@stevecharm
My question is still if anyone can validate @mrdecible’s claims that “upgrading” power cords makes the tweeters extend higher, woofers extend deeper, etc. |
I hate to judge too quickly but this appears to be one of those endless Brer Rabbit and Tar Baby threads. Or in the words of my favorite Tar Baby, “What about this? What about that?” |
To the question of the first aftermarket power cords... Not the exact date but early 1980s is a good guess Monster Cable was one of the founders, and might be THE founder of aftermarket speaker wires.. But anyway, yeah probably soon after the speaker cable upgrades started..
Placebo, yeah, not the right word, it is stolen from another field and re-used. However the audio 'idea' behind the use of the word is a problem which might be strong enough to give the word a second useful meaning. Thus it becomes what it is used for. Thus saying placebo cannot be used is nonsense. If enough folks agree (and I agree too) then it becomes 'standard English'. So we all know what the word refers to in audio usage. No problem. That it means something different than the exact origin in drug clinical trials is not big deal I am certain the word existed BEFORE those trials, and was appropriated for that usage too. I can easily defend the use of the word but not the claims of the folks using it! On the other hand, perhaps the placebo effect is on the part of the naysayers. Thus they can hear the differences, yet their minds tells them there is not difference. Just as possible as the reverse placebo' claims.
|
colin44ct35783 posts01-13-2019 4:26amCAPS, the bigger the better, pump the current...limit voltage drops and drive the spl.Most transformers, the most expensive and important part have become so small over the years...but monster caps refreshed at 50-60 times per second does the job...if they can melt or brown a bus bar its all good! @ colin44ct357 Sounds pretty simple doesn’t it? This guy is a designer and a manufacturer of audio equipment. I have to admit, the first time I heard how much difference a power cord could make, it really bothered me. It wasn’t like it was subtle.
But its not hard to measure the effects of a power cord and with minimal equipment, you can sort out what’s going on. I’ve already done that. So:
There are two aspects, AC voltage drop and high frequency current limiting.
AC voltage drop is the voltage dropped from the wall to the input of the equipment in use. I’ve measured a loss of 40 watts on an amp that makes 140 watts, so no-one should be surprised that that might be audible as well. I used a 3 1/2 digit DVM to measure the voltage drop and it showed around 3 volts. This was a pretty standard but inexpensive Belden cord. A more expensive Belden cord with heavier gauge showed a lessor drop and more power out of the amp. So no mystery here.
The second issue is the high frequency current limiting. This is a bit trickier to understand, but its not quite rocket science. Almost any power supply consists of a power transformer, rectifiers and filter capacitors. When the the transformer voltage is higher than the capacitor voltage, the rectifier commutates (a fancy word for turns on and conducts). At that point the filter capacitors can charge up and will do so until the power transformer voltage falls low enough that the rectifiers cut off.
At that point the circuit using the power supply drains the filter caps. Since this happens 60 times a second, the drain is usually not very much at all, so its only at the very peaks of the AC waveform that the caps are be replenished. There might be only a few microseconds or milliseconds that this can happen, and quite a bit of current might have to flow during that time, essentially a high frequency event.
If the power cord limits current during this period, the performance of the circuit using the power supply might suffer, possibly due to increased IMD since the DC might have a bit more of a sawtooth on it than if the current was not limited.
There are some take-aways; if the circuit is heavily regulated, the power cord will make less difference. If the connections at either end of the cord gets warm during operation, you can count on a voltage drop. How much the voltage drop in a power cord affects the audio performance depends on the AC wall voltage and the equipment itself.
A lot of people point out that there is wiring in the walls and from the power company and so on. Of course! But Romex is pretty high performance; if you could legally sell power cords made of Romex they would have excellent performance. But that would pose a fire and shock hazard so power cords are all about how to work with stranded wire.
One way to measure a power cord’s performance is to measure the effect it has on the equipment in use. This is how I discovered that 40 watt loss I mentioned. If you have enough time and toys, you can set up a microphone in the room and measure frequency response and distortion rather than just testing the gear on the bench. I have a customer that used this technique to test filter capacitors in the power supplies of his amps.
This guy is also a designer and manufacturer of audio equipment. Power Supplies: Commentary for Consumers by Nelson Pass | Aug 1st 2009
In an amplifier, your utility, house wiring, power cord, and transformer provide the rain. The capacitor bank is the reservoir. The capacitors receive electrical charge every 1/120th of a second, reflecting two pulses of current from the transformer for every cycle of the 60 Hz sine wave provided by the power company. These pulses are of relatively short duration, and it is up to the power supply capacitors to store energy during the 6 millisecond or so electrical drought that occurs between charge pulses. We want a constant voltage (water level) from our power supply, and this is usually achieved by the use of large capacitors which store more charge, and large transformers which provide as much charge as is needed. You get the idea. Since we are not designing amplifiers here, but rather trying to get a handle on what constitutes quality in a market full of hype, I want to talk about some general ideas and comment on some of the common approaches used by manufacturers. Understand that we simply want a constant, noise-free, voltage to be available from a power supply, regardless of how much demand we place on it. https://www.passlabs.com/press/power-supplies-commentary-consumersHere is a post by an guy with a B.Sc.E.E degree. Note the date of the post, 2001. Science and Power cords 194.255.242.135
Posted by Ole Lund Christensen on April 21, 2001 at 16:49:18 In Reply to: Dissenting OPINION posted by waVeman on April 20, 2001 at 14:29:44: Some years ago a dealer wanted to show me the major improvement in sound caused by using a new power cord.
I was politely saying no, do not waste my time. But he insÃsted, and as he was an importantant dealer for my products, well I accepted to listen to a track on a CD, and then letting him change the power cord, and listen to the same track again.Having a B.Sc.E.E degree I knew that nothing would happen, and he was just victim of the placebo effect and a "snakeoil" cable distributor. So my brain was trying hard to ignore the message from my ears, I was hearing a major improvemnt of the sound. But as the truth is more important to me than my pride, I had to admit to the dealer, that I heard this improvement he was raving madly about. I left the shop, and spent 6 months trying to figure out what was going on. When the power has traveled 20.000 meter through standard cheap cables and connectors and fuses from the power plant to the shop, why did the last 1 meter cable matter? One day it hit me hard, it does not make sense because I am asking the wrong question.
the right question is: Why does the first 1 meter matter?
And the answer comes easy: Because the source of the problem is inside the power amplifier, it is not 20.000 meter away.
The power amplifier generates a lot of noise from the rectifier, and
the current in the power cord is very distorted. So the power cord is an antenna, radiating noise to all other components and interconnects.
So a shielded power cord reduce the radiation, and different connectors and cable designs affect the high frequency signals. Today all this is standard stuff, which you are required by law to measure to get EMC/CE approval in Europe, and there is lots of laboratories that measure this every day. So I have learned to listen and consider carefully the next strange idea. https://www.audioasylum.com/audio/general/messages/11/117899.html. |
@elizabeth
If I can easily show that the sound coming out of your speakers is still the same regardless of “upgrading” power cords, what argument would the “believers” have then?
|
