Comments invited on Rhodes soundproofing - avoiding the 'Schroeder effect'

[Major Bloodnok]

A comment by AndyP, in a separate thread ('Embrace my 79 Stage timbre, or start ripping things apart?') about bringing his Mark II up to scratch, prompts me to think again about soundproofing my Mark I Stage. Tinkling from the innards is not a problem when the amp is fairly cranked up; but when family life obliges me to practise with (closed circumaural) headphones, my activity is still not 100% silent.

AndyP reports some success in this regard with some spare Dynamat, applied to the inside of the harp cover. This is marketed as an automotive sound-attenuating product. My guess would be that such a material applied to my Mark I would work primarily by reducing resonance within the enclosed space, rather than damping vibrations in the cover itself. Possibly the Mark II cover behaves differently, but the Mark I harp cover is a fairly loose fit, especially at the ends. There is also an unnecessarily deep cut-out at the front to accommodate the output jack and controls, such that there is actually a tiny gap between the edge of the cover and the top of the namerail here.

I thought, therefore, that I might first try out ways of effecting a better closure around the harp cover, with a view to reducing direct acoustic leakage, if I can do so without making it unduly troublesome to remove and replace the cover for the purpose of occasional essential tweaks. Judicious use of adhesive-backed foam draughtproofing strip might be a good place to begin. I will report in due course.

In the meantime, has anybody here experimented with soundproofing the Rhodes?

I suppose also that, if I make a really efficient seal and thereby reduce ventilation, I must consider condensation. What will happen if, after I replace the harp cover on a warm, muggy day, room temperature drops on a winter's night? Perhaps it would be a good idea to place one or two silica gel dessicant sachets in some accessible location within the piano?

[Tom999]

I have an '82 mark II with the plastic keys so it was plenty loud. I read that thread also and thought I'd give it a shot - I used "Dynamat Xtreme Bulk 3ea 32"x18" sheets" (12 sq ft).

Comes in three pieces, just peel and stick. I cut each piece sideways as 18" is just a little over the inside dimension surface (front to back). I overlaid each piece by 50%, so essentially I have a double layer in the lid. Single layer on the inside sides. On the bonus side it adds some sturdiness to the plastic top.

Does it work? To some extent. It's not 100% quiet now but I notice a difference. I didn't have enough left over for inside the rail but wonder if that would even make much difference.  The highest octave is still very clacky. I don't think it's possible to completely silence the action on these. I'm not entirely sure where it's generating the hard clack from, I assume the pedestal somehow, but from working on this piano and looking at other types of actions, these keybeds aren't exactly state-of-the-art.

As for moisture I don't think the dessicant pouches (if you can find room) would make much difference, there is too much space between the keys for humidity to enter.  If it was really a concern I could see maybe adding one of those plug-in dehumidifier rods like they use in safes.