I have been reading how some think that uprading an replacing a perfectly good AC cord for an amp can improve the sound. Considering what AC has to go through before it even gets to a wall outlet, how can a few feet of AC cord affect anything when one considers electicity does not care what a cord looks like or how much you (over) paid for it.
These same people claim that replacing a fuse can noticeably improve sound.
To me all this is just plain ol'' BS!
Is there any truth at all to this?
These same people claim that replacing a fuse can noticeably improve sound.
To me all this is just plain ol'' BS!
Is there any truth at all to this?
The mains cable can change (by a small amount) the source impedance seen by the PSU. This can (slightly) change the shape of the charging pulses in a capacitor input PSU. Poor amp design can couple these to the audio circuitry. General rule: if changing the mains cable changes the sound then there is probably a weakness in the design of your amp, however much you paid for it. Similarly for fuses.
A 'better' one might make no difference, but a 'worse' one (e.g. highish resistance and/or high inductance) might give slightly smoother charging pulses. Don't assume that expensive cables are necessarily 'better'. If you read the sales blurb you can see that some of the makers simply don't understand electricity, or at least hope their customers don't.
Another issue is ground lead impedance. It could be that a thinner, higher impedance ground lead could force more of the signal return currents (at low frequencies) to travel via the interconnects' screens rather than the mains ground wires. A 'worse' mains cables might reduce ground loops, by raising the loop impedance.
Another issue is ground lead impedance. It could be that a thinner, higher impedance ground lead could force more of the signal return currents (at low frequencies) to travel via the interconnects' screens rather than the mains ground wires. A 'worse' mains cables might reduce ground loops, by raising the loop impedance.
Humans are very suscpetible to suggestion, especially when it concerns something they don't really know anything about but which might have a big impact. If enough people say something is true, then that something becomes truth. Just think about how many times history has proved us wrong and continues to do so.
Those that have knowledge about that something will not be fooled so easily, though.
Same thing here with HiFi, there are audiofiles and audiofools.
Personally I think that changing AC cords and fuses will not make any difference when it comes to equipment that has been designed to meet EMC criteria. You're not going to change the properties of a high level mains signal more than a negligible amount with just a short length of conductor.
When it does make a difference, there's probably something fundamentally wrong with that equipment, like DF96 mentioned, or you're fooled into believing it does. If there is a preceptible difference, it's time for some double blind testing. If the difference persists, it's time to track down the real culprit.
I run my audio equipment on their standard AC cords but behind a mains filter. I can't hear the difference with or without filter, but I keep it there anyway for peace of mind.
Those that have knowledge about that something will not be fooled so easily, though.
Same thing here with HiFi, there are audiofiles and audiofools.
Personally I think that changing AC cords and fuses will not make any difference when it comes to equipment that has been designed to meet EMC criteria. You're not going to change the properties of a high level mains signal more than a negligible amount with just a short length of conductor.
When it does make a difference, there's probably something fundamentally wrong with that equipment, like DF96 mentioned, or you're fooled into believing it does. If there is a preceptible difference, it's time for some double blind testing. If the difference persists, it's time to track down the real culprit.
I run my audio equipment on their standard AC cords but behind a mains filter. I can't hear the difference with or without filter, but I keep it there anyway for peace of mind.
I guess when all is said and done, a little peace of mind can be good.... as long as it does not cost too much.
I suppose a high quality fuse can help a depending on the circuit and the fuses involved.
However, I still have a problem with the mains.
Installing a better amp mains than the wiring in the walls can help?
That's like saying installing one strong link in a a chain where all the other links are weaker and expecting the whole chain to be stronger. The most common house wiring gauge in the US is 12-14 for most room 110 outlets. So why install a 7 gauge amp mains?
I suppose a high quality fuse can help a depending on the circuit and the fuses involved.
However, I still have a problem with the mains.
Installing a better amp mains than the wiring in the walls can help?
That's like saying installing one strong link in a a chain where all the other links are weaker and expecting the whole chain to be stronger. The most common house wiring gauge in the US is 12-14 for most room 110 outlets. So why install a 7 gauge amp mains?
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A cable has resistance and capacitance and inductance.
Changing the geometry of the cable changes the relative proportions and the absolute values of these impedances.
Once you change those impedances you have changed the filtering effects.
That is what DF & Jit are referring to.
A good amplifier (or other equipment) should remain unaffected by changes in the interference coming in through the mains. A poor bit of gear could easily be heard to respond to changes in mains borne interference.
A change of cable parameters can affect the interference that escapes from the mains to the gear.
That's where removing the fault in the gear comes into the equation. Sort the problem. Don't reduce or hide the problem by fiddling with cables.
Changing the geometry of the cable changes the relative proportions and the absolute values of these impedances.
Once you change those impedances you have changed the filtering effects.
That is what DF & Jit are referring to.
A good amplifier (or other equipment) should remain unaffected by changes in the interference coming in through the mains. A poor bit of gear could easily be heard to respond to changes in mains borne interference.
A change of cable parameters can affect the interference that escapes from the mains to the gear.
That's where removing the fault in the gear comes into the equation. Sort the problem. Don't reduce or hide the problem by fiddling with cables.
The worse offenders on the AC power supply chain are:
1. Contact resistance of the plug/receptacle. If the receptacle in the wall has weak springs, oxidated lamels (running a space heater in it will do that), then the instantaneous voltage drop on that connection can be important. In Eu some countries have different outlets - the 16A one with grounding (Schuko or CEE 7/17 style) has a bigger diameter prongs (4.8 mm) than the 2.5A CEE 7/16 Europlug ones (4mm). Using the wrong cable in the wrong socket will lead to imperfect contact.
To make things worse, the Russian plugs have the same spacing as EU plugs, but theyr prongs are 4.5mm in diameter. Sockets conforming with that standard are found in a lot of former "east-european block" countries.
US plugs are better designed because they need to handle higher currents by default and they are polarized (hot/neutral). An universal 15/20A receptacle is designed "host" a 15A or a 20A plug. Obviously that receptacle is the best upgrade for a 15A household device, but only if the wiring in the wall is also upgraded to 20A (#10AWG), otherwise is not "legal" per NEC.
2. Diameter of the conductors inside the cord. In order to make the cord flexible, some manufacturers choose really thin wires (for example in EU adequate only for 2.5A, or in US #18AWG). Those will add to the voltage drop and they are definitelly smaller than wiring in the wall.
3. Fuse. The fuse itself has to have a certain voltage drop over it in order to develop the temperature faster than the protected circuit. So yes, eliminating the fuse can improve the voltage drop, on expense of increasing the risk of fire. It is strongly NOT my advice. There are faster fuses (filled with sand usually) that have a lower voltage drop compared with the regular ones, but I doubt that is a very big variance.
4. I almost forgot. The automatic circuit breaker in the electrical panel has a sizable resistance, some inductance and a contact. All generate voltage drops.
Because the power supply of most devices is regulated, all this does not have any sizable effect on audition. The power amplifiers don't have regulated power supplies, but they usually have good PSRR by design. In some, PSRR is not so good, and the cable might make a slight difference at maximum volume.
But in most cases, it is just "whishfull thinking" in effect. Self-suggestion.
1. Contact resistance of the plug/receptacle. If the receptacle in the wall has weak springs, oxidated lamels (running a space heater in it will do that), then the instantaneous voltage drop on that connection can be important. In Eu some countries have different outlets - the 16A one with grounding (Schuko or CEE 7/17 style) has a bigger diameter prongs (4.8 mm) than the 2.5A CEE 7/16 Europlug ones (4mm). Using the wrong cable in the wrong socket will lead to imperfect contact.
To make things worse, the Russian plugs have the same spacing as EU plugs, but theyr prongs are 4.5mm in diameter. Sockets conforming with that standard are found in a lot of former "east-european block" countries.
US plugs are better designed because they need to handle higher currents by default and they are polarized (hot/neutral). An universal 15/20A receptacle is designed "host" a 15A or a 20A plug. Obviously that receptacle is the best upgrade for a 15A household device, but only if the wiring in the wall is also upgraded to 20A (#10AWG), otherwise is not "legal" per NEC.
2. Diameter of the conductors inside the cord. In order to make the cord flexible, some manufacturers choose really thin wires (for example in EU adequate only for 2.5A, or in US #18AWG). Those will add to the voltage drop and they are definitelly smaller than wiring in the wall.
3. Fuse. The fuse itself has to have a certain voltage drop over it in order to develop the temperature faster than the protected circuit. So yes, eliminating the fuse can improve the voltage drop, on expense of increasing the risk of fire. It is strongly NOT my advice. There are faster fuses (filled with sand usually) that have a lower voltage drop compared with the regular ones, but I doubt that is a very big variance.
4. I almost forgot. The automatic circuit breaker in the electrical panel has a sizable resistance, some inductance and a contact. All generate voltage drops.
Because the power supply of most devices is regulated, all this does not have any sizable effect on audition. The power amplifiers don't have regulated power supplies, but they usually have good PSRR by design. In some, PSRR is not so good, and the cable might make a slight difference at maximum volume.
But in most cases, it is just "whishfull thinking" in effect. Self-suggestion.
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FWIW I just checked my wall outlet voltage with my "Kill A Watt" meter and it varies between 116- 117 volts/ 59.9-60 Hz.
So, it's pretty good for the US.
I don't know exactly how accurate a "Kill A Watt" is but, for about $25, it's handy to have...... at least to know about how much watts anything is using, etc.
So, it's pretty good for the US.
I don't know exactly how accurate a "Kill A Watt" is but, for about $25, it's handy to have...... at least to know about how much watts anything is using, etc.
According to this article, in the transition period (1995-2008) 220 V countries changed to 230 V +6/-10% (244/207 Vac) and 240 V countries to 230 V +10/-6% (253/216 Vac). In reality this meant they could keep supplying 220 V or 240 V. From 2008 on it's 230 V +/- 6%.
The point I was trying to make still stands, a small voltage drop in wiring and fuse is insignificant with respect to mains fluctutions.
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Some time ago, I checked my meters using my AC line voltage.
Using my Keithley 2000 as reference I checked the following units.
Keithley 2000 6½ digit, multi-meter. From about 2001 $1200.
Keithley 177 4½ digit, multi-meter. About 30 years old, currently $375.
Fluke 8020A 3½ digit, multi-meter. About 30 years old.
Radio Shack True RMS 3½ digit, multi-meter. Maybe 8 years old.
Kill-a-Watt P4400 3½ digit, plug-in-meter. About 1 year old.
M8303½ digit, multi-meter. Similar to the yellow Harbor Freight units.
From an outlet store $4. About 5 years old.
Harbor Freight Cen-tech DMM’s
Cen-tech 92020 3½ digit, multi-meter. $4. About 1 year old. Very noisy.
Cen-tech 95683 3½ digit, multi-meter. Under $20. 4 months old. w/current clamp.
None of the meters have been calibrated.
Model AC________Voltage____Error
Keithley 2000____0126.00___ reference
Keithley 177_____125.75____ -0.2%
Fluke 8020A_____125.9_____ -0.1%
R/S 22-1758_____124.6_____-1.1%
Kill-a-Watt______125.6 _____-0.3%
M830___________126.5_____+0.4%
92020__________124.5_____ -1.2%
95683__________126.0______±0.0%
AC accuracy of the Keithley 2000 when reading a 120V AC 60 Hz signal
is calculated to be ±0.297V. Yep, not nearly as good as one might expect!
The accuracy takes a big hit when using the 750V range.
If we measure 99V on the 100V range then it’s ±0.09V.
AC Accuracy of the Keithley 177 when reading a 120V AC 60 Hz signal
is calculated to be ±1.03V.
Using my Keithley 2000 as reference I checked the following units.
Keithley 2000 6½ digit, multi-meter. From about 2001 $1200.
Keithley 177 4½ digit, multi-meter. About 30 years old, currently $375.
Fluke 8020A 3½ digit, multi-meter. About 30 years old.
Radio Shack True RMS 3½ digit, multi-meter. Maybe 8 years old.
Kill-a-Watt P4400 3½ digit, plug-in-meter. About 1 year old.
M8303½ digit, multi-meter. Similar to the yellow Harbor Freight units.
From an outlet store $4. About 5 years old.
Harbor Freight Cen-tech DMM’s
Cen-tech 92020 3½ digit, multi-meter. $4. About 1 year old. Very noisy.
Cen-tech 95683 3½ digit, multi-meter. Under $20. 4 months old. w/current clamp.
None of the meters have been calibrated.
Model AC________Voltage____Error
Keithley 2000____0126.00___ reference
Keithley 177_____125.75____ -0.2%
Fluke 8020A_____125.9_____ -0.1%
R/S 22-1758_____124.6_____-1.1%
Kill-a-Watt______125.6 _____-0.3%
M830___________126.5_____+0.4%
92020__________124.5_____ -1.2%
95683__________126.0______±0.0%
AC accuracy of the Keithley 2000 when reading a 120V AC 60 Hz signal
is calculated to be ±0.297V. Yep, not nearly as good as one might expect!
The accuracy takes a big hit when using the 750V range.
If we measure 99V on the 100V range then it’s ±0.09V.
AC Accuracy of the Keithley 177 when reading a 120V AC 60 Hz signal
is calculated to be ±1.03V.
I waited until that value came up again on the Keithley 2000. This was just a quick check to see how suitable each meter use for electrician type work on AC line voltages. The last 4 meters being in the $4 to $30US price range are surprisingly accurate. But for calibration (even an amateur calibration), one would not use a jittery, high distortion AC line as a source.
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