I purchased a Lionel FreightSounds UTLX 30K tank car (No. 6-85081) from my local Lionel dealer in 2019. I loved the look of this modern rolling stock, but was disappointed in its muffled sound effects.
A short time later, I purchased a FreightSounds PS-1 boxcar (No. 1926620) from Charles Ro and was happy with the sound effects from that car. The tank car has languished on my shelf while the boxcar was used constantly.
I wondered why the sound quality on the tank car was not as good as those on the boxcar as they were manufactured only a year apart. Did the boxcar have a better speaker? After I checked the Lionel parts site, I discovered that both use the same 8 ohm Baby Fat Boy speaker
I turned both cars over and realized that the holes on the bottom of the boxcar near the speaker were considerably larger than thoses on the bottom of the tank car. I used an 1/8 “ drill bit and to widen the holes. The difference was dramatic!
For reference, I added 4 entirely new holes to the car underside (next to, and through the oval shaped protrusion on the right side). I started the holes using a pin vise with a small-diameter bit as I was worried my drill would wander and damage the underside.
Take care when drilling out the three holes near the brake line. Set your drill to the lowest possible speed setting and work slowly.
Lionel enthusiasts who own this car might also find that the potentiometer,which controls volume, tends to move around inside the car and away from where it is supposed to be under the dome. I used a long slender object (a paint stir stick) to gently push the potentiometer back into place. I then secured it by taping the electronics assembly inside the car at the end, opposite the brake wheel with double sided tape.
After these two easy modifications, this 30K tank car, once a bit of a disappointment, is now one of my favorite cars!
