Super Simple theory on speaker cables

You're trying to describe some complicated things and seemingly understand them in simple terms. 

I'm not at all surprised that a Focal crossover is doing weird things to get the amplifier to push more or less power. That's how they mitigate aberrations in the performance of the drivers. My assumption finding something peculiar in a Focal crossover would be that it's trying to control a particular trait of the speaker. 

Damping factors tend to be a little more complicated than the number except in a very simple amplifier. Virtually all solid state amps degenerate the output devices with resistors. That tends to lower the damping factor. Feedback loops tend to fight against the degeneration by making the the voltage gain stage, itself often degenerated, compensate for the truncated gain characteristics of the output devices and raise the damping factor. The result is more complicated output impedance characteristics than a damping factor rating might imply. 

Since most amps have feedback, and that's where they get a significant amount of their damping factor, it's reasonable to assume anything presented as a load to the output will influence the momentary damping capability of the amp. However, wisely implemented feedback will do what feedback should do; simply control the load. 

Looking to the measured properties of a variety of cables seems to suggest that those building them have some understanding that adding impedance and capacitance does effects the sound. Typically they go for the higher capacitance to ameliorate inductance since an amplifier's damping capabilities are more robust at lower frequencies. 

That's my line of thinking at least. 

The midrange resistor on my Magnepan 20.7 seems to adjust the tone of the mids rather than the loudness. Adding the 1.0 ohm resistor (furnished) warms the mids and aligns them better fit to the bass panel. So the fact this is happening to the Magnepans just tends to confirm the op here theory a bit. 
Thought the treble resistor does seem to be to reduce the loudness. as well as change the tone. Just to mention.

@Kosst_amojan
I did a complete analysis of the speaker in XSim. Gathered acoustical and impedance plots. The only thing that circuit did was lower the impedance.

You can remove one cap and resistor section with nearly zero effect to the voltage transfer function. With a "normal" low pass filter, you can raise the impedance, with the identical transfer function, and eliminate the resistors.

I’m confident in my conclusion: The crossover was deliberately designed to have a low impedance point.

Best,
E

Hi @elizabeth,
Yeah, I put that in a different category. Several high end manufacturers have some sort of level setting which DOES show up in simulations as altering the output. I think those circuits are legit, whether dials or resistor changes.

What I'm talking about are how simulations miss how changes to the impedance curve alters the sound, even when the simulation says it does not.

This is kind of like how we assume tube amps are more sensitive than SS amps to hard to drive speakers.

We think, oh, it's a SS drive, what can 1 ohm change in impedance to? Actually, a lot.

Best,
E

@erik_squires 

I don't see what the problem is with that. That's very characteristic of Focal. That's how they get their unusually small woofers to create the bass performance that they do.