More power = control?

[Vaughan Odendaa]

Has damping factor too low (say <50) for their speaker/wiring system.

I thought most experts agreed that damping above 30 is, for all intents and purposes, good enough. I think Floyd Toole eschews this in his books as well.

Either damping above 30 isn't good enough, or the outrageously high DF numbers have some benefit. From what I've read and understand now is that high damping factor values above a certain value are meaningless when all is said and done after you take the crossover, voice coil resistance, speaker cabling etc into account.

I must agree that if two amps are not volume matched or level matched then it could throw the entire demo process off.

 

[PENG]

I thought most experts agreed that damping above 30 is, for all intents and purposes, good enough. I think Floyd Toole eschews this in his books as well.

Either damping above 30 isn't good enough, or the outrageously high DF numbers have some benefit. From what I've read and understand now is that high damping factor values above a certain value are meaningless when all is said and done after you take the crossover, voice coil resistance, speaker cabling etc into account.

I must agree that if two amps are not volume matched or level matched then it could throw the entire demo process off.

I have no comments on what Floyd Toole said in his book as I have not read it. I do have faith in whatever he said he would likely be right as long as it is not taken out of context. To me, may be even above 10 is enough in most cases, but in some cases, even at 50, it could make enough of a difference to be noticeable by the listener. Its like power, you may not need as much you have, but it is good to have more than have less if you want to have the option to own difficult to drive speakers (just one example). Anyway, I am not trying to tell you to make your amp decision base on DF, not at all. I am just trying to point out in some cases, DF, say 20 vs 100 from 20 to 20kHz, could be one of many reasons why one amp could sound different than another. When I a say in some cases, I meant rare cases. Again,I believe (or guess) the last two factors I listed would more likely be responsible for the perceived difference in most cases. By the way, had you not brought up DF as a topic, I might not even have included it in my list of factors.

 

[jonnythan]

F = ma

A greater force can make a mass change its velocity at a faster rate.

Imagine a baby pushing a bowling ball back and forth. Babies are weak. An adult can push it back and forth much faster because adults are stronger.

That's basically what the damping factor is. If a driver is in the middle of a movement when it is asked to make a different movement, a stronger amp can make it change its motion more quickly.

 

[KEW]

F = ma

A greater force can make a mass change its velocity at a faster rate.

Imagine a baby pushing a bowling ball back and forth. Babies are weak. An adult can push it back and forth much faster because adults are stronger.

That's basically what the damping factor is. If a driver is in the middle of a movement when it is asked to make a different movement, a stronger amp can make it change its motion more quickly.

True, but the question is how much is enough? Say you have a baseball instead of a bowling ball. Now a professional weightlifter has no decisive advantage over a normal adult.

I'm not sure if you mean more powerful when you used the term stronger, but if the smaller amp is powerful enough, all the stronger amp offers is the ability to quickly blow the speakers if you turn the volume knob too high. Nonetheless, I am a proponent of ample power, because it is generally hard to know how much is enough since manufacturer's impedance spec's are so bogus.

 

[mtrycrafts]

F = ma

A greater force can make a mass change its velocity at a faster rate.

Imagine a baby pushing a bowling ball back and forth. Babies are weak. An adult can push it back and forth much faster because adults are stronger.

That's basically what the damping factor is. If a driver is in the middle of a movement when it is asked to make a different movement, a stronger amp can make it change its motion more quickly.

Yes, a greater force can do that if you apply it quickly enough. But, how fast you want that ball moving also depends on how much force is enough.

Now, an amp cannot respond stronger or faster than an input signal demands so that extra 1000 watts that is not demanded will do absolutely nothing to make that cone move faster or further, right? Slew rate is not, as far as I know, power dependent. And, that too has limits that beyond it has no bearing on audibility.

 

[PENG]

Damping factor and power should be dealt with separately. From what I understand the OP is talking about how one amp may have better control of the speaker it drives, over another. So far damping factor and power have been mentioned. Damping factor has some effect, but anything higher than a certain value may not have any audible effects, let alone better or worse quality. The OP also said he thought most experts agree 30 is the number. I am not sure if we can google up all those experts but it really does not matter because aside from tube amps, virtually all solid state amps will have DF>50. So if 30 is good enough then it is not an issue. Low DF does not automatically results in poorer sound either, it might just contribute to subtle audible difference when combined with other factors, and that is just a "may be".

Power, on the other hand definitely would affect how an amp may sound depending on many variables. One such variable is the load characteristics of the speaker. As an extreme example, you can have an amp that is more powerful than another for a certain speaker and yet swap out this speaker with one that has a totally different load characteristics, the reverse could be true. I suppose one can say that an amp that has the abiltiy to maintain its rated output regardless of the load characteristics (impedance vs frequency), then it has greater control of the load (the speaker) than an amp that is highly current limited such that as the impedance of the speaker varies with the signal, at some points it may demand higher current can the amp can deliver in a linear fashion. Now of course, even that fictitious highly current limited amp I used in my example would have no trouble controlling any load as long as it is operating well within its limitations.

[Note that for those technically minded, by referring to impedance as opposed to resistance, the phase angle aspect is implied]

 

[mtrycrafts]

Damping factor and power should be dealt with separately. From what I understand the OP is talking about how one amp may have better control of the speaker it drives, over another. So far damping factor and power have been mentioned. Damping factor has some effect, but anything higher than a certain value may not have any audible effects, let alone better or worse quality. The OP also said he thought most experts agree 30 is the number. I am not sure if we can google up all those experts but it really does not matter because aside from tube amps, virtually all solid state amps will have DF>50. So if 30 is good enough then it is not an issue. Low DF does not automatically results in poorer sound either, it might just contribute to subtle audible difference when combined with other factors, and that is just a "may be".

Power, on the other hand definitely would affect how an amp may sound depending on many variables. One such variable is the load characteristics of the speaker. As an extreme example, you can have an amp that is more powerful than another for a certain speaker and yet swap out this speaker with one that has a totally different load characteristics, the reverse could be true. I suppose one can say that an amp that has the abiltiy to maintain its rated output regardless of the load characteristics (impedance vs frequency), then it has greater control of the load (the speaker) than an amp that is highly current limited such that as the impedance of the speaker varies with the signal, at some points it may demand higher current can the amp can deliver in a linear fashion. Now of course, even that fictitious highly current limited amp I used in my example would have no trouble controlling any load as long as it is operating well within its limitations.

[Note that for those technically minded, by referring to impedance as opposed to resistance, the phase angle aspect is implied]

Maybe we should ask him what he thinks he means by his recurring terminology:
but at the same time I've heard people eschew the idea that high powered amps provide extra "grip", as it were.
what "grip" he wants it to mean?
Certainly we may have different interpretations beyond the implication of impedance and sufficient power to drive that load.
If he is after how well the cone will stop when needed that, I think is independent of power, no?

 

[PENG]

Maybe we should ask him what he thinks he means by his recurring terminology:
but at the same time I've heard people eschew the idea that high powered amps provide extra "grip", as it were.
what "grip" he wants it to mean?
Certainly we may have different interpretations beyond the implication of impedance and sufficient power to drive that load.
If he is after how well the cone will stop when needed that, I think is independent of power, no?

You are right, it isn't clear what he meant by that.

 

[Vaughan Odendaa]

what "grip" he wants it to mean?
Certainly we may have different interpretations beyond the implication of impedance and sufficient power to drive that load.
If he is after how well the cone will stop when needed that, I think is independent of power, no?

I've discussed this with several people and most of them use the terms "control" (more power offers better control of the speaker), some claim more wattage "grips" the cone better. Now I assume when people use the term "grip" I assume they talking about control, or perhaps are confusing damping factor for wattage.

The implication being that more power, in and of itself, can somehow provide an iron grip on the cone, hence more linear control, hence punchier bass, etc etc etc. That is how I understand their use of the word because it sounds more intuitive than say, "extra power provides better control in the sense that if the load demands it, the speaker can play louder, with less compression). You'll find magazine and online publications use the terms "control" all the time.

 

[cpp]

Saw this at True Audio

An audio power amplifier's damping factor is defined as the ratio of the load impedance to the output impedance of the amplifier.

Example 1:

Amp output impedance at 1k Hz is known to be: 0.25 Ohms

Impedance of the test load is 8 Ohms (at 1k Hz)

Damping Factor = (Load Impedance) / (Output Impedance) = 8 / 0.25 = 32 (dimensionless ratio)


Now, add a 0.25 Ohm speaker cable between the amp and the speaker and measure the damping factor at the speaker terminals and you would get: Damping Factor = 16
(Note that damping factor varies with frequency)

interesting

 

[Gordonj]

I've discussed this with several people and most of them use the terms "control" (more power offers better control of the speaker), some claim more wattage "grips" the cone better. Now I assume when people use the term "grip" I assume they talking about control, or perhaps are confusing damping factor for wattage.

The implication being that more power, in and of itself, can somehow provide an iron grip on the cone, hence more linear control, hence punchier bass, etc etc etc. That is how I understand their use of the word because it sounds more intuitive than say, "extra power provides better control in the sense that if the load demands it, the speaker can play louder, with less compression). You'll find magazine and online publications use the terms "control" all the time.

Just because a mag article uses the term "grip" does not mean that it is an correct term. More power from an amp does not add "grip" as in control. It will however do as you quoted above -"extra power provides better control in the sense that if the load demands it, the speaker can play louder, with less compression".

Gordon

 

[Steve81]

The implication being that more power, in and of itself, can somehow provide an iron grip on the cone, hence more linear control, hence punchier bass, etc etc etc. That is how I understand their use of the word because it sounds more intuitive than say, "extra power provides better control in the sense that if the load demands it, the speaker can play louder, with less compression). You'll find magazine and online publications use the terms "control" all the time.

Magazines and online publications also tout the benefits fancy wires.

Suppose you have Amplifer A rated for 50W clean output into an 8 ohm load and Amplifer B rated 200W clean output into an 8 ohm load, and an 8 ohm resistor to keep things nice and simple. If the combination of the input signal plus amplifier gain only amounts to 10W of output into your 8 ohm resistor, all else being equal between A and B, there won't be any special difference between the output of the two amplifiers. After all, why would there be? Amplifier B shouldn't be putting out even an extra nanowatt of power, so all its extra reserves are meaningless in this situation.

 

[mtrycrafts]

...-"extra power provides better control in the sense that if the load demands it, the speaker can play louder, with less compression".

Gordon

But, what compression are we really talking about here?
Amp clipping and speaker thermal compression or linear motion travel are two issues. Adding more power to a speaker that has exceeded its linear travel will not help anything but makes it worse. Same with thermal issues.

 

[Gordonj]

But, what compression are we really talking about here?
Amp clipping and speaker thermal compression or linear motion travel are two issues. Adding more power to a speaker that has exceeded its linear travel will not help anything but makes it worse. Same with thermal issues.

Compression from the amp exceeding its range of output and distorting is what i was referring to when using his quote from a previous post.

And they are indeed different items then speaker thermal compression or distortion caused by the speaker driver exceed its gap.

Gordon

 

[mtrycrafts]

Compression from the amp exceeding its range of output and distorting is what i was referring to when using his quote from a previous post.

...
Gordon

Then this is amp clipping, right?

 

[Gordonj]

Then this is amp clipping, right?

Yes. In some amps just before clipping, the amp will actually have an audible compression as the amp is out of headroom and on the edge clipping.

Gordon

 

[Vaughan Odendaa]

Correct me if I'm wrong but if a receiver has insufficient current for dynamic peaks the frequency response could change completely?

 

[Irvrobinson]

Correct me if I'm wrong but if a receiver has insufficient current for dynamic peaks the frequency response could change completely?

No. What happens is that the amp clips, and you get distortion.

 

[Vaughan Odendaa]

Okay so the frequency response of the receiver isn't affected if it clips? Just added distortion.

 

[Irvrobinson]

Okay so the frequency response of the receiver isn't affected if it clips? Just added distortion.

Frequency response technically refers a properly operating device operating within its design parameters. If an amp is clipping it is not operating within its design parameters, so any notion of a formal frequency response goes out the window.

I suppose you could look at it that clipping injects distortion into the output signal, and distortions appear in the frequency response, so it is affected, but that is a really weird way of looking it.

You never want an amp to clip.

If you look at the parameters for a "perfect" audio amplifier you get:

- A infinitely HIGH input impedance, to minimize the current requirements on the source. (In fairness, the high input impedance argument has been questioned by some, like Krell, who claim that you want relatively high current feeding the amp, to reduce things like EMI effects. For real-world components I like to see a nice high (50Kohm+) input impedance.)

- Infinitely LOW output impedance, to increase power transfer efficiency to the speakers. There's a really awesome article on this site here by the incredibly knowledgeable Richard Pierce that explains damping factor and output impedance.

- Unlimited power, so the amp never clips. This one is obvious.

- It should be a perfect voltage source, regardless of load impedance. This means that if speaker needs 16 volts to produce a given sound level, the amp should be able to provide it even if the speakers impedance is very low, like 2 ohms. (Most amps can't do this.)

- The amp's power efficiency should be nearly 100%. In other words, a perfect amp would consume only as much electrical power as it takes to provide the output signal. Class D amps come close. Class A amps are worst in this regard.

- The amp should have zero distortion. All this means is that when a given frequency is input to the amp that is the only frequency that should appear at the output. No others.

- The amp should have zero noise. Noise is just distortion that's uncorrelated to the input, and is (hopefully) measured in microvolts.

- Zero DC offset. Uncorrelated DC current in an AC circuit is a distortion. And it is really bad for your speakers.

I probably missed some parameters in this stream of consciousness post, but you get the idea.