Grand 2: Elimination of power supply noise and mechanical differences with the Grand

[Hiphiman62]

Hello,

As a regular reader of the forum, I decided to create an account to share technical information about the Nord Grand 2, which I acquired a few weeks ago after trying out many models. I was able to compare the Nord Grand and the Nord Grand 2 simultaneously. In my opinion, the 2 is better because the key action is a bit firmer and, above all, less noisy and less bouncy when the hammers fall. When I first turned it on at home, I was furious to find that the power transformer produced a really loud hum, amplified by the very large aluminum case; unbearable! So I decided to desolder this transformer and place it in a decoupled box from the chassis; it's the only effective solution. I took the opportunity to examine the RH3 keyboard and compare it to the one in the Nord Grand using photos found on this site. There must be some technical explanation for these differences.

1: Contrary to what has been said in the forums regarding the key weight, the hammers are identical in both versions. They are the W3 and B3. So how can this sensation be explained? I would say the viscosity of the grease? It's quite surprising.

2: The method used to reduce noise was to replace the foam strips glued to the bottom of the chassis with a multi-ply plywood panel on which the keyboard rests. It's effective! The top of the Nord Grand, made of aluminum, is itself covered with a wood panel, and you can see that it is effective in absorbing resonances.

3: I noticed two damping modifications in the RH3 keyboard that would explain the reduction in key rebound (see the photos where these two areas are indicated by red rectangles).

4: Regarding the elimination of the hum, I can confirm that no sound is audible after the modifications. It's not exactly aesthetically pleasing, I admit, because I used what I had on hand. The box is screwed onto the piece of plywood, which is itself screwed into one of the nuts on the chassis designed to hold the wooden cabinet. This operation is completely reversible without damaging the chassis. The heat given off by the transformer isn't high; I don't think there's a risk of overheating. In any case, it's temporary; I'm going to adapt a ventilated enclosure. I should mention that I'm an electronics technician, so this operation isn't complicated for me.

Below you'll find some high-resolution photos to provide maximum detail. Since my English isn't very good, I'm using Google Translate.

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[pterm]

Thanks for the excellent pictures and mechanical comparison. I found this interesting!

[Beemer2]

I too was an electronic technician and have the Grand. I do not hear any transformer hum but am so interested in removing the thumping noise from the hammers and the key action. I have not yet opened the case so I have difficulty in identifying from your photographs which ones refer to the Grand and which to the Grand 2 as both seem to have plywood bases. Perhaps you could clarify for me?

[Hiphiman62]

About the transformer and key noise:

You might not hear this noise because your environment is already noisy, but in a quiet room it can become very noticeable.
All Nord keyboards seem to be affected to some extent, depending on the size and stiffness of the chassis.
It does not appear to be the 50 Hz mains fundamental that is most audible, but rather its 100 Hz harmonic, to which the human ear is more sensitive and to which the aluminium chassis may resonate more easily.

Key noise seems to follow a similar principle: vibrations from the keyboard are transmitted to the chassis, and any damping material probably only slightly reduces what has already been transmitted. Decoupling the source is likely the most effective method.

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GRAND 1 vs GRAND 2

- For the GRAND 1, the only photo I could find is this one: link. I do not own a GRAND 1 myself.

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- The photos show that there is no wood, only a damping material glued under the chassis. The keyboard is directly screwed to the chassis, so vibrations seem to be transmitted. The glued material probably only slightly reduces what is already transmitted.

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- In the GRAND 2, the keyboard rests on plywood, which is itself attached to the chassis. Two factors could explain the difference:
1. Keyboard decoupling → less vibration transmission
2. Chassis resonance absorption → the plywood may act as a damping layer

- Other manufacturers, like Yamaha or Roland, use a similar principle: some keyboards are mounted on wooden or melamine bases (e.g., RD2000).

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Key rebound and touch

- I have noticed that the GRAND 2 feels firmer and more precise, and the key rebound on release is much less pronounced than on the GRAND 1. On the GRAND 1, keys can bounce multiple times at the top, while on the GRAND 2, there is usually only a single bounce.
- This difference could result from three complementary factors:
1. The plywood supporting the keyboard seems to provide a stiffer base, reducing chassis flex and micro-oscillations, which stabilizes the mechanical reference.
2. The type and placement of the damping material under the keys (foam and felt), which differs between GRAND 1 and GRAND 2, could also limit rebound and affect touch. On the photos, the red rectangles show that both the material and its position change between generations.
3. The viscosity of the grease lubricating the moving parts may slightly increase resistance to movement, limiting rebound and giving a sense of density.

- Even though the GRAND 2 mechanism remains very similar to the GRAND 1, these three factors combined could explain the perception of a “heavier,” firmer, and more precise keyboard, with much more controlled rebound.

- I have also tested the Kawai CN201 and CN301, and it seems that from this generation onward, the keyboard becomes similar to the GRAND 2 (except for equal-weight hammers and let-off removal). This is my personal observation.

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Technical and practical conclusion

The key noise, both on press and release, is probably not caused by a single factor: mechanism, mounting, chassis rigidity, and damping materials all appear to contribute.
For the GRAND 1, it seems unlikely to achieve a significant modification: too much work for an uncertain result, especially if attempting to replicate the RH3 improvements.
For someone seeking firmer touch and less noise, a possible solution could be to sell the GRAND 1 and move to the GRAND 2.