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Surge protectors-why is it restricting sound?

Discussion in 'audio' started by Philim, Apr 15, 2013.

  1. markt

    markt hello

    I think of hifi as a circle of self produced and incoming dirt, battling it's noisy electronic environment but still managing to give something beautiful despite itself.

    It's all imperfect.

    DANOFDANGER pfm Member

    Ok so do you believe in shielded heavy duty high quality power cables ?, or any other exotic cable that suggest improvements over the mains supply.

    Or are you just suggesting components before the amplifier which are on the same circuit have a inherent effect on the resulting output. Eg conditioners, surger protectors, x y caps etc.
  3. markt

    markt hello

    Do I believe they (posh audio cables and bits) will make a beneficial difference? Possibly very small and hardly discernable difference, yes. Not worth the effort, not over and above already oversize but unsheilded house wiring, the sheilding will just be tried to a ground with finite impedance at RF and limited use.

    Does everything effect everything else? Probably, yes, I think so.

    Is it something that can be cured by 'audiophile' equipment, I don't think so, I have not found anything worth the money.

  4. markt

    markt hello

    With the possible exception of a diy DC blocker, which a few knowledgable diyers on this forum have used and think is beneficial to them.

    All this has given me an idea.

  5. sq225917

    sq225917 situation engineer

    I use the Sjoistrom Audio DC blocker. It massively reduces the mechanical him on my power amp transformer and also lowers the small amount of sizzle I get at my speakers. It ha no apparent downsides.
  6. markt

    markt hello

    A good start on this subject btw can be found on Martins acoustica website mains related page: http://www.acoustica.org.uk/

    Ben Duncans Black Box series articles published in Hifi News late ninties (and I believe still available from him) are a good read too.

    It's a very complex subject the likes of which I'm unlikely to have any useful answers to other than preventing problems appearing in the first place.

  7. markt

    markt hello

    Sounds good, at the very least it does something plausable.
  8. dweezil

    dweezil pfm Member

    Also the transformers are ac throughout so wouldn't any of the storage they allude to in magnetic fields only be available for one input cycle?
    ie 0.02 seconds
  9. ToTo Man

    ToTo Man the band not the dog

    Mark, whilst I'm in the process of replacing my power strips it's probably a good time to check the condition of the plug wiring in my older gear with non-moulded plugs and make sure they have the correct values of plug-top fuses fitted! I was wondering if you could advise on the following please:

    I have a 1974 Yamaha CR-1000 amp/receiver (70wpc RMS output @ 8 ohms), a 1977 Yamaha CR-2020 amp/receiver (105wpc RMS output @ 8 ohms), and a 1976 Pioneer SX-1250 amp/receiver (160wpc RMS output @ 8 ohms). The rated power consumptions are 250W for the CR-1000, 890W for the CR-2020, and 1200W for the SX-1250.

    With basic application of the P=IV formula, the CR-1000 will draw on average 1.1A thus warranting a 3A fuse, the CR-2020 will draw on average 3.9A thus warranting a 5A fuse), and the SX-1250 will draw on average 5.2A thus warranting a 10A fuse.

    This of course ignores peak and/or in-rush current consumption, so I'm wondering if the fuse values should be upscaled to 5A, 10A and 13A (or even 5A, 13A and 13A), respectively? Is there an approximate 'overshoot' formula I can apply or am I better to invest in a power monitor and monitor what the actual consumption is from each unit on switch on? (As the equipment was purchased used I cannot be 100% sure of the ratings plug-top fuses the equipment originally shipped with, hence my confusion!).

    PS - Surprisingly, the "power hungry" SX-1250 is fitted with similar gauged (i.e. relatively thin!) brown twin-core flex that the CR-1000 is fitted with. I'd have expected a heavier gauge of cord on the SX-1250 given the unit's relatively high power draw. Perhaps they weren't so safety concious in the 70's???!!! :confused:
  10. sergeauckland

    sergeauckland pfm Member

    It would seem so, wouldn't it!

  11. markt

    markt hello

    No, those values are peak values ToTo, unlikely ever to be seen except for momentary inrush, I take it these are usual class a/b or class b designs, maximum power usage had to be displayed on the case leading some to think that that is what they actually used all the time! My class a/b amp is 150w/8 ohms and uses 30w idle so a long way from that max figure.

    The fuse in the plug top is to protect the lead and should be so the fuse capacity is in line with the cable capacity, if something in the appliance goes short circuit the cable must be protected from over ampage by a fuse that will blow before the cable melts or catches fire, In other words you shouldn't put a 13amp fuse in a plug for 0,5mm flex.

    This is a common confusion as to what a fuse is actually for and more recently equipment has a detachable lead and fusing of the actual equipment is either on the chassis or inside on the psu, this protect the equipment not just the cable, the cable must be fused so the cable is protected from melting regardless of the chassis fuse, the reason it is fused in the plug top regardless of the chassis fuse is because the detachable lead could be used with other unfused or modified equipment, the fuse in the plug top of a detachable lead is to protect the cable and not the equipment as such.

    I have several older pieces of equipment from the 90s that just have a plug top fuse and no internal or chassis fusing so the plug top fuse is the protector of the lot.

    3 amp should suffice in the plug tops but many use 5amp or even 13amp on skinny cable that usually should be running a 3 amp fuse!

    It's your choice, but the electrician (not me) will say for safety you size the fuse as low as possible without the risk of blowing on in-rush, I'm sure loss adjusters would use post accident info to their advantage if it were possible.

    Talking of power monitors, I've just bought another from Maplins as my old one was not working, very impressed with the new one which includes power factor and VA as well as the usual volts/amps/kwh, cost me twenty pounds, ther was another model without the PF for ten pounds, these are good devices to have around and every one should have one!


    PS, I need to dig out an electric installers wiring code book, there is something I'm missing on this but I don't know what.
  12. markt

    markt hello

    5 amp fuse for the larger Yamaha ToTo the Pioneer too, but test a 3amp on those and see if the inrush takes it out..
  13. ToTo Man

    ToTo Man the band not the dog

    Great minds think alike, Mark, - I was in Maplins yesterday and bought the very same monitor! :)

    Thanks for clarifying what the wattage ratings on the back of equipment represents. I had a fair idea that the consumption through "normal use" would be much lower than the printed values (especially given that I only listen at between 1wpc and 10wpc!) but was clueless as to what the inrush consumption may be. I guess I'll find out tomorrow when I add the power monitor to the circuit! ;)

    PS - Is there an easy way to determine the approx gauge of a flex lead? The lead on my SX-1250 has always been of slight concern to me, but it was the lead that Pioneer supplied and has appeared to be fine for the last 35 years so one would hope it is of adequate gauge(!)....
  14. markt

    markt hello

    It's probably a 0.75mm core, they usually have some writing moulded into it to indicate. If it's in good nick I'd not change it, it'll be ok size wise. Compare against an old scrap of lamp flex if nothing else. There is nothing actually wrong with increasing the cable diameter a bit, you might be able to get a size up through the chassis cable clamp but sometimes after you push it back in you might find that the clamp is just making a mess of the cable and it's too big and you end up going back to the skinniest cable as there are no spare clamps in the parts bin.

  15. ToTo Man

    ToTo Man the band not the dog

    A couple of interesting observations from using a power monitor I recently purchased from Maplins:

    My mains supply ranges between 238V and 248V, mostly sitting at ~244V, which is a little higher than I expected given that UK mains is now supposed to be ~230V, but I guess is still well within the limits (especially those of my older gear which is properly rated for 240V). On the other hand, perhaps this higher mains voltage is the reason why I need to keep replacing my 230V GU10 Halogen light bulbs a little more often than I think I ought to!...

    I've also been monitoring the consumption of my CR-1000 and CR-2020 amplifiers, which have rated consumptions of 250W and 890W, respectively. The CR-1000 in-rush consumption measures ~352W, which implies a maximum draw on start up of ~1.5A, therefore a 3A plugtop fuse is indeed sufficient here. The CR-2020 in-rush consumption measures ~478W, which implies a maximum draw on start up of ~2.1A, so again a 3A plugtop fuse would probably be sufficient for this unit too, assuming the consumption never exceeds ~690W (which I guess it probably won't since I only use ~10% of the amplifier's RMS power output capacity). FWIW the idling consumption of the CR-1000 is ~68W and the CR-2020 is ~46W, which makes me feel a little less guilty about leaving them on all day! :D ).
  16. Mike Reed

    Mike Reed pfm Member

    Assuming all this research will cause you to transpose your 13amp. plug fuses with 3 amp. ones. I'd be interested to see if you notice any degradation of dynamics over a period of listening.

    Not into fuses myself, but my logic dictates that reducing fuse sizes is counter productive from an s.q. standpoint.
  17. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!

    The mains voltage is 230V +10%-5% they didn't change all the power stations and transformers just the tolerance, it was far cheaper ;-)

  18. sergeauckland

    sergeauckland pfm Member

    Unfortunately this logic is wrong. The energy for music peaks comes from the reservoir capacitors, NOT the mains. Consequently, the tiny difference in mains impedance resulting from correctly fused plugs, compared with excessively high fuses is totally inconsequential.

    Also, consider that the mains has to go through a transformer and rectifier before it even gets to the reservoir capacitors. The resistance from those two completely swamps fuse resistance differences.

  19. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Yer wasting ya time Serge. I've tried explaining all these things before and to no avail... once people have imagined a difference no amount of science seems to matter :D
  20. Mike Reed

    Mike Reed pfm Member

    As Jez says, Serge, you're wasting your time. The ability to explain everything in technical terms is all well and good, but not a consistently true arbiter of the real world (of hifi).

    I wouldn't have a clue whether one would tell the difference between mains fuses on an averagely good system as I don't use them at all. However, the difference manifest by obviating mains fuses is very marked on some kit/systems. This is only feasible on properly installed dedicated mains, though, which limits its use somewhat.

    Theoretically, though perhaps not technically, I still maintain that a 13amp fuse should be preferable to a 3 amp. one. As the fuse only protects the cable, what's the point in downsizing fuses anyway?

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