Example 1: Zimo MX - older kit in 21pin Class 37

Kit: MX644D; IceCube28X18X08; SuperCap6800uF stay-alive

So many versions of the Bachmann 37 are available... this one is a fairly simple 21pin modern version...

Despite providing a dedicated space for a speaker, the flat 20x40 one suggested doesn't give great performance, so we're going for some minor modifications to accomodate a YouChoos Flame10 instead.

Here we see both the Flame10 and the suggested flat speaker side-by-side. We want to retain the roof fan, so chop off one end of the plastic mount where the Flame will sit beneath. It will be a tight fit, but will go.

Grind down the small ridge in the inset area so that the speaker can sit flat.

Next add the driver at the rear end (model comes with one driver at the front end already).

For independent control of the cab lights, we need to rewire the rear cab light to FA3/AUX4 of the decoder - solder wires directly to the 21pin plug. The front cab light is already on its own control (FA2/AUX3), so nothing to change there. Don't forget that a resistor is required on the positive wire to the rear cab light, as we have now bypassed the model's circuit board for this LED.

Tried to fit an inexpensive 1000uF electrolytic capacitor as stay-alive, but it just won't squeeze in under the fan, so switch up to a SuperCap6800uF instead, which lays flatter, and gives excellent backup power.

Tidy up...note the electrical tape over the cab light controls at the rear end, as we have wired directly instead.

Back together...

With the Flame speaker range being replaced with the IceCube range, we decided to see what bigger and better speaker we could improve this model with. With no more modifications, we can fit a dual IceCube 28X18X08-2W. The roof fan vibrates a little, but this is easily secured with a couple of blobs of Black Tack hidden away underneath, and the extra output from the IceCube is excellent.

Example 2: Zimo MS Kit and Simple Speaker

Kit: MS440C; YLR4020FLAT

A simple approach to the 21pin Class 37 from Bachmann... we plug in the MS440, and screw in a YLR4020 Flat 2W speaker, which is what the model is designed for. In this case we have a 2pin connector installed too, so the body can be removed from the chassis completely, but this isn't necessary. The 40x20 2W flat speaker actually works surprisingly well, as is certainly an easy solution.

Please note that these guides are provided as useful resources for you, as-is. YouChoos cannot be held responsible for errors in the information, or for any damage caused to your models or equipment if you choose to follow any of the steps detailed here.