AR Speaker Protection from DC Current

[Carlspeak]

32 minutes ago, LouB said:

 

Once again, with or without the caps in place, I don't notice with my old ears any significant difference between the caps or not.

Thanks for everyone's input on this!

 

Lou

I didn't think you'd notice a difference. The transfer function of those large caps is way out of the pass band.

32 minutes ago, LouB said:

 

 

[DavidR]

Why are crossover caps given both VAC and VDC ratings if they can't/won't pass DC current?

[iso]

1 hour ago, DavidR said:

Why are crossover caps given both VAC and VDC ratings if they can't/won't pass DC current?

They can pass AC and hold DC-charge...

Kimmo

[GlennW]

The DC rating of a capacitor would be the voltage level at which arcing would occur, and all the magic smoke would escape.

A detailed analysis of speaker protection is done in Doug Self's book "Audio Amplifier Design Handbook".  Some of his points:

1. Series capacitor is large and expensive.  A large electrolytic type has measurable distortion.  This level is significant compared to distortion rating of a good amplifier.
2. Fuses have to be operated close to their rating to provide meaningful speaker protection.  Used close to their rating, fuses degrade and may have nuisance failures.  Fuses also have measurable distortion when operated close to their rating. 
3. He recommends relay protection circuits.  The electronic circuit driving the relay can differentiate between amplifier failure and audio signals.  The relay contacts have no measurable distortion. 

I am not aware of any packaged relay protection circuit devices.  The Vellemann kit or other similar ones offered on EBay require case, power supply, etc.

Regards,

Glenn