Skeptico Saloon: An Objectivist Joint

[jaddie]

..and subscribed.

 

[audionewbi]

Here is something which has always troubled me ever since I have started reading about cables. When a pure copper cable and gold copper cabled are measured they both seem to measure identically however people claim the silver has better treble. Can it be that we need more sensitive measuring mechanism or the cable makers are trying to lie?

 

[jaddie]

Quote:

. Can it be that we need more sensitive measuring mechanism or the cable makers are trying to lie?

We can measure well below the threshold of audibility of any electrical parameter.  
 
So....

 

[ToddTheMetalGod]

I've been getting into computers more than headphones lately (I take turns between my hobbies so I don't start to get bored). I need to learn more about sound science though and I'm really starting to like the objectivism approach to audio. I believe that a DAC and amp should be transparent and measure well, leaving the headphones to change frequency response (aside from maybe a little equalization to fix small imperfections). I think my problem with equalization is the potential for distortion, then again no matter what you do distortion will always exist.
 
I, too hate that people can so easily be fooled in audio, this is a hobby where some people won't listen to science even with proof shown to them... it kind of frightens me. I mean if they understand the information that proves something (i.e. measurements showing that copper and silver cables have almost exactly the same frequency response), how can they believe it is different?
 
I hope I don't start an argument with this...
 
Edit: By the way, I'm not saying cables have no effect on sound quality. For example, magnetic shielding is important (particularly around sources of electromagnetic radiation, when running my computer under extreme load on Folding @ Home my un-shielded Xonar DGX picks up a lot of noise). I have a question about cables, does the purity of the copper or stranded/solid wire actually have an impact on the function a piece of audio equipment?

 

[ToddTheMetalGod]

Quote:

We can measure well below the threshold of audibility of any electrical parameter.  
 
So....

 
Most people cannot understand many measurements of electrical parameters though, so it leads to a barrier in communication when discussing objectivism.

 

[esldude]

Quote:

 
Most people cannot understand many measurements of electrical parameters though, so it leads to a barrier in communication when discussing objectivism.

Yes, but some even who understand, still don't believe the measurements. 
 
I think it is the old gut vs head problem.  You can know something is so in your head, and have that gut feeling which disagrees with it.  Pretty hard to ignore that gut feeling. 

 

[ToddTheMetalGod]

Quote:

Yes, but some even who understand, still don't believe the measurements. 
 
I think it is the old gut vs head problem.  You can know something is so in your head, and have that gut feeling which disagrees with it.  Pretty hard to ignore that gut feeling. 

That's true. It is hard to ignore it, but sometimes you just have to use the proven science to expand your understanding of things.

 

[xnor]

Quote:

I have a question about cables, does the purity of the copper or stranded/solid wire actually have an impact on the function a piece of audio equipment?

 
From sound.westhost.com
Quote:

Oxygen free copper (or OFC) supposedly means that there is no oxygen and therefore no copper oxide (which is a rectifier) in the cable, forming a myriad of micro-diodes that affect sound quality.  The use of OFC cable is therefore supposed to improve the sound.
Try as I might (and many others before me), I have never been able to measure any distortion in any wire or cable.  Even a length of solder (an alloy of tin and lead) introduces no distortion, despite the resin flux in the centre (and I do realise that this has nothing to do with anything - I just thought I'd include it

.  How about fencing wire - no, no distortion there either.  The concept of degradation caused by micro-diodes in metallic contacts has been bandied about for years, without a shred of evidence to support the claim that it is audible.

 
 
Quote:

I think my problem with equalization is the potential for distortion, then again no matter what you do distortion will always exist.

If you don't go crazy the only problem I see is digital clipping. You can prevent that pretty easily though by using a digital preamp to pull down the EQ curve below 0 dBFS or not boosting stuff.

 

[ToddTheMetalGod]

Thanks for the help Xnor

. Yeah I figured cables really didn't make a difference, I once saw the results of a blind test in which one setup was used and the variable was the conductors from the amplifier to the speakers. In the test, one listen was done using an "audiophile grade" speaker cable and the other a coathanger. The results from the blind listeners concluded that the coathanger sounded better (obviously this was likely a guess, unless resistance or magnetic shielding came into play). I always figured wires didn't make much of a difference unless they were of barely functional quality, but it's always nice to have a well built cable. Yeah I'm still skeptical about equalization though (since I am terrible at it). As long as equalization is done downwards in volume, clipping shouldn't become a problem.

 

[jaddie]

Thanks for the help Xnor

. Yeah I figured cables really didn't make a difference, I once saw the results of a blind test in which one setup was used and the variable was the conductors from the amplifier to the speakers. In the test, one listen was done using an "audiophile grade" speaker cable and the other a coathanger. The results from the blind listeners concluded that the coathanger sounded better (obviously this was likely a guess, unless resistance or magnetic shielding came into play).

There is a possibility that the additional inductance of spaced conductors like coat hangers could affect high frequencies, but it would depend on the complete electrical circuit including the complex load of the speaker.  Spacing two conductors in an AC circuit creates a huge single-turn coil. Not saying thats what happened in that case, but it is one potential difference.  The additional inductance of spacing wires at a few inches should not, on it's own, affect anything.  But when taken in combination with a load the whole thing becomes a filter, and the effects can easily creep down into the audio range. The effect is highly dependent on the specific speaker load, and you can't generally say it would be audible.
Quote:

I've been getting into computers more than headphones lately (I take turns between my hobbies so I don't start to get bored). I need to learn more about sound science though and I'm really starting to like the objectivism approach to audio. I believe that a DAC and amp should be transparent and measure well, leaving the headphones to change frequency response (aside from maybe a little equalization to fix small imperfections). I think my problem with equalization is the potential for distortion, then again no matter what you do distortion will always exist.

There is a possibility for extreme EQ to cause overloads in some situations, but there are also ways to avoid this and still use some rather significant EQ.  
Here are a few examples.  
 
First, no EQ applied:
 

 
Now, with a radical +15dB at 8KHz applied with a simple 10-band graphic EQ. Note that even though there is 15dB of EQ dialed in, the resulting peaks changed by less than 6dB.  This is because of the limited bandwidth of the equalizer, and that statistically there was very little energy in the file at the 8KHz band center.
 

 
Finally, the original with +6dB of shelving EQ from 1KHz and down.  Literally, half the spectrum had 6dB of boost applied.  Now we see our expected 6dB of peak level change:
 

 
So the answer is, you can apply some rather significant boost so long as the bandwidth is controlled, which is exactly what you would do for headphone EQ.  Also, there's a lot less energy in the high half of the spectrum most of the time, so you have more EQ headroom there.  However, this one precaution: If the EQ is applied in the digital realm, and the equalizer DSP software does not provide for an overall gain adjustment, you could have an issue if your original looked like this, which is our original without pre-adjusting for EQ gain:
 

As you can see, peaks are already a fraction of a dB from FS, no room for any boost there.  Good digital EQ provides an overall gain adjustment to compensate for the gain of an equalizer.  Once that's done, you can pretty much EQ at will without clipping anything post EQ, including your amp.  An analog EQ before an amp would require enough total system headroom to accomplish EQ without clipping. 
 
There's also nothing wrong with using EQ in 'cut' mode only to achieve the same resulting curve, it just takes a bit more understanding and thought, and realizing that the result cause a general volume drop with the benefit of better sound.  For example, in the third graphic I applied a 6dB shelf boost below 1kHz.  The same effect could be had by applying a 6dB shelf cut above 1KHz, and we would have ended up with much more peak headroom. 

 

[uchihaitachi]

Even a length of solder (an alloy of tin and lead) introduces no distortion, despite the resin flux in the centre (and I do realise that this has nothing to do with anything - I just thought I'd include it 

.  How about fencing wire - no, no distortion there either.  The concept of degradation caused by micro-diodes in metallic contacts has been bandied about for years, without a shred of evidence to support the claim that it is audible.
 

 

[jaddie]

Quote:

Even a length of solder (an alloy of tin and lead) introduces no distortion, despite the resin flux in the centre (and I do realise that this has nothing to do with anything - I just thought I'd include it 

.  How about fencing wire - no, no distortion there either.  The concept of degradation caused by micro-diodes in metallic contacts has been bandied about for years, without a shred of evidence to support the claim that it is audible.
 

Well, that's sort of like saying you can't taste salt in water.  It depends on how much you mix in.  If "distortion" includes all forms of signal alteration, then if you have enough of anything, there will be distortion.  Even good, large gage oxygen-free copper, if you have enough, takes it's toll, and becomes easily audible at several hundred feet. 
 
Galvanized steel fence wire?  No problem measuring and hearing that, at at less length than copper by a long shot.  
 
As far as degradation caused by micro-diodes in metallic contacts, if you haven't experienced an oxidized contact causing distortion, just consider yourself fortunate.  It happens shortly before the contact completely breaks down, and is not all that uncommon, certainly documented, but perhaps only in the context of a contact reliability study.  In short, just about any contact material except for 24k gold will oxidize given enough time and exposure to the wrong atmosphere and conditions.  Low contact force permits oxidation growth between contacts, which is only semi-conductive, and depending on the materials, non-linear.  We don't see the effect very often because good engineering has worked around it with high force contacts, or the right plating sealed off from the atmosphere.  High current and voltages also break down oxidation, so you won't find this happening in speaker circuits very much.  But yes, it exists, is documented and we do have to deal with it.

 

[bigshot]

Quote:

I think my problem with equalization is the potential for distortion, then again no matter what you do distortion will always exist.

 
The way to think about that is to weigh the huge and clearly audible benefit of equalization against the minute and pretty much inaudible distortion of a halfway decent equalizer.
 
On my receiver, there is a direct bypass button. It bypasses all of the equalization and DSPs... and even the tone controls and just patches direct from input to amp to output with no processing. When I push that button, The soundstage shrinks, the tone becomes opaque, and the overall sound feels flat. Switch back in the processing and the whole thing opens up and becomes clearer. I'd never be satisfied with the sound of my system if I wasn't able to adjust it.

 

[uchihaitachi]

Quote:

Well, that's sort of like saying you can't taste salt in water.  It depends on how much you mix in.  If "distortion" includes all forms of signal alteration, then if you have enough of anything, there will be distortion.  Even good, large gage oxygen-free copper, if you have enough, takes it's toll, and becomes easily audible at several hundred feet. 
 
Galvanized steel fence wire?  No problem measuring and hearing that, at at less length than copper by a long shot.  
 
As far as degradation caused by micro-diodes in metallic contacts, if you haven't experienced an oxidized contact causing distortion, just consider yourself fortunate.  It happens shortly before the contact completely breaks down, and is not all that uncommon, certainly documented, but perhaps only in the context of a contact reliability study.  In short, just about any contact material except for 24k gold will oxidize given enough time and exposure to the wrong atmosphere and conditions.  Low contact force permits oxidation growth between contacts, which is only semi-conductive, and depending on the materials, non-linear.  We don't see the effect very often because good engineering has worked around it with high force contacts, or the right plating sealed off from the atmosphere.  High current and voltages also break down oxidation, so you won't find this happening in speaker circuits very much.  But yes, it exists, is documented and we do have to deal with it.

I was quoting xnor. I never once thought of using fencing wire nor a length of solder as cables!

 

[jaddie]

Quote:

 
The way to think about that is to weigh the huge and clearly audible benefit of equalization against the minute and pretty much inaudible distortion of a halfway decent equalizer.
 
On my receiver, there is a direct bypass button. It bypasses all of the equalization and DSPs... and even the tone controls and just patches direct from input to amp to output with no processing. When I push that button, The soundstage shrinks, the tone becomes opaque, and the overall sound feels flat. Switch back in the processing and the whole thing opens up and becomes clearer. I'd never be satisfied with the sound of my system if I wasn't able to adjust it.

Agreed, the benefits are worth it.  However, equalization in and of itself doesn't add distortion, other than a modification of frequency and phase response.  If its used to compensate for something else that has produced an undesirable anomaly, equalization that compensates for that can actually reduce distortion.  It's only an issue if the resulting gain forces program material above a clipping threshold.