The distortion in the speaker's acoustic output may be improved or reduced by adding resistance; that depends on exactly what effects are causing the acoustic nonlinearity and how they correlate with impedance nonlinearity. However, you were not measuring acoustic distortion but current distortion. The cable resistance was merely the current sense resistor - this is the point which some people seem unable to grasp, wedded as they are to the tired and unphysical idea that speaker cables are a source of distortion themselves.vzaichenko said:
Extrapolating from resistor nonlinearity to cable nonlinearity (on the spurious ground of extra length) is poor engineering, presumably based on poor understanding.xrk971 said:
If cables distort then your measuring cables distort too, so you cannot rely on any measurement.
This thread is getting increasingly silly. It appears that many contributors are confused by the physics and maths of a simple potential divider.
I am confident that all here will agree that there is an effect. However, it is not nonlinearities in the cable that are causing the change, it is the cable's impedance which is changing the outcome. With no cables, the amp has the best chance of fighting the non linearities, a resistive cable makes it less possible for the amp to do so. Think of it like a spring...a slinky suspending a golf ball vs a garage door spring. The slinky has less control of where the load goes..yet, both are still linear within the range of operation. (granted, this analogy falls apart terribly fast as springs are typically linear over a range of extensions then become highly non linear prior to plastic deformation).
As to your resistors, it is important to understand the physical processes involved in making the resistors, the materials of the resistor, the material resistance characteristics, as well as the environment the resistor is placed into.
Such things as voltage dependent resistance, how it's trimmed (if any), endcap (termination) materials...so many things..
Sometimes, the simple substitution is not quite as simple as suspected. Trust me, I've banged my head against that wall many a time..😱
Jn
Maybe resistor brand change analogy was not good. Regarding resistor endcap termination, maybe that might be similar to how the speaker cables are terminated (opening up yet another can of worms). Soldered, soldered to banana jack, crimped to banana jack, Speakons, bare wire screwed down with binding post clamp, etc. I agree that the effect of a loose spring vs a stiff spring really influences how the load at the end can be driven.
If this is true, the effect is negligible and orders of magnitude lower than the coils (in serie with bass and parallel too), output transistors resistors components in series, as well as the inductors of the transducer which has all 1000x more resistance than the 0.05R 3 meter wire.
A lose connections on the other hand will cause distortion in high frequency. I doubt the makers of electrical components leave microscopic gaps to smear the high frequencies.
It's the changes in the resistance of the cables that causes the changes in the measurements. I don't think that's a matter of belief or that there's anything to argue about, unless you meant something else.
Some measurements with a microphone might be the only way to really see the true end result of cabling changes.
You really like to beat the dead horses here, again and again and again.
Add feedback to the story to spice it up. 😀
Add feedback to the story to spice it up. 😀
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Both Wesayso and myself have come across the odd mic measurement of a speaker where a cable caused the phase of the to show some changes. In my case, it was the proximity with another cable - a mains power cord. Made me scratch my head though how it can show up as an acoustic measurement from the speaker.
I knew this would degenerate into the usual cable thread. And I can't believe DF96 is still banging his head on this wall.
Jeff, I'm thinking about this kind of test - I've got a Behringer C3 studio condenser microphone, need to bring it from the other office along with the microphone amplifier. Then we can run a rather clean experiment.
Speaker impedance non-linearity seems to be noticeably higher below 200Hz with the longer cable.
Parallel wires carrying current attract. This combined with the compliance characteristic of typical insulations would allow mechanical resonance, with mechanical losses of the insulation determining the Q. Has anybody swept speaker cables to determine the nature of this electromechanical resonance?
Dan.
Dan.
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