Cable and EMC discussion (Split from "What if the Audio Critic was completely right")

[nick_charles]

Quote:

Do you have any tests or measurements that shows the effects of EMC on audio frequences or any audio gear?.
 

There are really two issues here. 1, what changes (if any) occur to make the audio fidelity (over the audible range) change, i.e noise, distortion, FR, crosstalk, group delay... blah drone etc...
 
2. More importantly can we humans detect these differences
 
For me (2) is more interesting and while we have decent (not outstanding )  perceptual systems we are surprisingly crap at detecting some differences that a $30 USB ADC and freeware software will trivially pick up. More interesting still is how we can fool ourselves into detecting differences where none exist i.e comparing A and A but thinking we are hearing A and B. My all time favourite is the audiophile who brought his beloved Bryston amp along for a shootout with a modestly priced Onkyo amp. After listening to and extoling the virtues of the Bryston he described the flaws in the Onkyo in great detail, then his mate turned the Onkyo off and the music kept playing, he had been listening to the Bryston all the time...... 

 

[jnjn]

Quote:

There are really two issues here. 1, what changes (if any) occur to make the audio fidelity (over the audible range) change, i.e noise, distortion, FR, crosstalk, group delay... blah drone etc...
 
2. More importantly can we humans detect these differences
 
For me (2) is more interesting and while we have decent (not outstanding )  perceptual systems we are surprisingly crap at detecting some differences that a $30 USB ADC and freeware software will trivially pick up. More interesting still is how we can fool ourselves into detecting differences where none exist i.e comparing A and A but thinking we are hearing A and B. My all time favourite is the audiophile who brought his beloved Bryston amp along for a shootout with a modestly priced Onkyo amp. After listening to and extoling the virtues of the Bryston he described the flaws in the Onkyo in great detail, then his mate turned the Onkyo off and the music kept playing, he had been listening to the Bryston all the time...... 

For me, the question is even simpler.  What standards for EMC compliance can be used to make all gear impervious to all EMC related problems such that systems are NEVER susceptible to any cordage changes or manipulations.
 
The tests are easy to do, the results simple to quantify, the fixes....a wee bit more difficult..
 
I also concur on the human condition you cite.  Expectation bias is a biggy..
 
Cheers, jn

 

[JRG1990]

There are really two issues here. 1, what changes (if any) occur to make the audio fidelity (over the audible range) change, i.e noise, distortion, FR, crosstalk, group delay... blah drone etc...

2. More importantly can we humans detect these differences

For me (2) is more interesting and while we have decent (not outstanding )  perceptual systems we are surprisingly crap at detecting some differences that a $30 USB ADC and freeware software will trivially pick up. More interesting still is how we can fool ourselves into detecting differences where none exist i.e comparing A and A but thinking we are hearing A and B. My all time favourite is the audiophile who brought his beloved Bryston amp along for a shootout with a modestly priced Onkyo amp. After listening to and extoling the virtues of the Bryston he described the flaws in the Onkyo in great detail, then his mate turned the Onkyo off and the music kept playing, he had been listening to the Bryston all the time...... 

The 2 most important questions and exactly what I am wondering with all this discussion of EMC, this is the first i've heard of EMC having an effect on audio beyond a 50hz - 60hz hum i've had this grounding problem before a very audiable 60hz hum from a poorly grounded sub which was sorted with a ground loop isolator.

Also if manufactures don't worry about EMC should we?, I will google for tom van doren later and have a read.

 

[mikeaj]

Quote:

The 2 most important questions and exactly what I am wondering with all this discussion of EMC, this is the first i've heard of EMC having an effect on audio beyond a 50hz - 60hz hum i've had this grounding problem before a very audiable 60hz hum from a poorly grounded sub which was sorted with a ground loop isolator.
Also if manufactures don't worry about EMC should we?, I will google for tom van doren later and have a read.

(emphasis added)

As I earlier mentioned, I know next to nothing about EMC, but this is not the right attitude to have, at least for those selling a product.  A lot of companies design this way and occasionally end up with a product with a big problem (e.g. expensive mega-farm heavy machinery with all the latest controls makes the radio not work when powered on), and then they spend a lot of money and waste time getting to market by hiring consultants to bail them out and fix the problem...
 
A lot of times, there's no special attention to good design with respects to actively avoiding EMC issues.  It's just luck that many systems have no issues.
 
On the consumer side, I'm curious that one would suspect there would necessarily be an issue with EMC, and that this would actually make an audible impact on performance.  I see the possibility, but I don't see this as an invalidation of anything.  Of course, I'd rather not have some bizarre scenarios of nasties coupling into amplifiers and getting oscillation that fries caps or tweeters, but that seems the exception rather than the rule.

 

[jnjn]

 
Quote:

The 2 most important questions and exactly what I am wondering with all this discussion of EMC, this is the first i've heard of EMC having an effect on audio beyond a 50hz - 60hz hum i've had this grounding problem before a very audiable 60hz hum from a poorly grounded sub which was sorted with a ground loop isolator.
Also if manufactures don't worry about EMC should we?, I will google for tom van doren later and have a read.

Here ya go.  Anyone or any company would be very well served to attend one of his seminars.
 
edit:  I must state that I have no professional nor personal affiliation with Ton Van Doren.  I do not profit nor gain in any way by either referrel or mention of his name.  I took his seminar several years ago and found it to be excellent.  In the two days he presented, he made only two small errors on the first day which were of no consequence to the discussion.  I mentioned them to him on the side afterwards, but they were insignificant enough that I can't even remember what they were..

http://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2004/October/Experimental_Demo.pdf
 
diagram 1-11 on page 9 and diagram 1-17 on page 12 detail why the return path varies with frequency.
 
4-8 on page 25 shows a star ground problem based on IR issues.
 
If manu's don't worry about EMC, should we?? 
 
We don't have to.  But then again, as a result of them not worrying about it, we have all kinds of cable based issues, with audiophiles claiming power cords and IC matter, and esoteric cable manufacturers claiming all kinds of pseudo-science.
 
Get rid of the EMC problems, and you eliminate the need for an aftermarket high end cable.
 
Sometimes people get the mistaken impression that I believe high end cables are justified..  That is incorrect.  I work to eliminate them.
 
Cheers, jn
 
 

 

[jnjn]

Quote:

Of course, I'd rather not have some bizarre scenarios of nasties coupling into amplifiers and getting oscillation that fries caps or tweeters, but that seems the exception rather than the rule.

It was the exception, I ran that system for 3 years and popped the caps only once.  Of course, it had to happen at a party where there were armed bodyguards in suits.  I had to change my underwear.
 
In actuality, the issue allows hum, noise, pops, ticks to get into the system as well.  As I said, just moving the cables together can sometimes be enough to drop the loop coupling below audible.
 
Cheers, jn
 

 

[JRG1990]

I've never heard a difference between any cable and even without EMC the snake oil cables would sell well purely on placebo.

I was wondering my sub has a ground lift switch, ive never lifted the ground because ive never had a grounding problem with it but would it be a good idea to lift the ground anyway intrestingly in the manual it appears to be saying the same thing about grounding as you there might be grounding problems if theres a loop though the sub panel, mains wiring, source, and back to the sub on pin 1 of the audio inputs. Ground currents traveling though this loop impose different voltages along the path at different gain stages within the circuitry, thus creating noises.
Then it says the switch does not affect safety and does not open the connection thru pin-1 to the panel but increases resistance from 0 to 1000 ohms , so should I increase the resistance to 1000 ohms or not?.
Maybe some manufactures aren't that clueless then.

 

[jnjn]

Quote:

I've never heard a difference between any cable and even without EMC the snake oil cables would sell well purely on placebo.
I was wondering my sub has a ground lift switch, ive never lifted the ground because ive never had a grounding problem with it but would it be a good idea to lift the ground anyway intrestingly in the manual it appears to be saying the same thing about grounding as you there might be grounding problems if theres a loop though the sub panel, mains wiring, source, and back to the sub on pin 1 of the audio inputs. Ground currents traveling though this loop impose different voltages along the path at different gain stages within the circuitry, thus creating noises.
Then it says the switch does not affect safety and does not open the connection thru pin-1 to the panel but increases resistance from 0 to 1000 ohms , so should I increase the resistance to 1000 ohms or not?.
Maybe some manufactures aren't that clueless then.

If all systems could be made cable invarient, I think that eventually the entire aftermarket cable industry would reduce or dry up.  But I suspect you may be correct.
 
Your system:
If it ain't broken, don't fix it.  Their writeup sounds decent enough.
 
Is your sub balanced input?  The "pin 1" reference sounds like it is.
 
Subs seem to have a historical issue with hum..it appears that lots of users will put it in a convienient spot in the room which is out of the way and near an outlet.  Using a different outlet is tantamount to the gauntlet across the face... Hum city.   Going balanced is the best method at resolving that problem, and has always been a method of gaining EMC.  I suspect many sub manus had to go balanced or figure out how to lift the ground safely.
 
Subs of course, don't have interchannel timing issues which can affect soundstage.  Below 500 hz we lose ability to detect interchannel timing delays, so even if there are 20, 50, 100, even 200 uSec delays there, who cares?  The main concern is, can we knock all the knick-knacks off the shelves and stun small (or big) animals..
 
Cheers, jn

 

[JRG1990]

My system is balanced the sub is the krk 10s which is balanced, most nearly all studio/pro gear is balanced, my speaker amp is connected to the subs outputs (balanced pass thru) so any grounding issues with the sub could affect the amp, also I made the special effort so all my audio gear is pluged into the same power strip.
You should really start a new thread on EMC and its effects on audio and how to reduce the effects.

 

[jnjn]

Quote:

You should really start a new thread on EMC and its effects on audio and how to reduce the effects.

Hey, maybe next year...
 
And to think, we've really only discussed lie number 1...
 
I'm going to have to figure out how to fix my default pic directory so I can drop the test configurations I have for measuring ground loop sensitivity and eliminating it.
 
Have a wonderful new year everybody.
 
Cheers, jn