2. cables
  3. 124345-1776

Direction of aftermarket fuses (only for believers!)

It is with reluctance that I start another thread on this topic with the ONLY GOAL for believers to share their experience about aftermarket fuses.
To others: you can call us snobs, emperors w/o clothes,... etc but I hope you refrain posting just your opinion here. If you did not hear any difference, great, maybe there isn’t.

The main driver for this new post is that I am starting a project to mod my NAD M25 7 ch amp for my home theater. It has 19 fuses (2 per channel, 4 on the power supply board, 1 main AC) and I will try a mix of AMR Gold, SR Black and Audio Magic Platinum (anyway that is the plan, I may try out some other brands/models). As it is reasonably difficult to change them, esp the ones on each channel module that requires complete disassembly, I would like to know what the direction is for these models mentioned and of course, others who HAVE HEARD there is a difference please share your experience on any fuse model you have tried.

Fuses are IME directional:
Isoclean is one of the first to indicate the direction (2008/2009) on their fuses. Users of HiFi Tuning (when the awareness rose quite a bit amongst audiophiles) have mostly heard the difference.

As an IEEE engineer, I was highly skeptical of cabling decades ago (I like the speaker design of John Dunlavy but he said on many occasions that cables nor footers matter at all, WRONG!). Luckily, my curiosity proved me wrong as well. I see the same skepticism that I and many others had about the need for aftermarket cables many, many years ago now on fuses and esp on the direction on fuses.

Another example is the direction of capacitors (I do not mean electrolytic types). Even some manufacturers now and certainly many in the past did not believe it can make a difference sonically. Maybe some do but it takes time in the assembly to sort and put them in the right direction/order (esp as some of the cap manufacturers still do not indicate "polarity") so that maybe is one argument why this is not universally implemented.








jazzonthehudson
jea48
4,788 posts
 

atmashere said:

^^ You won’t have arcing- that would be audible! A small amount of arcing has a way of turning into a lot of it in a short period of time...

Well that depends. On the AC mains side it depends on the size of the conductors and or the surface area of conducting contacts, bus, ect, and is directly proportional to the connected load passing through the arcing connection. Example say a branch circuit consists of #12awg wire. The continuous connected load is only 1 or 2 amps. The wall receptacle is old and the contact pressure is poor when a plug is inserted into the receptacle. Or maybe the receptacle is fairly new and the homeowner didn’t tighten down one of the terminal screws on the neutral or hot branch circuit conductors making a good solid connection. Can/could there be a slight small amount of series arcing going on with the 1 or 2 amp connected load? Would a 1 or 2 amp load create a lot of heat in the connection of the #12 wire to the side terminal plate/screw of the receptacle? Could the surface area of the #12 wire and the receptacle screw/terminal plate/contact, and male blade of the plug dissipate the heat? Now all bets are off if the home owner plugs in a big power hungry amp into the receptacle..... (Note: If the branch circuit wiring is protected by an AFCI breaker the arc fault sensing device of the breaker may/will trip the breaker open. It would depends on the amount of series arcing going on.)

Arcing can cause/create RFI and can be transferred through a conductor or through the air. Can it be audible through an audio system speaker?


On the power supply side of the secondary side of the power transformer.

Best example is a cold solder joint. Not in the main DC rails necessarily, though that would probably be heard through the speakers. In that event it would more than likely eventually burn itself free creating an open circuit. But how about an arcing cold solder joint in a circuit that does not consume a lot of energy?

atmasphere's avatar
atmasphere
12,171 posts
 
^^ Arcing is often audible with audio equipment. An arcing power switch can make quite a racket!

If you have arcing in an older house wiring system, failure of the arcing component (wall socket or the like) is eminent. It can also be a fire hazard.

Any connection has a certain amount of resistance. As current flows through it the resistance causes heat. A cold solderjoint will heat up faster than a proper solderjoint.

When a fuse blows, it will be warm or hot if you remove it at the time of failure. Its heat that blows a fuse. So it should be no surprise that any fuse runs at a temperature and that there will be a voltage drop across it. Keeping the voltage drop to a minimum by optimizing the contacts helps the fuse as it will run cooler since the heat it makes is supposed to be made by its internal element not its contacts.  
jazzonthehudson's avatar
jazzonthehudson OP
277 posts
 
>> I’d like to hear from AC power cord designers/manufacturers. Do any of them test the wire they make their cords with for directionality? They can't simply be reversed by the user though, of course.

Some PC w/o shrink sleeves on plugs/IEC and thin threads like NordOst Valhalla can be tested, simply swap the ends. I may try that on my remaining Valhallas.

BTW, I am finally testing the fuse and their directions on my NAD M25 using PADIS fuses and report back if they are indeed the Furutech OEMs. 
atmasphere's avatar
atmasphere
12,171 posts
 
^^ Do you understand how power cords are wired? If you get it wrong, Bad Things happen!

BTW, the effects of a power cord are much easier to measure than that of fuses. I've seen a power cord rob an amplifier of about 1/3 of its total output power!
almarg's avatar
almarg
9,670 posts
 
Some PC w/o shrink sleeves on plugs/IEC and thin threads like NordOst Valhalla can be tested, simply swap the ends. I may try that on my remaining Valhallas.
Although if that is done and a difference is heard, it by no means proves that directionality of the wires is responsible. For example, the act of simply removing and reattaching the connectors would seem to me to have a greater chance of being responsible. Assuming, of course, that care has been taken to eliminate other possible extraneous variables, such as differences in warmup state (many here have asserted that days of warmup may be required for some solid state equipment to achieve optimum performance), or the re-initialization that occurs in some designs (especially those which include digital circuitry) when power is removed and re-applied, or even (as some members here have asserted in other threads) the act of physically manipulating the cord, allegedly necessitating significant time for it to "settle."

Best regards,
-- Al


More to discover