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So who is going to write up the tutorial on "How to build Custom RCA's to maximize the RLC performance of your signal path"? Or, "How to time align your system by modifying the signal cable."

Does equipment that can measure RLC accurately enough for the purposes of tweaking RCA construction even in the realm of possibility for the average DIYer, cost wise that is?

If I knew how to properly measure RLC of the cable / source / amp system, what the heck I was looking at and how it affected the sound I'd build some cables. It would be a neat experiment to build cable with different wire and see if the preceived changes in sound match up with expectation from the scientific data.

I can see it now... Neutrik Connectors with Canare instrument cable from the head unit to the eq. Canare RG-6 connectors with Belden Coax from EQ to XVR, a Stinger RCA to the Tweeter amp (got lucky), Mogami twisted pair and Echimman (sp?) to the mid amp, Starquad with Parts Express special RCA to MB and Soundcraft RCAs with hand braided sliver wire to the sub (for that magical bass extension, but all scientifically proven of course). Then you buy a new crossover and you have to start all over. AHHHGGGG...

Anyway, I really don't need another thing to have to tweak, but it would make me feel really smart to know how to measure and modifiy a cable to change the response of my system.

Thanks for bringing the technical knowhow Werewolf. You are making me want to go get out my old text book from the one EE class I took in college.
 

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T-Ro said:
If I knew how to properly measure RLC of the cable / source / amp system, what the heck I was looking at and how it affected the sound I'd build some cables. It would be a neat experiment to build cable with different wire and see if the preceived changes in sound match up with expectation from the scientific data.
That was done 25 years ago and published in the J.AES, at least for speaker wires (whose potential sonic benefits should far outweigh RCA cables due to the much lower impedance load). Fred Davis was the author. If I recall, he even included in his test group a set of jumper cables he had lying around...
 
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Discussion Starter #43
Mark's point is VERY well taken ... and helps to address the above post.

I have stated that the signal transmission can't be impacted unless RLC is impacted. Very true. However, this does not mean that any difference in RLC is audible. And it does not mean we should be on an eternal quest to minimize RLC.

A few cases-in-point :

1. Imagine an RCA cable connecting a preamp, with source impedance of say 200ohms, to an amplifier, with input impedance of say 10kohm. How much should I worry about reducing cable resistance from 2ohms to 1ohm?

2. In my above example (which I still need to finish), we saw a VERY long RCA cable introduce a low-pass at 80kHz. How much should I worry about improving that to 160kHz? Or 320kHz?
 
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Discussion Starter #44 (Edited)
OK ... how does an 80kHz first-order lowpass impact phase in the audio band?

Here's the Transfer Function (derived by simple voltage division):

Vout/Vin = [1/jwC]/[R + 1/jwC] = 1/(1 + jwRC)

where w=radian frequency=2*pi*f, R=1k, C=50ft*40pF/ft=2000pF

In general, a Transfer Function is a complex function of frequency, which really just means that the frequency response has two parts : a magnitude function vs. frequency (often erroneously equated with frequency response in audio), and a phase function vs. frequency. All we need to do is find the magnitude and phase of a complex "number" ... or function of frequency, in this case :)

The Magnitude Response is :

|Vout/Vin| (in dB) = 10*log{1/[1 + (wRC)^2]}

somebody can tell me the magnitude response at f=10kHz, 20kHz, 40kHz, 80kHz, 160kHz, 320kHz :)

The Phase Response is :

Angle[Vout/Vin] = -arctan{wRC}

somebody can tell me the phase response at f=10kHz, 20kHz, 40kHz, 80kHz, 160kHz, 320kHz ... and in so doing, answer the question : what does the phase response of a first-order low-pass filter look like? :)
 

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We could simply ask what affect phase has in the audio band as well - and bypass your little homework assignment.

Which is audible, but not disagreeable.
 
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Discussion Starter #46
Absolute Phase : audibility is debatable ... but at some point it certainly is audible, as easily demonstrated by looking at extreme values of group delay.

Relative Phase : quite audible, as it impacts how one driver interacts with another acoustically (be it the corresponding driver on the other channel, or another driver on the same channel at crossover)

Once again, I'm not arguing in favor of cable sonics :) Just answering a question posted. No need to consider the homework if disinterested :D
 
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Discussion Starter #48
This is the Magnitude and Phase Response of the first-order low-pass filter formed by the cable capacitance & source resistance described above :


FREQUENCY.....MAGNITUDE........PHASE

10kHz.................-0.068dB........-7.2 degrees

20kHz.................-0.27dB..........-14 degrees

40kHz.................-0.98dB..........-27 degrees

80kHz.................-3.0dB............-45 degrees

160kHz................-7.0dB...........-64 degees

320kHz................-12dB............-76 degrees

640kHz................-18dB............-83 degrees

Conclusions :

- The magnitude response should look familiar : -3dB at 80kHz, asymptotically approaching a 6dB/octave rolloff as frequency increases.

- The phase response always seems to be a point of confusion ... there is no single number for the phase of a filter : -45 degrees at 80kHz, asymptotically approaching -90 degrees as frequency increases.

- Even in this artificially exaggerated case, the audio band impact ... including both magnitude and phase ... is minimal.

- Is this the response for any RCA cable? Of course not! Will it be different for a different source resistance? Yes. Will it be different for a different cable, of different length and capacitance? Yes. Can the techniques presented here be used to calculate the possible (but unlikely) audio band impact of any RCA cable? YES :)
 
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Discussion Starter #50
Science (and logic, to Mark's point) will not blind you ... in fact, quite the opposite :)

It's the light of a best friend, for navigating your way through the dark world of audio bullshit :D
 

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werewolf said:
Science (and logic, to Mark's point) will not blind you ... in fact, quite the opposite :)

It's the light of a best friend, for navigating your way through the dark world of audio bullshit :D
I'm afraid that mankind's superior belief that they can expain EVERYTHING in this life through science and logic , is sorely flawed when it comes to music. Production , reproduction , ect .... Music is an emotional experience way beyond the Ones and Zeros , bits and bytes. And it is a VERY narrow view for one to think they can explain everything with technical explanations.
A HUGE part of listening to music is experiencing the emotions it brings to an individual , and if a part of THAT experience is influenced by a percieved joy due to owing an individual's cable of choice , NO AMOUNT of math or technical explanation can ever help ... but instead only serve to dampen the joy of experiencing music itself.
I feel sorry for narrow and close minded individuals who thinks everything sounds the same , due to some math ....
 

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AVI said:
I'm afraid that mankind's superior belief that they can expain EVERYTHING in this life through science and logic , is sorely flawed when it comes to music. Production , reproduction , ect .... Music is an emotional experience way beyond the Ones and Zeros , bits and bytes. And it is a VERY narrow view for one to think they can explain everything with technical explanations.A HUGE part of listening to music is experiencing the emotions it brings to an individual , and if a part of THAT experience is influenced by a percieved joy due to owing an individual's cable of choice , NO AMOUNT of math or technical explanation can ever help ... but instead only serve to dampen the joy of experiencing music itself.
I feel sorry for narrow and close minded individuals who thinks everything sounds the same , due to some math ....
The brain, in all its complexity, can't act on information that isn't there. Unless you're suggesting that there's some unaccounted for force at play that's yet to be discovered, then you must recognize that the only media that is responsible for the music is in the electrical realm. That is, the information originates on the CD and has to make its way to the brain -- so the earliest stage is electrical, and if it can be shown that the two electrical signals are identical then the logical conclusion is that the brain has the same information available to it in both cases. So the task, then, is clearly to demonstrate that the two electrical signals are the same. This has been done.

So the question isn't whether or not you enjoy it with the new cables. If that makes the experience more enjoyable to you, nobody's telling you not to do it. But recognize that, for those who aren't influenced by such superficial things, that "upgrade" serves no purpose but to drain the wallet and distract from potential upgrades that could generate a REAL influence (ie. physically manifested in the sound wave).

Edit: to clarify my first sentence, when I refer to "information" I'm talking about the external stimulus. The internal representation of that stimulus can of course change. It appears you're saying that your brain processes that information differently with the knowledge that the special cables are present. That's not unreasonable.

But while I'm at it, I should point out that there isn't a breakdown in logic, as you suggested in your post. Everyone in this thread so far has acknowledged that the brain uses a number of different cues to form the experience. In fact, that's been my point all along (and I assume werewolf's too) -- these very cues need to be eliminated when the question comes up as to whether or not the cables themselves contribute to a perceived difference in sound.
 
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Discussion Starter #54 (Edited)
AVI ... you've made a very fundamental error. You're confusing the electrical/mechanical/acoustical reproduction of music, with the human enjoyment of music.

Reproduction lends itself completely, totally and thoroughly to science and logic ... and emotion has nothing to do with it. The ACCURACY of reproduction is completely determined by ... "numbers".

Furthermore, the mathematical description of the universe is not a "belief system", whose accuracy is open to interpretation. The universe under the scientific method is, afterall, objectively testable.

Now the other category is enjoyment of music. And enjoyment is, I'll grant, an emotional experience. We certainly don't know everything yet about the chemistry of emotion ... but i sure wouldn't bet against science in this category for very long either ;)
 
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Discussion Starter #55
To further illustrate my point ... if two cables present identical voltages to loudspeakers, the loudspeakers have no choice but to create identical acoustical outputs. One may choose to believe otherwise, of course, but unfortunately logic reigns supreme.

Perhaps one gives a better "emotional enjoyment" ... particularly obvious, of course, when variables are not properly isolated ;) As Mark stated ... nobody is trying to prohibit your belief system ... especially the cable manufacturers and salesmen !! :D
 
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Discussion Starter #56 (Edited)
Something else I remembered, in the category of "comprehensive RLC modelling".

The new buzzword among megabuck cable suppliers seems to be "energy storage". Now ... isn't THIS outside the realm of RLC modelling?

The answer is absolutely NO. The capacitance (C) in the electrical model is the element we use to represent electrical energy storage. The inductance (L) in the electrical model is the element we use to represent magnetic energy storage. So ... all forms of electromagnetic energy storage are already completely comprehended in the RLC model we have been discussing :)

And no, you can't have two cables with identical frequency responses but different "energy storage." Sorry ... have to look elsewhere to support crazy claims.

Bottom Line : Until cable manufacturers start claiming gravitational effects in their cable sonics, we've got a pretty comprehensive description ;)
 

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it might just be RLC, but saying that is very misleading, because the resistance of the cable changes with the frequency. at high frequencies, the resistance rises and can be significantly high, looks like the impedance curve of a speaker. certain techniques like teflon coating reduces high frequency impedance which is why DIY CAT5 cables sound better.

also, i know for a fact that cable shielding also matters. i can put my finger near the cable and get static noises.
 
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Discussion Starter #58
maybe you missed the several times in this thread where I included noise immunity/shielding as an important property as well?
 

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cotdt said:
it might just be RLC, but saying that is very misleading, because the resistance of the cable changes with the frequency. at high frequencies, the resistance rises and can be significantly high, looks like the impedance curve of a speaker. certain techniques like teflon coating reduces high frequency impedance which is why DIY CAT5 cables sound better.
Resistance does not significantly rise with frequency. The way I define "significantly", it would have to come somewhere close to the several kilohm input impedance of the amplifier. But it doesn't. It'll add only a couple ohms. No one would call that significant.

Besides, like I said elsewhere, the easiest and cheapest way to combat the skin effect is by increasing wire gauge (thereby increasing surface area), not by implementing special new strand/dielectric properties or cable geometries.
 

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werewolf said:
maybe you missed the several times in this thread where I included noise immunity/shielding as an important property as well?
I read this entire thread and didn't notice you mentioning shielding at all, so I had to mention it.

The expensive cables have different RLC values as compared to cheap radio shack cables, so I wouldn't be surprised if people hear differences. if i remember correctly, they have lower L and C, but slightly higher R than cheap cables.

The larger debate here is measurements versus hearing. There are those who claim that all cables, all sources, all decent speakers, and all amplifiers sound exactly the same, and they use (flawed) blind tests to prove it, and somehow the results agree with them. Yet to me the difference is like night and day. Usually I can both hear and measure a difference, but not always. In the case of amps and sources, it is not easy to measure since the response is almost always flat even with terrible-sounding equipment, and distortion is also low. Linear and nonlinear distortion entirely influences the sound and nothing else, this is the theory and I'm not disputing that. Nevertheless, with more sophisticated measuring equipment, people find that often there is indeed a measurable difference just like their ears have told them long ago. For example, you can have two speakers both EQed to flat response, and both have distortion below audibility. Let's say one is a magnesium cone, and the other is a sliced paper cone. However, the difference between the two drivers is easy to hear because the two cones have different timbre. This means they have very different local frequency response but you need a very high resolution frequency response measurement, so this is a case where we can't measure it but in theory it's measurable. I think it's similar with other audio things like amps and sources. We hear the difference but the differences are not easy to measure, so this is why I put hearing over measurements.
 
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