nap200 transformer hum

I have had a 200 for a while now and have never experienced such a hum. Have you double-checked all of your connections? Having never experienced such a hum, I'm at a loss as to what may be wrong, but wanted to confirm what you probably suspected, which is that an audible hum is not normal for the 200.

Good luck.

MBM

The hum could be related to:

1) "Dirty" main power supply. What other appliances, items etc. are on the same circuit as the NAP 200? A dedicated line may clean this up.

2)"Dirty" supply from utility company to your house/appartment. If this is the case, does the hum "disappear" late at night/early in the morning (traditional low electricity demand periods)? If this is the case, then you either live with the hum or move.

3)A loose mounting of the transformer in the case (may want your dealer to check this if you are not mechanically inclined).

4) Are all 4 feet firmly on the ground/table/etc.? If the amp can be rocked, then this may be contributing to the hum.

5) Try plugging the amp into other electrical outlets. Does the hum still exist? Try it at a friends (or dealers) location and see if the hum still exists.

Good luck,

Or maybe the amp just doesn't know the words

I guess you could claim to have the "Glenn Gould" of power amps.

Geofiz, I like you line "if you up plug it does it still hum "
everbody who has read this post wanted to say it.........

Thanks Geofiz for your suggestions.
1). the hi-fi is on a spur so there is no other equipment on the same circuit.
2). the hum seems to be the same all the time, so supply from utility company does not seem very likely to be the cause.
3). Richard Dane has also suggested transformer bolts may need tightening but i do not feel iclined to open up the case, it's only been here a week.
4). the amp seems to be sitting stably and I have tried it on an isolationplatform without noticeable improvement.
5). I've tried it in another socket on a different circuit, and using a different mains lead, and also feeding it from a Chord Clearway mains enhancer, all seemed to make no difference.

I have now arranged to borrow the dem amp from the dealer, who says that on does not hum at his premises, to compare with mine at home. I hope that may answer the question as to whether this particular amp is just a noisy one.

Thanks for your interest.

Phil.

P.s. Not sure why I am described as a Junior member, am past my half century. perhaps I need to get more active on the forum.

Hi Phil

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P.s. Not sure why I am described as a Junior member, am past my half century. perhaps I need to get more active on the forum.

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Answer:- Your guess is correct.

Distortion on the mains supply normally varies, depending on the time of day and other demands in your area.

A constant physical hum from the case implies either that you have seriously crap mains all the time, or that the transformer (which should be rigidly mounted) is loose (or a related fault)

Let us know how you get on with the other 200.

Good luck.

Just to let you know, the other nap200 arrived yesterday. It's really quiet, have to almost lay your ear on the case to hear any noise. other than through the speakers. Guess which one is going to stay!

phil.

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guess which one is going to stay!

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loosen the tranny bolts sell the amp it will be back soon now i can sell the dem model that ain't shifting, very crafty ploy.
sorry sir/madam my new demo unit is not for sale.what a dealer
only joking of course.