I've had this Nak receiver for a few years now, but I've noticed that with a subwoofer connected, there is a loud and deep 'pop' every time I switch from one source to another or even if a DVD soundtrack changes from 2-channel to 5.1.
I've tried changing subs but the problem persists. I suspected it was a problem with the earthing and tried connecting a earthing wire supplied with a sub to the metal housing of the Nakamichi. Also didn't work.
Has anyone had this kind of problem before? I'm considering having a look on the inside...
Any tips would be greatly appreciated!
I don't know the design of this reciever, and do not have any schematics or engineering information to know the design.
This is a general comment:
In many of these recievers at this level they don't have very good muting designed in to their system. When switching sources, the audio is not being muted.
This is a theory of why the noise is not on the main speakers, but present on the sub woofer. Because the switching noise is of very low frequency, this is why the sub woofer is making noise. The main speakers lack the low frequency sensitivity that the sub woofer has. This is one way of looking at it. It is also possible that there is muting for the main speakers, and none for the sub woofer.
If the reciever does have muting in to its design that is supposed to mute when switching modes, then there is an obvious defect. When a source is switched, or a mode is changed, the output would mute for the duration of the switching interval. This is usually for a period of about 100 ms.
Your best bet is to contact the service rep for nakamichi and ask the question there.
I have serviced many recievers made by other manufactures. The higher end models all had muting in their design. This way, the output was muted when the source was changed, and when the reciever was turned off or on.
Jerry G.
452 views
Usually answered in minutes!
Thanks a lot for that very insightful answer! Funnily enough, Nakamichi service in Japan actually replied to an email I sent, the entire text of which read:
"Check the MUTING circuit at the AV10.
Check and confirm there is no DC voltage at the output of the AV10 to the
subwoofer."
This suggests you were spot on with your muting circuit theory. (I think the reason they mention DC current is because I told them I saw sparks when pulling out the sub cable connected to an earlier Dali sub I had. However, I'll assume for now that was related to the sub and not the receiver as I don't have this problem with my Yamaha sub).
Now, I'm not sure what this level of receiver is, but when it first appeared around 2000/2001, it was reviewed as a good value $1500 AV receiver so I suspect that this switching noise is probably an unintended defect or sloppy assembly.
I read on another forum that one guy who had interferene/ buzz was advised by Nakamichi to bend and pull apart some cables. That seems a bit more specific than the instructions I got - I'm not fully sure what checking the muting circuit involves...looking at it? Probably more is required to solve the problem. Maybe I shouldn't have told them I'm an engineer.
When I get the time, I may open up the receiver and see if I can see any badly grouped cables. Is typically anything in there I might not want to touch?
Failing that, this thing is going into repairs...
×