How about pointing out what issue and the author ? Doesn't ring any bells to me but i would like to see what they had to say. Sean
Thanks guys. I had a chance to look at it briefly before leaving for a wedding today ( another poor sap bit the dust ).
I found this quite interesting to say the least. I tried discussing this with John Curl, Jon Risch, John Dunlavy, etc... and some of those well versed in electronics back about a year or two ago over on the Cable Asylum.
Here is a link to a thread that i started pertaining to this very matter:
While much of the terminology that Herve used in the article is slightly different than our form of "electronics gibberish" over here, i think that what he had to say is probably QUITE valid. Keep in mind that i'm coming from a point of view that is familiar with RF and how important impedance matching, velocity factors ( or as he called it "propagation speed" ), etc... can be to getting a system TOTALLY dialed in.
I have NO doubt that there are gains to be made in this area. Unfortunately, i do not have the equipment necessary to do such testing and that's why i was asking Mr Risch and Mr Curl for help. Evidently, Mr Deletraz (the author of the Stereophile article ) didn't have it either as he had to ask a local engineering school and teacher of physics and acoustics for help.
If you do an advanced search going back about two years or so, using "velocity factor" as the text and "Sean" as the author, you'll also be able to find a few dozen references that i've made to "tuning" or resonating cables to the proper impedance. Other than the public queries to professionals that are more knowledgable in the field than i am, i have never seen anyone mention this in terms of applying "RF based technology" to audio systems. As such, i would have to say that this might be a "whole new ball of wax" to deal with. Don't confuse "impedance matching networks" with the "networks" that MIT and Transparent use as they are quite different. They are dealing with trying to correct Td ( Time Delay ) distortions across the audio bandpass and not impedance mismatches from component to component. Sean
I'm intrigued... I just might give it a try. Here are my initial impressions/findings.
--I would choose a cable that is easy to work with. Soldering resistors to tiny wires can be quite a challenge, as can soldering tiny wires to interconnect ends.
--I'm a bit suspect about computing the intrinsic impedance of interconnects simply from the geometry of the cables. I have some nice cables that consist of teflon-coated silver wires twisted together--I don't think it's easy to calculate the impedance of those.
--However, I looked at three websites: Nordost, Alphacore, and Audioquest. Only Nordost gave an indication of cable impedance. On their Red Dawn interconnect cable, they give the capacitance per foot and inductance per foot. I used those values and the second formula in the Stereophile article and calculated a characteristic impedance Zc= 122 Ohms. (Understand, I have not particular bias for Red Dawn cable... I've never owned it and have no idea how easy it is to work with).
Okay, now I'm getting enthused about this.
The "nominal" or "characteristic" impedance of a cable will vary with frequency. This is a VERY different measurement than "series resistance" that one could measure with a multimeter.
Taking "worthwhile" measurements on cables requires some expensive equipment i.e. a "TDR" ( time domain reflectometer ), a quality signal generator, a spectrum analyzer, etc... While there are TONS of companies / individuals that have the necessary gear to do this, i guess that nobody has ever REALLY taken the time to do such testing. According to "theory", the difference in interconnects / loudspeaker cables should not be noticeable under any "normal" listening conditions with "well designed" gear. Then again, i know that Frank Van Alstine has demonstrated that some gear is HIGHLY susceptible to cable changes. He considers this to be a case of "poor design" on the engineers' part.
If you remember, there was a time when "theory" was that the Earth was flat while being the center of the Universe. Maybe we are on the verge of a new "breakthrough" since some of these "up and comers" seem to have a slightly more open mind and are willing to do their own homework / research instead of quoting "book text" to us. So as not to completely offend the "old schooler's", i have to add that we now have FAR greater test equipment and technology today than we have ever had in the past. As such, we SHOULD be able to test, measure and explain more than we could in the past.
Ray Kimber has the necessary equipment, does a LOT of testing on cables and knows his theory ( as far as i'm concerned ). Let's see if we can get him to join in on this one and see what he thinks. Sean