Ah ha, I see. It's been a ling time since I've read the famous Cerwin Vega speaker cable tests, IIRC RF was a problem there. But if it had to do with IMD I can not remember. Time to dig.
I was not thinking RF. I was thinking about control of the speaker. By bringing the speaker cable RFZ down into the regime of the speaker impedance, that is where the amplifier can exert the most control. A speaker impedance is not only frequency dependent, it is velocity dependent, a dynamic impedance dependent on the actual program material.
Using IMD measurement to measure this issue is the best way I can think of using existing equipment.
jn
In fairness, depends what context you're working in. High resistance wire can sometimes be useful in what might otherwise be a mismatched system context, e.g. a low Q driver designed for use with a high output impedance amplifier, stuck on the end of a more typical voltage source amp. Just one way of applying a desired EQ (and if people prefer alternatives, power to them, I'm merely observing this from a factual POV, not advocating, or, for that matter, discouraging in a relevant setting).
That would be Transparent Cable. Not always so 'little' either. Say hello to the (ahem) 'Magnum Opus'. All $65,000 of it. Yes, to the best of my knowledge, that ruddy great carbon-fibre face-hugger has a very small inductor and a lot of epoxy in it. IIRC there is also a series RC Zobel in the smaller splitters, and since this monster is the range-topper, they tweak the values to the customer's nominal speaker / amplifier load, with a target corner frequency for the inductor of about 50KHz (I'm inferring from various sources / bits of information & the original patents, but I don't think I'm very wide of the mark).
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Why do fancy speaker cables so often look like they do something cool? 🙂
By RFZ you do you mean impedance at radio frequencies? If so, why would a speaker need control at RF?
Here's the "excellent post" being asked about:
This reads like a discussion of buying a guitar, not sound reproducing equipment. It reads like euphonics rather than accurate reproduction. There's "nothing wrong" with that, but people don't seem to want to admit it.
If by "hear a positive difference" you mean a more accurate reproduction of the source, then you need to actually hear the source as well, else you're comparing to something in your imagination.
Because the 1/4 wavelength RF reflections may interfere with the audio signal causing IM side bands in the Audio BW.
Hans
@benb,
Not necessarily "something in your imagination." Maybe that's the only explanation your imagination produces, but probably not the only possibility.
For example, if you compare two amplifiers and you may be able to hear hum, or other audible flaw in one, that is not present in the other amplifier. More likely that the amplifier with hum, etc., is the less accurate one for that particular characteristic.
Not necessarily "something in your imagination." Maybe that's the only explanation your imagination produces, but probably not the only possibility.
For example, if you compare two amplifiers and you may be able to hear hum, or other audible flaw in one, that is not present in the other amplifier. More likely that the amplifier with hum, etc., is the less accurate one for that particular characteristic.
"It's like a colour or a taste, some like it and others don't"
-With colour there is a spectrum that can be measured, personal preference is a preference of a colour spectrum.
-Food components are analyzed and identified, personal taste is a preference for a mix of those components
-Perceived differences between speaker cables are said to be heard when there is no measurable difference. How is this possible? Bias and power of suggestion!
IME, the perceived differences do wear off if you give it fair consideration!
-With colour there is a spectrum that can be measured, personal preference is a preference of a colour spectrum.
-Food components are analyzed and identified, personal taste is a preference for a mix of those components
-Perceived differences between speaker cables are said to be heard when there is no measurable difference. How is this possible? Bias and power of suggestion!
IME, the perceived differences do wear off if you give it fair consideration!
No it was meant in the most litteral way.
Whatever positive may mean to you to make you decide to spent the money.
The same group or orchestra playing in a different location results in different sound, not to speak of the huge differences caused by your location with respect to the source.
So what’s accurate ?
Hans
Yes, impedance at RF frequencies. That minimizes the amount of energy stored in the cable at audio frequencies.
A good test would be to parallel 4 zips so that the RFZ is roughly 25/30 ohms, and measure IMD. Then, split the 4 zips, bundle the grounds together, bundle the hots together, and remeasure IMD.
Jn
Differences can be very well measured, the point however is what has to be measured to get a good correlation with what we hear.
A cable is not just the simple result of some LCR figures. On top of that there is an interaction from Amp and Speaker. So you cannot look at a cable in isolation.
Hans
When it comes to bass drivers my own personal preference lies with an EBS alignment using (very) low Qts drivers actively driven by a low output impedance amp in a ported box around Vas (some experimentation is necessary) tuned to driver Fs.
The 3-6dB drop off below ca. 100Hz of the bass shelf is usually quite nicely taken care of by room gain or if need be the typical bass control on some (pre-)amps.
Hmmm, OK. Thanks for the answer but I don't understand how RF impedance minimizes AF energies. If this was mentioned earlier, I missed it. Can you point me to something that would help?
FWIW, I can not find that old Cerwin-Vega cable test. The used a multi-tone signal and different loads. IIRC they saw RFI (surprising) and it varied by time of day. Not the same thing you are talking about, but interesting none the less.
Dodging question noted.
Right, but he won't answer because what he had posted about DACs in the past.
What kind of comparison are you referring to? If it's your typical subjective comparison, all bets are off.
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