Nord One Up Ncore NC500 amps, Class D ready for prime time .....

Devg,

I'd open the amps and make sure all connectors, op amps, and cables are snug, seated properly and secure. You could also try running everything in your system from one single outlet and see if that changes anything. Emotiva and other companies make inexpensive DC blockers that you can try that will quiet transformer type hum. Is your outlet dedicated or are there any other devices on that leg of the AC panel? Electrical issues can be difficult to track down. I'm sorry you are having some issues with it.
 
joeinid said:
Devg,

I'd open the amps and make sure all connectors, op amps, and cables are snug, seated properly and secure. You could also try running everything in your system from one single outlet and see if that changes anything. Emotiva and other companies make inexpensive DC blockers that you can try that will quiet transformer type hum. Is your outlet dedicated or are there any other devices on that leg of the AC panel? Electrical issues can be difficult to track down. I'm sorry you are having some issues with it.
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Joe, I have three outlets on a single 30amp dedicated line. Two are unused at the moment and a Synergistic Research Powercell 10 UEF conditioner is plugged into the 3rd one. I connect everything to the conditioner.
 
Wow, that's what I want. If I had it to do over, I'd do a 30 amp line or similar. I hope your issue is easy to resolve.

Devg said:
Joe, I have three outlets on a single 30amp dedicated line. Two are unused at the moment and a Synergistic Research Powercell 10 UEF conditioner is plugged into the 3rd one. I connect everything to the conditioner.
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A question.

I have the Khozmo passive preamp here and I am comparing it to the Nuforce P9 active preamp. Now there are two complications in that one is active and the other passive. Also one is phono and the other XLR. The problem for me is that I do not have two similar cables with one having phonos and the other XLRs so I can't do an apples to apples comparison until next week.

Has anyone compared an active to passive preamp with the Nord? Has anyone any experience with XLR/phono connections?

I have already rejected a bad internet bought XLR/RCA adaptor and bought a decent Cardas one.

I will be able to do such a comparison next week as will a colleague once the UK post gets the right cables in the right place. But I am getting odd results using Cardas Golden Reference, Nordost Valhalla, Tyr,Frey and Transparent Audio Super cables. I know it is unbalanced using cables that cost more than the amp but I already have some of these cables (I do not own not all of them, I am not that far gone :-).

I will report what we find next week of course but I am interested in other people's experience.
 
Devg,

What preamp are you using with the Nord's?

Are the Nord's off on their own (mono amps directly adjacent to a loudspeaker) or in a rack with other components nearby?

Is the noise coming from the amp chassis itself or thru the loudspeakers?

Have you tried powering off (not just put in standby, but powered off / unplugged from A/C completely) other components in the system one by one to see if the problem resolves itself? Eventually weeding out all other component influences until only the Nords are left with power and turned on? Then, does the problem hum still remain?
 
I get a slight hum from my speakers with the Nords. I got an active tube pre and a little Tisbury passive and the passive is more noticeable when hooked up to the Nords. But this is only when nothing is playing and I walk up to put my ear to the speakers. I guess I thought it was par for the course with these amps...
 
In order to really understand exactly what the amplifiers are out putting noise level wise..... disconnect the input interconnect cables at the Nord amp side that come from your preamp and leave the power amps connected to the loudspeakers and powered up. Now put your ear up to the loudspeaker and check. This will be the true noise level of the amps.

After doing this exercise and when you plug the inputs back in coming from the preamp, if there is added noise it's coming from the preamp not the amps.
 
MikeCh said:
In order to really understand exactly what the amplifiers are out putting noise level wise..... Disconnect the input interconnect cables that run to your preamp and leave the power amps connected to the loudspeakers and powered up that will be the true noise level of the amps. Any difference in noise level is coming from the preamp in this instance.
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I'll try that when I get home. The noise doesn't bother me as its only when the room is real quiet and I put my ear up close but I do remember my previous amps not being like this. With the tube pre I was always get some hiss but the passive was surprising when it was noisy with the Nords, I could have had poor connections on the passive, the inputs and outputs are not the best quality either.

I noticed the hum was less when I switched from my conditioner to the surge protector. I wish I could plug both straight to the wall but not enough outlets.
 
With my Conrad Johnson gear, I get a terrible hum UNLESS everything is plugged into the same outlet.
 
MikeCh said:
Devg,

What preamp are you using with the Nord's?

Are the Nord's off on their own (mono amps directly adjacent to a loudspeaker) or in a rack with other components nearby?

Is the noise coming from the amp chassis itself or thru the loudspeakers?

Have you tried powering off (not just put in standby, but powered off / unplugged from A/C completely) other components in the system one by one to see if the problem resolves itself? Eventually weeding out all other component influences until only the Nords are left with power and turned on? Then, does the problem hum still remain?
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Hi Mike,

I am using a Cary SLP-05 preamp with the Nords. The Amps are on the floor on maple block. My setup is a bit weird as I have to accommodate HT in the same room/setup.

The buzzing noise is coming directly off the Amp chassis and not through the speaker. Its like a 60Hz buzz from transformer and I can hear it when I have 1/2ft from the Amp.

I am yet to troubleshoot it since I wanted to check with other users if this buzz is normal or not. Now since you and other confirm that they don't hear in their system, I will start trouble shooting it, like you asked.
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My amp is dead quiet and through the speakers too. A ground problem?

Devg, very nice system you have.
 
I have heard about amps getting 60hz hum. One solution I saw, believe it or not, was plugging all components into the same outlet. I thought Class D amps were not affected by this type of hum <shrug>
 
Devg

Is it just one unit or both? That may help you determine whether it is a power issue or a connector issue like Mike had with Jerry's amps. If you are trying to use SE cables with an adaptor that could be your problem. The Cary is fully balanced so you need to find a pair of balanced cables and try it that way and see if the problem goes away. Some gear doesn't like the conversion.
 
PeteG said:
My amp is dead quiet and through the speakers too. A ground problem?

Devg, very nice system you have.
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Not sure Pete. My Pass is dead silent when plugged into the same outlet or conditioner.

Jack said:
Devg

Is it just one unit or both? That may help you determine whether it is a power issue or a connector issue like Mike had with Jerry's amps. If you are trying to use SE cables with an adaptor that could be your problem. The Cary is fully balanced so you need to find a pair of balanced cables and try it that way and see if the problem goes away. Some gear doesn't like the conversion.
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Jack, Both the Amps buzz. So I suspect it may not be the Amp but something to do with incoming power - maybe a DC offset. I run fully balanced from DAC to Pre to Amp.
 
Devg said:
Not sure Pete. My Pass is dead silent when plugged into the same outlet or conditioner.



Jack, Both the Amps buzz. So I suspect it not to be the Amp but something to do with incoming power - maybe a DC offset. I run fully balanced from DAC to Pre to Amp.
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Hmmmm (no pun intended)

p.s. Nice setup Devg.
 
Devg

I suspect you may be right and the only to find the culprit is to do what Mike suggested a while back which is to run the amps alone and then add one upstream component until you find the offending component. At that point try a cheater plug on that component and see if it goes away. The other option which I intend to do in the morning when mine arrives is to pop open the case and verify that every connector is still properly seated. As I have experienced the joys of UPS international shipping on more than one occasion I alway open a component and look for interior irregularities. I received a NIB tube preamp from Toronto last year that had pristine double boxes but had been "flat dropped" from such a distance that the transformer had been broken loose from it's mounting. Ground issues are really not that uncommon of a problem with components from "boutique" companies that are designed and built for one power system and then converted to another. For larger companies that design and build for multiple power systems that doesn't seem to be a problem.
 
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