How much does the damping factor matter?

[highfigh]

Any coil has resistance, it is only a question of how low/or high it is. If you measure it with an ohmmeter and it reads 1 ohm, then it is 1 ohm and this 1 ohm resistance has nothing to do with motor characteristics. if you pass an a.c. through this resistance it will not decrease. I agree with those who said it should be consider external, but we can always agree to disagree.

Huh? Why and how would the AC resistance of a coil remain constant?

Damping factor is rated at a specific frequency, right? Any speaker will present a variety of resistance values to an amp's output, so it will be necessary to specify what frequency is most important, or show a graph, in order for this to really have any meaning. Since the amp's output impedance doesn't really change (AFAIK), a graph of the damping factor will follow the speaker/crossover impedance curve, won't it?

Minimizing cone overshoot is part of the balancing act by speaker manufacturers- compliance, mass, magnetic structure, voice coil, etc. Obviously, a motor assembly with excessive mass isn't good for accuracy, but an extremely low mass assembly usually has a higher Fs and less overshoot, but the compliance would need to be higher to work well at lower frequencies.

 

[WmAx]

Obviously, a motor assembly with excessive mass isn't good for accuracy, but an extremely low mass assembly usually has a higher Fs and less overshoot, but the compliance would need to be higher to work well at lower frequencies.

Mass has nothing to do with 'accuracy'. Mass as a singular variable, with other factors balanced/compensated to account for mass, then mass has only one effect on response: sensitivity.

-Chris

 

[WmAx]

I fail to see the big deal here. Damping factor (output impedance) only has an audible effect when it's EXTREMELY low , which requires output impedance to be 'stupid' high. Usually only an issue with tube amplifiers that use an output transformer with extremely high DCR on the output tap, (or if you use extremely low gauge wire, or place a resistor in line with the speaker and amp) thus causing the easily predictable/calculated frequency response errors in conjunction with the impedance of any particular speaker.

So what is the big deal?

-Chris

 

[PENG]

Huh? Why and how would the AC resistance of a coil remain constant?

I never said what you thought I said, far from it. The redundant answer to your question is simple, no the a.c. resistance, or more correctly, impedance of a coil would not remain constant if the frequency of the signal changes.

I said if you use an ohmmeter (the output is d.c.) to measure the resistance of a coil then it is the resistance of the coil. For a.c. we call it impedance. I was simply saying that part of the impedance (impedance=the overall effect of resistance, capacitive reactacnce and inducive reactance, it is a complex number) is the so call d.c. resistance; and that does not increase just because you pass an a.c. signal through it.

I did not say it would not change either I said it would not decrease (please read, because it could, at very high frequency due to for example skin effect, but that would be negligible for what we are dealing with here. As you know overall impedance will change with a music signal but I was only talking about the part that was measured with an a.c. signal from the ohmmeter. Reminder again, impedance is mathematically expressed as: Z=R+jwL+1/j(wC), where w=2¶f, f being the frequency, L the inductance, C the capacitance and R the resistance.

I hope this is clear for you this time. I try to avoid technical details in my posts, but even without the technical stuff, if you read with a little more patient you would not contradict something that I know you otherwise would not......

 

[PENG]

I fail to see the big deal here. Damping factor (output impedance) only has an audible effect when it's EXTREMELY low , which requires output impedance to be 'stupid' high. Usually only an issue with tube amplifiers that use an output transformer with extremely high DCR on the output tap, (or if you use extremely low gauge wire, or place a resistor in line with the speaker and amp) thus causing the easily predictable/calculated frequency response errors in conjunction with the impedance of any particular speaker.

So what is the big deal?

-Chris

Chris, don't you think it is kind of futile? So far, a few of us have tried, but obviously unsuccessful. The OP appeared to be wondering if there is consensus but this seems to be one of those topics that you just cannot get consensus. Many people read what they google, and things that are googleable are not always based on well understood scientific principles, some are but many are based on misconception.

 

[TLS Guy]

All us "audio enthusiasts and their rabid cousins, the audiophiles" thank KEW, TLS Guy, highfigh, PENG, mtrycrafts, and the others for this good thread.

It seems that concern over damping factor is another holdover from the days when all amps had vacuum tubes and low damping factors.

A woofer's damping, or suspension compliance, as well as the mechanical compliance from its cabinet design probably has as great or greater effect on achieving adequate damping, or "tight bass" than the amplifiers electrical damping factor. TLS Guy, could you comment on which has a greater effect?

Just the same, after reading all this, I admit I looked up my amp's damping factor in the manual , just to be sure. I'm glad to say that it is 450 .

I guess the final word on damping factor is that in most if not all solid state amps, it is high enough not to matter .

Absolutely, damping and Qtc are the speaker designer's responsibility, not the amplifier designer's responsibility.

This is a silly thread now. This only might be an issue with a tube amp, with a very high output transformer secondary resistence. There probably is one out there, and at least one deluded "golden eared" bloke that thinks it is "liquid."

 

[mtrycrafts]

I fail to see the big deal here. Damping factor (output impedance) only has an audible effect when it's EXTREMELY low , which requires output impedance to be 'stupid' high. Usually only an issue with tube amplifiers that use an output transformer with extremely high DCR on the output tap, (or if you use extremely low gauge wire, or place a resistor in line with the speaker and amp) thus causing the easily predictable/calculated frequency response errors in conjunction with the impedance of any particular speaker.

So what is the big deal?

-Chris

How would you separate the effect of 'stupid' high output impedance that cause the amplifier FR to follow the FR of the speaker rather closely as the impedance increases, from the DF by itself? Or, can you?

 

[mtrycrafts]

... Many people read what they google, and things that are googleable are not always based on well understood scientific principles, some are but many are based on misconception.

Hope Richard Pierce is not one of them

 

[WmAx]

How would you separate the effect of 'stupid' high output impedance that cause the amplifier FR to follow the FR of the speaker rather closely as the impedance increases, from the DF by itself? Or, can you?

You know good and well that dampening factor and output impedance are the same thing, simply expressed differently. Output impedance is a far more useful expression, however, as damping factor must be specified along with load impedance.

One can easily simulate the load reaction using basic simulation software to determine actual response effects using specific load with specific output impedance.

Most solid state amps have a very low output impedance such as 0.1, 0.2 Ohms, or lower, and have no appreciable reaction. But when you get to say, 2-5 Ohms output impedance (not unheard of values for tube amps), the reaction can be extreme, depending on the speaker.

-Chris

 

[KEW]

I fail to see the big deal here. Damping factor (output impedance) only has an audible effect when it's EXTREMELY low , which requires output impedance to be 'stupid' high.
-Chris

How low is extremely low.
I have two integrated amps from the early to mid 80's.
The Technics has a damping factor rated at 20 (4ohms) and 40 (8ohms)
The Sansui is rated at 60 (8 ohms).

Modern amps which publish a damping factor tend to have numbers much greater than these. At the time, a DF of 60 was pretty much state of the art.
So, I have to wonder:
1) Is this simply a short-coming of these old amps? Are these numbers inadequate? Is this an area where electronics have advanced greatly?
2) Do the damping factors of the 80's equate to the specifications published for modern gear. Power ratings have generally gotten sloppier snce then, but I don't know about Damping Factor.

While there does not appear to be a solid consensus. It seems that most feel it wouldn't hurt to expect a minimum value of 100. I don't know if this is a real need or if the attitude is since any decent amp would exceed 100, it should be expected.

Thanks!

 

[highfigh]

How low is extremely low.
I have two integrated amps from the early to mid 80's.
The Technics has a damping factor rated at 20 (4ohms) and 40 (8ohms)
The Sansui is rated at 60 (8 ohms).

Modern amps which publish a damping factor tend to have numbers much greater than these. At the time, a DF of 60 was pretty much state of the art.
So, I have to wonder:
1) Is this simply a short-coming of these old amps? Are these numbers inadequate? Is this an area where electronics have advanced greatly?
2) Do the damping factors of the 80's equate to the specifications published for modern gear. Power ratings have generally gotten sloppier since then, but I don't know about Damping Factor.

While there does not appear to be a solid consensus. It seems that most feel it wouldn't hurt to expect a minimum value of 100. I don't know if this is a real need or if the attitude is since any decent amp would exceed 100, it should be expected.

Thanks!

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.

 

[highfigh]

Mass has nothing to do with 'accuracy'. Mass as a singular variable, with other factors balanced/compensated to account for mass, then mass has only one effect on response: sensitivity.

-Chris

As far as accuracy, I was referring to the fact that a heavier cone can't accelerate/decelerate as quickly as a lighter one and that it can't produce the signal as faithfully at some frequencies when this is the case. That's also why I referred to the balancing act by manufacturers.

 

[TLS Guy]

How low is extremely low.
I have two integrated amps from the early to mid 80's.
The Technics has a damping factor rated at 20 (4ohms) and 40 (8ohms)
The Sansui is rated at 60 (8 ohms).

Modern amps which publish a damping factor tend to have numbers much greater than these. At the time, a DF of 60 was pretty much state of the art.
So, I have to wonder:
1) Is this simply a short-coming of these old amps? Are these numbers inadequate? Is this an area where electronics have advanced greatly?
2) Do the damping factors of the 80's equate to the specifications published for modern gear. Power ratings have generally gotten sloppier snce then, but I don't know about Damping Factor.

While there does not appear to be a solid consensus. It seems that most feel it wouldn't hurt to expect a minimum value of 100. I don't know if this is a real need or if the attitude is since any decent amp would exceed 100, it should be expected.

Thanks!

Have you been really reading and understanding this thread?

Any damping factor over 10 which translates to a source resistance of around an ohm is adequate. Any damping factor over 10 (8/source resistance) can not possibly have any audible effect under any circumstances.

All solid state amps will have a source resistance well under an ohm. There probably are some tube amps with a source resistance higher than that due to cheap poorly designed output transformers, but they are an aberration.

Back in those far off days when I was a boy, firms like Partridge made really big expensive output transformers for firms like Harold J. Leak, to keep the resistance of the transformer secondary low. That means thicker copper wire, and so more copper and weight.

The other issue, if the Qtc of a speaker is below 0.7 then damping factor of any amp is irrelevant.

We really don't need more discussion on this. That is the physics of it and that's that. Any perceived benefits of higher damping factors are another chapter in the big book of myth and audio delusions.

 

[WmAx]

As far as accuracy, I was referring to the fact that a heavier cone can't accelerate/decelerate as quickly as a lighter one and that it can't produce the signal as faithfully at some frequencies when this is the case. That's also why I referred to the balancing act by manufacturers.

Wrong. Higher mass will accelerate just as fast as a lighter mass, given more power input = sensitivity difference. Nothing more. Nothing less.

-Chris

 

[lsiberian]

Wrong. Higher mass will accelerate just as fast as a lighter mass, given more power input = sensitivity difference. Nothing more. Nothing less.

-Chris

Wouldn't a heavier mass moving at a lower rate of acceleration generate the same amount of air movement as a lighter mass moving faster?

 

[WmAx]

Wouldn't a heavier mass moving at a lower rate of acceleration generate the same amount of air movement as a lighter mass moving faster?

Mass has nothing to do with air movement. Displacement does (excursion and surface area determine this).

-Chris

 

[mtrycrafts]

You know good and well that dampening factor and output impedance are the same thing, simply expressed differently. Output impedance is a far more useful expression, however, as damping factor must be specified along with load impedance.

One can easily simulate the load reaction using basic simulation software to determine actual response effects using specific load with specific output impedance.

Most solid state amps have a very low output impedance such as 0.1, 0.2 Ohms, or lower, and have no appreciable reaction. But when you get to say, 2-5 Ohms output impedance (not unheard of values for tube amps), the reaction can be extreme, depending on the speaker.

-Chris

Thanks, my bad. Yes, they are the same and hence cannot be separated and the same FR reaction.

 

[mtrycrafts]

...The Technics has a damping factor rated at 20 (4ohms) and 40 (8ohms)
The Sansui is rated at 60 (8 ohms)....
Thanks!

In another word, not to worry about that number, plenty good enough
Other things to worry about room acoustics and speakers

 

[KEW]

Have you been really reading and understanding this thread?

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

Any damping factor over 10 which translates to a source resistance of around an ohm is adequate. Any damping factor over 10 (8/source resistance) can not possibly have any audible effect under any circumstances.

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.

 

[djreef]

Chris, don't you think it is kind of futile? So far, a few of us have tried, but obviously unsuccessful. The OP appeared to be wondering if there is consensus but this seems to be one of those topics that you just cannot get consensus. Many people read what they google, and things that are googleable are not always based on well understood scientific principles, some are but many are based on misconception.

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

DJ