I have a Cambridge Audio Minx X301 subwoofer that makes a constant low-level crackling noise. Similar to a Geiger counter / static type sound.
The noise is not affected by the volume control and the sub is still usable but the sound is very noticeable in a silent room. Only the cutoff control has any effect on it.
I initially sent the sub panel for repair with someone who deals with a lot of these. He tried the following:
After that didn’t work I decided to make this a practice project and tried changing another capacitor, the 3.3v voltage regulator and oscillating crystal. Mainly because they were cheap components that were easy for me to solder rather than any technical insight.
Freeze spray doesn’t stop the noise.
There are not many other components I am able to change. The TL064CN op amp is pretty much the only original IC. Could this cause such a noise or should I consider or test any other parts?
The noise is not affected by the volume control and the sub is still usable but the sound is very noticeable in a silent room. Only the cutoff control has any effect on it.
I initially sent the sub panel for repair with someone who deals with a lot of these. He tried the following:
- Substituted the power supply to confirm the problem is on the amplifier PCB
- Checked all capacitors he could, including SMDs and replaced a couple anyway.
- Replaced the ADC (AKM 5358AET), DSP (STA309A) and main amplifier chip.
After that didn’t work I decided to make this a practice project and tried changing another capacitor, the 3.3v voltage regulator and oscillating crystal. Mainly because they were cheap components that were easy for me to solder rather than any technical insight.
Freeze spray doesn’t stop the noise.
There are not many other components I am able to change. The TL064CN op amp is pretty much the only original IC. Could this cause such a noise or should I consider or test any other parts?
The cutoff works as normal and will silence the crackle if turned right down, but then of course the normal audio is cut.
Because the noise is fairly low level, I wondered whether I could work around it by putting a resistor on the speaker output to lower the overall volume and make the sub useable again?
Just reporting back for anyone else with a similar problem...
After replacing almost everything I could on the board and resoldering many existing joints, I found the culprit was the 5v voltage regulator (LM1117). The output voltage looked fine at 5v but flickered very slightly on my voltmeter in time with the noise. Swapped this part and the noise has gone!
After replacing almost everything I could on the board and resoldering many existing joints, I found the culprit was the 5v voltage regulator (LM1117). The output voltage looked fine at 5v but flickered very slightly on my voltmeter in time with the noise. Swapped this part and the noise has gone!