[Trismos]

I read a skeptical electrical engineers comment that went something to the effect that he found it hilarious that there may be hundreds of kilometers of power lines between the source and the outlet to your audio gear yet some people seemed to think by spending outrageous money on exotic materials and recipes for that the last meter between outlet and amp there could ever be a realistic difference. (Please excuse the run on sentence...)

Seems to be a rather valid point. I can understand having products that clean up dirty AC. I run a Virtue M-901 off battery power and the background noise level is pretty much non-existent. But a lot of the cables out there are not intended to act as filters. Or do they anyways?

Regards
Dave

[S Clark]

I have a best friend that is a skeptical engineer.  He was positive that I was playing a trick on him while listening when changing power chords.  Basically he was certain that it was all in his head, except that he spotted the differences each time I blindly changed (or didn't change) power cords to a cdp.  He finally acknowledged that pc could make a real difference, but had no explanation. 
From my perspective, in good science observation trumps theory.  If theory doesn't explain repeatable observations, then the theory is incomplete. Our senses are more sensitive than we know.  Not everything that goes on in the brain in interpreting sound is related to frequency response curves.
Scott

[Phil]

perhaps the dirt is indeed delivered to the PC, which acts as a filter.  One preamp I used had its own great filtering and didn't react to a change in the PC.  All the other equipment I have had did react and it wasn't subtle.  That is true even when using an isolation transformer.  So, does the PC offer further filtering that the isolation transformer doesn't?  Digital sources always seem to react the most. 

[dBe]

I read a skeptical electrical engineers comment that went something to the effect that he found it hilarious that there may be hundreds of kilometers of power lines between the source and the outlet to your audio gear yet some people seemed to think by spending outrageous money on exotic materials and recipes for that the last meter between outlet and amp there could ever be a realistic difference. (Please excuse the run on sentence...)

Seems to be a rather valid point. I can understand having products that clean up dirty AC. I run a Virtue M-901 off battery power and the background noise level is pretty much non-existent. But a lot of the cables out there are not intended to act as filters. Or do they anyways?

Regards
Dave

I tend to run on myself, so no worries.

First, let's look at his premise:  it is backwards.  It is not the last meter (or so).  It is the first.  We have to look at this from the equipment side.  It is like the water purification straws that are available for hikers and survival kits.  You can drink from some nasty sources and get potable water.  The straw is a filter to rid the supply of potentially life threatening organisms and toxins.  Fortunately a cable designers' task is much easier.  All we have to do is juggle some easily identifiable and quantifiable parameters to improve SQ.

The hard part is getting past the "common knowledge" that LCR is all there is to cables.  An audio cable is a system that involves additional design parameters:  what is the material and it's' purity?  What is the wire consist?  Is it stranded or solid core.  What are the gauges of the strands, if multi strand?  What is the dielectric and the density of that dielectric?  What is the dielectric absorption of the insulation?  What is the velocity of propagation of that wire?  Is it plated and if so, with what material at what thickness?  What is the method of termination?  What type of termination is used?

Then we have to consider transmission line dynamics to determine optimum lengths of cables considering the frequency or range of frequencies.  Then we take into consideration the lay of the cable.  Is it a parallel run, twisted pair, helical wind or Litz configuration?  Will a combination of lays work better?

Designing an audio cable of any sort is a design exercise that involves small gains or losses or no change at every level.  All of this results in a filter that is optimized for the application.  Quite frankly speaking interconnects are easy.  I can design an analog interconnect to produce any result I want.  Want more bass?  No problem.  A bump in the mids or highs?  Same story.  The hardest cables are power cables with high performance digital cables close behind.

All of this takes hours and hours with untold design goats produced to get there. That is where the expense comes from along with sourcing the finest materials.

Most EEs produce widgets for the masses and have been taught how to do so.  Like my theoretical physicist audio guru told me years ago:  "We know how this stuff works, basically.  What we don't fully understand is HOW it works."

Make any sense?

Dave

[Mike Nomad]

Unless the cable is passing [fill in the blank] with zero loss, it is acting as a filter.

But a lot of the cables out there are not intended to act as filters. Or do they anyways?

[DaveC113]

The pc's ground wire connects the grounds of your components together, most of the time it's the same ground that your interconnect cables are connecting. So, the pc's ground wire can certainly have an effect on sound. That's only one of many things the pc has an effect on, but often overlooked and it's an easy explanation of how pcs are capable of changing the sound of a system.

[brj]

Nice explanation.

And those Sawyer water filters are fantastic!

[Speedskater]

Consider these thoughts on AC power lines & cables and why the last few meters can be more important:

a] AC cables can and do act as interference antennas (both receiving & transmitting).

b) The higher the interference frequency the more loss (as a transmission line) the AC cable has.  So the farther away the high frequency interference is, the less gets through to your equipment.

c] The higher the interference frequency the shorter the antenna effective length needs to be.

d] Most of the interference is being generated by your other components.

[Brad]

After Dave's note on "untold design goats", I had to do some googling:






Sorry for the off-track post, but the thought/image had me chuckling

[Triode Pete]

I tend to run on myself, so no worries.

First, let's look at his premise:  it is backwards.  It is not the last meter (or so).  It is the first.  We have to look at this from the equipment side.  It is like the water purification straws that are available for hikers and survival kits.  You can drink from some nasty sources and get potable water.  The straw is a filter to rid the supply of potentially life threatening organisms and toxins.  Fortunately a cable designers' task is much easier.  All we have to do is juggle some easily identifiable and quantifiable parameters to improve SQ.

The hard part is getting past the "common knowledge" that LCR is all there is to cables.  An audio cable is a system that involves additional design parameters:  what is the material and it's' purity?  What is the wire consist?  Is it stranded or solid core.  What are the gauges of the strands, if multi strand?  What is the dielectric and the density of that dielectric?  What is the dielectric absorption of the insulation?  What is the velocity of propagation of that wire?  Is it plated and if so, with what material at what thickness?  What is the method of termination?  What type of termination is used?

Then we have to consider transmission line dynamics to determine optimum lengths of cables considering the frequency or range of frequencies.  Then we take into consideration the lay of the cable.  Is it a parallel run, twisted pair, helical wind or Litz configuration?  Will a combination of lays work better?

Designing an audio cable of any sort is a design exercise that involves small gains or losses or no change at every level.  All of this results in a filter that is optimized for the application.  Quite frankly speaking interconnects are easy.  I can design an analog interconnect to produce any result I want.  Want more bass?  No problem.  A bump in the mids or highs?  Same story.  The hardest cables are power cables with high performance digital cables close behind.

All of this takes hours and hours with untold design goats produced to get there. That is where the expense comes from along with sourcing the finest materials.

Most EEs produce widgets for the masses and have been taught how to do so.  Like my theoretical physicist audio guru told me years ago:  "We know how this stuff works, basically.  What we don't fully understand is HOW it works."

Make any sense?

Dave

Dave,
Makes a ton of sense... As Dave pointed out, it's not that simple to implement...

I think most people (using common sense) think of a power cord as a simple AC connection device... most are... However, a well designed & fabricated power cord can act like noise filter, helping to eliminate the audible EMI/RFI anomalies that exist in the real world like Speedskater referred to... It's not a subtle improvement in most cases but an obvious one; both audibly & visually...

Most EE's have never worked in a power plant, substation, on the T&D lines with the capacitor banks, automatic sectionalizing devices, etc. like I have & still do... You cannot believe the intricacies of the relays & protection devices and the funky, craziness you can observe from different cabling, wiring and even layout of components... It's all in a state of flux (literally sometimes)... crazy DC grounds, etc...

My $0.02,
Pete the P.E. (Polish Engineer -  )

[BobM]

And don't forget, these subtleties we hear are NOT measurable using common tools, for the most part. If it is not measurable it does not exist, per many engineers. What they forget is that it is not measurable given the measuring devices available to them today.

There is so much we don't yet fully understand at a quantum level (yes, I used the word) and electrons are fundamental to quantum physics. It is trial and error with a little bit of basic theory thrown in. Designers sometimes get lucky after trying many different materials and topographies. That's called research.

[dBe]

After Dave's note on "untold design goats", I had to do some googling:






Sorry for the off-track post, but the thought/image had me chuckling

Not ba-a-a-a-a-ad, Brad.

Que funny 

Dave

[dBe]

Thanks for the added input, guys.  It is hard to touch all of the basses when discussing cabling of any type.  Simplistic explanations and applications are OK when dealing with brute force power delivery.  Quality AC for technical applications is quite different.  A close look at lab application power is a good place to start as an audiophool.

AC interference and contamination is getting worse all of the time.  A wireless mic system is a great toy for looking for AC noise.  Turn on a cellphone in close proximity to a cheap wireless mic and you will know what I mean.  How often do people read the disclaimer and notice on the back of a CD, DVD or BluRay player about FCC compliance?  Noise is EVERYWHERE.  Here in Albuquerque we have Sandia National Labs, radio, TV and repeaters on Sandia Crest and microwave repeaters in abundance around here.  We have interference from ULF transglobal communications up to UHF... almost DC to light.... about two billion watts worth as an estimate.  The greatest problem we face here is the antenna mode that Speedskater noted.  In other areas where heavy industrial manufacturing is being done may have a greater problem with EMI than RFI.  Doesn't matter.  Noise sucks.  Noise is audio poison.

Dave

[*Scotty*]

Faraday shielded room and battery powered AC regenerator anyone.
Scotty

[HAL]

Have the battery powered true sinewave 2KVA AC regenerator.  Even true sinewave, is still about the same distortion level as the wall AC, but without the hash. 

Battery powered electronics and a faraday cage!

[dBe]

Have the battery powered true sinewave 2KVA AC regenerator.  Even true sinewave, is still about the same distortion level as the wall AC, but without the hash. 

Battery powered electronics and a faraday cage!

Uh, yeah!

Dodd Audio rules... along with a couple of other companies, eh, Rich?!  I love my battery powered stereo gear,  Still gotta have good, clean power for the subs. and other toys, though.

Dave

[DaveC113]

Have the battery powered true sinewave 2KVA AC regenerator.  Even true sinewave, is still about the same distortion level as the wall AC, but without the hash. 

Battery powered electronics and a faraday cage!

Batteries aren't as good as most people think... by themselves they won't be as good as a decent linear ps.

[dBe]

Batteries aren't as good as most people think... by themselves they won't be as good as a decent linear ps.

True story.  That is why I make the BatteryBUSS and some other goodies, too.  It is still about noise and output impedance, even with batteries.

Dave