably pretty good." You've got that great Sansui fixed, right?

Yep, the Sansui sounds good but I've been using the Marantzs to facillitate comparing speakers. It'll be interesting to see how the Sansui fares A-B'ed against newer stuff, but that is a ways away.

 

[njedpx3]

I read quite a bit about this from way back. As far as I know there seem to be two schools of thought. One, such as Crown Audio, thinks it is very important.

http://www.crownaudio.com/pdf/amps/136224.pdf

Another, that may be sort of a sober thought:

http://www.monstercable.com/mpc/stable/tech/A2412_Damping_Factor_Article.pdf

There are many more that down play the importance of that number if you google the topic you will find them. Most would agree that >100 (the real world number will be much lower) should be good enough and that high numbers are achivable by applying lots of negative feedbacks (good/bad?, that would be another topic).

PENG,

Very interesting . The crown audio article is excellent and correctly explains damping factor and the need for a higher number to prevent "ringing" or "time smearing" due to Newton's second law: inertia.

The Monster article (Autosound 2000, Inc.) is downright scary in that the current limitation of amplifiers is never mentioned as they discusss constant voltage and theoretically unlimited power into a theoretically perfect zero ohmn speaker, then it goes into an EDF (effective damping factor) that is relatively low derived damping factor.

Later,

Forest Man

P.S. - scientific voodoo ..since any audio signal never can be asymptotically ever damped all the way to zero ...every sound every made is still circulation around the world ... sometime in the future they will filter and amplify Lincoln's Gettysburg address and you can hear it as he originally spoke ... all the things you have ever said EVEN SCARIER... scientific voodoo.

 

[PENG]

Same here!

Unfortunately, around here, the well known bands all get booked in the mega-size steel and concrete stadiums. The old boom box down in the garage sounds good in comparison!

In that case I fully agree with you as long as you have a nice boom box.
I am closed enough to the concert halls in Toronto. Even then, I would refer to symphony orchestras only for a valid comparison. Jazz and pop live concerts use electronics expensively so no wonder my home system can withstand a 2 hours delayed A/B comparison every time.

 

[highfigh]

The Monster article (Autosound 2000, Inc.) is downright scary in that the current limitation of amplifiers is never mentioned as they discusss constant voltage and theoretically unlimited power into a theoretically perfect zero ohmn speaker, then it goes into an EDF (effective damping factor) that is relatively low derived damping factor.

The funny thing about audio equipment, the perceived sound and how we describe it often comes down to "It sounds good, to me", even if it can't be found to reproduce the signal perfectly through measurement. We see enough different designs that are considered "the best", "State of the Art", etc even though they aren't necessarily so. Theory is how this stuff is designed and then the results are measured. That said, Richard Clark and David Navone are well known in car audio and have been, for decades.

The paper was for educational purposes and it seems that you may have overlooked "If an amplifier were theoretically perfect", at the beginning of the section about Damping Factor. Also, at a certain point, some things like like current limitations of amplifiers must be assumed. However, in a 12V system, a battery can supply a lot more Volt-Amps to an amplifier than a 120VAC supply can.

 

[3db]

I quickly read through this thread and what I understand to be true from a summary point of view.

1.) Damping FActor was/is an important spec if using tube amps with an output transformer stage.

2.) Doesn't really apply to SS amps becuase of their low output impedance.


back to item 1....isn't this relationship akin to matching outuput impedance of a tube amp to that of its load for maximum power transfer?

 

[basspig]

I quickly read through this thread and what I understand to be true from a summary point of view.

1.) Damping FActor was/is an important spec if using tube amps with an output transformer stage.

2.) Doesn't really apply to SS amps becuase of their low output impedance.


back to item 1....isn't this relationship akin to matching outuput impedance of a tube amp to that of its load for maximum power transfer?

Damping factor isn't any LESS important with tube or ss amplifiers, as it still is one of the defining characteristics of an amplifier. It's what the speaker's back EMF looks into, so it's darned sure to play a role in the overall system.

Tube amps are current source devices; the plate to plate impedance on the primary is typically around 6,600 ohms with a rail voltage of 450 volts. The transformer must match that to an 8 ohm driver. When you have a 1:1 match, the damping factor is 1. So, why can't tube amps have a low output impedance, you may ask? Well, they can, it's just that you'd have very little useable output power because the voltage swing would be small, and you'd be limited by the DCR of the secondary winding.

Solid state amps can produce a large voltage swing (as much as 242 volts rms at 100 amps, in the case of the PowerSoft K20 Digam series digital PWM amplifiers) while having source impedances of a few milliohms. They are voltage source devices.

Damping does not become irrelevant with SS amplifiers. Without it, some speakers would get downright sloppy.

I think a good way to demonstrate damping factor is to tap or push in on the woofer of a connected loudspeaker and observe the physical resistance both when it's connected to an amplifier output stage and when disconnected. You'll find that on vented and open back designs, the damping of the cone is pretty much the same, regardless of the cable thickness you've connected. When there's no connection at all, the cone will move easily and will ring. Connected, the cone will thump without ringing. It's an interesting little experiment that tells a lot about the effects of damping on drivers.

 

[PENG]

I quickly read through this thread and what I understand to be true from a summary point of view.

1.) Damping FActor was/is an important spec if using tube amps with an output transformer stage.

2.) Doesn't really apply to SS amps becuase of their low output impedance.


back to item 1....isn't this relationship akin to matching outuput impedance of a tube amp to that of its load for maximum power transfer?

Unfortunately in this case it is hard to match a load that is far from being constant.

 

[mtrycrafts]

I quickly read through this thread and what I understand to be true from a summary point of view.

1.) Damping FActor was/is an important spec if using tube amps with an output transformer stage.
...
back to item 1....isn't this relationship akin to matching outuput impedance of a tube amp to that of its load for maximum power transfer?

But, the drawback with that is is that the frequency response of the amp will follow that of the speaker's FR and you will have a euphonic setup. But, hey, some like such sound characteristics.