So I'm putting my preamp into its chasis today and I get to the fuse holders for the wall current. I'm hooking up 12ga from the wall and fairly large wire to the transformer and than there are the fuses. I installed 2amp glass tube fuses. the wire in it is tiny......Is this something that is considered? Is there a certain type that is better than another?
It has to be that way to work. The total resistance of a wire is a function of diameter and length anyway. A 1/4" length doesn't have to be nearly as big as a 25' length. Don't worry about it.
Slo-blo fuses will survive high in-rush currents where fast blow types of the same current rating will pop. If you have lots of power supply capacitance, you can have high in-rush current.
Take the VA rating and divide it by your nominal mains voltage. Multiply by 1.33. That's your fuse rating. Use a slow-blow fuse. If the fuse still blows on turn-on, install a soft-start circuit.
So for, say a 200 VA transformer running on a 120 V system, the appropriate fuse would be: (200/120)*1.33 = 2.22 A. So use a 2 A or 2.5 A fuse (standard values).
~Tom
So for, say a 200 VA transformer running on a 120 V system, the appropriate fuse would be: (200/120)*1.33 = 2.22 A. So use a 2 A or 2.5 A fuse (standard values).
~Tom
Thanks for the replies. I use a soft start...no blown fuses. I was more thinking about the bottleneck of the tiny wire in the fuse. Slo-blo fuses look to have a longer length of tiny wire coiled up in them. Thanks again...Evan
The electrons might slow down at the bottleneck, but they will cope. Electrons are very flexible like that.
For a moment, I thought this thread was going to be about which type of fuse makes for the best sound.
It is, isn't it? The suggestion is that you use massive solid platinum cable to wire up your amp to the mains, then pass the current through a filament as thick as a human hair. Why use the massive mains cable at all?
I guess if you use platinum mains cables then you have to buy the appropriate directional cryo-treated gold-plated fuses to match, otherwise the electrons will become confused and simply revert to obeying Maxwell's equations.
The real point is that a fuse is a very primitive, flawed version of the ideal current overload breaker - the one that has no series resistance or inductance but which trips out once a very specific envelope of time and current has been exceeded.
... if there is such an extremely thin wire inside the fuse, and all electrons have to squeeze themselves through it, won't they become quite long electrons (QLE)? And can the fuse break the current flow before the recent QLE has passed through it completely? Is this why slow-blowing fuses show a delay?
Rundmaus
Rundmaus
Just for interest,
Under fault conditions you only want heat to occur in the fuse element. The idea is that the fuse in the plug should protect the cable.
Remember that a fuse does not blow at the current shown on it. This can be up to 1.5 times the rated current. Remember fuses have a voltage clearance as well as current this is why HRC links have sand in them to quench the arc!
The function of the fuse and the sonic ability are a different case. The mains cable should be electrically "functional". The ability of the cable to carry current is a different situation to RF cancellation. The noise from a fuse on mains is of less concern than on DC rails where you "can" bypass with a capacitor due to the DC situation!
The level of safety is the Number 1 criteria.
Cables on mains should be double insulated, have correct colours. If the fuse is rated to close to running current it will mechanically fail due to mechanical stress. This happens when the fuse element heats and cools-expanding and contracting the element due the heating effect, then breaks. Just some trivia🙂
Mains inrush current sometimes called magnetisation current of the primary winding will cause fuse failure if the correct types are not used.
There is more to be gained from RFI cancelling. Some fuse links tarnish and create a bad connection, this causes sonic and electrical safety problems. Talking audio, fuses do not sound very good. Breakers are always a better alternative sonicaly, however the voltage ratings and clearance times + convienience of fitting fuses make them difficult to use. This is compared with the sonic "gain".
Regards
M. Gregg
Under fault conditions you only want heat to occur in the fuse element. The idea is that the fuse in the plug should protect the cable.
Remember that a fuse does not blow at the current shown on it. This can be up to 1.5 times the rated current. Remember fuses have a voltage clearance as well as current this is why HRC links have sand in them to quench the arc!
The function of the fuse and the sonic ability are a different case. The mains cable should be electrically "functional". The ability of the cable to carry current is a different situation to RF cancellation. The noise from a fuse on mains is of less concern than on DC rails where you "can" bypass with a capacitor due to the DC situation!
The level of safety is the Number 1 criteria.
Cables on mains should be double insulated, have correct colours. If the fuse is rated to close to running current it will mechanically fail due to mechanical stress. This happens when the fuse element heats and cools-expanding and contracting the element due the heating effect, then breaks. Just some trivia🙂
Mains inrush current sometimes called magnetisation current of the primary winding will cause fuse failure if the correct types are not used.
There is more to be gained from RFI cancelling. Some fuse links tarnish and create a bad connection, this causes sonic and electrical safety problems. Talking audio, fuses do not sound very good. Breakers are always a better alternative sonicaly, however the voltage ratings and clearance times + convienience of fitting fuses make them difficult to use. This is compared with the sonic "gain".
Regards
M. Gregg
LOL. I would bet that an entrepreneur could find a ready market for audiophile-grade fuses, at, say, $200 a "pop." An ex-boss of mine would buy them to protect his $600 cables.
Hello,
Why is the fuse there in the first place, to keep your house from burning down or protect the preamplifier?
Many transformers are considered to be inherently safe. Poof the smoke comes out but there is not enough heat to catch things on fire. They are listed to operate without a fuse. If you are concerned about the DC in the preamplifier the fuse on the AC primary is way too slow to protect anything.
So why is the fuse there?
DT
All just for fun!
Why is the fuse there in the first place, to keep your house from burning down or protect the preamplifier?
Many transformers are considered to be inherently safe. Poof the smoke comes out but there is not enough heat to catch things on fire. They are listed to operate without a fuse. If you are concerned about the DC in the preamplifier the fuse on the AC primary is way too slow to protect anything.
So why is the fuse there?
DT
All just for fun!
- Status
- Not open for further replies.