Is this RFI and what could it be doing to my sound?
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tomek

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Last night I was listening to some tunes on my 2 channel rig and since I wanted to listen more critically I went up to turn off my air purifier. The air purifier sits next to my power conditioner behind my rig. As I shut it off, I heard a loud crackle come out of the left speaker. I looked down and noticed that the power cord of my air purifier was touching my speaker cable. I lifted the cable up off the power cord and tried again and noticed no crackle. I repeated this several times and concluded that it was most definitely the power cord of my tiny little air purifier that was causing a crackle when turned off.

Now realizing this, I looked at my setup and wondered what the mess at the back of my gear might be doing to the sound. There are several power cords, plus the actual gear itself, tube amp and power conditioner.

Could this mess back there be causing audible changes to my system and how can I get around this?
 
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tortie

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Yes, it will surely add noise to your system. Route your cables properly. Line up all the ICs & speaker cables separately from your power cables.
 
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halcyon

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You can try two different things:

1) Buy shielded (Properly shielded, not just ferrite clamped) AC power cords to all your equipment, including the air purifier. This will reduce/remove induction from the AC power cords to your interconnect and speaker cables. IMHO, this is the recommended method (shielded AC cables can be bought for a decent price and they should not make a detrimental sound to your system).

2) Buy shielded interconnects (and some would say speaker cables, but I don't recommend the latter). This is usually more expensive, because you will have to find out which IC cables really offer a measurable shielding. You often can't trust manufacturer data on this. Unfortunately there are very little 3rd party measurements about IC shielding efficiency. Also, electrical engineers and hifi-nuts say that shielding (which raises the capacitance of the ICs) has a slight detrimental effect on the sound. This is also supported by blind listening tests (Finnish Hifi-magazine 2003).

In adddition, you could try connection all your motor using gear (most air purifiers have a motor) and non-audio equipment to different AC outlet and hopefully a different AC path altogether. This should reduce the amount of AC quality loss caused by the non-audio gear.

What is a good AC cable with proper EMI/RFI shield? I wish I knew. I've used Supra Lorad myself and my friend has measured it briefly and he tends to think it is a good cable and not too expensive (actually it's cheap if you consider most high end AC cables).

regards,
halcyon
 
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drewski

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OOOPS- I just read Halcyon's post and realized mine was pretty much a duplicate of what Halcyon wrote!


My guess is that it was probably moreso that your air purifier was plugged into the same circuit as your 2 channel rig. Even though you have power conditioning, there's often a lot of noise when you turn on and off appliances. I'd try to take any appliance off of the circuit that you run your 2 channel system on and go from there.

From your post, you already have a power conditioner, so that's a start... what kind is it and are you also running good power cords? That will help the most with RFI interference. Unfortunately, it's not cheap!!!
 
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tomek

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Ok, I guess I didn't make this clear.

My audio gear is plugged into the line conditioner, my air purifier into the wall.

It DIDN'T make any popping sound or crackle when the purifier's power cord was a considerable distance away from the speaker wire.

When they were in contact, the speaker would make a popping sound when I turned the purifier off. This was a wire to wire issue I think.

EDIT:

as for power cords, I'm using some shielded Volex cables that were recommended by some here as good, thick guage, shielded cables.
i have noticed before that there is a low level hum that my speakers are always giving off. i assume this is because they are efficient (97db) and i'm running off a tube amp which always has some noise. the left speaker has a louder hum though, and its the side where the speaker wire runs right past all the power cords from the line conditioner. perhaps i'll fiddle tonight and see whether some of that hum is associated with the power cords.
 
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