My opinion is... you want as few links between the incoming a/c and your equipment. A dedicated a/c line powering high quality outets, then quality power cords connected directly to your equipment. One would want to steer clear of the current limiting protectors for their amplifiers. Some are designed in a fashion that will limit your dynamic range performance. There are a few good power conditioners and more not so good conditioners available. That would be for you to decide. I am a firm believer in KISS (keep it simple stupid.) |
are the benefits negated or not realized by plugging in the upgraded cord into say a panamax type surge protector rather than directly into the electrical outlet? |
This question is asked time and time again. Below you will find one of the best worded and condensed explainations I feel available as written by John Risch. I hope you find it informative.
Dan Harmon
dedicated audio
AC Power Cord Effects by Jon Risch
So, how in the world can a power cord make any difference, if it is properly rated for the current draw, and is UL listed?
Like many questions about audio systems, this one seems very logical and reasonable. Just use Ohm's Law to calculate the current draw, and viola, we have the voltage drop, and we have the cold hard facts, Yes?
No.
Like many overly simplistic answers, this one does not take into account all the facts. Let's look at a hypothetical power amp to start. Lets say it is a moderately high power design, and is rated to draw about 8 amps from the wall at full rated power. That's about 960 watts from the wall. We won't even get into side issues of switching power supplies, which play total havoc with the simple Ohm's Law approach, we will stick to linear power supplies.
So if the AC cord is UL listed for 10 amps, it is likely an 18 gauge cord. Many 18 gauge power cords are rated for 10 amps of current. How is this rating determined? By how hot the cord gets while carrying the rated current, NOT how much voltage drop there is.
In our hypothetical amplifier, the RMS voltage drop in the 6 foot cord would be approx. 1/3 of a volt according to Ohm's Law. This does not take into account the wall outlet contact, or the IEC connectors if present, nor does it take into account any other factors, just the resistance of the 18 gauge wires in the AC cord.
On the face of it, this seems quite harmless. How could a third of a volt make any difference? Well, because the voltage drop is NOT 1/3 of a volt! Has Ohm's Law been repealed? Are engineers all insane?
No, just an overly simplified analysis that failed to take into account ALL the factors. So what could possibly make that much difference. Well, for one, it would help to know that linear power supplies refresh their DC reservior from the AC line in bursts of current, current peaks that are in time with the peaks of the AC line. That is when the filter capacitors are refilled, when the AC line voltage its it's peak value, and the output from the secondary reaches a level above that which the PS capacitors have been drained to. Instead of a nice steady drain of 8 amps, we have current peaks that
last only for a brief moment, and the 8 amps is an RMS amount.
What this means is that because the current is being drawn only for a fraction of the AC voltage cycle, or for about 1 thousandth of a second (one half cycle lasts for 0.0083 seconds). The peak currents can easily reach ten times the RMS value. What is the voltage drop for 80 amps? At this point, the resistance of the AC plug contacts, and even the bond inside the cord between the plugs and the internal wires become a significant factor. It is not hard for the voltage drop to reach 5 volts or more. The AC line peaks never reach the full value, because the line cord has lost some of it.
Power amps depend on receiving the full measure of AC line for their full rated power, so such a drop will reduce the actual output power in a seemingly disproportionate amount. A 200 W amp may be reduced to 170 watts before clipping.
The above (still simplified) analysis assumes a steady signal, and a steady current draw. Musaical dynamics make it a much less consistent thing, and the dynamic demands will cause dynamic perturbations.
This is not the only effect on the power amp. These current peaks can easily cause AC line distortion, and the heavy current draw can generate harmonics on the line, the hash from the rectifier diodes can increase, a whole series of events occurs that are not immediately obvious just by thinking of the amp as a simple resistor and using Ohm's law.
Most house wiring is either 12 gauge or 14 gauge, while many OEM cords are 18 or at best, 16 gauge. Most OEM cords do not have shielding or any provision for reducing radiated EM fields, do not have premium AC outlet plugs or premium IEC plugs for better electrical contact at these junctions.
So what happens with a bigger power cord? Replace that 18 gauge cord with a 14 gauge cord, and the voltage drop will go down by a factor of about 2 and a half.
Include shielding in that cord, and the possiblity of radiated EMI/RFI goes down compared to an unshielded cord.
Shielding and radiated EM fields might not seem relevant since the house wiring has neither advantage. However, the house wiring is not laying right next to the other component's AC line cords, or right next to the line level or speaker interconnects. Reduced levels of induced RFI and radiated EMI/hum fields would not hurt SOTA sound reproduction.
Since the AC power cord is usually laying right in there with all the other AC cords, and probably the speaker cables, and the interconnects (some people even bundle them all together for neatness, OUCH!), it is quite possible that a premium AC cord will help reduce interference in the system, and raise the amount of power available before clipping,
and smooth any AC line distortions, etc.
This is all without even going into secondary effects, or other more esoteric aspects. Just a more nearly correct way of applying Ohm's Law to the real situation. Add in ferrite filters, built-in filter components, shielding effects, and the esoteric aspects, and it should be obvious that AC cords are not at all simple, nor are they a no-brainer.
There is the issue of resonant situations. Certain power cords and power supply transformer primaries might tend to resonate at RF or high frequencies. This resonance might make RFI/EMI problems worse, changing to a different cord will change the resonant frequency, and change the RFI/EMI effects.
The plugs are not a trivial issue either, and may be more responsible for sonic improvements than the other factors.
Hubbel and other premium plugs and sockets will increase contact area and pressure, reducing contact resistance and other contact related problems. It has been claimed that poor AC plug contact can cause micro-arcing, with it's attendant hash being injected directly into the audio component.
It is not as simple as just simple wire resistance. The connection at each end of the cord adds resistance, the wall outlet socket adds resistance, etc.
For the raw wire, round trip:
12 gauge, approx. 6 feet = 0.0206 ohms
14 gauge, approx. 6 feet = 0.0328 ohms
standard AC power cord
18 gauge, approx. 6 feet = 0.0830 ohms
Measuring real AC power cords, I get around 0.128 ohms for an IEC 18 gauge power cord, and about 0.022 ohms for a 12 gauge IEC cord, not including the AC wall socket connection.
Why is the 18 gauge resistance so much higher than just the wire resistance? Ever tear one of those cheap cords apart? Poorly crimped or barely soldered connections are responsible for the bulk of the extra resistance.
Preamps and CD players all have their special requirements: CD players require shielding to help keep the digital hash that back-feeds from the circuitry out of the rest of the equipment, preamps need a nice steady voltage for minimum noise, and freedom from RFI, etc.
Fancy AC power cord geometries might also reduce the inductance of the 6-8 feet of line cord, raising the available voltages. But this would be limited to the ratio between the length of the power cord vs. the wall run. Such geometries often reduce the radiated energy, and aid shielding of the cord.
Some power cords might have a built-in filtering action, like the water jacketed ones, that have the conductors and insulation surrounded by a conductive fluid. This fluid might short out and reduce/damp any EM fields the cord would conduct to the component besides the 60 Hz AC power signal.
It also helps to keep in mind that we are not supplying a Sears rack system, that any system which aspires toward the SOTA is going to be more sensitive to minute effects and minute improvements. How much does a big fat shielded power cord help things? Probably about as much as upgrading from an OEM interconnect or zip cord speaker cable to
some decent aftermarket cables, some systems are more sensitive to AC cords, some are less sensitive to cords.
As always, the bottom line is: you have to listen for yourself, and see if their is any benefit for you, on your system, with your listening habits.
Do AC cords have the potential to influence high end sound? Yes.
Jon Risch |
I wish I had.I gotr this info from WWW.UHFMAG.Com.go to the site therei s some interesting reading there. |
I'd like to interject some "technical" info and personal observations into this thread. As was mentioned previously, the logical train of thought is that a power cord should minimize voltage drop via minimal series resistance AND try to minimize noise. As usual, there are several different ways to do things with various trains of thought on the subject. Most all of them are valid, but some may be more effective than others given the specifics of the situation and design.
While the use of heavy conductors is common in aftermarket cords, one could also use several smaller conductors to achieve similar gauge size with greater flexibility. The use of several smaller wires also lends itself to configuring the wires in a specific array, i.e. twisting, braiding, spiral wrap, litz array, etc... These types of designs have several benefits.
First of all, all of the aforementioned designs are automatically less susceptible to RFI. In other words, it is less likely for these configurations to act as an "antenna" when directly compared to a common "side by side" or "stacked triangle" patterned cord. This is due to minimizing the inductance present in the cord itself.
Since these cords are less likely to act as "receiving antennas", the reverse is also true. Due to the various geometries and designs, these type of wire arrays also tend to reduce the amount of radiated magnetic fields and RFI. Besides the fact that our low level signals are being fed via interconnects that run in close proximity to our power cords, there is more to think about than just the magnetic field that is present. If you have a "noisy" device, such as digital gear, it is possible for the RF present in the device to be fed back down the power cord. In effect, the cord COULD become a transmitter of that RF signal to nearby cables / cords. Using "fancy geometries" can help minimize this situation and make it harder for the RF to "load" into the cord.
As was mentioned by other members, some cords also make use of ferrite cores for noise suppression. These work by TRYING to create an impedance mismatch. While we are normally trying to pay attention so that we don't run into impedance mismatches in most cases, that is not what works best here. By creating a wide gap in the impedance of the cable and the air around it, the ferrited cable effectively "chokes" the RFI out. Ferrite also works due to the fact that it is "modulated" by the common mode signal that is present from all of the wires going through it. Irregularities are "somewhat" filtered or absorbed by the transformer action of the ferrite.
Something to keep in mind though is that ferrite DOES saturate. Under heavy current conditions, ferrite can change value momentarily and / or permanently be altered. This is one of the reasons that ferrite is NOT commonly used on power amplifiers that pull large amounts of current. Due to the ferrite saturating, some keen listeners have noted a lack of dynamics, compression, smearing, loss of detail, etc... In other words, for ferrite to work best WITHOUT having side effects, it should be used in low current situations OR make use of a VERY large piece of ferrite to minimize the chances of saturation.
As to where aftermarket power cords are most effective, that is up for debate. I'll try to present a logical look at things and explain my thoughts so that you can follow along or know where i'm coming from in case you want to debate : ) Since we are using cords primarily for their lower resistance / greater current capacity / filtering action, let's look at what SHOULD be the most susceptible to reaping benefits from their use.
Since it is commonly accepted that digital gear is EXTREMELY noisy, that might be one place to start. The fact that the digital gear is typically a source component is also another factor. As was pointed out in another thread, "what is lost or polluted at the beginning can't be recovered at the end". With this in mind, my thoughts and experiences are that digital gear responds best to "fancy" power cords. This is NOT to say that other devices such as preamps and power amps do not respond to power cord changes, only that the results may not be as noticeable or consistent.
One of the reasons that changing the cords on digital sources is a two-fold benefit can be explained as such. First of all, we are dealing with a digital device. While the effects of minimizing noise going INTO any component should be obvious ( reason 1 ), try and reverse the situation. Since most digital sources have relatively small power supplies ( transformers, filters, filter capacitors, etc...), there is less isolation from their internals and the power line. As such, it is easier for noise generated WITHIN the component to "back up" into the electrical system. There are pulses of data being read and transmitted, clock frequencies being generated, etc... Much of this is also powered by some type of switching power supply. As such, the devices are NOT stable loads and introduce a lot of glitches, surges, spikes, hash and RFI into the electrical line.
This brings us to reason 2 why i think digital gear should be your first choice when replacing factory cords. By adding the increased "filter action" of a "fancy geometry" power cord, you can minimize the amount of information that is allowed BACK into the electrical system. In effect, this helps keep ALL of the other components from having to deal with the trash that otherwise might have been pumped into them via the common electrical connections. This results in OVER twice the effectiveness of changing cords on any other device, especially an analogue component. Of course, i'm assuming that the factory stock cord that was supplied with the unit is of at least reasonable construction and capable of supplying enough current without major voltage sag to start off with.
As to some further explanations as to why power cords may be less effective on power amps, preamps, etc..., the answer is quite simple. These devices TYPICALLY do not generate as much noise and normally have quite a bit more filtering in the power supply. While increased power supply reserve ( large filter capacitors ) and sturdier rectifiers ( turn AC voltage into DC voltage ) DO help the situation, RFI can still ride through all of this. In the radio communications field, it is common practice to superimpose DC onto an RF line or vice versa. As such, the increased filtering / heavy duty power supplies in these "non digital" devices does help to isolate it from incoming line noise and interference, it does NOT negate it or completely isolate it from some very specific elements. As such, the added "filtering" of a "fancy" line cord can only benefit the situation ( given proper current capacity ).
Some of the "oddball" devices that one might not think of as being "digital" or generating electrical noise might be amplifiers in the Sunfire product line and other "switching" type power supplies, some subwoofer amps ( commonly called "Class D", etc.. ) "digital" tuners, some newer "room correction devices", etc... As such, they are all likely to be candidates for power cord upgrades.
One last thing. Digital devices are typically VERY susceptible to "modulating" the power supply due to external excitation i.e. "vibrations". I have literally watched ( via a high frequency oscilloscope ) how tapping the case or shelf that a digital device was resting on generated noise back INTO the power line. Keep in mind that the designer of this device had already taken steps to minimize such things from happening. For example, the transformers were mounted on foam rubber supports, the chassis had damping compound applied in several different areas, ALL of the capacitors along with most of the other internal components had damping compound applied, etc... Even with COMPLETE attention to such detail, the ability to introduce noise via chassis excitation into the line was still evident. While most of this was more apparent going to ground, there was also noise being fed into the hot and neutral. Now you also know why many people suggest electrically isolating "digital" components from analogue components.
This also goes to show that many of the "damping and isolation" tricks that we do can amount to SO much more than what we initially thought or imagined. This also means that most of these devices will work best with their "lids" ON and lightly mass loaded. Besides helping to keep the internals and chassis from vibrating due to being modulated by airborne vibrations, the damped lid will also act as a shield. This will keep the RFI that the digital gear IS generating from being sprayed around the room and into other components.
Hope this helps answer some questions and gave you something interesting to read. As usual, i'm always open to comments or rebutalls. Please feel free to add to this or correct anything that you might feel is in error. Sean
>
PS.... Sorry for the novel, but i don't know when to stop : ) |
Ken1, I'd recommend searching for members who own the same equipment you do. There is a thread on systems people own or try the virtual systems. There advice is the best you'll get in that cords are so system dependant. My Sony SCD-1 is far and away best with the NBS Statement. I've tried A LOT of cords and if I was asked by a Sony SACD owner I'd advise to start there.
Leaf, I want to here more about your water boiling. Please start a new thread on it, sounds like you could raise some good discussion. |
Hey Leafs, did you actually try the boiling water experiment yourself? If so, that is a great way of explaining why aftermarket pc's make a difference. After many tests, and after reading many of the power cord debates, I almost automatically upgrade the pc on any new component. Even pc's in the $150 price range make a noticeable improvement. |
I have been reading these posts on power cords for a while. As Snooker says, everyone has an opinion. I will make an analogy to an expensive bicycle; manufacturers will cut on the less noticed components (ie. seat post, bars, etc.) to maintain price points. In stereo equipment, one of these areas may be the power cord.
Although I am no expert, it seems the power cord has 2 primary functions, to transmit current and to keep out noise. Larger gauge wires carry more current. Better terminations on your cord (and a better wall outlet) should reduce losses and noise. Shielding and ferrite suppressors help keep out noise. I have one (somewhat) expensive power cord and it runs to my main 2-channel power amp, since the amp draws the most current. My other cords have been upgraded to Volex or Hubbel 14awg shielded cords with ferrite suppressors added. By going through an electronic supply outlet for both the cords and suppressors, the cost was relatively low (about $20 per cord). My next upgrade in this area will be having the electrical in my house upgraded with dedicated power lines for my stereo equipment. These upgrades have worked for my associated equipment. If you have an expensive system, you may notice a difference with better cords on all components (and don't forget the power conditioner - another thread!). |
Ditto, D-K above. Also, if you get 1 pc on trial, try first on pre or cdp; when connected, let the pre/cdp play a bit before you embark on serious listening. |
Ken: The Cable Company offers this service on the cables/cords that they carry. I would ask Brian at BMI directly about his products as I am pretty sure that they are still sold direct. Other than a local shop or the Cable Company you will just have to check out each manufacturer. Many have a 30 day return policy. It's a lot of work, but better than buying and reselling, I agree. |
Since there are so many different power cords to choose from, and the fact that they're system dependent, is there someplace that allows you to return a cord if you don't like it's sound in your system? Or is it all a big crapshoot?
Things can get expensive in a hurry if you have to buy and sell several cords before finding one that works. I've had friends recommend the Shunyata King Cobra, Electraglide Fatman and BMI Whale. How's a fella to know which one to gamble on?
My system consists of a Joule Electra preamp, Sony 777es SACD player, Electrocompaniet EMC-1 CDP (trying to decide which one I'll keep), EAD PM 2000 amp, Aerial 7B speakers, Harmonic Tech Pro Silway IC's and Kimber 8TC speaker cable. I primarily listen to jazz, vocals and some pop.
Any suggestions would be welcomed.
Thanks,
Ken |
Ditto on Snookers advice. There is plenty of info to go on and very little to add other than new products as they pop up, reviews by new owners and questions to the already existing threads. As to why you would add them to a system, I think that the answer is obvious (to improve the sound). What other reason would there be? Being skeptical is a good thing, though first hand experience is the only way to form a true opinion and this seems to be where you are headed. As far as the poll goes I would estimate that less than 1% of the members at this site believe that a good PC in the right application is a form of snake oil. Good does not need to be expensive in that I use some $50 PC's that make a hell of an improvement over stock. On the other hand I use some pricier ones that make a heavenly improvement. The trick is finding the right ones for your taste and each piece of equipment in your setup as synergy, as always, is the ruling factor. |
Enter "power cord" as a search query in the Discussion Forums. Approximately 500 threads will come up and you can choose the ones that suit you.
You will see that there are a lot of opinions..............
Make your own. Feel free to stink up the place with yours.
Most of us have too. |
Depends how you look at them. They certainly make a marked difference in many but not all systems. Both good & bad.
What you have to be careful of is buying expensive power cords that actually sound a lot worse than the stock cords! |
I have been restling with this upgrade for awhile. My curiosity finally got the best of me. I bought two MIT-z cables and 1 MIT z-II cable. Have not heard a big difference. I just ordered 4 more MIT-II cables to upgrade every cord in both H/T and Stereo system. Should be getting them soon. Then I will know if this up-grade is for real. I will post if I here a noticable difference. |
I am also a skeptic when performance claims are made for which there is no objective support. Our hobby, however, is not always predicated on "scientific proof". My attitude is be skeptical, but remain open to experience, and -- most of all -- listen to what your ears tell you.
There is some "objective" basis for high-quality power cords providing better performance. At the least, they behave in much the same way a transformer does to buffer out problems in the electric power. Additionally, high-quality power cords certainly have heavier wiring, which makes it possible for amps to draw more power, cleanly.
I recently upgraded the power cords on my Bryston power amps. I bought AudioQuest power cords which are equipped with either 2 or 3 ferrite units, which reduces the amount of RF transferred through the cord. There was some improvement, but I'm not sure I'd call it dramatic. However, since I bought the cords on sale from HCM Audio (check their Web site -- www.hcmaudio.com -- because the sale is still on), I think the investment was a good one. |
Stock cords are 18AWG cost like 3 bucks.Aftermarket cords are 14/10 AWG have high quality plugs and IEC.
Take two Kettles.One stock.Cut the cheap plug off one.Put on a high quality Hubbel or equall on the other.Plug them in.Stock unit takes 3 minutes to boil water.Unit with better plug boils water in 1 minute.hy.I will leave it up to you to fugure. |
Because they sound better. And that's really all you need to know. Not that I do know, but I do know. Try a good one, and you'll see, and then you won't know either, but you'll know. That's the best I can do, hope it helps. |
