Linearity of i = f(u) is not of prime interest. Linearity of acoustic output is what counts. Overal effect of ohmic resistance between amp and the speaker is not immediately obvious and requires some analysis. It could improve or worsen distorsion. I think it was already discussed on diyaudio, somewhere in Blowtorch II thread maybe, PMA had some measurements...
If acoustic output is in linear proportion with the voltage on speaker terminals then BesPav is right. But AFAIK it's not just the voltage...
If acoustic output is in linear proportion with the voltage on speaker terminals then BesPav is right. But AFAIK it's not just the voltage...
Linear circuit elements cannot cause distortion. The clue is in the description 'linear'.
Linearity of acoustic output is what matters, of course, but this is more difficult to measure. Of one thing we can be sure: if the tests described in this thread genuinely showed that cables caused distortion then the 'true believers' would quote them for ever as evidence of their position; they would forget that acoustic output is what matters.
Linearity of acoustic output is what matters, of course, but this is more difficult to measure. Of one thing we can be sure: if the tests described in this thread genuinely showed that cables caused distortion then the 'true believers' would quote them for ever as evidence of their position; they would forget that acoustic output is what matters.
The measurements Valery posted show otherwise. Measured distortion was obviously higher when there was a cable attached to the speaker. It looks to me like the speaker and wire combination together are the cause of the distortion, possibly the wire causing the amplifier to be unable to control/remove the distortion. Whatever the case the ultimate distortion at the speaker was higher with longer wire while nothing else in the test was changed.
Clearly.
Amplifier picks feedback signal from it’s output, while load consists of Rwire + Rspeaker.
Also speaker have a secondary electrodriving force of Mms connected to a coil winding moving in Bl.
Secondary current of last EDF source must be totally consumed by amplifier’s output. This is damping factor nature. But some voltage of this secondary current will be dropped on the wire resistance and amplifier’s voltage feedback loop can’t see that current fully.
Current driving allows speaker to be underdamped and this straightly influence to sounding because firstly changes Qes of the speaker.
Really?
Say, set relatively high frequency 10 kHz, load your amp to a pure resistive current sensing 0,1-0,01 Ohm metal strip Dale LVR series or Bourns TO-220 thick film.
Allow no overloading, say, set output power to 5 Wt.
Then compare distortion with taken at 1/100 of rated power or, say, at 1 mWt.
Pavel took some good measurements of voltage vs current drive in 2015:
Current drive of speakers and speaker distortion
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Measurement results
At 30Hz, 100Hz and 200Hz the speaker distortion was also same with voltage drive and current drive, with the vented box. Ratio of individual harmonics was the only difference. At 40Hz, distortion with voltage drive was lower, 0.887% compared to 1.30% with the current drive. At 61Hz, at resonance, distortion with the current drive was lower, 0.292% compared to 0.545% obtained with voltage drive. These were the biggest differences measured with the vented box.
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We can see that with closed port, distortion was decreased at all frequencies of measurements, 40Hz, 61Hz and 80Hz. At 100Hz, both methods have shown the same distortion.
The benefit of the current drive can be seen at higher amplitude of membrane displacement, when the deviation from linearity of the speaker parameters is higher.
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Measurement results
No improvement in nonlinear distortion was observed for tweeters and midrange speaker. The only notable improvement was for a woofer, below 100Hz, at a closed box.
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Cheers,
Jeff
PS Ooops, Pavel already posted his current vs voltage tests.
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No! This is a classic case of measurement being more than a number on a meter; you also have to understand what you are measuring so you can correctly interpret the raw data. The cause of the distortion, as I keep saying, is speaker nonlinearity. All the cable resistance does is make this distortion visible, via Ohm's Law. It is exactly the same as measuring any current by seeing what voltage it drops across a small resistance.jwilhelm said:
This is becoming surreal. Are we now to imagine that the cause of amplifier nonlinearity is not active device nonlinearity but the resistive load on the output? That may be 'cause' in the legal sense but it certainly isn't cause in the logical and scientific sense.BesPav said:
I have been several times very surprised that my colleagues, electrical engineers by education, but not practicing, did not understand properly how resistive divider worked .....
Speaker is just a load with complex impedance, it can’t be linear or nonlinear.
It can be well controlled and have linear signal at input terminals or badly controlled, having nonlinear signal at input terminals.
Valery shows that two cases, well controlled load with less distortion and bad controlled load with more distortion.
Yes, you still can’t understand how speaker moving mass inertia becomes amplifier heatsink temperature and why this is so.
Let me know, what and how much current flows through the wire between amplifier and speaker when there are 0 Volts at the amplifier output terminals?
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Have you ever heard about nonlinear L, such as in coils with iron core?
Just to remind, pure voltage drive and pure current drive are extreme ends. Inbetween cases are not covered.
Speaker cables makes a difference. Kimber cables did some research on the subject and designed a wavy (braid pattern).
However there is much snake oil in cables because it is a good market, cost not much to produce and profit margins are good if people "believe".
You can see how to wave the pattern, very simple. Kimber Kable - 4PR
some higher end cables have a little more wires with an air core center, it is even better: Kimber Kable - KS-6068
If the measurements are valid from the experience it would be interesting to see how wavy cable assembly perform.
Kimber 12 VS Speaker Cable | Hifi Phono House
detail of hifi cables, how it is made inside. Very educative
•parallel capacity: 444 pF / meter
•Inductivity: 0.12 uH / meter
•Resistance: 0.005 Ohm / meter
•Cross section 2 x 9,25 mm2
However there is much snake oil in cables because it is a good market, cost not much to produce and profit margins are good if people "believe".
You can see how to wave the pattern, very simple. Kimber Kable - 4PR
some higher end cables have a little more wires with an air core center, it is even better: Kimber Kable - KS-6068
If the measurements are valid from the experience it would be interesting to see how wavy cable assembly perform.
Kimber 12 VS Speaker Cable | Hifi Phono House
detail of hifi cables, how it is made inside. Very educative
•parallel capacity: 444 pF / meter
•Inductivity: 0.12 uH / meter
•Resistance: 0.005 Ohm / meter
•Cross section 2 x 9,25 mm2
He he.
What about Safe Operating Area?
Magnet field flow?
Inductance?
Steel permeability?
Why core maded by set of thin plates?
Be sure, i’m ready about this, have seen by my own eyes how improperly manufactured high-frequency trafo was really melted at working conditions, not saying about fired cores which was improperly loaded/overloaded.
Designed a what?
I think you mean 'they braided some wire'.
Indeed it is. Why anybody would give a trajectory copulation though is questionable, when perfectly ordinary parallel pairs (or a twisted pair if you feel so inclined) do a perfectly good job. Braided wire of any kind is not exactly novel, and wasn't when Kimber started marketing theirs.
It really isn't.
I have a german speaker (WHD is the old brand), they are not nice sounding and have cheap 'german' plug type connections. Maybe if the cause of their bad sound is not the cable, people tend to generalize good cables with good speakers.
Good speakers in audio shops have good $$ cables, people associate the cables to the good sound. That could be as simple as that.
Good speakers in audio shops have good $$ cables, people associate the cables to the good sound. That could be as simple as that.
I can hear the difference between 12ga solid copper Romex vs 16ga OFC stranded zip cord. It's quite noticeable the improvement in bass authority (measured amp DF is significantly improved as well), and highs are brighter.
I think just good quality heavy gauge wire is all that is required for speakers. I remember a thread here a couple years ago where they were recommending doing macrame with some Cat5 garbage for DIY high end cabling. It's hard to see how a few strands copper plated steel junk would be superior to some good old fashion TEW.
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