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advice re: hum and passive distribution bars.

Need some advice from the experts please. I've got two dedicated 20 amp lines installed ( on circuits 1 and 3 on the same side of my electrical panel , hopefully in phase?) they travel across my garage into my living room ending with 4 available power points. When I use both lines(normally one for the cd the other for the amps. see system for more details) I have a very very low level hum only heard with ears near to speakers. However when I connect all my system to just one of the dedicated lines using a two way adaptor to help accommodate the three pieces in my system. I have no hum . Any ideas to what I should get my electrician to change with regards to the two lines installed ( for example. widen the cable runs further apart or twist them together? , change earthing at circuit box? ) which will allow me to use both of them with no hum. Lifting the ground (tried on the cd or pre but didn't try on amp) which I'd rather not do anyway didn't help. I use XLR cables throughout and don't have any tv's/ cable boxes in the same room. Also what are your thoughts on the possible advantages or not on using a high quality passive power distribution bars such as, but randomly selected,Supra, ESP, Nordost ( thor) or Acoustic revive (RTP-4) which always get rave reviews where one is only using a single electrical output but obviously mixing digital and analogue components on it. As compared to using the separate dedicated lines. Thanks.
pcoombs

Showing 4 responses by pcoombs

pcoombs's avatar
pcoombs OP
84 posts
 
Kirkus, I don't think I explained myself very well, The two breakers I'm using are both on the left hand side but have a different breaker between them. So its the top one and third one below it. Thanks again for interest. Philip.
pcoombs's avatar
pcoombs OP
84 posts
 
thanks for the post Kirkus , I'll try and get a voltmeter soon . I'm presuming that they come with two probes so I can insert them into both 'hots' at the same time.? Not quit sure what you mean when you asked "Are they wired to two physically separate electrical boxes, or have you used any ground-isolated outlets or such?" All i know is my main breaker box has 14 separates breaker box/switches on both sides with the two ones used for my system amongst them (in the top and third positions as I described before) How would I check if these where ground -isolated or not? If I didn't want to go to all the hassle of having new electrical boxes installed as you suggested would is help or make any sense to just get the electrician to put the two sets onto just one circuit sort of like bi-wiring speaker cables? and just free up one of the 20amp circuits for something else. Or even just use one of the lines as is for the whole system with an added distribution bar of some sort. Thanks again Philip.
pcoombs's avatar
pcoombs OP
84 posts
 
Ok, heres the update, tested lines with volt meter. Definitely both circuits on same leg. which is good .All screws in outlets where fully tight. I tried all three components on one circuit only, both with and without cheater plugs throughout with same results, no audible hum. ( just a super faint sense of some noise compared to nothingness when I de-mute my line stage , which I'm presuming is perfectly normal) I've also put two components, for example amp and cd on one line and the line-stage with a cheater plug on the other line , again no hum. So the hum which is, I should stress very very low in nature can only be heard when I use both circuits without any cheater plugs being used. I went up into my garage loft to look at the cable runs. they are stabled together along various joists There is in the middle of the loft floor possibly the garage a door opener power supply/transformer? sticking up which the cables run to about 6 " at its closest . Would it be worth spreading the cables apart from each other and further away from whatever that is? Even if i manage to somehow remove the last vestige of hum from when using both lines I'm still wondering if I should focus on only using one anyway along with a quality distribution bar.
pcoombs's avatar
pcoombs OP
84 posts
 
Thanks for the advice Jea48 I'm going to try it. Just to be certain I understand the bare wire should attach between and connect to both the receptacles by just pressure after (tightening back down) onto the bottom metal body work ( supporting straps) that has the holes used to screw duplex into wall. Rather than the actual earth wire screw that are located on bottom left of each receptacle. At least as a temporary test method. Thanks again Philip.
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