Speakers for DCC


This post combines new material with some hidden away in other posts. The photo below was of a common speaker such as those supplied with Loksound decoders. They are quite suitable for large body diesels and other larger models that have enough room.

This was the 25mm (1″) 4Ω  1.5Watt speaker and enclosure used for a 42 class diesel project. A silly but important point is make sure you solder the speaker wires to the speaker terminals before you seal it in place!

It is very important to make sure that the enclosure is fully SEALED around, and behind the speaker. The bigger the enclosure, the better but we are usually stymied by lack of space. See below for using Canopy Glue for sealing.

One of the best speakers I have used is the so-called “Sugar Cube” speaker. With even a small enclosure, they are remarkably compact combined with good sound quality. The ESU version is 12mm x 14mm and 5.5mm thick:

This is a sugar cube speaker with wires attached and ready to have an enclosure wrapped around. This enclosure is a little deeper than the depth of the speaker to improve the bass response.

I prepare some styrene strips equal to the height required and use a small machined metal block as an aid to assemble the pieces using a styrene cement.

The next photo shows one of the best TIPs that I have. If you are using super glue for assembling anything, use a small piece of teflon bearing material (or even thicker plastic) and drill a small depression into it. Put a drop of super glue in to the recess and it will last up to an hour or more without going off! It also helps when applying styrene cement. [PTFE teflon sheet can be purchased on eBay by searching for ptfe sheet]

To seal the speakers into their enclosure, I prefer to use “Canopy Glue” as it is sticky and remains in place, plus, it dries clear. As with the super glue, the best means of applying it is with a thin applicator such as a T Pin or a tooth pick:


The speaker enclosure doesn’t have to be rectangular – consider a cylindrical one to fit inside the smokebox of a steam loco. I have fitted them to brass steam locos including 30 class, 36 class and whitemetal 32 class. Like this:

The curved part has been cut from a small section of plastic pipe which needs to be filed flat as in the previous photo. Two end plates have to be shaped to fit.

The benefit of the smokebox speaker is that the sound is coming from the correct part of the loco. The photos below show a 25mm speaker fitted to a custom housing in the tender of a 36 class brass loco. The sound was brilliant – but it was clearly radiating from the wrong end of the loco.

Fitting the cylindrical speaker can be difficult. In my brass 30 class (small) loco, the smokebox door was loose so I was able to remove it. For the larger 36 class boiler, I was able to insert the speaker from the firebox end of the boiler tube:


This is an iPhone 4S speaker purchased from eBay. In this case I have split the speaker to see what was happening inside. As I understand it the chamber on the right is an acoustic cavity to improve the sound. The port where the sound exits is shown with a pink arrow, just below the speaker itself.

Here we have a 40 class diesel look-alike modified from a Kato RSD4/5 model. I like this model as it is well engineered and very smooth and powerful with 2 large flywheels. The tight space in the narrow hood filled with mechanism and weights meant I couldn’t easily fit a sugar-cube speaker but and iPhone 4S speaker sat nicely on top of the motor.
A close up shows the sound port on the RH end of the speaker.
Here is a sound file using an iPhone 4S speaker with an ESU V4 Loksound decoder programmed with an ALCO 12cyl 244 (FT) #73401 sound file. The loco sound volume is quite low and would be deafening if run at full volume.

I note that iPhone 4S speakers are currently (24/3/19) available on eBay from as little as $1.58 ea (+ GST) and with free postage.

For an even smaller loco, consider other iPhone speakers. The first 3 work but you would need to experiment.  The iPhone 5 speaker may be a good option for a small loco.

Solder directly to the contact springs.

iPhone 5 speaker showing the parts that can be removed.

If you have had any interesting success with speakers, I would be happy to post that on this blog (with acknowledgement). Rick

Drilling Holes in Foam

Since my layout uses foam sheets as a trackbed, there is a need to drill holes, often many of them, through the foam.
The drill used is made from a piece of metal tube. I use brass tube which does the job and is available in in a variety of appropriate diameters (eg. K&S). I use two main sizes:

  • 6mm for track feeders and points (turnout) wiring.
  • 12mm for mounting Servos in foam
  • + 10mm for other odds and ends

You could use aluminium tube but it doesn’t hold its edge well. Steel tube would work well if you could get the size.

This is why I needed to drill lots of holes in foam: Track feeders; Points wiring; Servo Mounting plus other odds and ends.
Prepare the cutting edge by bevelling the end of the tube on the INSIDE.
I carry out that operation on a lathe using a scraping tool but it could be done in a drill for short tube drills.
It may even be possible to use a tapered reamer to form the bevel. There may be a need to touch-up the edge from time to time.
Use a battery drill on a fast speed. This 12mm hole is through 50mm foam to fit a micro servo
(eg Tower Pro SG90 or my preference Micro 9g Metal Gear Servo). The marks on the “drill” indicate just how deep I need to go for the servos.
The result is a very clean hole
For 12mm brass tube it is necessary to reinforce the end held in the drill to prevent crushing.
I machined a small piece of aluminium in the lathe (about 20mm long) and epoxied it into the top end. But anthing will do eg. a piece of dowel or plastic can be hand filed while spinning in a power drill and have a (say) 6mm 1/4″ hole drilled through.  Or fill the end with epoxy and drill a hole.
A hole is necessary through the middle so you can use something to push the waste foam out.
Pushing the waste out… and below:

Here 4 holes have been quickly drilled to accept a servo with minor trimming.
In this photo a hole was drilled under a point to carry the wiring from the micro switch under the layout.
Note the use of a length of paper drinking straw to line the hole so that the chemicals in the foam don’t attack the wire insulation.
The straw is held in place with a dab of PVA woodworking glue or similar.

This is the underside of the layout showing five 6mm holes, lined with a drinking straw, to carry track feed droppers.
The centre 6mm hole carries 3 wires from the microswitch fitted to the point.
The 4 x 12mm overlapping holes have accommodated the micro servo and its connecting wire.
Working Expanded Styrofoam (EPS) can produce a SNOW STORM!!
I use a suitcase type vacuum cleaner with the nozzle directed at the work area whenever shaping EPS
The drilling process is fairly mess free but care needs to be taken when pushing the waste out of the drill.
The attachment shown above holds itself on by suction and has a hole to accept a drill to capture waste before it escapes!
Brilliant for working up under a layout. My suitcase type vacuum came from a local chain store (BigW in Australia).

Drilling Acrylic Panels

Drilling holes in acrylic sheet is easy with a small modification to the cutting edge of the drill. You should then have clean holes with no cracking in the acrylic.

Shown above is a small drill with the cutting edge suitably modified such that it has a “scraping” action, rather than digging into the plastic. The diagram below shows the effect required. Some sources indicate that the included angle of a drill for acrylics should be around 60° rather than the normal 120°
I don’t subscribe to this view as it is already difficult enough to grind the cutting edge of very small drills without having to alter the included angle as well. I use standard drills and just “blunt” the cutting edge as shown later.
Drill angles
Here is a set of modified drills I keep on the workbench with a piece of drilled acrylic so that I can test the fit of things like switches, bolts and screws etc.
This is one way to produce the “scraping” effect on the cutting edge. Use a Dremel tool mounted in a holder or in a vice with rubber jaws.
Make sure you wear eye protection and a face shield in this operation.
It is also possible to “touch” the cutting edge on a fine bench grinding wheel provided it has sharp corners but the Dremel is best for tiny drills. This photo shows a diamond impregnated disk but a normal brown abrasive disk will work (with a face shield). Do both cutting edges on the drill.
I always use a magnifier to carry out this operation.

Here is an interesting link from an Aussie Plastic Fabricator on how a pro sharpens his drills and other tools for plastic.