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Cartridge/RFI

I just bought a used BAT VK-P5 and I am getting a buzz from both channels that will increase and decrease with the volume control. I have Nuforce 9.02 mono amps that I know have RFI issues. I can also notice a change in the buzz when I touch or move the tone arm. Is the cartridge reacting to RFI? Has anyone else had any experince with this type of problem? Everything sounds great when I am playing records, but this is just eating at me. I have played with different cables and that helps somewhat. I even get the buzz when the turntable is disconnected from the phono pre.
I didn't notice the problem with other tubed pre's either.
Thanks for any and all input.
Jeff
jdodmead

Showing 3 responses by morris

morris
29 posts
 
I had bad hum/rfi problems. It was due to an unshielded interconnect between the turntable and the transformer. Are you using an unshielded interconnect between the preamp and the mono amps? You can test whether it is the interconnects by using some freebie interconnects, which are all shielded. This is a technique recommended on the VPI website and it worked for me. Also, if the BAT uses tubes for the phono stage, it may help to replace the tubes in the phono stage with some low noise tubes. Also, make sure everything is grounded properly to reduce RFI. I feel for you, since I lived with the hum for almost a year before figuring out the cause.
morris
29 posts
 
I checked your system. If you are using Nordost blue heaven interconnects anywhere between the turntable and the amps, that could be the problem. I have been using red dawn and blue heaven and they were prone to RFI hum when used in the phono chain, even though they produced no hum, when connected to the DAC. I looked at your system. Is the turntable rack on wheels? If so, you could probably isolate the turntable better if you took the wheels off the equipment rack. Good luck...
morris
29 posts
 
I'm not a technical guy, but touching and moving the cables and equipment can affect the RFI. When I had the buzz the same thing happened. I think it is similar to an FM antenna when you move it around. Since this is a common issue, try searching on the Audio Asylum Vinyl Asylum and here to see how others dealt with it. Again, I'm not technical, but my understanding of this is that the cartridge emits a very low level signal which is then amplified much more than a line-level CD/DAC signal. As a result, you are amplifying the RFI garbage as well as the nice tunes going through your Scout. This is also why phono tubes have to be very low noise (and explains why you could hear hum/hiss without the Scout connected). You are pushing the envelop of what I know, but I'm glad to help if I can. Hopefully, others can provide a more nuanced explanation.

Thanks for the compliment. Even with all the technical puzzles, like hum, I've really enjoyed the system.
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