Speaker cables and their frequency responses

Did i hear you say "WHAAAAAT ?!?!?!" when you read the title of this post ?

Take a look at an article on Nelson Pass's website. Do yourself a favor though and open up the link below in a seperate "window". This way, you can switch back and forth between that article and what you're reading now.

http://www.passlabs.com/articles/spkrcabl.htm

Bare in mind that this article was researched and probably written back in 1979 and published in early 1980, so some of the names and models have changed.

In specific, take a look at what Nelson has labled as "figure 4" on the second page. If you study that chart, you will see that it has both a frequency range across the bottom and a resistance scale across the side.

There are two important deductions that can be derived from this chart. One is that some cables are notably lower ( the old Fulton Gold and Monster Cable ) than others ( like the 24 gauge zip cord ) when it comes to "series resitance". A cable that is higher in series resistance ( like the 24 gauge wire ) will act as a "buffer" between the amp and speaker ALL the time. This means that the amplifier will have less control over the drivers but at the same time, the amplifer will see less reflected EMF ( electromotive force or "voltage" ) if the speaker is highly reactive. The longer the run of this cable, the bigger the "buffer zone" i.e the less control of the drivers due to even greater signal loss going out to the speaker and / or reflected back down the line. This can be either a grave disadvantage or benefit depending on what one is trying to achieve. Most folks would consider this "bad", especially when trying to reproduce something accurately and using speakers that are not highly reactive.

The other important "deduction" one can make from this chart is that signal transfer is NOT linear from cable to cable across the frequency range. As can be seen, some are FAR flatter than others. While some have a relatively straight line with a rise at the top end, others are only "flat" within the bass range and then flare up drastically as frequency rises. However, these "curves" are NOT the frequency response of these cables.

If you take the results of the series resistance curves and invert them, THEN you'll have a basic idea of what the frequency response / power transfer characteristics of that specific cable is. In other words, instead of a rising high end, you get high end roll-off. Keep in mind that this is with a relatively benign ( non reactive ) load applied. Using a typical dynamic driver speaker, the results could be far more exagerated. Under extreme conditions, some cables with very specific electrical characteristics coupled with highly reactive loads can create "bad" sound and even hazardous electrical conditions for the amp that is trying to load into them.

As can be seen, the Fulton and Monster are basically only good for woofer or subwoofer operation whereas some of the others ( Polk, Mogami, etc..) are quite excellent up to appr 10 KHz or so. THOSE cables and cables of similar design are the ones that you want to investigate. That is, IF you want "accuracy" over a wide frequency range.

If you think back, didn't your ears tell you that the bass was a LOT more solid when you switched to "Monster" ??? The fact that you lost detail and high frequency information didn't seem quite as noticeable compared to how much more impact, "warmth" and "smoothness" the system picked up. While a cable of this type might be good in a system that is overtly bright, hard and glaring i.e. using low quality digital recordings and cheap cd players, it is of little to no use in a full range HI FIDELITY system.

On the other hand, some of those "wide band" cables achieve their phenomenal results at the expense of simplicity. Some have very complicated geometries ( Polk ) and require stabilizing networks ( zobels ). Due to the cables high capacitance and extended high frequency capabilities, some amplifiers ( typically high quality, wide bandwidth models ) can go into oscillation and destroy themselves. This was a BIG problem back then. Goertz cables are prime examples of this type of design in a modern day product. Fortunately, the previous problems with high capacitance speaker cables was recognized and we now have the know-how to correct such situations.

Of course, there are current designs that try to achieve the best of both worlds i.e. low inductance and "reasonable" capacitance. Some that come to mind are various designs by Kimber, Audioquest, Axon, XLO, etc... This is not to say that all of these cables are created equal or use similar designs. Some offer excellent electrical characteristics but may be able to be improved in terms of their physical geometry and how they come terminated from the factory.

The point that i was trying to make out of all of this is that:

A) The audible effects of cables was well documented over twenty years ago. Both Nelson Pass and J. Peter Moncrieff /IAR published VERY similar reports and findings way back then.

B) The differences in cables ARE real. As such, one should strive for finding cables that are the most "benign" or "neutral" in terms of electrical characteristics and frequency response while offering the lowest series resistance possible.

C) Choosing cables to "correct" problems within a system should be a last resort. Get the basics ( selection of components and matching of the speakers to the room ) right and then go from there. In plain English, the components must work together and not leave massive gaps between them. Fine tuning a system with cables might be able to fill in "small gaps" but should not be done to cover "gaping holes" or "canyons".

Hope this explains some things and helps someone out. It can be quite confusing trying to understand the situation that you may have been dealing with. Sean
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