Eliminating RFI

Dear All
I am experiencing problems for the first time with RFI through my Singlepower headphone tube amp. I have concluded that it is due to an unclean power supply as I do not pick up this interference using a wall plug in another room in the apartment and as I have also swapped out power cables and interconnects in the room to no effect. Most of my equipment is UK 240 volts and I run the mains (Brazil 110 volts) through the transformer to the equipment - however, I have never experienced any problems with this equipment - but as the headphone amp is 110 volts I am running it directly through the Brazilian mains (without the transformer) and I am now having problems.
Does anyone have any suggestions for me to eliminate this interference? I need to keep all my gear in this room so moving it all to another room is not an option unfortunately.
Many thanks

EMI is tricky. I suggest that you check that the outlet ground is connected and securely tightened. Also other devices connectd on that same electrical line can re-radiate EMI back into that outlet. See what else is on the same line and unplug each device one at a time to see if the problem goes away. Be very suspicious of computers.
You may want to try some Stillpoints ERS cloth, just a little should do the job.
buy a cary audio cad 5500,its a tube cd buffer that removes RFI from the signal & it works like a mo fo.
You might need one of these


LOL ;)

...sorry for not being constructive ....i just couldn't help myself....
Thanks - just what I have been looking for!!
"Thanks - just what I have been looking for!!"

WAIT! Don't forget to audition THIS model, too!
Ok, seriously, here are some possible ideas:
1) Is there any way to run the current to the headphone amp thru your 240 volt stepdown transformer, or does it REQUIRE an input voltage of 240?
2) Or, if using ERS cloth, what I've been told is that lining the little outlet box casing with the ERS material is the way to do it, and not to use "too much."
3) Possibly consider a "power conditioner" that has its own transformer, or some even better technology.
4) Check the Singlepower owner's manual to see if there's anything about grounding which you may have overlooked.
5) Contact Singlepower directly for pointers.
6) Google search, if all else fails.
Thanks Bill.

The amp runs on 110 volts and my transformer is a step up transformer which I use with my UK 240 volt equipment so I cannor run the amp through this transformer.

I presume my step up transformer is also cleaning up the power as I have never experienced RFI with this gear, only when going through the Brazilian mains.

I may try this ERS material - where would be the best place to use it on the amp? By outlet box, do you mean where the mains is located at the wall socket? Would you just stick it around/over this wall socket?

As suggested I will also contact Singlepower.

Thanks again


I'm told that one needs to be VERY careful not to get any ERS paper inside any component chassis, because it has conductive particles that can really wreak havoc on the internal circuits of such equipment, with shorting, etc. So, if using on the amp, make sure to put it on the OUTSIDE, one sheet on the top of the unit to start with.

The part of the outlet assembly that I'm referring to is the housing (box) itself, that metal casing that the outlets sit within. I was told to just line the inner surface of this outlet box with a single layer of the ERS material. This means that the sockets would have to be removed, leaving the empty housing box, which would then be lined by the ERS paper. Apparently, the ERS cloth has a high damping factor, so if put TOO close to the signal path, or if used in too large of quantities, it can restrict dynamics. Staying just inside the box's inner surface should be okay, though. You may want to contact Stillpoints about this topic also.

It would seem to me that the first order of business would be to rule out a circuit malfunction on the part of the amp in question, hence the contacting of Singlepower as you mentioned. If that turns up nothing, then I'd proceed to the ERS cloth, and see if that would work.

The helmets would be a last resort......

Etbaby said:
"I suggest that you check that the outlet ground is connected and securely tightened. Also other devices connectd on that same electrical line can re-radiate EMI back into that outlet. See what else is on the same line and unplug each device one at a time to see if the problem goes away. Be very suspicious of computers."
Sounds like a very good idea. Another question: Have you checked to see if the problem occurs with the other outlets in that same room (if there are any others in that room)? If none of the other outlets cause the problem, then it's likely that particular outlet. If not, then it's likely that particular room and/or electrical line.*
*This is of such interest to me (in case you were starting to wonder....) because I'm in the middle of dealing with my OWN RFI/EMI problem, which may be solved, not sure yet.
I have checked each and every outlet in this room and the same problem occurs. The problem also occurs in all the outlets in the room next door. I have tried unplugging all other devices, swapping interconnects and powerchords but to no avail. I am no expert on these things so what do I look for to determine if the outlet ground is connected?
"I am no expert on these things so what do I look for to determine if the outlet ground is connected?"
Neither am I. (I THINK there's a copper wire in the middle of the thing that screws down.) Etbaby may know. I'll bet Albert Porter knows, too. I had an electrician install the Porter Ports for the dedicated circuit that we recently added. For me, one of the downsides of attempting something like that as a "do-it-yourself" project would have been the somewhat unpleasant prospect of getting electrocuted.....
Have you made any progress with your RFI problem?*
*My own RFI problem has been largely ameliorated, but not entirely solved. This is an extremely difficult problem given that RFI can be airborne or carried through the lines, or sometimes generated by the equipment itself. Another dilemma is that dampening materials can sometimes cause dynamic range constriction. Also, trying to find a single, coherent source of information on this topic has been difficult for me. So it would improve my morale to know that someone else (i.e., you) has been able to defeat or at least largely tame this beast.
Unfortunately not, although I am starting to think it is also airborne. When I was adjustimg my speaker cable by taping it to the floor (to stop it hanging in the air) the RFI seemed to reduce in strength. So, with a CD, Amp and Speakers I get the RFI through the speakers and if I plug a headphone amp straight into the mains with nothing else other than a headphone cable I still get RFI. Very frustrating. I am auditioning some Audiopax gear at the weekend and I have asked the dealer to bring some power conditioners as well to see if this helps.
Another idea that may or may not help: Ferrite cylinders that clip around your cables. Don't know for sure how much dynamic damping they cause. A pricey alternative to consider would be Z Sleeves by Z Cable. Here's a link to those:
Z Sleeves by Z Cable
I've never used them, only heard of them. Good luck and don't give up yet.
A small "Faraday cage" may work. A Brass or copper screen box that would cover the encloser of your headphone amp. Thinking about it for a moment, I have seen various "metal" mesh containers and other "mesh" office supplies at Office Depot and even Wal-Mart. They are painted, so I don't know the metalurgy. I am certain that the stores would think not highly of anyone scraping the paint off of them before purchase, but they seem cheap enough. For a few bucks it might be worth a try.

If you can find shorting plugs, try them in any unused inputs on your preamp. They are helping me w/similar issue. Cheers,