Goertz still the choice with Vandersteen?
Thanks, Unsound. And kudos to Goertz for providing quantitative information about the square wave response they are depicting. Other manufacturers commonly show such waveforms with no indication of time scale, or of the test conditions under which the waveforms were obtained. Still, though, both the relevance and the meaningfulness of this information are questionable and debatable. For a number of reasons: 1)The sheer perfection of the response that is depicted for their cable, on a time scale that would reveal imperfections involving much less than 1 us (1 microsecond, or 1 millionth of a second), leads me to question whether they have really used a 4 ohm speaker as a load (as stated), or if instead they used a 4 ohm resistor. A good quality 4 ohm resistor would provide an essentially perfect match to the 4 ohm "characteristic impedance" of their cable at essentially ALL of the many ultrasonic and RF frequency components which together constitute the very fast transition times of the test signal, while no speaker will come close to doing that. In fact, in much of the ultrasonic region the impedance of most dynamic (box-type) speakers may very well be a closer match to the 100 ohm characteristic impedance of the "conventional" cable they were comparing with. Which in turn could very possibly reverse the results of the comparison, making the "conventional" cable the winner. Suspicion that the load which has been used is a 4 ohm resistor rather than a speaker is further heightened by my next comment. 2)Based on the conventional definition of risetime and falltime, that being the amount of time for the signal to transition from the 10% point to the 90% point between the two voltage levels of the square wave, it appears that the rise and fall times resulting with the "conventional" cable are around 8 us. That corresponds to a 3 db bandwidth of 0.35/8 us = 43.75 kHz, which would probably be low enough to cause phase shifts that are audibly significant under some circumstances. However, after doing some calculations the only explanation I can think of for how use of a "conventional" speaker cable could result in such a limited bandwidth would be the low pass filter formed by the interaction of the inductance of a cable having considerably higher inductance than most audiophile-oriented cables, with a load impedance that is low enough to be in the vicinity of 4 ohms at ultrasonic and higher frequencies. As I indicated above, dynamic speakers are likely to have impedances which are MUCH higher than that at ultrasonic frequencies, which would result with the conventional cable in MUCH faster risetimes and falltimes, and MUCH greater bandwidths. And consequently with a MUCH squarer looking square wave. 3)Many speaker cables have considerably lower characteristic impedances than the 100 ohm cable that was used in the test, often in the 10 to 50 ohm area. And of course the 25 foot length of biwire cable that was used is atypical of most setups. The shorter the length of that cable, the faster the depicted 8 us risetime and falltime would become, even under the unrealistic condition of a 4 ohm load impedance at ultrasonic and RF frequencies. 4)The overshoot depicted for the conventional cable, most of which occurs within 2 us and which is present only at the amplifier output and not at the speaker terminals, I doubt has much if any audible significance, and may be contributed to significantly by interaction with the feedback and other characteristics of the particular amplifier that was used. It is also way less significant than the overshoot, undershoot, and ringing that I would expect to occur with many solid state amplifiers which use significant amounts of feedback if the Goertz cables were to be used without a Zobel network. Which raises the question of how uniformly effective the particular component values used in the Zobels would be in suppressing that ringing across a wide range of amplifiers, having differing gains, bandwidths, and feedback parameters. I could go on. But again, even though I commend Goertz for providing this information, and you for citing it, it probably raises more questions than it answers. Best regards, -- Al |
Al, Well you put much more thought into that than I would ever have ever dreamed of. Kudos! The cable length did catch my eye as being atypical to say the least. I was merely trying to put the OP's question in relationship to CTsooner's 04-29-15 post. In that re: the CTsooners concern about keeping time alignment between all frequencies: the folks at Alpha-Core (Goertz) once told me that they used Thiel loudspeakers. Thiel used to recommend the Goertz cables. Of course when Jim Thiel was still alive and in charge at Thiel, time alignment was one of his priorities. I have found the Goertz MI cables to work best with my Thiels so far. I have not heard the Goertz cables with Vandersteens (though I've heard many different Vandy's, many times, in many different systems and in many different rooms. Though only speculation, I would think the Goertz speakers cables would work especially well with Vandersteens. Many others that have tried the pairing seem to agree. Alpha-Core offers a generous return policy, I'd suggest the OP give them a try. |
