05 Feb

Fitting a sound box to a sugar cube speaker

Whether your sound box is injection moulded, made of resin or 3D printed, sound box installation is basically the same…and it’s very simple!

You’ll need some glue (cyanoacrylate/superglue) or solvent cement, a few toothpicks, a hobby knife and some tweezers.

The sound box should be fitted on the diaphragm side of the speaker. Depending on the make/model of sugar cube speaker, this may be open to the touch or it may be covered by a thin layer of protective black material and/or surrounded by a thin white gasket.

We recommend that, where fitted, the white gasket surrounding the diaphragm, along with any black covering material, is carefully removed prior to fixing the sound box. This will allow for a better seal between the sound box and the speaker.

When you have the speaker prepared, apply a small but continuous bead of glue or solvent cement around the narrow lip of the sound box. It’s best using a cocktail stick to do this at it enables accurate application. Be careful not to get any glue or cement onto the diaphragm or surround.

Offer up the speaker with diaphragm facing into the sound box and press the two parts together, holding them firmly until the glue has dried or the cement cured. Follow up by applying a thin bead of glue or cement (again, using a cocktail stick) around the outside of the join between the gasket frame and the basket.


You’re now ready to solder the speaker to the sound decoder and install it in the locomotive. We always recommend that a tiny amount of liquid flux is used on solder tabs and pre-tinned wires to ensure that good solder joints are achieved.

NB. Due to the nature of manufacturing process, when using a 3D printed sound box, occasionally printed parts may have small air gaps between some layers. Brushing a thin coat of solvent cement across the inner surfaces of the sound box prior to installation should seal any such gaps. You may also be able to use PVA glue to the same effect, but it may take longer to dry.