Home Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Propeller Head Plaza ]
[ Alert Moderator ]

Follow-up by the OP

The point I was trying to make is it is not sufficient to make observations (without measurement) and draw conclusions on affects and develop theories as to causes.

Case in point ... One very well known and respected designer in high-end audio used known priciples to come to a conclusion and possible issue in speaker cables. That being, EMI and RFI can be induced or absorbed by any cable of a given length. It is resaonable to assume that these currents flowing on a cable can mix with audio frequencies and produce heterodynes or intermodulation artifacts that fall with the audio spectrum. This is well known and measurable fact. It is basis for radio reception and detection. From this the idea of building very precisely made Zobel networks to help filter or attenuate these RF signals before they enter the loudspeaker, effectively producing high impedence to these frequencies at the load, helped in reducing these IM artifacts. The result in subsequent listening tests confirmed the measurements, with improvement in inner detail and imaging. Further measurement and listening helped fine tune and improve the design over time. This is good engineering. Using proven and measurable phenomenon to come up with an applicable theory, creating a device and measurings its affects, and THEN using subjective observation to prove the measurement.

Conversely, another manufacturer comes to conclusions and develops theory based on subjective listening, and then backward engineers to a solution to a problem that may not exist. Develops the device, does more subjective listening and hears a difference and concludes the device solved a problem. Mind you, the problem may have not existed in the first place, the test were uncontrolled and lacked measurement to quantify the problem or even detect if indeed there was problem. Furthermore the secondary subjective test may have had other variables which skewed the apparent positive results but supported the solving of the alleged problem theorized.

So now we have $50 Myrtlewood blocks between our gear and cables that claim to have break-in times due to things like "standing voltage because good dielectrics make poor conductors" as measured on a multimeter. Also citing phenomenon like triboelectricc charge as another factor. The problem is anyone who knows electronic theory will tell you measuring voltage such as dialectric charge using a multimeter is going to give a false measurment. The multimeter behaves as a high impedence load to such charges and the measured voltages will be much higher, by a magnitude of about 1000 compared to what exist on the low impedence loads in audio gear. So while he measured, he measured incorrectly and is using existing theory to explain a phenomenon that while it exists, problably does not happen for the reasoning he is proposing. And his products are designed using this reasoning.

First off you can take any dialectric and measure a 100 microvolt charge with a multimeter. However if you present a low imnpedence load to this same charge the voltage measured is only a few millivolts. That's a 1000 times smaller potential. Also, an existing dialectric charge on a cable has a specific and fixed time constant of discharge usually in micro-seconds at the capacitances involved. Also triboelectricc charges are created only when a cable is flexed and moving and dissipate using the same time constants. Most times they discharge very rapidly and create crackles and pops. (as a sidenote, there is much data proving that "biasing" has no effect on these discharge time constants, nor does it prevent the charges from occuring)

He claims it take weeks for cables to "relax". How did he come to this conclusion? Subjective observation and erroneous measurement. However, he contuinues with this reasoning, sells some of the most expensive cabling on the market (they do sound good though), and is viewed as an expert. Having done work on cables and the affects he describes as my field of research at MIT I disagree with many of his conclusions.

There are other factors with measurable and well understood affects that cause the described phenomenon of long cable break-in times (which is a real thing BTW as many of you know). But none of it is mentioned in this or several other cable manufacturers papers. They GUESSED wrong and are sticking to their stories. After all they have a rep, and more still sell expensive devices that claim to counteract these issues of break-in. Based on these incorrect theories drawn from subjective observation and backward engineered theoretical concepts.

The point is ... measurement can and should coexist with subjective observations. But one cannot substitute one for the other. And one should never really only on subjective listening when developing products to be sold at very high prices. There should be SOME solid data to support the costs.


Edits: 11/24/12 11/24/12 11/24/12 11/24/12
This post is made possible by the generous support of people like you and our sponsors:
  Amplified Parts  

Follow Ups Full Thread
Follow Ups
FAQ

Post a Message!

 Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]