NAD S300 Amplifer humming

Distortion is categorized in Hum, Motorboating etc. Anyway see page 9 of owner manual for help.
NAD C325BEE AMPLIFIER OWNER'S MANUAL ' ManualsLib

For further help see page 24 of Service Manual

NAD C 325BEE SERVICE MANUAL Pdf Download ' ManualsLib

The main amplifer ICs have taken a dump. Time to go shopping!

No, the difference will not cause hum. Other things will.

Search engine "audio system hum".

Have someone who has experience working with circuit boards take it apart and look at it. They'll probably be able to tell you what parts can be replaced. If it's anything as simple as capacitors and resistors, then you can find the exact parts you need at AllElectronics.com

When they said it was a multilayer structure, that means either there are multiple circuit boards, or it's all surface-mount soldering on both sides of one board. To be on the safe side, assume it's surface mount. It's much more difficult to work on.


Hope that helps!

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/cameron_463100ffd54b591d

Hi there,
I'm also a Nad fan. I find this pretty odd that you should loose two in such a short space of time. The cutting out is due to the "protection circuit". I would be inclined to get your speakers checked out as if they are faulty or not "matched" to the amp, it will trigger the amp to "protect itself" and shut off.

Hi, where did you get the new front?
Yours, Reemt Rentzsch

if the hum is in the sound output you have a blown power regulator

Sounds like thermal problem, probably voltage regulator section of Power Supply. Open up look for signs of hot spots on circuit board

i would suspect a missing supply or speaker protect relay shorted? or staying closed too long. I'm not familiar with this model but a common failure is bad connections. Inspect all heat sinked parts and small value resisters used as fuses. Look for cracked solder joints on all parts, tighten pcb grounding screws. Memory is most likely powered by a high value cap or stack cap that maybe bad. Or the diode used to charge during usage maybe leaky , other part in ckt leaky, or the memory device itself is drawing excessive current off the memory cap. I have seen small 0.1uf disk caps turn into 1k resistors.

Yes you will need a pre-amp for your turntable, there is no phono input on this amplifier. Please update the question & let us know if the information given was useful to you - Good Luck!