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Follow up questions regarding my NAD C375BEE

I recently placed a posting regarding the protection circuit activating on my NAD C375BEE running Totem Model One Signature speakers. A poster on another forum indicated that the NAD is not robust enough to operate at the impedance load presented by the Totems and that I have damaged the amplifier. Prior to my purchase I did some internet research and found many folks running Totem speakers (including the Mani 2!) using NAD amplification without this issue. Any information or guidance regarding this dilemma would be greatly appreciated. If any readers noticed my first posting I failed to include my REL Strata II subwoofer in my roster of equipment. The REL developed a hum when I introduced the NAD into my system. Coincidence or related to my problem?
Thank you, Joseph
joseph54
runnin
397 posts
 
Update:
It looks like the OP started a thread at Audioholics at the same time, it's about the NAD C375, Totem Ones as well with the NAD protection circuit activating too. Later on in that thread, he adds that his previous integrated, an Anthem 225, had issues too. One speaker was much quieter so he had to adjust the balance knob and decided the Anthem was going and bought the NAD.

Now the NAD needs the balance adjusted too, but it's shutting down as well. Anyway, it's all there in the thread, 2 capable guys are helping him and they think the Totem ones or the sub is damaged.
pgawan2b
122 posts
 
Tls49, good point and thanks for the correction.
almarg's avatar
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almarg
9,670 posts
 
A number of good comments and suggestions have been provided above. I'll add one further thought while awaiting feedback on what has been suggested:

Are you certain that the two speakers are connected with the same phase, i.e., that + and - are not interchanged in the connections to ONE speaker?

If the two speakers are not connected in phase with each other, some of the results would be vague and diffuse imaging, and weak bass. I'm thinking that in some circumstances a result might also be the channel imbalance you have perceived, and also a perceived reduction in volume (which would be further compounded in one channel by the balance control offset). If so, to achieve reasonable volume and bass perhaps you are turning the volume control up high enough to overload the amp, with the clipping distortion that would normally result from doing that perhaps being prevented by the amp's soft clipping feature and/or by the amp's unusually large dynamic headroom.

Also, as Pgawan2b suggested, verify that the bridged mode switch on the rear panel is set to off/stereo. If the speakers are connected as a normal stereo pair but that switch is set to bridged mode, it would cause similar effects to those I described above for an out of phase speaker connection.

Regards,
-- Al
almarg's avatar
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almarg
9,670 posts
 
One more thought: Make sure that the black wire from the REL is connected to one of the negative (probably black) speaker terminals on the amp, and not to one of the positive (probably red) speaker terminals. If the black wire is interchanged with either the red or the yellow wire from the REL, and is connected to a positive speaker terminal on the amp, I believe that could account for all of the symptoms you have described here and in the other thread that was referenced above, and (consistent with what you have reported) could result in the amp shutting down even if the sub is turned off.

Regards,
-- Al
zd542
5,339 posts
 
"Are you certain that the two speakers are connected with the same phase, i.e., that + and - are not interchanged in the connections to ONE speaker?

If the two speakers are not connected in phase with each other, some of the results would be vague and diffuse imaging, and weak bass. I'm thinking that in some circumstances a result might also be the channel imbalance you have perceived, and also a perceived reduction in volume (which would be further compounded in one channel by the balance control offset)."

That could be the problem. If you play a recording that normally has a solid center vocal image, wiring the speakers out of phase with each other will make the vocals sound like they are coming from one of the side walls, and not the center. Its very easy to hear. You can't miss it.

Another cause for the channel imbalance could be your room. If you have something like the right speaker near a corner and the left near a free space, one speaker will have to work harder to match the volume of the other one.

Also, if you bought your speakers used, go over all the screws and make sure they are tight. They can loosen up over time.
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