Nait XS-2 damping factor

FWIW, I have heard a Sugden A21 with various Naim and non Naim sources sound beguilingly good into a pair of Quad 11L speakers... now those were not overly efficient, and the delicacy and timing was gorgeous.

Simon

Huge posted:

 

This is why the figure the marketing people quote as the "Amplifier Damping Factor" is largely irrelevant, and actually misleading.

This made me smile... I think, and I'm probably as guilty as many, give marketing professionals an unjustly bad name on this forum... in technology most marketeers I know are not engineers... their disciplines are often  economics and communications.. for specific technical messaging they are very reliant on the technical product managers and product/engineering consultants.. and so if terminology like Amplifier Damping Factor appears in collateral, almost certainly that will have come from the engineering/product manager/consultant ...that  does not make it right however ... but I very much doubt it's the marketing people  who have invented it.

Simon

Simon-in-Suffolk posted:

FWIW, I have heard a Sugden A21 with various Naim and non Naim sources sound beguilingly good into a pair of Quad 11L speakers... now those were not overly efficient, and the delicacy and timing was gorgeous.

Maybe they are well-damped. I should have written well-damped, efficient speakers with the Suggie.

C.

It's amazing that this thread, about something that hardly anybody understands, or realises actually exists, is still rumbling on. It's a funny old world. 

This is nothing. Good for another 4 pages yet. Minimum.

C.

Chris, I assume you were talking mechanical damping? It interesting that Russell Kauffman believes damping materials in the speaker gets in the way of micro detail and subtlety ... and he apparently does use damping in his Russel K speakers ... and therefore you would have thought the amp would need to be quite demanding to sound good, but his speakers appear to work very well across a range of amps including entry level with great immediacy.

Simon

Simon-in-Suffolk posted:

Chris, I assume you were talking mechanical damping?

Er, all I can say is that (in the days when I read the magazine) Hi fi World published impedance v frequency plots for various speakers they tried. Speakers like the LS3/5A and Guru QM10s gave gently rounded traces. They were described as well damped. The 'sound quality' part of the review would often say how such speakers sounded good with valve amps (which they would refer to as lightly damped), and I made what I took to be the implied link.

The broad (no doubt simplistic) advice rang true for me after I bought my N-Sats for my Nait 5. And subsequently for the Naim amp and speakers I have now.

But depite my prediction of another four pages, above, the OP appears to have lost interest....

Chris

Huge posted:

IB, the problem is that to use DF in reference to the amp alone is meaningless as there's nothing to damp.  When looking at an amp and speakers this same measurement gives a incorrect perception of the damping of the system.

Take for instance my speakers
They are 8Ω nominal impedance, and the bass/mid driver has a resistance of 6.9Ω
(N.B. their minimal impedance is 6.7Ω. but below 2.5kHz, the minimum impedance is about 7.4Ω)

So taking an amp with a high output impedance of 0.4Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.4 + 0.02 + 0.05 + 6.9) = 1.085.

So taking an amp with a low output impedance of 0.004Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.004 + 0.02 + 0.05 + 6.9) = 1.147.

So reducing the amp output impedance by a factor of 100 has increased the DF by about 6%!

This is why the figure the marketing people quote as the "Amplifier Damping Factor" is largely irrelevant, and actually misleading.

Huge, I believe your calculations are fundamentally flawed, as you are including the speaker impedance in the denominator, dividing into a nominal speaker impedance (8Ω).

Damping factor is

In simplidtic terms, speaker impedance /amp output impedance 

6.9/0.004 = 1725 for one amp, and 6.9/0.4 =17.25 for the other. But yes, the real world includes the cables etc. there are two ways of allowing for them, and I don't have time at present to try to assess which is correct, so I present both using your figures: both show a much more significant difference between the two amps than your calc suggests:

(Speaker impedance + other impedances seen by amp)/output impedance of amp

(6.9+ 0.02+ 0.05)/0.004 = 1742

(6.9+ 0.02+ 0.05)/0.4= 17.4

Or

Speaker impedance / (output impedance of amp + other impedances between amp and speakers)

6.9/(0.004+0.02+0.05)= 93

6.9/(0.4+0.02+0.05)= 14.7

Innocent Bystander posted:

Huge posted:

IB, the problem is that to use DF in reference to the amp alone is meaningless as there's nothing to damp.  When looking at an amp and speakers this same measurement gives a incorrect perception of the damping of the system.

Take for instance my speakers
They are 8Ω nominal impedance, and the bass/mid driver has a resistance of 6.9Ω
(N.B. their minimal impedance is 6.7Ω. but below 2.5kHz, the minimum impedance is about 7.4Ω)

So taking an amp with a high output impedance of 0.4Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.4 + 0.02 + 0.05 + 6.9) = 1.085.

So taking an amp with a low output impedance of 0.004Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.004 + 0.02 + 0.05 + 6.9) = 1.147.

So reducing the amp output impedance by a factor of 100 has increased the DF by about 6%!

This is why the figure the marketing people quote as the "Amplifier Damping Factor" is largely irrelevant, and actually misleading.

Huge, I believe your calculations are fundamentally flawed, as you are including the speaker impedance in the denominator, dividing into a nominal speaker impedance (8Ω).

Damping factor is

In simplidtic terms, speaker impedance /amp output impedance 

6.9/0.004 = 1725 for one amp, and 6.9/0.4 =17.25 for the other. But yes, the real world includes the cables etc. there are two ways of allowing for them, and I don't have time at present to try to assess which is correct, so I present both using your figures: both show a much more significant difference between the two amps than your calc suggests:

(Speaker impedance + other impedances seen by amp)/output impedance of amp

(6.9+ 0.02+ 0.05)/0.004 = 1742

(6.9+ 0.02+ 0.05)/0.4= 17.4

Or

Speaker impedance / (output impedance of amp + other impedances between amp and speakers)

6.9/(0.004+0.02+0.05)= 93

6.9/(0.4+0.02+0.05)= 14.7

 

IB I believe you have misunderstood Damping Factor.

Damping Factor is the electrical Damping of the movement of the speaker cone.  The speaker cone, when moving, behaves as a motor/generator system and this is controlled by the drive voltage from the amplifier trying to dictate the movement of the cone.  However the control exercised by the output voltage is degraded by the circuit resistance opposing the current that's produced by the voice coil acting as a generator (N.B. the full circuit resistance is important here, not just the one part of the circuit resistance internal to the amplifier).  If you want to formally understand this look at the Thiele-Small parameters of speakers.

Both your calculations have part of the circuit resistance in the numerator and part of the circuit resistance in the denominator.  This assumes that one part of the circuit resistance is having the opposite effect to the other part of the circuit resistance.

Adam Meredith posted:

Hungryhalibut posted:

It's amazing that this thread, about something that hardly anybody understands, or realises actually exists, is still rumbling on. It's a funny old world. 

If two nerds in a forest talk to themselves and no-one else is present - do they generate any light?

M

Adam Meredith posted:

Hungryhalibut posted:

It's amazing that this thread, about something that hardly anybody understands, or realises actually exists, is still rumbling on. It's a funny old world. 

If two nerds in a forest talk to themselves and no-one else is present - do they generate any light?

Yes, apparently they do, even if someone else is present...

Huge posted:

Innocent Bystander posted:

Huge posted:

IB, the problem is that to use DF in reference to the amp alone is meaningless as there's nothing to damp.  When looking at an amp and speakers this same measurement gives a incorrect perception of the damping of the system.

Take for instance my speakers
They are 8Ω nominal impedance, and the bass/mid driver has a resistance of 6.9Ω
(N.B. their minimal impedance is 6.7Ω. but below 2.5kHz, the minimum impedance is about 7.4Ω)

So taking an amp with a high output impedance of 0.4Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.4 + 0.02 + 0.05 + 6.9) = 1.085.

So taking an amp with a low output impedance of 0.004Ω, adding 4x4mm connectors = 20mΩ total, 2 speaker wires (12AWG, 5M) = 0.05Ω and adding 6.9Ω, gives an electrical damping factor of 8 / (0.004 + 0.02 + 0.05 + 6.9) = 1.147.

So reducing the amp output impedance by a factor of 100 has increased the DF by about 6%!

This is why the figure the marketing people quote as the "Amplifier Damping Factor" is largely irrelevant, and actually misleading.

Huge, I believe your calculations are fundamentally flawed, as you are including the speaker impedance in the denominator, dividing into a nominal speaker impedance (8Ω).

Damping factor is

In simplidtic terms, speaker impedance /amp output impedance 

6.9/0.004 = 1725 for one amp, and 6.9/0.4 =17.25 for the other. But yes, the real world includes the cables etc. there are two ways of allowing for them, and I don't have time at present to try to assess which is correct, so I present both using your figures: both show a much more significant difference between the two amps than your calc suggests:

(Speaker impedance + other impedances seen by amp)/output impedance of amp

(6.9+ 0.02+ 0.05)/0.004 = 1742

(6.9+ 0.02+ 0.05)/0.4= 17.4

Or

Speaker impedance / (output impedance of amp + other impedances between amp and speakers)

6.9/(0.004+0.02+0.05)= 93

6.9/(0.4+0.02+0.05)= 14.7

 

IB I believe you have misunderstood Damping Factor.

Damping Factor is the electrical Damping of the movement of the speaker cone.  The speaker cone, when moving, behaves as a motor/generator system and this is controlled by the drive voltage from the amplifier trying to dictate the movement of the cone.  However the control exercised by the output voltage is degraded by the circuit resistance opposing the current that's produced by the voice coil acting as a generator (N.B. the full circuit resistance is important here, not just the one part of the circuit resistance internal to the amplifier).  If you want to formally understand this look at the Thiele-Small parameters of speakers.

Both your calculations have part of the circuit resistance in the numerator and part of the circuit resistance in the denominator.  This assumes that one part of the circuit resistance is having the opposite effect to the other part of the circuit resistance.

 

Huge, I could equally well suggest that you have misunderstood damping factor. It may be that we will simply have to agree to disagree, but there is no sense in your calculations that give the nominal speaker impedance as the numerator and the actual impedance as the denominator while relating to amp impedance (though it would make sense related to declared amp DF at a the dominal impedance, simply correcting a nominal Impedance for actual, but that is not what you quoted).

l'm away at present, with very limited internet access, but having had time to consider after now posting the  the calculations I made yesterday, it is clear that as far as the speaker is concerned, which is the whole relevance of DF, what matters in terms of DF is the impedance of the amp and other circuitry incliding the cabling (14.7Ω against 93Ω for the two amps in the above example, as that is what the speakers see. However if an amp declares  DF into a specified impedance (e.g. 8Ω), as some do, as opposed to an output impedance, then that 8Ω must be including the impedance of any cabling etc as well as the speaker itself, and comparisons between amps will indeed need to take into account the other factors - that doesn't alter the fact that the amp with the greatest DF into a given impedance load, e.g. 8Ω has a greater damping effect on a speaker in a given circuit that one with a lesser DF into same load.

Damping of the speaker in this context relates to damping of movement of the voice coil after the driving signal ceases, and is of particular relevance in speaker designs where the cabinet does not provide much damping. In essance a direct short - zero output impedance of the amp - will damp the speaker cone movement, and thus contribute to 'tight' bass, more than a significantbimpedance relative to the voice coil, in the same way that a short across the remninals of an electromagnetic motor resists movement due to back-emf.speaker damping in tnis context is damping of the movement of the speaker cone, not damping of resonances or reflections within the cabinet.

With reference to last post, far more useful would be to quote the amp output impedance, hawever teh slightly false notion of damping factor was coined many years ago and in some circles has stuck.  It is fine as long as used with understanding that it is only meaningful when considered into a defined speaker impedance, and that that includes ancillary circuitry including cables and connectors (or define what cables/connectors were used in determination of DF), and indeed at a given frequency or range thereof.

Huge is right. You are saying it yourself. It is the damping of the Voice-coil. But this Voice-coil is seeing a lot more impedance then only the amplifier.

Have a read through this : Clickclick

I hope it will clear things up a bit.

The link at the bottom of that Floyd E Toole write-up is also pretty interesting me thinks

Kazuhito - also good to mention that buying from a Canadian dealer might work well for you due to the low Canadian dollar. Dealers in Canada have the same Naim gear as the US dealers. There are two fine Naim dealers in Vancouver and they might be able to arrange delivery to you.  Just sayin'.

Great thread a lot to learn from the guys here

You mean about techies arguing? 

The Storm Audio Vertigo integrated has a rotary dial at the back called ' stormfocus 'which affects the amount of output impedance.

some reviews have said that its a damping factor control to get a better match to the loudspeakers.  Maybe " damping factor" as a descriptive term is misunderstood by so many that it might have a collective rightness in its wrongness.

TOBYJUG posted:

 Maybe " damping factor" as a descriptive term is misunderstood by so many that it might have a collective rightness in its wrongness.

Sounds a bit like a Rumsfeldism -  "There are things we know we know. We also know there are known unknowns......"

Simon-in-Suffolk posted:

TOBYJUG posted:

 Maybe " damping factor" as a descriptive term is misunderstood by so many that it might have a collective rightness in its wrongness.

Sounds a bit like a Rumsfeldism -  "There are things we know we know. We also know there are known unknowns......"

I don't know that one

Feeping Creaturism.

Flo-TLSC posted:

Huge is right. You are saying it yourself. It is the damping of the Voice-coil. But this Voice-coil is seeing a lot more impedance then only the amplifier.

Have a read through this : Clickclick

I hope it will clear things up a bit.

For clarification, I wasn't disagreeing with Huge on that aspect, but rather on his calcs coming out with damping factors of 1.085 and 1.147 as seen by the speakers, which I believe would be correctly expressed as 14.7 and 93 in the example cited. And a quick read of the linked article doesn't raise anything with which I disagree, other than observing that the arbitrary figure of 20 as the point where DF ceases to be significant could be debatable (though I'm not suggesting I have any reason to disagree with it). In the above cited example that would indicate a desired power amp of output impedance of ≤0.275Ω into a speaker of actual impedance 6.9Ω connected as above.

Far more meaningful than quoting damping factor, and, curiously, easier to provide as a definitive figure, would be the output impedance of the amp at bass frequencies (specified), but I suspect that the term DF was coined to seek to simplify for non technical people - and, as so often the case with technical specifications, not only is it but one factor in a multitude affecting sound quality, but it is also readily open to misinterpretation and/or misrepresentation.

as always, listening is the best way to determine whether an amp/speaker pairing works for the listener, but as I observed in an earlier post, in the absence of an opportunity to hear all anyone can do is seek the best available information, and that may indeed include consideration of "damping factor" in whatever guise, especially where there may be some indication that the speaker is underdamped physically compared to other designs, or otherwise in the absence of other definitive assessment information.

IB,

Principles:

1  Whenever the amp is powered, it's ALWAYS controlling the speaker cone.  When there's a signal, the amp is trying to accelerate the cone according to the signal; when there's no signal the amp is trying to keep the cone at it's neutral point.

2  Any time the speaker cone is moving, the effect of the magnetic field and the movement of the cone generates a back EMF.  Anytime that EMF doesn't match the output voltage of the amp a current is flowing through the output of the amp (& influenced by the output impedance), through the speaker cables and their connectors (& influenced by the their resistance), and through the voice coil (& influenced by it resistance).

3  The damping of the cone is dependant on sinking this current (i.e. shorting it through a resistance) to absorb the kinetic energy of the moving mass of the cone and voice coil. 

OK, analysis using simple 325 year old mathematics...

Take a single turn in the centre of the voice coil, it generates a back EMF.  That EMF drives a current that flows from it through almost 1/2 the voice coil's resistance in each direction.

In case you haven't spotted it, then consider an infinitely small section of the voice coil (anywhere in the voice coil, it doesn't make any difference).  In this case, from the view of that section of the coil and looking both ways, ALL the resistance of the voice coil is in series with the amp, and this is the same no matter where the section is.

Ergo the DF MUST take the resistance of the voice coil into account as that's in series with the amplifier's output.
To take the speakers resistance out of the calculation is complete nonsense; any calculation on that basis is just meaningless.

A quick query - Huge you describe resistance above as opposed to impedance .. so are you saying therefore the DF is irrelevant to frequency and based on the real resistance of the speaker- i.e. resistance is not dependent on frequency as opposed to impedance which is