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Servo 15 fuse uprating

Discussion in 'Subwoofers' started by sparkymarky, May 1, 2004.

  1. sparkymarky

    sparkymarky
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    A servo i have recently purchased doesn't appear to like the electricity supply in my house.

    I demo'd it at the previous owners house and it appeared to work fine. However turning it on in my house resulted in two blown fuses. These were 2.5 anti surge fuses, which i presume is standard issue.

    I have replaced this with a 3.15 anti surge, which incidently and much to my relief appears to work fine, on the basis of the following thought.

    The sub has a 400 watt rms amp. Therefore when turning on the amp, and when it draws the most current, it may draw the peak figure which (recollecting my days as an electrician!!) i would work out to be 565 watts. (rms/0.707=peak)
    Therefore, 565/240v = 2.35A (p=VI) which is obviously close to the fuse rating.
    With a slightly poor and uncontrolled mains supply maybe the supply could be at the 2.5 fuse rating for a period long enough to blow the fuse.

    Anybody concur or disagree?

    I am a little bit innebriated as i type so apolgies for typing/grammar
     
  2. ~Kev H~

    ~Kev H~
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    When the fuse went in my SVS I was tempted to uprate the fuse but decided against it in the end.

    The amplifier of my SVS is rated as 525 Watts and that also only had a 2.5Amp fuse fitted as standard.

    All I'll say is that you should think about whether you really want to be exposing the amplifier/driver to the posibility of having to deal with over 750Watts.. because a 3.15A fuse is going to allow this to happen.. To be honest I think the 600W limit imposed buy a 2.5A fuse is plenty and the last thing you want to be doing is finding/paying for a replacement driver.

    I guess it makes sense for there to be a surge in the current on power-up but it would worry me that something isnt right if the amp is drawing that much more than its rated at when you switch it on.

    - Kev
     
  3. sparkymarky

    sparkymarky
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    mmm yes but as it is working fine then it suggests to me that the power on surge is slightly higher than it should be, due to the electrical supply system of my house.

    I understand what you are saying and perhaps i should mention that on a couple of power up the sub was fine and the fuse did not blow. This leads me to believe that i was turning the sub on at the peak amplitude of the ac cycle in my house and so the peak of the sine wine in my house is slightly above what it should be, thereby blowing the fuse. The small amount above what should be the peak of the sine wave of course is replicated at the negative swing of the wave resulting in double the difference, if that makes sense!

    um, +2 during the positive cycle is also +2 during the negative cycle therby equalling 4 (please feel free to correct me as all this theory was a few years ago!)
     
  4. ~Kev H~

    ~Kev H~
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    :rotfl: brilliant...

    the mains electricity in this country is triple phase though.. with the three phases 120 degrees appart. So you dont actually get sine shaped voltage swings like you're thinking of.. well, thats what I got taught anyway, and it made sense at the time.

    Have you considered emailing Paradigm? Ask them if they have had any cases of this happening in the past..

    I understand the temptation to uprate it but fuses are by far the cheapest component in a sub... I just went down Maplins and bought a pack of 10 fuses incase it ever goes again. Cost me all of £1.79.

    What about the auto-on/off? When it has blown the fuse was that from you manually switching it on or from the Auto On switching? Could you not just leave it plugged in and rely on the Auto-On to switch it on when needed?
     
  5. sparkymarky

    sparkymarky
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    not quite as innebriated now, 'sine wine' lol.

    I couldn't get it to auto on without the fuse blowing either.
    I managed to get the sub started twice without a fuse blowing though.

    I hqad to use the 3.15a fuse to get it started consistently (this hasn't blown once) and now leave it in auto mode.
    Seems to work fine. Just need to get it setup properly now.

    I have read that someone else on here is using a 3.15A fuse and someone even took a 4A out of theres! Wouldn't fancy using a 4A but i think a 3.15 will be ok hopefully. I would use a 2.7 or similar if i could find such a fuse and see if that was enough but i cant find anything between 2.5 and 3.15.

    fingers crossed
     
  6. bob1

    bob1
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    Most people just put a 13 amp fuse in everything :D
     
  7. Nic Rhodes

    Nic Rhodes
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    Paradigm are useless here, been there, tried that wine :)

    I will stick a power meter on the sub and power it up. Be warned that sub powers are 'iffy' at best in their accuracy so I wouldn't read too much into that.

    I doubt 3.15 will cause any issues tbh
     
  8. CYRUStheVIRUS

    CYRUStheVIRUS
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    I put a 3.15 as in mine 6 months ago,
    Touch wood:D
     
  9. Nimby

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    This talk of uprating fuses is apalling.

    Let's assume you forget (or don't bother) to turn off your sub at night and you live near the ground floor in an older, high population density, multi-storey form of accomodation without fire alarms or fire escapes.

    The sub sits beside a foam-filled sofa. The sub overheats. The fuse doesn't blow. :rolleyes:

    I'm still waiting for a policy response from a moderator.

    Does a Paradigm representative want to comment on these safety problems?

    I know I wouldn't want one anywhere near my family or my property.

    Nimby
     
  10. sparkymarky

    sparkymarky
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    so what would you suggest in order to get around the initial spike on start-up?? The only way i can see is to start up with 3.15 then, with the amp hanging out, bridge across the fuse holder with something conductive remove the fuse so that the electrons now flow through the other item and then put in the 2.5A fuse.

    Don't know about you but whilst it could easily be done and i wouldn't be afraid of doing it using rubber gloves, it's not really worth the risk of damaging the board, cone or myself. I don't think that 0.65 of an amp is too much of an increase to cater for.

    I understand your concerns though.
     
  11. Nimby

    Nimby
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    I'm glad you added the last sentence.

    The rest is just bølløcks!

    Nimby
     
  12. sparkymarky

    sparkymarky
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    Excuse me? why so?
    In order to get a 2.5 fuse in there that would be the only way of doing it.

    Mods feel free to close if you want.
     
  13. avanzato

    avanzato
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    Sounds like Nimby will be better on this than me but IIRC there are two types of fuse available: Slow blow and Quick.
    If you put a quick blow fuse in place of a slow it will probably go 'quicker', so worth checking what type you need. From my little electrical knowledge at college fuses blow for a reason and it's best to find out why it's blowing rather than uprate the fuse.
     
  14. Nic Rhodes

    Nic Rhodes
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    Paradigm will not even acknowledge there is a fuse in side and tell you to go to an authorized service centre. I am glad the guys at RS are such experts here :)

    I am also 'twitchy' about fuse rating but the difference between 2.5 and 3.15 is sodd all.
     
  15. CYRUStheVIRUS

    CYRUStheVIRUS
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    I agree, a 3.15 will still blow before any real damage can be done.
    (although i do not recommend changing the fuse in any electrical appliance for a higher rated fuse).
     
  16. sparkymarky

    sparkymarky
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    yep i agree thats its not a huge increase.

    will be keeping it in there.
     
  17. Nimby

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    I still keep seeing this image of you fried to a crisp, still wearing an immaculate pair of pink Marigolds. :devil:

    Not a pretty sight! :eek:

    Don't try this at home children! :lesson:

    Nimby
     
  18. eviljohn2

    eviljohn2
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    Surely this begs the question of how well manufactured are fuses in the first place? :confused: I would imagine +/- 0.2A to be fairly common before we even begin to consider any variations with tempmerature, crystalline flaws etc.
     
  19. sticker

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    Well one of my Servo 15's blew its fuse about 8 months ago. I took it to my local Richer sounds who happen to have a resident engineer on site. He replaced the fuse with the 3.15 version and told me that it was a common fault on the Servo 15's. I queried whether the increase was a danger, he responded that .65 made no difference what so ever.
     
  20. wookie

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    You'll quite often find a US model of said subwoofer uses a higher fuse.
    USA voltage is about half of ours, the fuse in the sub is rated at double ours.

    You won't hurt a thing.

    :lesson:
    A 6amp fuse can carry a lot more than 6amps!

    If you are woried about upping the rating of the fuse, buy a "time lag" fuse 3.00TA.
     

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