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November 7, 2016 Rivarossi Cab Forward Super Speaker Installation

I found some very nice speakers on eBay that I thought might work for sound in my steam locomotives.  I've been using 28mm low cost speaker for years but when I ran into these I couldn't resist.  The price was right and the picture on eBay looked pretty good.


The eBay listing is:

2pcs 1" inch 4Ohm 4Ω 1W Full Range Audio Speaker Neodymium Magnet Loudspeaker

When I purchased them they were listed at $4.59 plus $2.00 Shipping.

I decided to install both speakers in a Rivarossi Cab Forward Oil Tender.  Currently I'm using MRC 1731 DCC decoders in my Cab Forwards and AC-9s.  The 1731 decoder has an 8Ω speaker output so I will wire the two 4Ω speakers in series to obtain an 8Ω load on the decoder.

This is my starting point.



I used the X-ACTO Circle Cutter to cut a pair of 1-1/16" holes for the speakers.  I had to cut off a few details under the bottom plate and trim the toolbox to clear the speaker openings.

Testing my design for total fit





I made a speaker enclosure from .04" Styrene sheet.  I slopped on a good amount of plastic cement to ensure the enclosure wouldn't rattle under heavy bass sound.  I used 2mm screws to hold the speakers in place, three from the bottom with washers and nuts on the speaker side and one 2mm screw from the speaker side into tapped holes in the Styrene.



The 1" speakers with the enclosure in place makes a very clean installation.



This picture shows my first mod for something not expected.



What I didn't expect was the Neodymium Magnets picking up metal objects from the track.  I used a small piece of fiberglass window screen to prevent the strong magnetic field of the speakers from sucking particles into the speaker cones.  




My second mod was to cover the fiberglass screen with a small piece of black silk to prevent itty bitty metal particles from going through the screen.


I now have four SP oil tenders equipped with dual speakers and MRC 1731 decoders, two for my Cab Forwards and two for my Kitbashed AC-9s.

The dual speakers sound fantastic, as long as I can find them they are my speaker of choice.  The only problem with these speakers their size (1.162" X 1.162" X .58") and the fact that because they are 4Ω you must use two to obtain an 8Ω load on the decoder.  I haven't been able to find the same speakers in 8Ω for a single speaker installation.  I tried several 4 to 8Ω resistors in series to use one speaker but that slightly dings the bass response.



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