Veaux Posted June 30, 2018 Share Posted June 30, 2018 Has this ever happened to you? My Eico HF-35 monoblocks are suddenly picking up radio stations, they didn’t do this before... Quote Link to comment Share on other sites More sharing options...
ACV92 Posted June 30, 2018 Share Posted June 30, 2018 I had a Klipsch sub that started doing the same thing. It was an old SW-10. Ended up replacing it with a couple of UMax 15's. Don't know what caused it though. Have you tried disconnecting the source input to ensure that it's not the amps? I'd disconnect the outputs as well. I'd be interested to hear what others have to say that causes this. Hopefully, something simple. Quote Link to comment Share on other sites More sharing options...
dbomberger Posted June 30, 2018 Share Posted June 30, 2018 I had the same thing happen once a few years back. Was near a military base and anomalies like that were not unheard of. I always wondered how that might happen. Offut Air Base by the way. Quote Link to comment Share on other sites More sharing options...
Veaux Posted June 30, 2018 Author Share Posted June 30, 2018 My Eico’s have “volume” knob (When I bought them the guy gave me some spiel about how it controls the amount of power they put out which isn’t volume or gain but it makes it louder, seems like volume to me, I probably should have paid more attention) When those knobs are turned all the way up and the preamp is turned all the way down it is fairly audible. I live a block away from TSU and I’m pretty sure it’s their radio station. I am using different cables and this is the first time I’ve used any of my tube amps here, I normally only do home theater at my home and my listening at my studio. I’m going to try different cables one at a time and see if I can figure it out. Will let y’all know if it’s these different unshielded cables or what. My preamp does NOT have an AM/FM tuner. Quote Link to comment Share on other sites More sharing options...
babadono Posted June 30, 2018 Share Posted June 30, 2018 Are you picking up AM or FM? I've heard of equipment picking up AM broadcasts because of a parasitic AM detector in their set up. After all, all it takes is a diode to detect AM. If it's FM I'm at a loss. Quote Link to comment Share on other sites More sharing options...
Guest wdecho Posted June 30, 2018 Share Posted June 30, 2018 A simple capacitor would fix the problem and many amplifiers employ such when they are prone to pick up higher frequencies. Amplifiers used for audio only need to amplify the audio band and are restricted to that frequency. A simple crystal radio will do the same thing. Unless it is a loud problem I was just ignore it instead of digging into the circuit. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted June 30, 2018 Share Posted June 30, 2018 RF pickup in audio amplifiers is not unusual in the presence of strong signals. You said that you are picking up stations. How many, and can you determine the frequencies? Are both amps doing this? If so, is one louder than the other? Since there are many possible causes of this, let's start with the simple approach: Disconnect everything from the amps, turn the input level controls up all the way and note whether you still hear any stations. If not, you can rule out the amps. If they are still present, start moving the speaker cables (which should be no longer than is needed to reach the speakers) around a bit to note whether anything changes. Do the same with the power cords of the amps. Out of curiosity, have you done any rewiring in the house or listening room or any work on the rain gutters? I'll elaborate on this in the future if needed. I don't know when I'll be able to get back on here, but will try to keep tabs on the discussion whenever possible and provide more details. Maynard Quote Link to comment Share on other sites More sharing options...
Don Richard Posted June 30, 2018 Share Posted June 30, 2018 A corroded or dirty contact can detect radio signals. This could be cables or other connections external to the amplifier, or dirty or poor connections on switches, potentiometers, or sockets internal to the amplifier. Does the problem occur with the amplifier disconnected from all other equipment or does it just happen with audio sources plugged into the amp? Quote Link to comment Share on other sites More sharing options...
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