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Thread: Hum in transformer |
    
New member Username: Tcch
Post Number: 4
Registered: Aug-07
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| Posted on Thursday, May 01, 2008 - 04:23 am: |
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I have just bought a new NAD C355BEE. I was suprised from the start that there was a slight hum from the transformer - not much, but audiable and annoying. I expected to be dead quiet. Has anybody else some experience with that problem, maybe also with other amplifiers? |
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Gold Member Username: Artk
Albany,
Oregon
USA
Post Number: 6806
Registered: Feb-05
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| Posted on Thursday, May 01, 2008 - 07:54 am: |
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Switch it out...if the next one has the same problem look at other products. |
Platinum Member Username: Jan_b_vigne
Dallas,
TX
Post Number: 12594
Registered: May-04
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| Posted on Thursday, May 01, 2008 - 12:05 pm: |
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Do as you're told!
Several reports of similar problems with NAD products. Don't bother trying to repair this amp. If you just bought it, swap it out for one that doesn't make noise.
. |
Silver Member Username: John_ashman
Albuquerque,
NM
United States
Post Number: 203
Registered: Apr-08
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| Posted on Thursday, May 01, 2008 - 06:57 pm: |
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Tcch, if there's a hum, they'll swap it out. I assume you mean from the amp, not through the speakers. Just a loose winding which can happen in toroidal transformers. We've seen it with many manufacturers. It's pretty rare on an NAD, but it happens. |
Gold Member Username: Artk
Albany,
Oregon
USA
Post Number: 6808
Registered: Feb-05
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| Posted on Thursday, May 01, 2008 - 09:18 pm: |
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Used to be quite common with Rotel. |
Silver Member Username: Nout
Post Number: 120
Registered: Mar-06
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| Posted on Friday, May 02, 2008 - 04:57 am: |
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..and Marantz as well.
The ones that have a class a switch: PM80, PM95, PM8000 and PM7200.
My 7200 has a slight hum, when resting my ear on the case, it doesn't bother me. |
Gold Member Username: Frank_abela
Berkshire
UK
Post Number: 2904
Registered: Sep-04
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| Posted on Friday, May 02, 2008 - 11:32 am: |
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Anything with a large transformer is susceptible to mains borne noise in the form of hum. True, some large transformers hum more than others, but in the end, if the mains is bad then the chances are your transformer will hum. This is true of any component irrespective of price.
By all means swap out the NAD, find something else, but this is the way of things.
Regards,
Frank. |
New member Username: Tcch
Post Number: 5
Registered: Aug-07
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| Posted on Saturday, May 03, 2008 - 04:06 am: |
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Thanks for all your comments. I will try to swap it.
About the mains: I carried the amp to a different locaton, where the mains should be ok. The hum was there as well. |
New member Username: Tcch
Post Number: 6
Registered: Aug-07
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| Posted on Tuesday, May 06, 2008 - 12:19 pm: |
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An update: I tried to swap the amplifier. In the store, the salesman connected it: the hum was even bigger there. Then he connected a new fresh open C355BEE - the same hum there as well. On the other hand, I didn't hear any hum from different equipment in the store - including some other NAD high power product.
So I had to return it. And I am sorry for that, because otherwise I really liked the amp. To bad NAD was not careful enough about this relatively straightforward detail, because I would be more than happy to pay additional money for a higher quality transformer with this package. |
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Silver Member Username: John_ashman
Albuquerque,
NM
United States
Post Number: 254
Registered: Apr-08
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| Posted on Tuesday, May 06, 2008 - 12:52 pm: |
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Interesting. We haven't had any issues at all with this piece. No noise, no hum, not at the store, not reported by customers. I'll look at it more carefully, but maybe there was a bad batch of transformers? How loud are we talking? From what I understand, physical hums are the result of a winding breaking loose from the epoxy. This seems to be more common with toroids for some reason, but has remained quite rare for us with NAD. When we sold B&K, it was a common and annoying hassle. |
New member Username: Tcch
Post Number: 7
Registered: Aug-07
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| Posted on Tuesday, May 06, 2008 - 01:55 pm: |
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How loud are we talking? - Hard question. I was able to hear it from 3m in my quiet room. In the store I was able to hear it when I was close to the amplifier. But more importantly: I did't hear anything from other amplifiers in the store (and some other stores).
I belive NAD can do better, and probably they will do better in the next round of production. I guess I am just unlucky. |
Platinum Member Username: Nuck
Post Number: 10181
Registered: Dec-04
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| Posted on Tuesday, May 06, 2008 - 05:33 pm: |
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Or NAD has transferred the old 'hum and hiss' from their AVR's to another product. |
Silver Member Username: Dmitchell
Ottawa,
Ontario
Canada
Post Number: 909
Registered: Feb-07
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| Posted on Wednesday, May 07, 2008 - 09:07 am: |
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Isn't that part of their signature sound? |
