DS speaker enclosures for the PA


The Dave Stubbs speaker enclosures for the USAT PA house 4 speakers. Since the stock speaker locations were in the fuel tank and the very rear of the loco, unprototypical sound for the bell and horns is unvoidable with only the stock speaker locations. Furthermore, since the loco is long, this negative effect is further magnified.

So, the design uses an additional 2 speakers that are full range and are placed behind the grills just aft of the cab.



QSI mount:

First, mount the QSI standoffs to the base plate with 4 - 8mm screws from the underside of the base plate. I chased the holes with a #41 drill

Forward speaker enclosure:

Now start assembling the forward speaker boxes that use the Tang Band WI1942S, put the speakers in the back side of the plate, into the recess, fix with 4 - 5mm screws. If you want the original wires to reach to the decoder, make the wires face to the left and right, i.e. one left one right. That will give you the most wire out of the box.

remove flash from inner edges of the box where the covers will attach, you can feel a lip, use a file or x-acto

after assembling the small forward speaker box, take it to a belt sander and sand the bottom flat, there are sometimes raised lips on the edge of the box, but more importantly, part of the screw heads protrude above the surface, which can cause warping when screwed to the base plate

Base plate:

You must remove the 12v supply board next to the smoke unit, but the smoke unit can stay.

Bolt the forward speaker box to the base plate

You can mount the QSI/decoder now or later

Below is a picture of 4 base plate assemblies (I have 5 PA's) with the speaker enclosure attached:

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Remove the existing screws that hold the top piece in

Screw the base plate in with 8 - 6mm screws.

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IMG 2686


Rear speaker:

You need to cut the triangular "web" away from the 2 mounting posts where the speaker box will reside.

I chased the 4 lid mounting holes in the box with a #41 drill, as well as the 4 holes that mount the speaker

I soldered 12" of wire to the speaker, with the colors of the wire indicating polarity. I opened the notch in the speaker box to accomodate this larger wire.

Mount the speaker box with the notch facing the decoder to the shell with 4 - 5mm screws to the 4 holes around the fan.

Now mount the speaker with 4 - 8mm screws, and do not overtighten.

Now mount the lid with 4 - 10mm screws.

IMG 2687

Fuel tank:

Remove the single tall post inside the fuel tank, flush with it's surroundings.

Moiunt with 2 USAT short washer head screws (blunt end, short ones that secure smoke units)

mount the speaker (we are working on a better seal)

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