Hey nerds! 3 high-quality cables, all sound different--why?

[JustDavid]

From an SPL point of view, noise that is flat across the frequency spectrum is white noise. Noise that is weighted to our hearing it as flat is pink noise.

I read your above-quoted to mean that Pink Noise follows the Fletcher-Munsen curves from "weighted to our hearing". It doesn't.

What Pink Noise is is 'equal energy per octave', versus White Noise being 'equal energy per frequency'.

 

[JustDavid]

Benj, nice explanation!

So now if you get to the question "are boutique cables worth the money?"

I don't think "boutique cables" should be all lumped together in one classification. The smoke'n'mirror percentage varies.

 

[UncleFluffy]

As a cheap-and-cheerful experiment, I'd probably inject a square wave at about 500Hz at the guitar end (with the guitar plugged in, sig gen in series with the pickup) and take a look at the wave shape at the amp input - a good scope will be able to show the difference between input and output signals. That will be enough to say how much of this is objective vs. subjective.

 

[fdeck]

As a cheap-and-cheerful experiment, I'd probably inject a square wave at about 500Hz at the guitar end (with the guitar plugged in, sig gen in series with the pickup) and take a look at the wave shape at the amp input - a good scope will be able to show the difference between input and output signals. That will be enough to say how much of this is objective vs. subjective.

Yes, that is the way. The easiest thing is to lift the ground leg of the pickup and insert the signal there.

 

[fdeck]

I have read and responded to these threads before. I hear a difference in some cables, sometimes profound, sometimes not. Full disclosure here, I am a recovering audiophile, and do not believe that all things perceivable by a human are scientifically measurable. (Great post on the Peter Belt principal BTW. Stereophile also did a double blind amplifier shoot out with Bob Carver that ended in litigation!)

At its core, subjectivist vs objectivist views may correlate or they may not. I remember replacing the zip cord speaker cables with some Mogami stuff on an electrical engineer friend's stereo after he told me all wire sounded the same. He was slack jawed.

Millions of dollars of research has gone into cable design. Almost every imaginable thing has been measured by manufacturers including the effect of the dielectric and the shielding material. (Vintage guitars wired with solid core cloth covered wire anyone?) And in the musical world, we have just barely entered the "active cable" universe, which apparently is a trendy thing in some audio applications.

I use the cables I like the most. I don't like spending a gazillion dollars on cable, and I don't. I accept that they do sound different to me, ABX, ABC, blind tested or whatever tested. I have to admit, however, that though I have accepted this for myself, it is very entertaining to listen to the opinions of people who either do or don't accept it, and how passionate the arguments get, considering that when in live performance, the differences might just disappear in the mix. Or not. ;-)

The Peter Belt Principle? Is that like the Peter Principle?

 

[elros]

bongomania, as bassbenj and lowendfriend have mentioned already: the cable along with the bass and whatever is at the other end of the cable makes a rather complex electrical circuit. Not so incredibly complex in the meaning that it has a lot of parts, but in the way these parts react with each other.
As mentioned, the different parts may act together to form a filter which can affect the audio part of the frequency spectrum. Change one part in this circuit (for example the cable) and it is likely to cause significant change in the filter parameters.
If the bass used is passive, the changes will probably be more dramatic, as the bass output will have a higher reactance (I think that's what it's called in English).
The audible effect of the cable is likely to be carried outside the audio part of the frequency spectrum as we lower the output impedance on the bass and also raise the input impedance of the pre-amp it is connected to.

Another thing:
The ear of a musician / audio technician is often very sensitive to subtle changes in sound. Measuring equipment, be it oscilloscope, spectrum analyzer or whatever, have their uses but also their limitations. I would not be surprised if the measurements don't show much difference between the cables, or if the tests are inconclusive.

 

[higgi]

No, because I described significant differences between three different cables, and asked why they sound so different--which is completely irrespective of whether I am using an active or a passive bass. The bass can be a "black box". Say I'm using a passive, which interacts more with cables than an active does--all three cables sound significantly different with that same passive bass, and the only difference is the cable. I clearly described how (a) all three cables are claimed to be low-capacitance; (b) one of the cables has what I perceive to be significantly higher treble content; and (c) one of the cables has a completely different perceived effect on the sound, which my (biased, fallible) ears hear as not just a change in the treble content.

I'm not trying to be ornery or complainy about this, it's just that there was a lot of information presented which some posters either didn't bother to read, or where they read it and decided I must be describing a sort of subtle placebo-oriented "different tone" that would be easy for them to dismiss. I do understand and agree with the premise that the bass itself forms a part of an LRC filter, and that this filter may not just have a treble rolloff characteristic.

For the record:
--I plan to buy a new audio interface in the next week or so, depending on sales/coupons/etc. that may come up.
--I will record sound clips with each cable, using an active bass, a passive bass, and a test tone.
--I will "pink noise" all three cables through the spectrum analyzer, and post the results.
--I will also use the active and passive bass signals as test sources, attempting to make them as consistent as possible, and post the spectrum analyzer results.

Have you tried an active bass yet? Did you notice as much of a difference?

From this post and your op, it was all done with a passive bass, you will get different sounds with different cables, period. They all have different inductance, capacitance, and resistance. It is much more dramatic with a passive bass.


An increase in capacitance will lower the system resonant freq or whatever increase the bass content, not just affect treble.


I am not seeing your mystery. I bet you have very sensitive hearing, that makes your compressor reviews that much more valuable.

 

[Pilgrim]

Any report yet? Inquiring minds......

 

[bongomania]

I just received my new interface yesterday (a Presonus Firestudio Mobile), so it will take me a couple of days to learn the various software, and then a couple more days to do the tests.

 

[Munjibunga]

One word: capacitance.

 

[UncleFluffy]

Impedance

 

[Munjibunga]

Impedance

That's a different word.

 

[bongomania]

Seriously guys? If you're going to post anything here, try to make it either constructive or funny.

 

[Munjibunga]

Seriously guys? If you're going to post anything here, try to make it either constructive or funny.

I'm sticking with capacitance. I suppose one could argue that it's RC impedance.

 

[UncleFluffy]

Sorry, was playing the one word game.

Impedance is the total effect of capacitance + resistance + inductance. The cable has all three, but capacitance is likely to be the most significant.

 

[Pilgrim]

Not so fast, my friends! (Lee Corso lives...)

IMO neither impedence nor capacitance are the issue; I believe that both are outside the scope of the question asked by Bongomania. The question he posed was:

"...So what's your take on this? Is it really possible to create a complex filter just by manipulating the wires and the specific conductive metals used in the cable or plugs?"

That's a yes/no question, and he proposed to study frequency response at the output to answer that question. Others may interpret the first post differently, but my interpretation is that causality was not part of the original question.

If a difference is found, then the cause of that difference is a separate question.

 

[UncleFluffy]

Not so fast, my friends! (Lee Corso lives...)

IMO neither impedence nor capacitance are the issue; I believe that both are outside the scope of the question asked by Bongomania. The question he posed was:

"...So what's your take on this? Is it really possible to create a complex filter just by manipulating the wires and the specific conductive metals used in the cable or plugs?"

Well, to be fair there were three questions:

Q1: "What's your take on this?"

A1: It's completely possible, especially with a passive bass, that the cables are colouring the tone in noticeably different ways. I'm very skeptical about claims that tone differences exist that can't be picked up by sensitive enough equipment. Electrons obey the laws of physics not of magic and would need to see the results of double-blind A/B testing before giving such claims any credence. (Note that Bongomania did not make any such claims in his original post).

Q2: "Is it really possible to create a complex filter just by manipulating the wires and the specific conductive metals used in the cable or plugs?"

A2: Yes. The potential complexity comes not just from the cable but the interaction of the cable with the other components in the circuit.

Q3: "What is really going on here?"

A3: This is the interesting question. My starting point would be to guess that some % is down to physics and some down to psychology. It should be possible to get a handle on how much is down to each with some simple experiments

- can you identify the cables blindfold with someone else changing them around?

- what's the frequency response of a cable measured in isolation?

- what's the frequency response of the whole system (guitar+cable+amp)?

- grab an LCR meter and measure L, C and R for for each cable

 

[bongomania]

I don't have the $1K plus that most hardware LCR meters cost--is this $200 handheld one known to be any good? http://www.tequipment.net/Extech380193.asp Or is there another one in that low price range that's worth owning?

Alternately, can I make one using the gear and parts I do have?
Analog scope
Function generator
Counter/timer
Multiplier
DMM
Scads of small components e.g. opamps, transistors, caps, etc.

PS: thanks for the more elaborated answer!

 

[fdeck]

I don't have the $1K plus that most hardware LCR meters cost--is this $200 handheld one known to be any good? http://www.tequipment.net/Extech380193.asp Or is there another one in that low price range that's worth owning?

Alternately, can I make one using the gear and parts I do have?
Analog scope
Function generator
Counter/timer
Multiplier
DMM
Scads of small components e.g. opamps, transistors, caps, etc.

PS: thanks for the more elaborated answer!

Rolling your own is more fun.

Here's an idea. You can get R out of the way by measuring the series resistance with a DMM, or just computing it from the wire gage. Measuring such low resistances is actually a bit tricky, and you might just be able to assume it is zero for the sake of this study.

Now build a voltage divider using a resistor and the "unknown" cable. Feed with the function generator, and measure the output at different frequencies. Do this with the cable open, then shorted at the opposite end. From the graphs of gain versus frequency, and the known resistance, you should be able to compute C and L.

Since I don't have a function generator, I would do all of this with my PC as both the generator and analyzer.

 

[fdeck]

For more fun, this link:

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has formulas for L and C of a coaxial cable. It's probably reasonable to assume that the cable has a polyethylene dielectric, since that's the most common.