2. amps-preamps
  3. 165892-160324

Preamp making loud pitched morse code sound

I just hooked up the final parts of my system this weekend and am getting this pretty awful noise that I can't figure out the source of. I would be GREATLY appreciative if someone were able to help me out. I'm very new to the hifi world so needless to say, it's pretty frustrating to finally have everything hooked up and get an awful noise when I was expecting smooth sailing (silly me?). 

I have a cambridge cxa81 integrated amp and kef ls50 meta speakers that I've had for a few weeks now listening to digital music through Tidal until my turntable/preamp arrived and it's been a great experience. I finally picked up my turntable/cartridge/preamp on Tuesday - rega p6 turntable, hana ml cartridge and sutherland kc vibe phono at stereo exchange in nyc. the sales rep was very nice and put everything together for me in the store to make sure things worked properly before I left. When he hooked up my turntable/preamp to a receiver/speakers in store, it sounded great but it was picking up some radio frequency which we found very strange. We thought maybe it was an issue with where we were and that the issue would go away when I hooked it up at home.

https://www.icloud.com/photos/#0sPNXSiNWROvNUUnRmh1YSglg here is a video of the issue i'm experiencing. I've been searching online since this afternoon and can't really find an answer. Everyone I hear talking about the kc vibe raves about how quiet it is which is obviously the opposite of what I'm experiencing. As soon as I turn up the volume to around 10-11 o'clock, you start to hear it at a decent level, then it gets louder as I turn the volume up. It's subdued when I actually play music, but you can still kind of hear it in the background if you try, or put your ear closer to the speaker. 

What I've tried from the time I've spent online looking for an answer: turned phone on airplane mode and turned off router (not sure how much that'll since I live in Brooklyn where RF/EMF is flying around everywhere), plugged the preamp into a different power source then everything else is plugged into, moved the preamp further away from the system setup, unplugged my tv...I think that's it so far. 

I also plugged my previous turntable, audio-technica lp120 to the kc vibe and still hear that sound. When I plug the lp120 straight to the receiver and use the onboard preamp, I don't hear anything. 

There's absolutely no noise when I switch the input to listen to music digitally, just when i turn the preamp on. 

Any suggestions? 
wally828
Post removed 
wally828 OP
9 posts
 
How did they “fix” it?

I tried running the preamp out to my recover without the turntable plugged into the preamp and still heard the noise. That eliminates the possibility of it being the TT, right? 
yogiboy's avatar
yogiboy
5,677 posts
 
"When he hooked up my turntable/preamp to a receiver/speakers in store, it sounded great but it was picking up some radio frequency which we found very strange."

Return it to Stereo Exchange and let them figure out what the problem is!
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millercarbon's avatar
millercarbon
12,531 posts
 
I tried running the preamp out to my recover without the turntable plugged into the preamp and still heard the noise. That eliminates the possibility of it being the TT, right?

Right. In this case then it is a problem with shielding or grounding in the unit itself. The wide bandwidth story is something clueless people hope the one they tell it to is gullible or clueless enough to believe. Susceptibility to RFI has nothing to do with wide bandwidth. 

Again remember, RFI is radio waves, they are everywhere. You could go out in the middle of Montana, you could shut down all the electricity on the planet. Radio waves come from stars too. What do you think radio telescopes are used for? 

So the noise is everywhere but like I said not usually loud enough or at a frequency we can hear. Phono stages and other high gain stages are particularly susceptible. Sometimes with a phono stage you can hear a radio station as clean and clear as if it were a tuner.  

That's because in this case it IS a tuner! All a tuner does is take the faint radio frequency noise from a wire we call an antenna, run it through some circuits that select (we say "tune") for a particular frequency, and then modulate and amplify it. A tuner lets us tune from one to another. What is going on here is the amp itself happens to randomly tune some frequency. Just like if you had an old timey tuner or watch one of those old movies where the guy is fiddling with the short wave, it is static, noise, whistles, all kinds of weird sounds, until he gets it tuned to the right frequency. What you have is tuned but not to any frequency in particular it is just stuck between stations so to speak.

This in layman's terms is what's going on. In even simpler layman's terms you got a lemon, take it back, get one that doesn't do that.
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