A hard look at the effect of cables


Hey guys
A fellow EE audionut directed me to these articles and I thought some of you might be very interested to read them too. Two arguably qualified engineers went through the pains to take high quality measurements of the effect of cables and their interation with a complex electrical load, such as a full range loudspeaker, and with a complex signal, such as music. The link below is to the final installment but be sure to also read parts 4 and 5 very carefully. Part 5's Figures 6.8 and 6.9 are really amazing. I had never seen such measurements and they definitely seem to correlate with what we hear. The cables lengths are longer than normal but I think the point is well made. Hope you enjoy this read as much as I did.

http://www.planetanalog.com/showArticle.jhtml?articleID=202102592

Arthur
aball
hi Psacanli, nope, haven't tried those, but i've tried many that are well regarded. I"d think I'd hear something. Could be that my gear isn't sensitive, tho that doesn't seem likely as I've never heard any real difference between power cords.
Is it really that difficult for a cable to carry a full range signal? I don't know much, but this is the first I"ve heard of this.
Of course not. The problem (if problem there is) is in the way that wire carries a wide-band signal; i.e. there may be attenuations & small phase anomalies in parts of the bandwidth...

But then, you can get similar anomalies just by using a single channel to amplify from dc to daylight AND expect a pair of passive boxes (speakers) to produce sound, accordingly from dc to daylight -- all of this in totally linear fashion. A tall order.
Just think about it! :)
If the Meridian approach was a smashing commercial success, I guess it would be more popular among manufacturers. Market forces, whatever they may be, seem to dictate otherwise. I got a kick out of your analogy with the fashion industry - perhaps I have more in common with my wife than I thought...
Waffle35,

You missed a big part in that a lot of the fun in audiophile is finding those "magical" pairings.

I agree - "freedom to mix and match for sound is the main reason many people pursue this hobby"

An Active Speaker is like a "straight jacket" to those looking to tailor sound to their own tastes.
you can get similar anomalies just by using a single channel to amplify from dc to daylight AND expect a pair of passive boxes (speakers) to produce sound, accordingly from dc to daylight -- all of this in totally linear fashion. A tall order.

A tall order! Exactly. It is not so much what the cables are being asked to do! It is really what the poor amplifier and complex transducer system has to handle - it all comes together at the amplifier that is often being asked to handle a dogs breakfast of signals/impedances.

A full range speaker with four (and often more) drivers and three crossovers and a supertweeter is being asked to produce reasonably flat response from 20 HZ to say 35 Khz. All the complex reactance interacts. All the diaphragms are moving all the time and their movement and inertia induces electrical energy back into the shared circuit with all the other drivers. The bass woofer requires several AMPS to produce bass signals and yet the tweeter and supertweeter respond audibly to the tiniest miniscule signals.

Now couple this all together with some wires and all to the same browbeaten amplifier, typically a power amplifier with an on paper flat response from 20 Hz to 100 Khz (into a resistor 8 Ohm load of course!!!!).

This system now has a lot going on and Power Amplifiers are not supernatural machines that can respond to anything and everything without the slightest signal interaction. Delivering a huge bass signal of several amps at 40Hz to 80Hz without causing audible intermodulation distortion of a small tweeter signal of a few milli-amps (thousandths of an amp) is a tall order! Worse - the reactance of the system is complex....the load swings from low impedance to high impedance depending on what frequencies the amp is asked for. Worse - the drivers have inertia and are moving....these are making the complex load not just frequency variable but time variable too - depending on the drivers movement and position. Worse - as you get further into a track the drivers voice coil heats up and this changes the way it interacts with the passive crossover as well as changing its fundamental response due to its rising resistance. Worse - over half the amplifier power is dissipated as heat in the crossovers alone (it never reaches the speaker drivers).

The idea that a high tech speaker cable or bi-wiring might help solve some of these issues is kind of on the right track but it is largely wishful thinking, as the problem is really the overall complexity of the total interacting system. It is incorrect to simply extol a cable for any perceived improvement it makes...there are surely more problems going on if such a small change makes a dramatic difference - a mis matched amp and speaker for example! In some cases a particular type cable may improve the stability of a system in others it may not...all will depend on the particular gear combination and how or what kind of detrimental distortion is being produced through the complex interaction.