DC blocker for NAD T777 V3

[Niklasmagnus]

Hi, I want to try an DC blocker to check if the hum/buzz goes away from my speakers (most audible at the surrounds that are closest to MLP). The NAD receiver are rated continuously 7x80 watt = 560 watt so need a DC blocker that can pass through the currant.
Will the Audiolab DC blocker work? I like the separate box format.
Spec:

Peak Load :	600VA
Audio Power Amplifier Compatibility	<2x150W or <

Or should I try the ifi DC blocker, spec:

ZERO DC Block technology	Blocks incoming DC – up to 1,200mV
Voltage rating	90 – 240 volts
Maximum current rating	> 7A
Max amplifier power	880W or VA on 220v 440W or VA on 110v
Continuous current rating

Thanks

 

[fpitas]

A DC blocker will have no effect on buzz from your speakers. It's used when the power transformer of the amp makes noise:

Mains DC and Transformers

ESP - The Audio Pages. Even a small amount of DC offset on the mains is enough to cause problems. Find out how it happens and how to fix the problem.

sound-au.com

 

[Niklasmagnus]

But cant the power transformer introduce noise all the way to the speakers?

 

[HarmonicTHD]

But cant the power transformer introduce noise all the way to the speakers?

Yes but that is often caused by ground loops not by DC being present on the AC mains.

 

[Niklasmagnus]

Yes, and the plan is to buy two ifi gnd defender, one for the receiver and one for the subwoofer. I can always return all of them if it’s not working.
But still not sure if the Audiolab dc blocker will reduce the NAD receiver capacity to deliver 560 watt continuously and some extra watt in peak? Or if I must go for the ifi dc blocker.

 

[Speedskater]

Is everything plugged into the same AC wall outlet?
The DC blocker will only reduce full power output by a few watts.

 

[Niklasmagnus]

Is everything plugged into the same AC wall outlet?
The DC blocker will only reduce full power output by a few watts.

Yes, all equipment are in same master/slave branch outlet. But I’ve tried directly without the master/slave also and connected to the four plug wall outlet. Feed by 16A directly from house terminal/ fuse box.

 

[Dundas]

Yes, all equipment are in same master/slave branch outlet. But I’ve tried directly without the master/slave also and connected to the four plug wall outlet. Feed by 16A directly from house terminal/ fuse box.

Have you tested with a cheater plug to see if lifting the ground eliminates the hum? For testing only, not a solution.

https://www.amazon.com/dp/B0986ZDH3J/

 

[Niklasmagnus]

No, but the idea is to test with potential solution, ifi gnd defender. If not working I can return to store. Not sure we have cheater plugs I Sweden, if not diy. But either way, it’s a big risk to use them.

 

[Dundas]

No, but the idea is to test with potential solution, ifi gnd defender. If not working I can return to store. Not sure we have cheater plugs I Sweden, if not diy. But either way, it’s a big risk to use them.

You are on an American forum. Might be a good idea to add your location to your profile.
Just get the iFi.

 

[Niklasmagnus]

You are on an American forum. Might be a good idea to add your location to your profile.
Just get the iFi.

Good idea, thanks.

 

[Niklasmagnus]

So I tried today first with the GND defender but no luck to reduce the buzz from the surrounds. Then I tried the DC blocker but no luck. Tried the combination but no luck. So I guess something in the NAD T777 are either broken or I have not figured out yet how to fix it. It should not buzz from the speakers.

One very positive thing is that I also tried the two products on my sub power amp which make ground loop noise and the GND defender works perfect. The reduction of noise was about 7dB. DC blocker didn’t do anything by itself and actually increased the noise in combination with the GND defender a few dB.

DC blocker was also tested if it adds anything extra to the experience but after switching back and forth a few times without hearing anything change I have decided to ship it back.