NAD C375BEE protection circuit activating.

[Traindude]

Greetings, I recently became the second owner of a NAD C375BEE which worked fine for two weeks and now activates the protection circuit after about five minutes of playing. My speaker connections are fine with no shorting, but I think that if the cables were shorting the protection would activate upon powering up the amplifier. Any advice on troubleshooting would be greatly appreciated and I would also like to know if triggering this circuit multiple times while seeking the source of the problem might damage the amplifier. Prior to the purchase of the NAD I ran an Anthem Integrated 2 with no issues.

NAD C3375BEE
Totem Model One Signatures
REL Strata 2 Subwoofer
Ultech UCD-100
Birdland Odeon Lite DAC
VansEvers Clean Line Power Conditioner

This is plugged into a Panamax Surge Protector which is part of a surge protection package made available through my power company as I live in Florida with frequent electrical storms.
I do not know if this might be part of the issue, but my REL has developed a hum upon my introducing the NAD into my system. The REL was not powered on the last two times the protection circuit activated.
Thank you,
joseph

I have purchased two of these amplifiers and they both have the exact same protection circuit issue. This is a common problem with this amplifier that NAD engineers decided to sweep under the rug and not address. I had both amplifiers repaired under warranty and several times each for the exact same problem afterward. It does not matter what equipment you have them connected to or how you use them they will fail repeatedly without any rhyme or reason. However, when they do work they sound excellent and are impressive. I own many NAD products and all of them work perfectly without any flaws except these amplifiers. It is really a shame because I want these amplifiers to work and be used daily. Not Always Dependable.

 

[TLS Guy]

I have purchased two of these amplifiers and they both have the exact same protection circuit issue. This is a common problem with this amplifier that NAD engineers decided to sweep under the rug and not address. I had both amplifiers repaired under warranty and several times each for the exact same problem afterward. It does not matter what equipment you have them connected to or how you use them they will fail repeatedly without any rhyme or reason. However, when they do work they sound excellent and are impressive. I own many NAD products and all of them work perfectly without any flaws except these amplifiers. It is really a shame because I want these amplifiers to work and be used daily. Not Always Dependable.

It seems this is a problem with the design of the protection circuit likely. They had the same problem on the C 370 amps. People modified that circuit, but I can find no published mods for your amp. The only solution would be a DIY mod. The circuit for the C 370 is available but not your amp.

Anyhow both amps have the same power into 8 and 4 ohm, there is no increase of power into 4 ohm, so obviously the amps operate close to the margins.

To be honest there is a lot better gear around than NAD. I have never been an advocate for that brand. Do you need an integrated? Yamaha have a decent one, and then there are the Rolls Royce of integrated amps the Creek.

I have no experience with them, but the Chinese are selling clones of the renowned vintage Quad 34 preamp and Quad 405 power amp for very little money on eBay. If they have followed the circuits to the letter, and they are simple, then they must be the best value in audio amplification out there. I have used Quad amplification exclusively now for 50 years and would not use anything else. The genuine articles of what they have cloned are going for upwards of $1000 now per item.

By the way the design of the Quad power amps is current dumping, which is pure brilliance. It is a feed forward design with a class A amp correcting the dumper output transistors. So you get class A performance without the heat and hassles. In fact they run very cool.