Radio frequencies picked up by phono stage.


I a while ago started picking up radio signals through my phono stage(I isolated it to that component) which is coming through my speakers. I have looked at every possibility in my apartment from reading exhaustedly on the subject here(even asking others for advice) and throughtout the internet. I have tried every possible solution offered. Nothing has helped. One expert told me that radio waves are coming in from outside my apartment which makes the most sense. He also told me to put the phonostage in a box wrapped in tin foil which did not help.

I live in a dense city area and I assume somebody put up an antenna which is interferring with my system because it initially sounded perfect. Complete silence. Digital is fine.

I've been told to simply accept it and get rid of analog and throw in my lot entirely with digital. I would hate to as I love analog so much. And comparing same recordings on analog and digital analog comes in some cases jaw-droppingly on top.

A strange thing as well one channel is much louder with the frequencies than the other. One is quiet enough that the music would cover the sound but the other is much too loud. I tried moving around speaker cables and same thing.  I have had two analog experts over though not engineers and neither was able to help me. 

Has anybody had this problem or known anybody with it? Were they able to solve it or did they have to give it up? I have tried both tube and solid state and same problem.

Thanks for any thoughts or advice you may have.

 

roxy1927

You must use SHIELDED PHONO CABLE

FINALLY, a real problem thread.

You of course use  shielded IC's. Does reception change with  physical location or with unit orientation?

 

 

 

Yep - What interconnect cables are you using?  I had the same issue and had to change interconnects (shielded).

+1 shielded ICs

If it is the phono pre, try grounding the chassis directly to a grounded outlet.

@roxt1927 - What is the phono stage and pre-amp (or amp) you are using?

Thanks

Something is acting as an antenna. Disconnect the cartridge leads, all four of them. Does the interferance go away? If not, disconnect the tonearm cables from the phono stage. Then disconnect the tonearm ground. Isolate the problem and you will find the solution. I have seen cartridges do this. The worst was a Grado Ref. Also, poorly grounded tonearms. Also think back. When did this start and what did you do just before it started?

The cart is the antenna. It's the only place that grounded foil wrap might make a difference. Maybe not.

A strange thing as well one channel is much louder with the frequencies than the other. One is quiet enough that the music would cover the sound but the other is much too loud.

Big clue here, hinting the problem is a connection or routing and not shielding, and that at the very least you should be able to bring the level of the noisy one down to the level of the quiet channel.

Have you tried listening while moving wires, wiggling connections, moving components? Move one wire at a time, starting with the noisy one. Start where it goes into the phono stage. Listen while wiggling the RCA. Twist it. Slowly unplug it part way. Listen the whole time. Then listen while moving the interconnect. Work your way like this all the way back to the cartridge pins. Do the same with them. I recommend tweezers.

Cartridge clips by the way, if they are loose- pull and crimp. Very important- use a round toothpick to avoid crushing! 

Was tracking this down with a friend one time, he picked up the phono stage to move it I said, "Freeze! Right there!" Turned out all he had to do was stand there holding it, I could hear music just fine. Seriously. It sounded real good. For some reason he kept on going looking for a better solution. Never could figure that one out. All he had to do was stand there holding it, I could hear just fine!

I tried moving around speaker cables and same thing. 

No idea what this means. Your problem is somewhere between the cartridge and the phono stage output. Unless your turntable is on speaker cables I doubt they have anything to do with it.

Change your phono cable first (if you have another), make sure it's shielded phono cable. I hope some of your audio friends can give you another phono cable. If you have broken soldering joint in one of your RCA or DIN connector you need another cable to make sure. 

Swap RCAs left to right, see if it follows the cable or the channel. Because the cables are ran so close together if one is noiser that could be a shielding issue if one cables shielding (left or right) was NOT working correctly... Possible broken or poor connection just on the sheilding.. I can see that being the issue..

 

You do have things routed it's not a rats nest.. 1" between cables and cross at 90 degrees and 1" between crossings.. A cable will normally yo yo as you raise it up or down. 

 

Clean ALL the connection and make sure they are plugged all the way in..

 

Regards

Any one or more of the above suggestions might help. I can only add a question , was the tinfoil grounded when you wrapped your phono stage in tinfoil?

Thanks for your resonses.

The phono stage I am using now is an inexpensive pro-ject after selling off a beautiful Allnic in frustration. But through the help of a friend I was able to try various stages and found the exact same problem.

I have tried moving the stage all around the room and no difference. I did not ground the box covered in tin foil and would be clueless as how to do it. My cables and interconnects are boutique labels such as Black Cat which give great sound for the price and I am told they are shielded.

This sound happens even when the turntable is completely diconnected from the stage so I don’t think the cartridge or turntable as anything to do with it and they were playing beautifully before the sound appeared.

So the sound is happening between the phono stage and the pre. and I have even swapped out these interconnects with no alleviation. This really has become impossible.

I will do more interms of cleaning connections. Have tried moving components but that is limited as I am in a very small space.

Maybe I should spend more time wiggling wires and connections

Millercarbon what did your friend eventually do as I doubt he wanted to stand there holding his phonostage everytime he wanted to listen to lps?

 

 

@roxt1927 - try the following

- get e length of wire, enough to attach to a grounding point and within rech of the phono stage

- attach one end to the grounding point

- touch the free end of the wire on the neutral collar of the input socket

- if it is still noisy touch the free end to the neutral collar of the output socket

Does anything change?

Regards

My cables and interconnects are boutique labels such as Black Cat which give great sound for the price and I am told they are shielded.

Some Black Cabels cables are not shielded if it’s not a dedicated PHONO cable. I owned several Black Cat interconnect cables and they are not good for phono signal, they are good as interconnect cables, but not for phono signal. Do you understand the difference between Phono cable and Interconnect cable? Change your cables if your model is the same as Black Cat Morpheus or similar models.

 

FWIW this could also be occurring at the output of the phono stage. I would at least try a different set of interconnects at the output of the phono section to see if that had any effect.

RFI can be really pesky. A phono section that picks it up can wind up being shipped back to the manufacturer for repairs, so usually some effort is made to prevent it happening. But not all designers work with the same tool kit! Several things affect RFI:

RFI injected at the input. RF beads can be installed to prevent RF getting to the input section if it makes it past the input connector. If the phono section is lacking 'stopping resistors' it can be prone to this sort of thing since the input device (tube or transistor) can then serve to rectify the RF, causing it to become audible. Stopping resistors can cause a Miller Effect high frequency rolloff, preventing RF from entering the gain stage. Don't worry if you don't understand what I've written, but if you send the unit back for repairs, point out this post to the manufacturer.

RFI introduced by poor grounding. This may be as simple as a bad power cord or a loose screw in the breaker box. Poor ground does include the grounding scheme of the equipment as well. 

The thing is, we're likely looking for something that has changed, since this problem suddenly showed up. For that reason I'm suspicious that the cause is outside of the audio system itself; IOW I think its a bad ground.

My cables and interconnects are boutique labels such as Black Cat which give great sound for the price and I am told they are shielded.

 

This is my old Black Cat Morpheus cables, they are not shielded!

They should NOT be used for a signal from a phono cartridge (no matter MC or MM) before the phono stage, they can be used as interconnect in analog chanin only after the phono stage.

 

 

You can get your FREE trial for Zu Audio Phono cables, try them and return them for full refund if you don't like them. At least you will be able to compare properly shielded cable to your Black Cat. 

I had radio pickup when I installed a Naim superline phonostage in place of a Michell iso, a known susceptibility of the superline, cartridge was a Dynavector 17D2 The obvious answer of just using the iso wasn't on as the superline was so much better in every other respect. Adding a 1nF to the 470Ω cartridge loading diminished the level to where it didn't intrude, 470pF was nearly as effective and preferable musically but no playing around with grounding various components made any difference, including changing the arm from my original Rega 300 with its rather odd grounding setup. Finally a change of rack to a largely non metalic one cured it, serendipitously as that wasn't why I changed it. I presume there was a focussing effect from the steel in the old rack, much as happens in a multi-element aerial.