DC detection via microcontroller

[wonderfulaudio]

Hi,

I am attempting DC detection via a micro-controlled relay in series with a sub driver. I can measure the subwoofer voltage via ADC. How do I go about detecting DC, fault condition?

Linking a very old thread
DC Blocking

Thanks and Regards,
WonderfulAudio

 

[jan.didden]

DC detection is harder than it looks. Assuming you want to detect DC with AC on it, you need to decide how low you want the low frequency cutoff, that is, which lowest frequency you want to consider 'DC'. In audio, you can consider anything below a few Hz as DC.

Two ways to detect it, using an integration process. Hardware-wise you can use an opamp integrator similar to a DC servo circuit (which in a sense is also a DC detector but inside a feedback loop). Or you can sample and integrate the signal in software.

There's probably a ton of example on the 'net; for instance for DC detection for speaker protection.

Jan

 

[bentoronto]

What is the source of the dc? Why is it a problem with a sub?

B.

 

[weltersys]

I am attempting DC detection via a micro-controlled relay in series with a sub driver. I can measure the subwoofer voltage via ADC. How do I go about detecting DC, fault condition?

Rod Elliot's circuit looks good:

Speaker Protection

He's covered a lot of failure modes that aren't in other protection circuits.

 

[bentoronto]

Tweeters need protection prolly more than that usually get esp in these days of multi-amping. But sub-woofers?????

Is there a truly monstrous dc surge from the amp starting or stopping? Would a simple time-delay address a start-up thump? Maybe the amp needs fixing.

B.

 

[weltersys]

Tweeters need protection prolly more than that usually get esp in these days of multi-amping. But sub-woofers?????

Ben,

The OP wants speaker protection from a (potential) "fault condition", which can deliver the full output of the amplifier's DC power supply to the loudspeaker, which may contain more than enough DC voltage to cook any voice coil.

Art