How do I get rid of the Hummmmmmm?
You can hear a distinct Hummmmm in the speakers. If you touch the control buttons for the MP3 player the Hummmmm gets louder. The Hummmmm increases when you turn up the volume. Sometimes there is almost like a static-like sound to the higher audio frequencies. Sometimes the sound is more tinny. It's almost like a charge is building up maybe. When the music is playing the hum is less noticeable. The hum seems to get worse progressively the more you use the displaced controls.
All controls that were displaced have been mounted in the old cassette players buttons. The tape circuits are off. The MP3 player switches with the Radio to the Amp. There is a charger but it was disconnected for now. The displaced USB port is extended to the back of the box where it also switches to the charger.
What I have tried so far:
- I have hooked up an Alternative MP3 player to the new Aux Input RCAs that also switch with the Radio to the Amp and the External MP3 player sounds great!
- I made sure the tape heads and wires were all removed from the cassette compartment area.
- I originally connected the audio with a headphone jack but now it is hardwired.
- I removed the Metal back case of the MP3 player and that helped a bit. All the wiring was strung through the metal casing.
- I have Tried an Audio System Ground Loop Isolator between the MP3 player and the Amp. That took away most of the hum but made the sound very "tinny" with almost no Bass.
- I tried Ferrites on the Audio cable between the MP3 player and the Amp and the Power Cord and a number of other places. There was no discernible change. The cables weren't long enough to loop so I used several ferrites in series.
- I have order a couple Audio Transformers so I can try and use them like the ground loop isolator if it is an impedance problem but I don't expect much different a result.
- I have plugged the AC cord into it's own circuit on my breaker box and that seems to help a little.
(My original MP3 player - boombox installation turned out great. The main difference is that most of the buttons were on the face of the MP3 player and only two buttons were displaced to the front of the box and that was the power and reset. The charger made horrible interference racket but you could just listen to the radio while it charged.)