Joe Rasmussen Usher S520 "Current Compatible" Crossover

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As I explained, when you design a speaker you have to have some kind of philosophy and sometimes words are not enough.

So, you're saying that "crossover noise" is completely without meaning? And if it has meaning, why are you hesitant to define it? You gave that as your principal design goal. How do you know that you achieve your goal if you can't even specify what the goal is?

If it's merely a marketing term you've latched onto, it's OK to admit that. And there's also nothing wrong with saying, "A flat impedance will remove much criticality from amplification choice, and that's the raison d'etre here."

'noise-floor modulated by current phase errors'

Noise floor of what, specifically?
 
If it's merely a marketing term you've latched onto, it's OK to admit that. And there's also nothing wrong with saying, "A flat impedance will remove much criticality from amplification choice, and that's the raison d'etre here."

If that satisfies you, then we will go with that. Just as long as we can be peaceable as "the peacemakers will inherit the earth." :)

 
So, you're saying that "crossover noise" is completely without meaning? And if it has meaning, why are you hesitant to define it? You gave that as your principle design goal. How do you know that you achieve your goal if you can't even specify what the goal is?

If it's merely a marketing term you've latched onto, it's OK to admit that. And there's also nothing wrong with saying, "A flat impedance will remove much criticality from amplification choice, and that's the raison d'etre here."



Noise floor of what, specifically?

SY, "crossover noise" or whatever is a silly, never mind that.
The good thing is that the speakers are close to resistive load with this tweak and that`s what every amplifier like, particularly solid state class AB amps.
 
SY, "crossover noise" or whatever is a silly, never mind that.

Yet that was given as the principal design goal...

In any case, a flat impedance curve can be a good thing. My own speakers stay +/-1 ohm from 200Hz to 10k and work fine with any amp I have in the house, so I can't really disagree with that aspect. This was always a sales point for Magneplanars as well.
 
Correct me if I'm wrong.

So, regardless of the revolutionary aspects claimed, as I understand the flow of Qi in a circuit, what you call "electricity," :D :D the current to voltage phase angle at the amplifier may be flattened, but the current to voltage phase difference at the drivers remains the same.

The caps and coils added buffer the current flow, much like "Power Factor Correction" used in wall power applications.

Am I right?

Best,


Erik
 
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frugal-phile™
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My own speakers stay +/-1 ohm from 200Hz to 10k and work fine with any amp I have in the house

What is the impedance like below 200 Hz? That is where there is almost always a problem. And i suspect there are no current amps in the house.

This work of Joe's is aimed at providing a loudspeaker that allows people to play with current amps, that it works with any amp is a bonus.

dave
 
I merely proffered it as an example of a speaker that has a relatively flat impedance and is thus amp insensitive. There are others (like the Maggies I mentioned). It's a reasonable thing to do in a design, but there's nothing new about that. My curiosity was piqued by the claim of some new notion about "crossover noise," but that turns out to be merely marketing.
 
frugal-phile™
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Yes your speaker has commendably flat impedance in the higher frequencies, but does so by ignoring the place where the biggist common issues are.

"noise" is a placeholder. No marketing happening here that i can see. Just an honest attempt to provide an oft missing piece to allow for playing with current amps.

dave
 
Yes your speaker has commendably flat impedance in the higher frequencies, but does so by ignoring the place where the biggist common issues are.

Not so much, no. With any of the amps I've used with it, it runs dead flat in that area. There's some cleverness in the design there.

"noise" is a placeholder

No, it was cited as the principal design criterion. It turns out to be meaningless. I'm not enthusiastic about marketing buzzwords.
 
Stereophile's review had the impedance curve of the stock version.

No current amps, but a couple of tube amps with high-ish impedances. Mine's a bit different in that I removed the passive high-pass to the mid-bass and rejiggered the cabinet volume to get a B2 as part of the acoustic LR4.
 
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