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Damping factor

Jeffery said:
Your bass may end up being more liberated than you'd like :D if your amp can't control your woofer :scratch2:
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Many McIntosh amps have very low damping factors and I don't remember anyone that felt they lacked control. In the 70's Mac wouldn't allow their amps to be tested, as the "Authorities" of the day (like Julian Hirsch) "knew" that woofers needed the "Iron Grip of Control" that only a high Damping Factor can provide. I bought into that balony for years, until I was finally forced to admit how useless DF was. It was, sadly, like losing an old and familiar friend.
:tears:

At any rate, he probably didn't have a hand in this Yamaha amp.
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Nelson Pass? He has done a fair amount of design for different companies, but you may be right.

And I like class A amps, just not sure many have really high damping factors.
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Single Ended Triodes are all Class A and they have very low Damping Factors.

Best Regards,
TerryO
 
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I get the feeling this is a pro sound versus audiophile war, I am on the pro side since we know how things sound and work for live shows.

However, a tube amp can depict the most complicated signal down to the last harmonic, just no snap for bass. (then thats where the speaker efficiency excuse comes in)

I look at things for more electronic accuracy before sound, but if it sounds like crap ?

I just know what I like, and thats my last comment on this.

Although a higher damping factor is better, both for each side of the equation.

Oh and ? does or does not a coil added in series add to counter EMF, cancel it out, or does the amp not care. (case in point)
 
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qsaudio said:
I get the feeling this is a pro sound versus audiophile war, I am on the pro side since we know how things sound and work for live shows.
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Hmmm, I never got that feeling at all and certainly didn't realize it was a war, I thought it was about Damping Factor.
:scratch2:

However, a tube amp can depict the most complicated signal down to the last harmonic, just no snap for bass. (then thats where the speaker efficiency excuse comes in)
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Who's making an excuse? Given a decent impedance curve, a SET amp with no feedback and low Damping Factor can give deeper bass than any Solid State AB amp, within their design limits.

I look at things for more electronic accuracy before sound, but if it sounds like crap ?
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Huh?

I just know what I like, and thats my last comment on this.
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That's actually what I thought it boiled down to.

Well then, thank you for taking the time to share your invaluable opinions.

Best Regards,
TerryO
 
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so the general consensus is that lower "Damping factor" doesn't really tell whether the amp is good or bad. it just another spec put out for marketing purposes?

now am really out looking for Yamaha CA 2010 even though the damping factor is quite low. Never heard class A before. Should be interesting.
 
Yes, it's a largely useless number. As Terry said, it's actually even less meaningful than THD, which is hard to imagine, but true.
 
dnewma04 said:
Yes, it's a largely useless number. As Terry said, it's actually even less meaningful than THD, which is hard to imagine, but true.
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I might add that from my own personal experience, that's it's not only hard to imagine anything less meaningful than THD, but is actually dangerous as well!

The last time I endeavored to imagine anything less meaningful, I was stricken by "Severe Synaptic Collapse" along with the cognitive disassociation that often accompanies it.
My wife was forced to rush me to the Hospital when she discovered me muttering to myself, while posting to a Audio Forum about the absolute necessity of High-End Single Crystal Speaker Cables!

I can only hope that this warning is timely enough to prevent the unwary from suffering the intense agony that I've experienced.

Best Regards,
"Traumatized" TerryO
 
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Your bass may end up being more liberated than you'd like if your amp can't control your woofer
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This is where it is helpful to have a woofer that has a little bit of self control. :D Think Qms v.s. Qes etc.
 
pht714 said:
now am really out looking for Yamaha CA 2010 even though the damping factor is quite low. Never heard class A before. Should be interesting.
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Yamaha's marketing materials around the time of that model were pointing out that optimum feedback isn't necessarily the maximum possible feedback. If the designer chooses to emphasize power amp stability, then reduced feedback is one of the likely consequences. It was a forward-thinking concept for the time, and probably does improve sonic results with difficult speakers.
 
dnewma04 said:
I presume you only use fully active systems and never utilize passive crossovers and only use very heavy gauge speaker wire with short runs?
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I been trying to understand, how does the crossover coil screw over the damping factor? (woofer only)

If each inductor lags the current by 90 degrees, the crossover coil will have CEMF, and the woofer will also have CEMF.

does that power just disappear? does the phase of each counter act each other?

I would think if I was an electron that having an with a very low output impedance of the amp should be good for all concerned.I just won't accept it as "meaningless".

Why would Crown, even care, if it was so meaningless, makes no sense.
 
qs, did you read any of the articles posted? The math is pretty clear on where DF ceases to matter, and you will see it in many, many places (even articles from the 60s), always the same. In the very best (i.e. worst) possible case, with a 4-ohm speaker that has essentially no resistance in the crossover, and none in the speaker wire either, damping factor ceases to make a difference around 150-200. In most cases, it's more like 25.

This doesn't exactly mean it doesn't matter at all. Start throwing 1/3-ohm resistors in series with a speaker and you'll see as the DF drops into the single digits, bad bad things happen. It just doesn't keep being better the higher you make it.

EDIT: P.S. I use Adcom GFA-565 in my living room and I like them. Damping factor is over 1000. I'm not some 5W SET amp guy with esoteric single-driver speakers telling you this.
 
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Progress!

Let's do some math.

We know that damping factor is a ratio, specifically, it's the load impedance divided by the output impedance of the amplifier. For now, we'll ignore how amplifiers attain low output impedance just for the sake of simplicity.

So, let's say we have an amplifier with a damping factor of 2000 and an impedance of 8 ohms.

DF = Load Impedance / Output Impedance

2000 = 8 / Output Impedance

Output Impedance = .004

All is well in the world, right? We have our staggeringly high damping factor but we've ignored something important.

We forgot to include the series resistance of the speaker wire between the amp and speakers. Let's redo the calculation now.

Again, we know that DF = Load Impedance / Output Impedance, but now we are going to add in the effects of the speaker wire into our equation to figure out what the "real" or "effective" damping factor is of the real world situation. For simplicity sake, we'll err on the side of caution and say that it's very low resistance wire and only presents a .1 ohm load.

DF = 8 ohm / (.004 ohm + .100 ohm)
DF= 8 ohm / .104
DF= 76.9

The advertised damping factor of 2000 is now only 77 at the terminals of the speakers.

Now, let's look at what is going on at the terminals of the woofer in a speaker system with a passive crossover.

It's not unusual to have a series resistance of 1 ohm in a passive crossover, but just for a best case scenario, let's say that it's only .25 ohm.

DF = 8 / (.004 + .100 + .250)
DF = 8 / (.354)
DF = 22.6 at the woofer.

Now, let's say the damping factor of the amp is 20000! Surely that must make a huge difference being an order of magnitude higher than 2000!

Unfortunately, the reality is:

DF = 8 / (.0004 + .25 + .1)
DF = 22.8

It's essentially the same.

Now, let's say that the amplifier in the same scenario is only at 50.

DF = 8 / Output impedance

50 = 8 / Output Impedance

Output Impedance = .16

Now that we have the output impedance of the amp with a DF of 50, let's subsitute into our scenario to see the DF at the woofer:

DF = 8 / (.16 + 1 + .25)
DF = 8 / (.51)
DF = 15.7



Do you see how most people just don't find DF that important? In the real world, the difference between a low DF amp and a ridiculously high DF amp is essentially moot at the woofer.
 
Jeffery said:
You sure about that?

And don't get me wrong, I own seven (I think) Crown amps. But loads of feedback was how Crown achieved those astonishingly high damping factors.

But as has been pointed out, run that through a passive crossover and it goes right out the window, and it's not really the be-all of amp specs anyway.
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Lots of NFB creates lots of Transient Intermodulation Distortion), which is hard to meter but easy to hear. High NFB gives you a lousy slew rate (which is your best clue re: TIM.
 
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mashaffer said:
This is where it is helpful to have a woofer that has a little bit of self control. :D Think Qms v.s. Qes etc.
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Separately powered subwoofers are a good solution for that so-called lack of bass 'punch'. You can design a LOT of NFB into a bass amp because TIM is unnoticeable at bass frequencies. Lots of damping factor to control that 12-15" cone. Use a clean, low TIM , high slew-rate amp for everything above about 70 Hz.
 
Ahh, DC resistance.

could it be Crown was more concerned about concerts , high power, using electronic crossovers ?

So high in fact they have to use compression or the whole mix stage show speakers get trashed on the first note ?

Seems a straight wired voice coil (s) would offer a pretty good amount of CEMF, hence the amps need to handle that with a very low output impedance.

Also doesn't the design (Crown) using "grounded Bridge" offer a very high DF be default ? and is why they don't sweat hard at all, all day in the sun ,cranked , year after year. because of such a low impedance for current to flow.

I would think that would be better (should be) even at low power with crossovers.
 
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