[Vicks7]

Hi All,
I have started picking up radio interference through my PPX SLAM. I have discovered that this is being picked up from the interconnect between the amp and cd player as when I change the position of the interconnect the interference varies. Other than swapping out my IC for something shielded (I presume the Van den Hull interconnect I use is not shielded), does anyone have any suggestions - it is really annoying

Thanks
James

 

[EdipisReks]

you could try ferrite beads on the ICs on the spot right before the jack on the Slam. also, try turning the amplifier and see if you still pick up interference. you could also try wrapping the ICs in aluminum foil, or moving your gear to another side of the room. i live in an area with a lot of radio stations, and RFI is a big problem. if you move your gear around, i bet you'll eventually find a position that is quiet.

 

[gordolindsay]

Good Luck!!!

That's about all the good news I can give you. I had that problem and tried everything, sheilded cables, ferrite cores, alumium foil, moving things around, keeping the IC's off the floor, making sure power cords and IC's were at a 90 degree angle, etc...

The ONLY thing that worked...buying a DC powered amp

 

[Solitary1]

Is there a cordless phone or wireless router closeby?

Quote:

Originally Posted by Vicks7 Hi All, I have started picking up radio interference through my PPX SLAM. I have discovered that this is being picked up from the interconnect between the amp and cd player as when I change the position of the interconnect the interference varies. Other than swapping out my IC for something shielded (I presume the Van den Hull interconnect I use is not shielded), does anyone have any suggestions - it is really annoying Thanks James

 

[Vicks7]

no, nothing like that I believe. It is so frustrating. Received my Merlins TSMs today and they really magnify the problem. Maybe a power conditioner is the answer.

 

[Blitzzz]

I've tried ferrite cores before, they didn't help

 

[Senn20]

You could build a faraday cage around your rig!

 

[Vicks7]

my speakers are also picking up the RFI and it is clear that the problem is the power supply. I will experiment with some power conditioners and see if this helps - it is really frustrating especially as my Merlin speakers arrived yesterday and it is really spoling the listening experience

James

 

[sacd lover]

Are you sure you dont have a ground loop?

 

[Usagi]

The length of an interconnect probably determines what radio frequency you're picking up.

 

[sidewinder]

Is it like that annoying sound you get when your cellphone is close to your speakers?

 

[rickcr42]

Don't know the topology of the PPX Slam but if it uses feedback the RFI could be entering through the headphone cord end and not the input side.

The "fix" is internal and consists of some inline resistance outside the feedback loop from amp ciruit output to headphone jack.Something around 100 0hms.Better even is one of these puppies.They work.Period :

http://www.jensen-transformers.com/datashts/oli3.pdf

If the amp is all open loop then again the ferrites on the input cords plus a simple RC RFI filter network right across the input RCA jacks and if extreme even some series inductance (ferrite beads)from the jack after the RC network to the amp input circuit.

Then there is the possibility of a cold solder joint internally.Happens.This causes what is known as "rectification" and actually will turn that amp into a radio receiver if at the beginning of the gain stage or at the end of a feedback loop.The simple fix here is identifying it and re-flowing the joint.

Other than those possibles you are pretty much screwed unless you can nail down the cause and either remove IT or the AMP from the path of the RFI.Sometimes just moving an amp six inches one way or another or even at an angle cures it and being 100% free worth a shot.

 

[Vicks7]

Thanks for all the advice. Even with the PPX out of the circuit and just using my two channel system I am getting the RFI. The actual noise is a radio station. How do I see if I have a ground loop?

 

[rickcr42]

Quote:

Originally Posted by Vicks7 Thanks for all the advice. Even with the PPX out of the circuit and just using my two channel system I am getting the RFI. The actual noise is a radio station. How do I see if I have a ground loop?

You mean with speakers also ?

Source ?

Have you a preamp stage between your source and amps and was inline with your headphone amp also ?

You need to identify where the RFI is entering and my guess is at the beginning of a gain stage or you would not be hearing it so clearly.If the source is vinyl then it is a no brainer but if not way harder to figure without more clues

 

[Vicks7]

Yes, through the Merlin Speakers. Source is an Eastsound E-5 CD Player. Preamp is Audiolab 8000LX and power amplifier is Tag Mclaren 60P. All gear is 240 volts so I run it through a step up transformer to up the Brazilian 110 volt mains supply. However, the PPX SLAM that was sent to me was 110 volts and when I plug this directly into the Brazilian mains I also get the RFI so I think it is coming from this mains outlet. I thought the transformer might have cleared things up but unfortunately not. I tried plugging the PPX SLam into other outlets in my apartment and in the room immediately next door to my listening room I also got RFI but did not get RFI in my main lounge. I have tried changing the configuration i.e. by taking the PPX Slam out of the system (I am using the SLAM with a loop out to my amp) but the RFI remained.
James