OK.
I don't really want to pick on you, but Julf quoting Paul W. Klipsch in his byline is a bit much if he can't answer where the engineering explanation for 'damping' and by what mechanism such a thing is achieved. This is the danger of seeking the high moral ground when in fact you say something that is more like standing in quicksand.
First of all, inductance basically results in a voltage source, not current source. So no current to be reflected as such. That fact that the speaker potentially produces EMF (voltage) means that you end up with two voltage sources in series. Things become incredibly complex, but there below 100 Hertz the EMF produces in predominantly motional EMF and above 100 Hertz we see an increase in inductive EMF, but this is then not a 'controlled bass' thing.
But rather getting into that aspect, consider this: The output impedance of an amplifier is an Ohm value. That is fine, being a voltage source it should be low, no problem there. Being low Z only means the amplifier can regulate the 'voltage' (as opposed to current). What is the Ohm value in series with? The load. Say you have 1 Ohm output Z and 8 Ohm load. Damping factor of 8? How? The amplifier sees its own 1 Ohm and the 8 Ohm in series and cannot define any ratio. It sees 9 Ohm and nothing else. No ratio, then no damping factor.
Plain physics.
What definition? That a voltage source amplifier sees it own impedance in series with the load, how does the amplifier know anything other that the sum of the two and how can it possibly know the ratio?
Julf, you are obfuscating. If there is such a mechanism, why is it difficult for you to explain it? It ought to be quite simple.
Julf, you are obfuscating. If there is such a mechanism, why is it difficult for you to explain it? It ought to be quite simple.
Last edited:
I expect the two impedances to be seen in parallel by both the voltage source and the load...
The one that prevents the Q from being infinite. Find your EE101 reference with the differential equations for an RLC (parallel or series) network it will give the accepted definition of damping factor.
Electrical and mechanical
https://en.wikipedia.org/wiki/Damping_factor
https://en.wikipedia.org/wiki/Damping_ratio
Another stunning conversation.
The one I have been repeating a couple of times...
Do you disagree with that definition? That is like saying you disagree with the idea of "miles per hour".
Ever heard of a concept called "feedback"? Have a look at what point the feedback loop is looking at.
It is indeed simple. I am not the one obfuscating.
This really has nothing to do with Hypex ncores, so I suggest you take your issues somewhere else. Unless you can show how this is actually relevant to this thread, I will consider this discussion done for my part.
Last edited:
This is pretty simple.
The (complex) speaker load, and the output resistance of the amp forms a voltage dividing network. As the load will vary its impedance, depending on the frequency, the resulting voltage across it will change as the total impedance changes.
If the speaker impedance is flat, it won't matter much. If the output impedance of the amp is small (i.e. damping factor is high) it likewise won't matter much. If the output impedance is really high - say 1,5 ohms, as some tube amps may have, and the speaker load is really complex, with really low impedances and heavy phase shifts, you're going to get a totally different freqency response from what an ncore 400 would get with the same load.
The smaller the output impedance, the less sensitive the amp is for complex loads.
If you add the fact that most tube amps doesn't have a purely resistive output impedance, you're in for some really nice math....
Johan-Kr
The (complex) speaker load, and the output resistance of the amp forms a voltage dividing network. As the load will vary its impedance, depending on the frequency, the resulting voltage across it will change as the total impedance changes.
If the speaker impedance is flat, it won't matter much. If the output impedance of the amp is small (i.e. damping factor is high) it likewise won't matter much. If the output impedance is really high - say 1,5 ohms, as some tube amps may have, and the speaker load is really complex, with really low impedances and heavy phase shifts, you're going to get a totally different freqency response from what an ncore 400 would get with the same load.
The smaller the output impedance, the less sensitive the amp is for complex loads.
If you add the fact that most tube amps doesn't have a purely resistive output impedance, you're in for some really nice math....
Johan-Kr
Exactly - and indeed your point about tube amps implies that the higher output impedance of tube amps actually modulates response deviations (voltage divider) by a lesser amount than expected.
Tube amps with their high output impedance have a few extra tricks up their sleve that lets them outperform what their measured wattage would imply, but it's quite off-topic for this thread.
I'm using a tube amp now, but I'm looking into Hypex DLCP and ncore or UcD amp modules, to go active...
Johan-Kr
EE101? RLC? That explains damping, but where does that explain 'damping factor' in amplifiers - that somehow the amplifier can create a 'brake' on cone excursions?
Electrical damping is another thing and is a characteristic of designing an alignment. That has nothing to do with a mystery force that corrects motion a la feedback, as Julf suggests.
The wiki entrances you point to are riddled with mistakes. That sometimes happens with wiki.
The most stunning error:
"But a driver with a voice coil is also a current generator..."
No, it isn't - it is a voltage source. Major bad!
"For every motion the coil makes, it will generate a current that will be seen by any electrically attached equipment, such as an amplifier."
Completely incorrect.
I cut my teeth on this stuff, it is interesting that loudspeaker designers very rarely talk about 'damping factor' and this is an amplifier designer thingy.
The reason is the they know how to work with Thiele-Small Parameters and they explain everything and how things hang together. Did you see my Allan Shaw quote? He knows.
Scott, I am really surprised, that you really should know better - but you are right at least when you say:
Close, you are almost there, since the electrical Q and the mechanical Q are in parallel, then we are left are left with mechanical Q and hence total Q will never become infinite. Indeed there were drivers back in the 30's and 40's that used Qm as the more dominant Q. They did this even before Thiele-Small parameters were defined - now we know that it is the total Q in the box that matters. but they did this almost unconsciously as they use non-feed back tube amps with high output Z. I suspect you may know this?
Now, rather than quote wiki, I will quote you Richard H. Small.
Why is 'damping factor' not ever mentioned in Thiele-Small Parameters?
Well, I found out because I actually raised the question with Richard Small. To him the notion of 'damping factor' was totally ridiculed, so much so that I was taken aback too, only to realise how true. He even suggested to me to add a 2R2 resistor to an 8 Ohm Foster driver that I had recently bought and he had tested and published T-S values. This driver, which had very high sensitivity, also very low Qe to explain the high sensitivity. It was also over-damped as a result. He said that adding the resistor would allow me to use a larger box and even specified the volume and tuning. The downside would be a reduction in 3dB approx sensitivity.
As a result, I was among the first to teach myself how to measure and 'manipulate' T-S values - we are going back to 1975.
The only things that controls an alignment is the alignment itself. Change the amplifier's output impedance simply changes the alignment. There is no mystery here. There is nothing else to explain it.
As for wiki saying:
"One example of a vintage amplifier with a damping control is the Accuphase E-202, which has a three-position switch described by the following excerpt from its owner's manual."
Again, no mystery here too, since 'damping control' was nothing more than changing the output impedance of the amplifier, hence change changing the electrical Q - so yes, changing the damping, but this has nothing to do with 'damping factor' with current folding back and supposedly being absorbed. That just ain't happening.
So with the Accuphase and similar amps, all you are doing is changing the damping of the alignment and of course it is audible, but that audibility also lead to a totally erroneous conclusion.
As Small said emphatically, "it's the alignment, stupid" and I was the stupid one who learnt a lesson I never forgot.
PS: One well-known speaker manufacturer and designer confided in me, that he had designed a small sealed box sub-woofer using the 10" Peerless HDS driver. He had worked out the volume that would get him the correct Fb he sought and the added 2 Ohm series resistance to give it an in-box Q of 0.6, half way between Butterworth and Bessel. He never ever made that public for fear of backlash against the false idea of 'damping factor' - I said "well done Michael, Richard Small would approved even if others wouldn't" and it was a great little sub.
True story.
Hi Johan
I am a tube guy too, but buy/build the NC400, if you like tubes, you will like them too and a big improvement on UcD generation. It's midrange articulation is up there with some of the best tube amps ever. I can give no higher praise than that.
BTW, the amplifier with the best bass I have ever heard, had an output impedance of 5 Ohm. The Vacuum State 18 Watt DPA-300B made 100 Watt Class A amps owners weep. Ask Bill Gaw the reviewer for Steve Rochlin, his solution was to buy them.
I am surprised you should say that.
See Bruno's 'An EE' Guide to Survival Between Microphone and Voice Coil."
http://www.hypex.nl/docs/papers/AES123BP.pdf
Herein, Hypex own Bruno Putzey touches on the topic of distortion profiles giving an impression: Bottom end becomes extremely “tight”, “powerful” and “controlled” and propagates “Damping Factor” myth.
Voila!
I bet you didn't know that.
The NC400 I am enjoying listening to have good bass, not because of the very low output impedance (the series inductor in line with the bass drivers have many times that), but because they are well designed. I know amplfiers with quite high output impedances that have some of the most beautifully controlled bass. I have an amplifier right here, a mere 40 Watt, that has an output impedance of 270 Ohm and it has excellent bass when driving a speaker that has an LCR trap to EQ the impedance and hence the output alignment follows the rules of a voltage-divider. That arrangement destroys the damping factor myth and I have done that demonstration to ardent believers playing Joe Morello drum solo on DMP recording and asked "where is the damping factor" and the penny finally drops.
That Paul Klipsch byline of yours about "quackery" - you actually believe in one of the greatest cons, if not the great myths of amplifier "goodness" that we have ever seen. I for one would feel very confident that I would have Paul Klipsch on my side if he was still around. He was after all a speaker designer and would know where the real damping would come from: The box alignment and nominally driven by a voltage source.
You have just sucker punched yourself good and proper.
This is what happens when people take the moral high ground like you presume to do. There is a certain lack of humility at play.
I was set straight about 'damping factor' by one Richard Small 40 years ago. I was wrong, he was right - and I learnt my lesson - and then figured out lots of things after that. I suggest maybe you do the same?
Look at my byline: It is much humbler than yours:
"Don't take anything I say as an affirmation but as a question."
Last edited:
What the heck are you on about? I "believe" in the *definition* of damping factor. Just as in the definition of speed is distance travelled divided by time - it doesn't say anything about if it is a good or a bad thing.
So, again, what part of the *DEFINITION* do you disagree with?
Is personal abuse you way of avoiding answering direct, factual questions?
Is this the tone of discourse you feel appropriate?
In any case, here are some hints for what we should do with this whole silly discussion:
I think that one says it all.
Joe, just a simple question: does a battery generate a voltage or a current?
Keep working, the eccentricity of your view of how things work is as amazing as it is wrong. I'll leave to your view of the world or there will be another closed thread. You seem to recognize "Q" damping factor has a simple mathematical definition (far predating you) of 1/(2Q). The fact that a speaker has a large amount of self damping (DC coil resistance) makes the amplifier output resistance below a point another meaningless number based spec.
Last edited:
Ooo, an amp wit a damping factor setting knob. yes factor as per definition i.e. the quota between source and driven impedance. If the driven impedance is the speaker or the speaker cable is one to think about
I suppose you agree to that if you measure either current or voltage when moving a cone by hand, something comes out of the driver? And if you do short the terminals, the cone become hard to move? If you tap it not shorted it rings, if you tap it shorted it sound less. Why can't different output impedance control the cone in the same way?
Here, in my slice of the multiverse its happening but you are probably in a very similar but still slightly different one. After all, you live upside down - must have some effect
//
Last edited:
Then I made the same stunning error a couple of pages ago. I assumed we were talking about what happens when a speaker is connected to an amplifier.
What happens to a voltage source (measured in Volts, which is shorthand for joule/coulomb) when it is placed in a circuit? Answer: the voltage is no longer static energy but kinetic, and current (measured in Amperes, shorthand for coulomb/second) will flow.
How silly to talk about the currents. Major bad indeed. Stupid, stupid me. You have an excessively abrasive way of showing examples of your humbleness, Joe.
Btw, did you hear this one? It needs to be spoken:
- What is a joule per second?
- Yes.
It is a voltage source. You don't know that?
Indeed it does.
Would you like to know why it is a voltage source?
Simple, the source impedance determines that. If it is low, it is voltage, if it is high, it is current.
This is basic stuff that hasn't changed in two hundred years.
Hilarious it's too easy, lighten up there Julf.
Joe have you ever heard of Norton and Thevenin equivalents?
Last edited:
Keep working, the eccentricity of your view of how things work is as amazing as it is wrong... You seem to recognize "Q" damping factor has a simple mathematical definition (far predating you) of 1/(2Q). The fact that a speaker has a large amount of self damping (DC coil resistance) makes the amplifier output resistance below a point another meaningless number based spec.
Scott, I don't think you have understood anything I have said because where is this 'eccentricity'? That is now just abuse of my character.
In fact, the notion of 'damping factor' is disregarded by the vast number of loudspeaker designers and engineers and including the founders of Thiele-Small Parameters, so abusing me will not hold water. You need to speak to somebody knowlegeable as you are now not getting the sense of anything I have to say, which is totally rational in every way. But it seems that anything I say is irrational to you?
BTW, there have been maths published on this.
We need to have an understanding of how a driver has a dual nature, that it is in fact a V/I converter, that the driver sees voltage across the terminals of the Voice Coil and has to convert that to current through the Voice Coil. The problem is that due to the dual nature of the driver, that also activates it and motional and inductive EMF, which are voltage sources, these modify the voltage seen across the Voice Coil, which in turn changes the current through the Voice Coil which are voltage sources that modify the voltage across the Voice Coil, which... oh dear, we seem to have a run-away...?
Current errors produced in the Voice Coil due to the driver also being a voltage source when energised, motional EMF, inductive EMF and microphic EMF, these are real things with maths behind it, and the maths prove that the singular value of the output impedance cannot control that. That is not theory, that is fact.
Are you following me - if not, then leave it there.
You are clearly an amplifier guy, I get that. But there are mechanisms at work here that needs an effort to understand and not be so dismissive, just because wisdom is coming out of the mouth of a donkey, which is the attitude you take to anything I say.
Tackle the issue, not the person. Ever play soccer?
Joe you lack a grasp of the very basic principles involved here (or at least you say things that are simply wrong by basic physics) that does not make you a donkey or a bad person. Trying to prevent others from being misled is not a personal attack on you.
Electrical and mechanical models of speakers are readily available that for the purposes here predict behavior well enough that what is left are secondary issues. This goes for current or voltage drive or anything in between.
- Status
- Not open for further replies.