Powered monitors thump when monitor controller is switched on and they are off.

[pucho812]

Have a monitor controller that is diecrete opsmp based and transformers coupled on the outputs.  This is at a friends studio.  What is odd is the monitor controller causes a thump in the speakers when turned on  even if the powered speakers are turned off.  It's a low thump so I am guessing d.c.  Once on it all goes away and functions normally.  Once the speakers are on, doesn't sound like an issue at all. Just the initial start up.
Would D.C. Cause such a thump in the powered monitors?
Is there any inline protection we could put in place between the monitor controller  and speakers?

 

[JohnRoberts]

Have a monitor controller that is diecrete opsmp based and transformers coupled on the outputs.  This is at a friends studio.  What is odd is the monitor controller causes a thump in the speakers when turned on  even if the powered speakers are turned off.

call ripley's believe it or not... Causing a thump in powered speakers even if they are turned off, is not typical behavior. 

It's a low thump so I am guessing d.c.  Once on it all goes away and functions normally.  Once the speakers are on, doesn't sound like an issue at all. Just the initial start up.
Would D.C. Cause such a thump in the powered monitors?
Is there any inline protection we could put in place between the monitor controller  and speakers?

Even with transformer coupled outputs that do not pass DC, they can still pass a LF thump from internal DC steps upstream from the transformer, just with the DC scraped off.

JR

 

[pucho812]

Even with transformer coupled outputs that do not pass DC, they can still pass a LF thump from internal DC steps upstream from the transformer, just with the DC scraped off.

JR

scraped off?