garylkoh
New member
- Thread Author
- #1
One of the most popular tips I've dropped is that there are differences in rating and use of fuses between US-designed and Euro-designed gear.
However, you need to be careful when changing out fuses as there are several things you need to know beyond getting the "right size". Selecting a fuse is not trivial and at Genesis, we spend a lot of time making sure that we pick the optimum fuse to put into our products.
1) There are two major standards by which fuses are "sized" - this is the Rated Capacity - measured in ampere at usually 250V. An IEC rating means that the fuse can continuously operate at 100% of the rated current. A UL rating means that the fuse can continuously operate at 75% of the rated current. This is important because if your piece of equipment has a UL rated fuse, and you replace it with an IEC rated fuse, you could be operating at 33% over-current without the fuse blowing - which might mean expensive repairs if your power transistors are overloaded by a fault and the fuse doesn't blow. If your product uses an IEC fuse, and you replace it with a UL fuse, the fuse may blow easily and you wonder why. (Genesis loudspeakers come installed with a UL rated fuse.)
2) Every fuse has a "Breaking Capacity". This is the maximum current that a fuse can safely blow without a catastrophic failure such as fire or explosion. If the fuse has too low a breaking capacity, the surge current could cause the fuse to explode and things could catch on fire. For example, the fuse is designed to protect a power amplifier - if the outputs are shorted out, the surge in current blows the fuse safely. If the replacement fuse is below the breaking capacity, the fuse could even melt the fuse-holder. The short circuit behavior of any product is a difficult thing to calculate - and the only way to do it might be to do some destructive testing. Blow up a couple of amplifiers, and see if the fuse explodes. This is a major issue if you use "audiophile" fuses.
3) Slow blow fuses are used when there is in-rush and peak current at start-up. They are designed to start working from cold. For example, that is why sometimes when you have been playing your system for some time. Turn it off, and then when you turn it on again immediately, the fuse blows. What could be dangerous is that "slow blow" fuses come with different speeds and react to different patterns of the surge. Technically, this is the I2t value - current squared times time - the heat energy needed to blow the fuse. If you use a fuse with too high a heat energy value, you could be damaging your amp/component while waiting for the fuse to blow in a short circuit situation. Too low a heat energy value, and the initial start-up surge blows the "slow blow" fuse. Not an issue with $3 fuses, but for a $500 "audiophile" fuse, it needs to be slow enough to survive the start-up surge, but fast enough to protect the output transistors of the amplifier if the outputs are short-circuited.
4) Pulse factor derating of the fuse wire. As a fuse wire is subjected to pulses of high current. Every time you turn your system on the fuse wire ages. See the attached picture of the cross-section a new fuse wire versus an aged fuse wire. The pulse factor derating tells you how many times you can turn on/off your amplifier before you should to replace the fuse.
An aged fuse wire will break more easily, but we might also infer that it won't sound as good. When replacing a 3-year old fuse that is close to the end of its life-span with a brand new fuse, you might conclude that an audiophile fuse made your system sound better when it actually could be because you replaced an old, worn-out fuse with a brand-new one.
5) Heat dissipation factor. All fuses heat up under operation. If the heat dissipation of the fuse is greater than the designed capacity of the fuseholder, the fuseholder could melt.
Before you consider changing out the fuse on your gear, please consider the above factors. There may be sonic advantages to changing out the fuse for an audiophile fuse. No risk, no gain. But please know your risks before you play the game. The wrong fuse could be expensive and/or dangerous.
However, you need to be careful when changing out fuses as there are several things you need to know beyond getting the "right size". Selecting a fuse is not trivial and at Genesis, we spend a lot of time making sure that we pick the optimum fuse to put into our products.
1) There are two major standards by which fuses are "sized" - this is the Rated Capacity - measured in ampere at usually 250V. An IEC rating means that the fuse can continuously operate at 100% of the rated current. A UL rating means that the fuse can continuously operate at 75% of the rated current. This is important because if your piece of equipment has a UL rated fuse, and you replace it with an IEC rated fuse, you could be operating at 33% over-current without the fuse blowing - which might mean expensive repairs if your power transistors are overloaded by a fault and the fuse doesn't blow. If your product uses an IEC fuse, and you replace it with a UL fuse, the fuse may blow easily and you wonder why. (Genesis loudspeakers come installed with a UL rated fuse.)
2) Every fuse has a "Breaking Capacity". This is the maximum current that a fuse can safely blow without a catastrophic failure such as fire or explosion. If the fuse has too low a breaking capacity, the surge current could cause the fuse to explode and things could catch on fire. For example, the fuse is designed to protect a power amplifier - if the outputs are shorted out, the surge in current blows the fuse safely. If the replacement fuse is below the breaking capacity, the fuse could even melt the fuse-holder. The short circuit behavior of any product is a difficult thing to calculate - and the only way to do it might be to do some destructive testing. Blow up a couple of amplifiers, and see if the fuse explodes. This is a major issue if you use "audiophile" fuses.
3) Slow blow fuses are used when there is in-rush and peak current at start-up. They are designed to start working from cold. For example, that is why sometimes when you have been playing your system for some time. Turn it off, and then when you turn it on again immediately, the fuse blows. What could be dangerous is that "slow blow" fuses come with different speeds and react to different patterns of the surge. Technically, this is the I2t value - current squared times time - the heat energy needed to blow the fuse. If you use a fuse with too high a heat energy value, you could be damaging your amp/component while waiting for the fuse to blow in a short circuit situation. Too low a heat energy value, and the initial start-up surge blows the "slow blow" fuse. Not an issue with $3 fuses, but for a $500 "audiophile" fuse, it needs to be slow enough to survive the start-up surge, but fast enough to protect the output transistors of the amplifier if the outputs are short-circuited.
4) Pulse factor derating of the fuse wire. As a fuse wire is subjected to pulses of high current. Every time you turn your system on the fuse wire ages. See the attached picture of the cross-section a new fuse wire versus an aged fuse wire. The pulse factor derating tells you how many times you can turn on/off your amplifier before you should to replace the fuse.
An aged fuse wire will break more easily, but we might also infer that it won't sound as good. When replacing a 3-year old fuse that is close to the end of its life-span with a brand new fuse, you might conclude that an audiophile fuse made your system sound better when it actually could be because you replaced an old, worn-out fuse with a brand-new one.
5) Heat dissipation factor. All fuses heat up under operation. If the heat dissipation of the fuse is greater than the designed capacity of the fuseholder, the fuseholder could melt.
Before you consider changing out the fuse on your gear, please consider the above factors. There may be sonic advantages to changing out the fuse for an audiophile fuse. No risk, no gain. But please know your risks before you play the game. The wrong fuse could be expensive and/or dangerous.
