Hi everyone,
I'm looking for some help on a Class D amplifier which is making some funny sounds.
The amp is a Definitive Technology Mythos STS, although from what I can tell it's basically the same as the Definitive Technology 7002, 7004, 7006 etc.
The main Class D amp module is a DS-3000 which I believe is used in many Class D amps and subs.
The amp itself works. However there is a low noise coming from the sub.
A continuous low volume humming (at low freq) and then randomly a loud scratching noise almost like the voice coil us rubbing on something.
The low hum is not really audible normally, but the random scratching is. In fact people in the house think it was a storm or something till I pointed out it was the speaker.
This happens with no input.
The circuit is basically
Input > Low pass > EQ > Limiter > Limiter high pass > Limiter low pass > Class D Amp.
I removed the cap between Limiter low pass and Class D amp, and the noise is gone. This indicates to me that the Class D amp is fine and the noise is come from before that.
I have checked the voltages and they are all fine. There is a +- 15V rail and it measures +15.05V and -14.95V. Does the 0.1V difference matter?
Does anyone have any suggestions as to what may be causing this random noise? Or which part of the circuit may be responsible?
Thanks
I'm looking for some help on a Class D amplifier which is making some funny sounds.
The amp is a Definitive Technology Mythos STS, although from what I can tell it's basically the same as the Definitive Technology 7002, 7004, 7006 etc.
The main Class D amp module is a DS-3000 which I believe is used in many Class D amps and subs.
The amp itself works. However there is a low noise coming from the sub.
A continuous low volume humming (at low freq) and then randomly a loud scratching noise almost like the voice coil us rubbing on something.
The low hum is not really audible normally, but the random scratching is. In fact people in the house think it was a storm or something till I pointed out it was the speaker.
This happens with no input.
The circuit is basically
Input > Low pass > EQ > Limiter > Limiter high pass > Limiter low pass > Class D Amp.
I removed the cap between Limiter low pass and Class D amp, and the noise is gone. This indicates to me that the Class D amp is fine and the noise is come from before that.
I have checked the voltages and they are all fine. There is a +- 15V rail and it measures +15.05V and -14.95V. Does the 0.1V difference matter?
Does anyone have any suggestions as to what may be causing this random noise? Or which part of the circuit may be responsible?
Thanks