NAD VISO HP50 Mods

I have had my pair of HP50's for a number of years now, but was only recently motivated to take them apart and see if any mods could be done. The impetus for my modifications is linked both to desire for improvements as well as to correct annoying issues with the build quality innate to the headphone.

Because no one will really care about the process or even what is being attempted unless they know the results will yield some worthwhile benefit, here are my impressions of the mod results.

• More comfortable with better seal! Nuff' said.

• Noticeably more texture to the sound. Possibly reflects better micro-dynamic performance.

• The bass is more solid. By this I do not mean there is more bass, in fact there is possibly less mid-bass post-mods. Rather the bass is more balanced, and the extra dampening has shown how the enclosure was previously hampering the bass performance because it needed extra structural dampening. Before the bass was good, but un-involving. Now it has an extra "it" factor.

• Mids were always great, and they still are. As far as I am concerned, no change to the mids means a successful modification.

• Treble was not made brighter, but has a gained a nice clarity. This probably related to the simple acoustic treatments on the cup. It would be cool to see how the CSD of the post-mod headphones.

• Black-ground is better than ever!

*Ask me for any additional impressions or areas of special interest.*​

Before we look at the mods I have implemented lets list the issues that are trying to be corrected.


1) The ear-cups squeak quite noisily when adjusted on the head. This is more of an issue of feeling cheap than the inhibition of function, but there is no good reason for the mechanical parts to not work smoothly.

2) Implement some kind of damping on the rear cup. There is only bare plastic in the default configuration.

3) Figure out a way to increase the rigidity of the cups. The most of the headphone is empty space, even areas that are not acoustically active, so there is room to increase structural rigidity.

4) Dampen the back of the driver and/or the inside of the main driver enclosure (This is a separate piece from the rear cup).

5) Make pads more comfortable in a way that does not mess up timbre.


Disassembly instructions:

• Take off the pads.
• Use a jewelers screwdriver to remove the four screws that appear.
• After the screws are removed, there will be a back plastic piece that is inset the remaining plastic structure. Use tape to lift this plastic piece out of the assembly.
• Remove the remaining screws that appear underneath and very carefully lift the black piece out.

BE VERY CAREFUL AT EVERY STEP TO PREVENT STRESS UPON SOLDER JOINTS.


Issue # 1

This was fairly easy to fix as it was ground that has already been tread by others. Take the headphones apart and place small strips of electrical tape over the pieces of plastic that are on either side of the hinge that connect the arms to the cups. In addition to this tape, I placed sticky-back felt on the are where those plastic pieces rub. This makes things nice and smooth... more importantly quiet. Might as well tighten those screws you see while you are at it.





Issue # 2

I simply placed a piece of felt under the hole where the driver enclosure area vents into the cavity created by the back of the cup. No reason to make this complicated.


(See pic above.)

Issue # 3

This takes a little more effort to accomplish. One the driver enclosure area is reattached to the back of the cup, you will see how there is a lot of empty space that is not involved with the acoustics of the headphone. The way that the driver seals against the center area means that it is very controlled. This also means we can fill the empty space to increase the overall rigidity of the headphone and better dampen any stray cavity resonances. To accomplish this goal, I used Hobby Lobby brand blutak to pack the empty spaces. Take a look at the picture for reference.




Issue # 4

I tried to place a piece of felt on the back of the driver, but figured out that there is a very significant problem with adding anything to the cavity to the rear of the driver. The space is so small that any addition, such as felt, will seal the vent off and mess up the mids. FAIL. Best to skip any changes here.



Issue # 5

I have been experimenting with placing foam under the pads in order to provide extra ear space for a while, but think I have finally refined the concept. You start with a piece of dense craft foam, cut to shape. Next wrap in electrical tape to give some structural support. Finally, cut a thin strip of felt and line the inner surface to prevent any resonances from messing up the timbre. This makes the pads SO MUCH more comfortable than stock.

 

These headphones are notorious for leaking when placed on my head. They always lose seal underneath my ears. I thought a angled bracket behind the pad might be beneficial after I realized the pad is closed and cannot be fiber-stuffed. The acoustics are such that mods may not really be necessary as they sound terrific but the build is just so cheap...

 

Just updated the main post by added pictures and general impressions.

@gibtg I hear you on the seal! I had the same problem, but find the solution I have arrived at is more than sufficient to fix the issue.

Regarding build quality, I am not sure if it is the added structural damping or merely that they no longer creak, but the overall build quality feels much better after adding the mods and tightening everything up. If you decide to do any of the mods I listed, let me know what you think!