Can a power cord increase the resolution of an Class D (SMPS) amp by more than 5% ?

Well, in the case of the new Hurricane power cord from Audioquest you can attribute part of its very high performance to wire directionality, which Audioquest now controls during manufacturing for power cords as well as speaker cables, interconnects and HDMI cables. Hel-loo! Wake up and smell the roses! 🌹🌹🌹

Is there some kind of parameter or specification that indicates power cable bandwidth?

I've never seen one... it would be a good spec to include.

Looking at @dep14 's calculator, it looks like for a typical home-use power cord (16/3 cable at 6' in length) you're only losing .6% of your voltage on a typical 120v 15a home circuit,

In practice you see more- the problem area with many inexpensive cables in the connection at either end. That is where you are most likely to discover that the cable is heating up and this calculator does not take that into account. It also does not calculate the impedance of the cable at higher frequencies, so I can't regard it as 100% accurate, although for general home electrical stuff its fine.

The problem here is that, like it or not, you can hear differences between power cables. My thinking is that if you can hear differences, there should be something measurable as well. I find it easier to measure the effects on the equipment with which the cable is used rather than to measure the cable.

In a class D amp, the idle current is quite low. But to actually make the power to drive real speakers, the amp has to draw power from the wall and at full power can draw quite a lot depending on the amp. If you were to put an ammeter in series with the amp's AC power, you would see the meter dance around as you ran the volume up while playing music. The thing is, switching amps need the power supply to be quiet and the current it needs has to be readily available. Most of the expense of any class D amp is its power supply.

@atmasphere 

Looking at @dep14 's calculator, it looks like for a typical home-use power cord (16/3 cable at 6' in length) you're only losing .6% of your voltage on a typical 120v 15a home circuit, that seems like it would be well within the margin of error of typical home outlets (which can range from 110v to 130v in actual output).  

Given that amplifiers are typically running at a small fraction of their maximum output (only a few watts except for very short dynamic peaks) how would such a small reduction in voltage actually be audible?  If it were wouldn't you see an even bigger difference between two homes where one's AC voltage averages at 117 volts and another whose voltage averages at 121 volts?

@atmasphere 
Wow.  I actually think I understood that.  Thanks for that clear explanation, Ralph.  Is there some kind of parameter or specification that indicates power cable bandwidth?

I’m having trouble seeing how a power cord could make a difference.  After all, the stock cable should be capable of delivering the full mains power available to the amp, and the power supply on the amp is going to clean up any minor amount of interference that could possibly sneak in between the wall and the unit.  

I've seen a power cord cause a loss of about 40 watts on a 140 watt amp. It was easy to see why- there was a voltage drop across the cord. I measured it with regular Digital VoltMeter (DVM); its not rocket science.

By contrast, the romex in the wall of most houses is much better performance, being made of solid core copper. But this material is illegal for use as a power cord; so yes, that last 6 feet can make a difference.

Here is an additional issue, that I think will affect switching amps more than other types of amps. The voltage drop is not limited to 60 hz. The problem is that there is a power supply in the amp that is made of a transformer, rectifier(s) and filter caps. The rectifier converts the AC from the transformer to DC and the filter caps store that voltage for use by the amp. In-between peaks of the AC power waveform, the caps get discharged. The rectifiers only conduct when the cap voltage is lower than that of the transformer; if the caps are only slightly discharged (the normal state of affairs) then the time that the rectifiers turn on is very slight, perhaps a few milliseconds or even microseconds. At that time the current draw might be profound; if the power cord does not have the bandwidth, the pulses charging the caps will be current limited.

This can be bad for a switching amp, which needs a really clean power supply to sound right, even if they don't seem to be drawing much power from it at any given time. So its worth it to try a power cord that has greater bandwidth (which romex already has...).

Thanks guys ! So much truth in this thread ;-) !

Nordost Vishnu on my CD player, network streamer and preamp give me improvements I would say they were  greater than 5%. On my bel canto ref 500m mono blocks, Nordost Vishnu and heimdall 2s gave a slight improvement, I’d say less than 5%. The heimdall 2s were better, but not by much. 

Voltage drop... if it's a concern for you.

Have at it.

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=5.211&voltag...

No matter what the voltage is at your outlet, the idea is to get as much of it to your gear as possible, so the age-old counterpoint/argument "what about all the wiring between the power plant and your house?" is moot.
Voltage drop, and the corresponding performance loss that results from it, is real and it’s scientifically measurable. Unfortunately, every power cord suffers from it, but to widely varying degrees - up to a 3% voltage drop is considered "acceptable" in power cord manufacturing.
If your amp is only fed 117 volts, it will not produce the same amount of power/performance as when it is fed 120 volts. Simple.

With that said, you certainly don’t need a power cable costing 4 or 5 figures to combat/minimize voltage drop.
Is there snake oil out there? Of course there is! How else can a company justify a $10,000+ power cord?
However, the mere existence of snake oil does not negate the existence of voltage drop and its effects.

Try some different cables with different gauges and go from there.

Cheers and good luck!

tutetibiimperes,

I know and understand why a lot of people feel power cords are just so much "snake oil". If you ever get a chance to try a few, well give it a whirl. Just keep an open mind and listen closely. You might be surprised. Maybe.....

I’m having trouble seeing how a power cord could make a difference.  After all, the stock cable should be capable of delivering the full mains power available to the amp, and the power supply on the amp is going to clean up any minor amount of interference that could possibly sneak in between the wall and the unit.  

Besides, if it was easy to greatly increase the performance of an Amp with a different power cord, why wouldn’t they just ship it with a different power cord?  Why handicap yourself is there’s such an easy solution?   

No, unless you want it to...

I have a Class D hybrid integrated amp with Hypex-400 modules.

I compared a small handful of upgraded cables in the $300-$350 range. Compared them to the stock cables that came with my equipment, I got varied results from no improvement, to a small improvement, to slightly worse sound. The differences I heard with these cables in my system was mostly in the upper bass range. Obviously the cables with the heavier upper bass made some of the lower mids sound ever so slightly veiled. I found one cable of the bunch to give me a very clean sounding upper bass which in turn gave a tiny improvement in the mids. Granted all these differences were extremely small, but I felt if I could hear a difference so it wouldn't hurt to  use them, right?  It took a week of going back and forth with these cables and was quite the tedious process. I would like to think I made an informed decision, and it would be money well spent. The cable I chose at the time was $325 new for a 6 ft. length. I found several  more of these cables used on Audiogon in a range of $120 to $150 each, so I bought them to wire my entire system. I do like the result, but I don't think I would buy mega buck power cords. IMO. 

I think so.

Prior to the Stereophile review I purchased my first switching amplifier a PS Audio HCA-2 to fill in for a solid state amplifier out for an upgrade. We had recently moved into an 1972 vintage California ranch home.

Right out of the box the PS Audio's presentation was somewhat forward with a startlingly plate glass transparency and a remarkable lack of congestion at higher listening levels. It wasn't long before I noticed I could hear what was being played faintly through a bedroom clock radio.

We began a major remodel which included upgrading the electrical service from 100 to 400 amp service. This required the utility to replace the cable from the grid. My electrician replaced the aluminum cable from the new main breaker to the new breaker panel and two sub breaker panels one of which was for audio only.

From the audio sub panel I used 10g for hot and common and an 8g ground within an uninterrupted metal clad BX housing to the metal receptacle boxes containing Hospital grade isolated ground receptacles and 10g DIY double shielded power cables. Bottom line here was beefy conductors and shielding for the area I'm in. Two runs to the Hi-Fi and two runs to the HT were just under 1K. Highly recomended.   

During all this the amplifier was steadily breaking in but that couldn't account for the degree of audible improvement we experienced nor could I attribute it to just the power cords.
The improvement was much more than replacing all the cheapo speaker cables and interconnects with my Cardas Golden Reference and slightly less than replacing my very old Shure V15 with the Benz Ruby Z.

One constant I've experienced with switching amplifiers up to my now dated Hypex nCore 400s is they all liked thick copper cabling and nothing silver or silver coated. NuForce speaker cable was noticeably better than the Cardas, if you can find it.    

shadorne6,844 posts04-29-2018 12:38amNo

Absolutely no!

Cheers George

Thanks for alll your inputs.

 Nothing mysterious...

100% - 2 times more resolution, like a new component (unreal)
50% - outstanding upgrade
25% - really good upgrade
10% - good upgrade
5% -  noticeable improvement
under 5% - 100 AB Tests needed to find a difference.

It's impossible to answer the question because there's no way to quantify this mysterious 5%

I would submit that changing out the amp power cord while leaving in the stock power cables of all other components, will probably have little benefit.

5% gain is quite a bit to expect with any pwr cord change from just a stock thick gauge cord.
I’ve been using upgraded cords for a long time,generally make my own,and without question they do lwr the noise floor,have better defined dynamics,and are generally smoother and more refined across the board.

I’ve owned many class d amps and I found that with all of them,they like being powered up all the time.My latest amp a Lyngdorf 2170 definitely likes being left on,not on standby,all the time for the very best in sound and also is ready to go at any time.

I recommend that you try a reasonable priced cord and listen for yourself and compare to a stock cord.

Kenny.

I substituted the power cords that came with my Merrill Audio Veritas monos with Shunyata Pythons and the noise floor,resolution,along with a more natural rendering of the music... did take a turn for the better. Great fit in my system!

An Ansuz D-TC power cord did just what lak mentioned above with my Aavik U300. Because of that I can play almost twice as loud. I never would have believed it if I didn't hear it in my home. Not sure what percentage of improvement I got but would say it was lot. If I have to guess I would say 20 - 30%.
Yes it's crazy expensive too. Full List is 20K for 2M

I've heard some owners of the Shunyata Research Alpha NR power cord that run class D amps say that it did lower the noise floor allowing more detail and resolution to pass through.
Personally, I have not tried it yet but perhaps in the future.
Seems like a large amount of money must be spent for a small margin of improvement, and it always seems to be that way with high end audio.

Never improved the speed. It did lower the noise floor allowing more detail and resolution to pass thru. Stock cord supplied by Theta replaced with Transparent Reference PC. 

As much as I dislike the crazy expensive over the top cables, replacing the stock cord with a $30 OFC cable (BLE Design on ebay) will bring an improvement.

No.  Will it sound different?  Likely.  Will it sound better? Possibly.

Try it and decide for yourself.

I hear better tone and fullness with some good power cords on Merrill Thor amps. They can make a difference. 

No