Rotel RMB1095 protection Mode

[giovanni1]

Hi all, hoping to get some advice... I just purchased this amp and was operating fine at a demo before I took it home. After hooking it up I find that the center channel goes into protection mode as soon as I increase the volume. Stays on if left at low volume. My center speaker is a Polk rated at 250w so I am sure that it can handle the 200w output from the Rotel amp. If I disconnet the center speaker the protection light goes off and all the rest of the channels are fine. Speaker wire has been changed out and still the same problem. Could it be the center channel speaker or something with the amp itself?? Any help appreciated, thanks.

 

[AcuDefTechGuy]

Use the Center speaker as the Left speaker. If the Left speaker now goes in Protection mode, then the Center speaker is probably faulty.

 

[lovinthehd]

Did you demo the center channel?

 

[giovanni1]

Did some work on it tonight and tried what you suggested. it seems it is the Polk center channel speaker that is causing the amp to go into protection mode. I have no idea why because up until now it was working just fine (and loud if needed) with my other amp. But with this amp it makes it cut out. So I had a set of crappy rear surrounds laying around from a previous system, and hooked one of them up as a center speaker. I can turn that one up as loud as I wanted to and the amp worked just fine.

I wonder what the problem is?? Any suggestions?

 

[lovinthehd]

Bad solder joint or connection somewhere? Failed crossover component?

 

[giovanni1]

Yes but.... would that not also affect the other amp?

 

[lovinthehd]

Yes but.... would that not also affect the other amp?

Happened in moving it/changing it out? Dunno.

 

[giovanni1]

This center channel has not moved from my room in about 5 years. Oh well....

 

[TLS Guy]

Did some work on it tonight and tried what you suggested. it seems it is the Polk center channel speaker that is causing the amp to go into protection mode. I have no idea why because up until now it was working just fine (and loud if needed) with my other amp. But with this amp it makes it cut out. So I had a set of crappy rear surrounds laying around from a previous system, and hooked one of them up as a center speaker. I can turn that one up as loud as I wanted to and the amp worked just fine.

I wonder what the problem is?? Any suggestions?

When that occurs, it pretty much always means the speaker has been over driven and at least one, and usually more speaker voice coils have been damaged.
What happens is that the voice coil heats and the enamel insulation on the VC wires burn. This causes shorting between the VC wire turns and lower impedance and cause the power amps to protect or blow. That center speaker is done, and should not be connected to any amp ever again, unless the damaged drivers are replaced.

 

[lovinthehd]

Back to my earlier question....you demo'd the center channel of the amp before purchase?

 

[AcuDefTechGuy]

Yes but.... would that not also affect the other amp?

So you still have the other amp and can test the center speaker with the other amp now?

 

[giovanni1]

The other amp was given to a relative. I suppose I could try to get it back for testing purposes. But like I mentioned before, I had that amp running for several years without problem.

And to answer the other question, Yes I did demo before purchase, allbeit very limited due to Covid. Just a quick... yes its powering on, there is sound and that was it.

If it is the speaker, could it possibly be that the Rotel amp is more sensative (or sophisticated) to be able to notice that there is a problem with the speaker?

 

[giovanni1]

Hi guys, I beleive I found the problem.... So I decided to start to take apart the center channel speaker just to see if the problem was something visible and obvious. Took a look at the woofers themselves first and everything looked fine. When I turned it over to begin dismantling the speaker connections, I saw a tiny, barely noticable hairline strand of speaker wire dangling around. At first it looked like a slight crack, but it moved when touched. It was sandwiched behind the gold connector for top and bottom end. It was awfully close to grounding out on the other terminal, so I removed it. Hoping this was the issue because I reconnected the speaker to the amp and voila, all was fine. I can turn it up as loud ad i wanted and no tripping the amp. pphheeww! Not sure how I did not look closer at the terminals before but... whatever.

Thank you guys for all your help!!