NS2 Power Supply Creating Lots of Static

[Cornopean]

Can you replicate the problem with any other keyboards? Those with external PSUs often cause the PSU to be located some distance away from the board, and therefore further away from waist-height guitars, so you may need to raise the PSU to get an equivalent test. I find it hard to believe that Nords alone would be susceptible to this problem, as they use fairly standard components. It might also be interesting to move the guitar near to the guitar amp PSU, the mixer PSU etc. and see if any of those exhibited the issue.

Al

[classicrockguy]

Thanks for chiming in. I have done pretty extensive testing with the various items I have handy. I've waved the guitar over my laptop power supply, the Mesa Mark V 25 guitar amp, the pedal board power supply, my old Mackie mixer, power cords, and even my wall around plugs and light switches. In all cases, a certain amount of noise is induced into the electric guitar depending on proximity and signal chain (the closer the guitar the greater the effect, the hotter the signal chain the greater the effect). In the case of a wall switch to a light, holding the guitar above the switch (presumably where the wires in the wall are on their way up to the ceiling light), the noise can be switched on and off along with the light.

In all cases, the level of noise induced by these various ac elements is relatively low, and the guitar has to be very close. It is also a fairly steady 60hz hum that does not seem to contain any "buzz saw" element. Frankly, it is exactly what I would expect.

In the case of the NS2, the level of noise induced into the guitar is significantly stronger and "dirtier". It also starts with the guitar much further away, as in 2-3 feet away. There is clearly something different about the NS2 relative to all of these other sources of ac interference.

The power supply in the Nord is internal to the instrument versus a seperate dongle like a laptop. When the keyboard is on a keyboard stand for performance it is about waist level. This is a "worst case" position relative to a guitar hanging around my neck. My idea to build a seperate housing for the NS2 power supply would be a desperate attempt to relocate it away from the waist level to the floor, thus creating enough distance from the guitar to alleviate the interference problem. As I posted earlier, this would be an extreme step that shouldn't be necessary with properly shielded equipment.

[pterm]

Since I was able to duplicate the issue with another new NS2, I must conclude 1 of 2 things:

1) I received 2 different new NS2’s with exactly the same defect (not likely), or
2) There is something in the design of the NS2 (probably the power supply) that produces an unusual amount of interference in a range that adversely affects electric guitar pickups.

I believe it is the latter. While I continue to receive assurances this is an unusual complaint, I wonder if anyone else is actually doing what I am doing? Are there others out there who are playing both electric guitar (pop/rock distorted signal chains) in close proximity to an NS2? Has anyone actually taken a guitar and held it near an NS2 to try and reproduce this unwanted behavior? This issue is very obvious and easy to reproduce, at least on the 2 NS2’s I’ve had my hands on.

Not sure where to go from here. Can the NS2 power supply be shielded some way? Do I live with this (e.g. try and work around it on stage) or return the NS2? I love it except for this major issue.

It's entirely possible two new NS2s exhibit this problem:
I went back through the forum and found a picture showing the power supply transformer's part number and manufacturer (Dantrafo). The part number doesn't appear in Dantrafo's catalogue, so I assume it is a custom part to Nord, produced in small batches.

Transformers contain hand-wound coils, so if an assembly error occurred, many in the batch could have the same flaw.

Transformer "leakage inductance" (magnetic field leakage) occurs when the magnetic field from the input side winding does not intersect the output winding. This is a function of the geometry of the core and the position of the windings. An assembly error at the transformer vendor could produce high magnetic flux leakage, accounting for the high interference you see.

Since Nord asserts this is unusual, faulty components in their supply could be the cause (rather than a Nord design flaw).

I hope Nord continues to look into this. I think they need to provide you a replacement supply or (another) replacement keyboard. You shouldn't need to shield this yourself.

It is a cumulative issue (more overdrive=more noise) that is common in the electric guitar world (try setting up in a club with neon lights nearby), but it is way over the top around the NS2. Does not matter which amp, which cable, or which guitar.

Interestingly, the wikipedia article on leakage inductance http://en.wikipedia.org/wiki/Leakage_inductance mentions Neon light transformers intentionally have high leakage.

I hope Nord helps you get this working the way it ought to work.
-pterm

[MattC]

Hello all,

I made a video of my issue.

In the video you can hear a power supply hum from my NS2 when I turn it on. My question here is: Is your power supply also humming like this? My dealer said that this would be in an acceptable range.

Then I use my bass guitar which is only connected to an audio interface. The closer I get to the Nord the louder the static noise becomes.

At 0:40 I turn the NS2 off and no noise comes out of the speakers.

So is this a normal behavior?



Best regards

[Mr_-G-]

Thinking about it, if you play keyboards OR guitar (but not both at the same time) an easy and cheap solution is to add a switch to the cable connecting to the guitar/bass. The switch should short the T and S terminals, same as the Neutrik 'silent plug'. Alternatively you could use a switch stomp box. Something like the Boss AB-2 or Boss LS-2 migth do the trick by connecting in one position to the effects & amp and in the other left disconnected.
When you play the guitar, switch it on and place yourself away from the keyboard.
That seems to me simpler thant moving the transformer outside the instument.

[classicrockguy]

Awesome responses. Thanks to everyone for the discussion. In regards to switching the guitar on/off and moving away from the keys when playing guitar, I can do this this dance with the guitar volume knob. Two issues 1) on some songs I alternate between the instruments during the song and 2) this would require 2 vocal mics in the 2 different stage positions. Still not a great solution to a problem that should not be there in the first place. However, for now I'm essentially using this general approach to work around the problem until I can fix it.

[classicrockguy]

Mattc your video is spot on. Try that with a single coil electric guitar like a strat and give the signal chain some overdrive and you will find the problem much more pronounced to the point the guitar is nearly unusable.

[Adams]

Just a long shot. I'm no electronics genius... My guitarist uses an old strat and wanders over to me on my stage 2 regularly. No noise here, but he is using a pod di'ed to the mixer. In one venue, the dimmers/transformers on the little house spot lights do cause hums and buzzes.

The Nord is a 2-pin mains connector. It must get a 'ground' or 'earth' from somewhere... ie your audio cables. What are you using further down the chain, mixer, di boxes, amp? Maybe that's what is letting a lot of noise in. Ask an electrician or keyboard tech if is it possible to externally ground the Nord. It doesn't sound like a 50/60hz buzz, but just a thought...

[classicrockguy]

I appreciate the tip, Adams. A Pod is an amp simulator that uses the analog guitar signal as its source, digitizes it, and then simulates different guitar sounds through it's digital algorithms. I do not believe it passes the "raw analog" guitar signal along. Also, the overdriven sounds produced by a Pod are modeled, not produced via overdriven analog circuits, which is what really multiplies the noise being picked up from the NS2 via the electric guitar coils. I doubt a Pod (or any other such device) would interpret induced analog noise from the guitar as needing to be "modeled" and reproduced into the DI/FOH signal chain, so in effect the amp sim approach would eliminate the problem. This is a great solution if I was a Pod guy, but I am not. I love the sound of real tubes (and I am pretty sure I am not the only guitar player who would say that). As I have stated previously, I should not have to alter my guitar rig/approach (which is nothing unusual) to accommodate a particular keyboard that doesn't play well with others, so to speak. (For any Pod lovers out there, I am not trying to make a comparison between digital amp sims versus old school analog. Both have their merits and supporters.)

An update on my saga ...

I spent a couple of hours this morning carefully shielding the electronics cavities of my PRS McCarty, and then dropped in all new electronics straight from PRS (pots, resisters, caps, etc.) The original pickup selector switch was a little noisy, as was one of the pots, so I figured I'd do everything I could to make that guitar as quiet as possible. Not that it wasn't, before, but now it is really quiet even running a modestly overdriven signal chain via a Boss overdrive pedal and the Mesa Boogie Mark V 25 on "crunch". With the NS2 off and other various electronics on (mixer, pedal board power supply, powered studio monitors, etc.), everything behaves "normally". The guitar is manageable and playable. Some minimal noise is there but nothing "abnormal" for this type of rig and settings. When I turn on the NS2, things get ugly when the guitar is within about 2-3 feet of the NS2. If the guitar shielding and new electronics helped, it is hard to tell.

Given I have tried 2 new NS2's, and at least a few others have been able to attest to the same issue (thanks to those who took the time to do some "real world" testing), I must conclude this is a design and/or manufacturing problem in the NS2. Either they missed something on the engineering side, or they subbed out their power supply or transformers to a 3rd party (maybe China?), and the parts are subpar and not performing correctly. In particular, I suspect the power supply transformer is "leaking" far more than intended for whatever reason. Even if they can claim it passes some USA spec (in other words, "it's legal for import"), that doesn't mean it's not a problem child. I could probably legally import a neon sign, but an electric guitar would not like to be next to it. An expensive stage keyboard is not supposed to behave like a neon sign (at least not by my standards).

I again challenge the folks that make/sell/support this keyboard to do some real world testing, and come back and say (honestly) it is okay. Actually, that would be great because then I would ask them to send me the NS2 they tested that did not have this issue. However, if it really is a problem (and I strongly believe it is), they need to come up with a solution (replacement power supply?) and offer it to owners like myself.

[DJKeys]

Just for sake of discussion, I play in a classic rock band as well, and play both guitar and keys on some songs, which means I am wearing my guitar while playing the keys standing, just as you describe.

My Stage 2 is a 2011 model and I have never experienced this issue you describe. It may very well be that my unit is older and has a different PSU than the newer models. My Guitars are Carvin DC-125 and G&L ASAT Junior (1999). I play through a modeler, though, not a real guitar amp, Digitech GSP 1101 through an Ashly mixer to a QSC K-10.

I have followed this thread and your troubleshooting procedures are methodical and detailed. I truly hope you find the root cause of this problem.

-dj