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Should an amplifier (NAD M33) be completely silent?

Sokel

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My Ice power did the same for a week or two when I first set it up.
From them on is dead silent,probably settled somewhere it liked through time.
(also has PFC)
 

restorer-john

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Funny about all this talk of buzzes and noise. Today I was fixing a not-so-fun but do-able job on one of my favourite little Rotel amplifiers. It's been sitting in the queue for a several years (because it's mine), and came across something I've never seen before. Unrelated to the problem I had to fix, but interesting nonetheless:

Complete insulation of one side lower chassis side panel with respect to the entire frame.

They implemented nylon washers, not unlike TO-3 insulating washers and ~0.3mm nylon 'pads' to prevent just one panel (RH lower chassis) creating what I expect to be a horizontal loop (single turn). A toroidal transformer sits in the rear left, and the base panel is not conductive (composite material) Clearly a production 'change' to eliminate hum/buzz from the toroid in the chassis. Just for fun, I removed the insulating washers and re-assembled and the residual hum/buzz was considerably worse. So it worked.

I've always understood the classic mounting bolt to lid shorted turn with toroidals, but a chassis outer frame horizontal loop? Never seen that before and never seen a method to 'break' an outer chassis 'loop'.
 

Kal Rubinson

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I have an Audio Research SP-8 preamplifier to repair with so much transformer noise I can hear it from 5 ft away...
I had an Audio Research MP-1 with the same malady. After a while, I could not tolerate it.
 

dorakeg

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Regarding coil whines, computers suffer from this as well, esp. for high end graphics cards. In the past, I tried a bit of super glue to the base of the coils and this solves the problem.
 

fpitas

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I 5 have 30yo+ Adcom amps running in my multich rig and none of the units physically buzz or hum.
Plus, I can stick my ear in the horn of my JBL speakers and hear no hisssssss ?
SO, Where's the progress? LOL
If that's a Nelson Pass design, he's always been careful about noise. My First Watt J2 is hooked right to my horns, but no audible noise.
 

Jukebox

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Good evening,

I recently started my audio journey and it’s been a joy! I’m struggling with a (maybe silly) beginner-question that I hope you can help me with. It’s my first post, looking forward to your replies.

I have a NAD M33 and I’m happy with it. Recently I noticed that it makes a soft buzzing sound, which is only audible when I put my ear close to, right above it (can’t hear it at the listing position).

To prevent getting fixated on it, I’d like to understand if it’s normal for the device to make a soft buzzing sound or if it should basically be completely silent?

Your wisdom is more than welcome.
Thanks and nice evening!
It s normal. Tested 5x M33 so far and all have the same noise. Same goes for the C298 being very similar construction.
Nothing to worry about.
 
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PBN94

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It s normal. Tested 5x M33 so far and all have the same noise. Same goes for the C298 being very similar construction.
Nothing 5o worry about.
Note that a C298 does not sound at all like an M33 ;)
The problem of the M33, although annoying is very easily corrected in the workshop, it's a shame to live with it.
 
OP
L

LP1313

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It s normal. Tested 5x M33 so far and all have the same noise. Same goes for the C298 being very similar construction.
Nothing 5o worry about.
That’s good to hear, total peace of mind now ;-)
Nice evening!
 

SIY

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hum ... all DACs based on ESS xxxx or AKM xxxx sound the same ?
Borrow both and test at home :)
We see this sort of implausible claim frequently. But somehow, always lacking actual evidence (like ears-only testing with basic controls). Will you be the one to finally provide actual data demonstrating this to be true?
 

PBN94

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Nah man, my equipment is not revealing enough :facepalm:
Hello,
In fact my example was not good, I listened and compared the NAD C298 / NAD M33 I found the M33 was better (less rough, more musical) and I bought it.
I wanted to say that I think that not all Purifi 1ET400A based implementations sound the same.
But if you think otherwise, no problem.
Have a nice day.
 

PBN94

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We see this sort of implausible claim frequently. But somehow, always lacking actual evidence (like ears-only testing with basic controls). Will you be the one to finally provide actual data demonstrating this to be true?
Hello,
As I said before my example was not good, (like my English, I get help from deepl translation)
The topic was NAD C298 vs NAD M33, you took the sentence out of context.
I registered today to answer the initial question of the topic and help this person, I am not a forum specialist ...
Apparently, there are also crusading warriors here always ready to sacrifice a newcomer !
I have since bought an integrated amplifier that must be much worse on paper but sounds much better than the NAD to my ears. So, the target is the musical satisfaction and not the technical specifications.
Sorry to have disturbed you, have a nice day.
 

restorer-john

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After a while, I could not tolerate it.

I sold a pair of highly regarded Class A amplifiers because of excess transformer noise. Why pursue electrical S/N when the amplifier sets an elevated acoustic noise floor itself?
 

HarmonicTHD

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I sold a pair of highly regarded Class A amplifiers because of excess transformer noise. Why pursue electrical S/N when the amplifier sets an elevated acoustic noise floor itself?
Next to DC blockers, would a different transformer be less noisy (“mechanical vibration”) in your opinion? What specs to look for for low transformer hum?
(One of my 800VA ring transformers is quiet, the other hums sometimes).
Thx
 
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kongwee

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Un shield power cords, interconnect and/or speaker. Wires cross all over the place. Too much non audio device connect along your sound system power strip. Unnecessary stuff like lights, charger, tv, fan..... Etc beside your system. Live in urban apartment. Some of the stuffs I can think of.
 
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