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Understanding Speaker Output on Nikko NA-550

Hi,
I'm trying to understand this label on the back of my amp (Nikko NA-550). Specifically I'm referring to this image: https://vintage-audio-heritage.fr/download/file.php?id=57573 .

First off, are these two separate output channels or are they wired to the same channel and just allow switching between two sets of speakers?

Then I'm trying to understand the impedance rating given:
  • what does the notation A.B and A+B mean? I'm assuming different configurations of the speakers and/or wiring. Does it also apply to a single set of stereo speakers or only if using one set per output (4 speakers total)?
  • how do I interpret the impedance rating? Does "4 ~ 16 Ohm / speaker" refer to the allowed impedance range the speakers must be rated at?

Thanks a lot for your help.

jgruff

Showing 1 response by chrisgreen

chrisgreen
1 posts
 

I have a NA-550. I have a 6 ohm pair of speakers on A and an 8 ohm pair on B. I run A+B all the time. I think this is technically out of spec, but is it anything I need to worry about?

Also, the 6 ohm pair is much louder than the 8 ohm pair. Different speakers, obviously. Also different gauge, type, and lengths of speaker wire. Can anyone suggest why there is such a disparity in the volume of the two pairs?

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