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2011-Aug

basic Cables & Sound Quality

Nick Name: Golden Ears Registered Date: Aug 25, 2011, 23:33:44 IP ADRESS: *.56.123.5 Views: 9483

Cables & Sound Quality

 

 


A listening session with a cable manufacturer

A few months ago, I was at a high-end audio show. The show had a really diverse selection of all sorts of audio gear. Among them was company A, a maker of high-end cables, who had swapped cables in earphones and speakers from other vendors with their own products on display. Among the speakers they they had, there were two identical pairs of speakers from company B, where one pair had its internal cables redone with company A's audiophile grade cables and the other had not been unmodified.

 

I went into their booth, heard the explanations from the company, and then asked, "I do not understand how speaker cables could tangibly affect the sound. I guess that the sound could be changed somewhat if the cable has completely different capacitance and inductance values from the stock ones, but is it even possible to have a significant difference between cables?"

 

The guy at the booth replied, "Theoretically, what you say might be true, but if you actually hear it out, you'll notice the difference. Why don't you listen for yourself?"

 

And listen I did. And funnily enough, the sound had actually changed. So I inquired again:

 

"The bass becomes a tiny bit weaker while the treble becomes slightly boosted - do you have any specifications on the capacitance or the inductance of these cables? I'm sure that they must have been measured over R&D.", to which the guy was hesitant before reluctantly replying,

 

"The development team must have them somewhere, but we don't have any data at the moment."

 

"Structure wise, the cable seems like it would have a lot of capacitance - is there a specific reason why it was built this way?"

 

His reply was that "Generally what we heard from people in the audio industry was that the best sounding audio cables are made from single, flat crystals - that's why we decided to go with it."

 

Once I heard that, I understood why they made such a product, so I stopped asking questions and quietly left that booth.

 

Now, let me explain why something like this happens in plain English.

 

 

 

 

Changing sounds in analog circuit
In an analog circuit, the sound changes whenever there's an excessive amount of either capacitance or inductance (I hear complaints that this isn't plain English - hold on, the explanations are right around the corner).

 

This is because capacitance does not allow bass signals (low frequencies) to pass through easily (the resistance increases) while allowing treble signals (high frequencies) to pass unhindered - this is due to the structure of capacitors, which are usually made by having two parallel conducting plates connected to each other by a wire.

 

In contrast, inductance hampers treble (high frequencies) from passing whilst presenting little obstacle for bass signals (low frequencies). This is also due to the structure of inductors, which are generally coils of wires.

 

(If you're confused, the following article will help: Crossover networks and filters)

 

If you're still confused, then just remember that 'if a cable that is carrying audio signals has a lot of capacitance, you get less bass, and if it has a lot of inductance, you get less treble' - this is all you need to know.

 

The really interesting thing is that most audio cables do not have enough capacitance or inductance to make a perceivable difference. If you do hear a significant - not placebo - difference in sound, then this probably is an indication that the cable used has a huge capacitance or an inductance compared to stock cables.

 

The cables that I heard from company A were quite flat - this is a structure that drastically increases capacitance, and that was the reason why the bass sounded weaker. This sort of sound is marketed the company as a 'clean, transparent sound', but that is only if you have a positive view of it; the exact same sound could also be 'lacking it bass' if you were critical.

 

Some readers might be wondering at this point,

 

"Well, we know that the sound could change if you use high-end cables - I don't see the problem with using them then."

 

Not to say this is completely wrong, but there are several other things to take into considerations before we jump to a conclusion.

 

 

 

Role of cables
What do you think goes through the mind of a manufacturer that makes loudspeakers, DAPs, or amplifiers regarding cables? Would you think that they consider the changes in sound due to different cables?

 

From the perspective of every single manufacturer - excluding the cable makers - cables have no effect whatsoever on the sound. This is a valid observation since the absolute majority of cables have such small capacitance and inductance that the sound is unaffected; if they were in fact to take into consideration the painful few exceptions, their products would end up with distortions when used with any other cable.

 

That is, the role of cable is not to distort the signal coming through it, but rather to relay it completely unchanged and without distortions. And most cables do this job just fine - in reality, I thought that the speaker with the stock cables from company B had a better overall balance.

 

Some of you might still be thinking,

 

"Whatever the case, my speaker has an overemphasized bass, so I should use a cable with a high capacitance to establish a balance."

 

Of course, when there is an excess of bass, using a cable with high capacitance will indeed tame it somewhat. However, this sort of adjustment is better done through rearranging speakers rather than using cables. If this cannot fix the problem, then using a digital equalizer is still preferable in terms of sound quality.

 

This is due to the phase difference, which occurs whenever there is a high inductance or capacitance in an analog circuit.

 

 

 

Phase difference and sound degradation

Generally, equalizers are avoided within a high-end audio system - most audiophiles attribute this aversion to the fact that using an equalizer leads to a degradation in sound quality.

 

But why, precisely, is it that an equalizer adversely impacts the sound? Those who have studied electrical engineering would answer here that this is caused by a phase shift. What, then, is a phase shift, and what is an equalizer?

 

In engineering jargon, equalizers are analog filters that act on specific frequencies. Such filters are made by arranging capacitance and inductance depending on the effect required - the problem is that whenever a signal flows through capacitance or inductance, there is a change in phase between current and voltage. And this difference leads in turn to the peaks of current and voltage being out of sync, which then causes a lower maximum power.

 

02_Coil_current_voltage_phase.jpg

When passing through an inductor (e.g. a coil), the current leads the voltage by 90 degrees in phase.

 

04_Capacitor_current_voltage_phase.jpg

When passing through a capacitor (e.g. two parallel conductors), the voltage leads the current by 90 degrees in phase

 

In terms of physics, this means a decrease in power (measured in Watts), or work done per unit time. The power is the product of voltage and current, and if the two phases are not in sync the amount of usable energy diminishes (you could confirm this by simply multiplying the magnitudes of the voltage and current on the graphs above and comparing this to the optimal case).

 

For audio, this has the effect of diminishing the dynamic range or intruding noise. This is the reason why equalizers are not used in high-end audio.

 

Word of caution

: Digital equalizers work differently from analog equalizers.

 

Why the sudden ramble about equalizers, you ask?

 

Well, we've established earlier that the change in sound from cables is a result of high capacitance or impedance - but this is functionally indistinguishable from using an analog equalizer.

 

The really unfortunate bit is that audiophiles balk at the very thought of using an equalizer, all while investing fortunes in cables. Rather ironic.

 

Personally, I feel like this money would be far better spent on modifying your listening room, or a high-quality digital equalizer.

 

 

 Creative Commons License
Images, text and measured data by Golden Ears Corporation is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

 

Golden Ears Test System - for more information (Link)
1. HATS: Bruel & Kjær - Head and Torso Simulator Type 4128C
2. Microphone Amplifier: Bruel & Kjær - NEXUS Conditioning Amplifier 
3. Audio Interface: Lynx L22
4. DAC: Golden Ears D/A Converter
5. Headphone Amplifier: Golden Ears Headphone Amplifier 

How we test
1. Headphone / Earphone
2. Speaker
3. Amplifier / DAP
 

How to read G.E. Graph
1. Earphone / Headphone
2. Speaker (Directivity Pattern)
3. DAP / Amplifier

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