Sound unit interference

[CookieOldParticipant @cookieold]

Can anyone please help , I have installed a RTTL sound unit in my boat , but am getting really bad interference when the motors spin up , If i remove the fuse from the motors the unit sounds great . All the motors have got the suppressors soldered on the power tags . I have moved the sound unit and speaker 3 feet away from the motors but it had no effect.Any help would be great.

Dave

[CookieOldParticipant @cookieold]

[harry smith 1Participant @harrysmith1]

Hi Cookie

Try the sound unit on another battery next to the boat, the interference is either from the common battery supply or frequency interference from the motors.

[Malcolm FraryParticipant @malcolmfrary95515]

2 basic ways that interference can happen

Via the radio. The motors generate interfering radio signals that are radiated by the wiring. Your suppressors should prevent this. Long wiring on input leads to audio amplifiers are good at picking this up. Long speaker leads do this as well. The output transistors act as the crystals in an olde-worlde radio to detect the signal, then amplify it so that you hear it better.

Via the power supply. The motors put a load on the power supply which causes the voltage to vary slightly. An amplifier running on this voltage might well detect this variation and amplify it. If there is an "iffy" bit of ground line, the amplifier might "see" voltages changing with respect to its ground line, and amplify them.

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