Biamping 3805: Wrong Poliarities?

[Jack]

Have biamped the 3805 following instrutions at this site. Problem is that the bass part of the front speakers have reversed polarity. In other words the test sound comes of the opposite speaker than the one indicated by the 3805. Have checked my wriing and it seems ok. Is there something I'm missing?

The treble speaker has the correct polarity as when I turn off the power to zone 2 (i.e., the lower frequency speaker) the test sound comes out of the correct front speaker.

Any thoughts (other than that I'm some sort of idiot)?

Thanks.

 

[nova]

So far everyone that I have heard of who bi-amped with the 3805 zone2 has had this problem. I just switched my inputs, others have used zone3, either option seems to correct the problem.

 

[Jason Coleman]

This is true...the channels are reversed when bi-amping. It's strange but consistent. Simply switch your RCA cables at either end and it'll be correct. However, once you do this, there will most likely be a slight hum from the bi-amped fronts. It's barely noticeable (1' or less), but it's still annoying. I'm not sure if we're creating an internal ground loop of some sort, but almost everybody that has done this experiences this hum. But...it's very minor and not an issue unless you sit within a foot of the speakers. Either way, the bi-amp of the mains is such a big improvement and easy (relatively) not to mention FREE!

Jason

 

[nova]

Huh,.... I cannot hear a hum. Where do you hear it most? The part of the speaker that is bi-amped with zone2? Main part? All? I may have to sit up close and really listen to see if it is there on mine.

 

[Jack]

Thanks. I was begining to think that I was nuts after having checked and re-checked the wiring about 10 times. I'm surprised that this site does not mention the problem in the 3805 review where they tell you how to biamp.

 

[gene]

Thanks. I was begining to think that I was nuts after having checked and re-checked the wiring about 10 times. I'm surprised that this site does not mention the problem in the 3805 review where they tell you how to biamp.

Jack it is difficult for us to mention a problem that didn't exist in our test unit. When I meet with Denon at Cedia next week I will bring this up with them, although their tech support I spoke with in the past didn't seem to think there was a problem.

 

[Jack]

Jack it is difficult for us to mention a problem that didn't exist in our test unit. When I meet with Denon at Cedia next week I will bring this up with them, although their tech support I spoke with in the past didn't seem to think there was a problem.

So I guess it doesn't happen with all of the 3805s but clearly it happens with some of them. Would be kind of interesting to know how Denon explains it. By the way, I did the wiring as you mention in the article but switched the assignment to zone 3 and there is no problem with the polarity.

 

[pikers]

Have biamped the 3805 following instrutions at this site. Problem is that the bass part of the front speakers have reversed polarity. In other words the test sound comes of the opposite speaker than the one indicated by the 3805. Have checked my wriing and it seems ok. Is there something I'm missing?

The treble speaker has the correct polarity as when I turn off the power to zone 2 (i.e., the lower frequency speaker) the test sound comes out of the correct front speaker.

Any thoughts (other than that I'm some sort of idiot)?

Thanks.

That the instructions say to use Zone 3 might be a start Really though, I've noticed over the years that the polarity on Denons can be flipped internally. I'm sure they aren't alone, but no matter; just swap the rcas and you're in bidness.