As Raj would say, "I Swear to Cow, that's Loud!"

So, one of the new QR 1720 locos I have recently purchased was the Egg & Lettuce one, uou know, green and gold - the Bicentennial paint schemed one that QR did - QR 1723. While I was purchasing it out from under Scooters nose, I also purchased a sound decoder from the same bloke, that he hadn't gotten around to installing yet.

The electronic sound and controller gizmo is an ESU 95455, LokSound Select 6 AUX, this is the v4.0 LokSound decoder that comes factory preprogrammed with the Wuiske version of the 8 Cylinder EMD 645E (FT) engine. The decoder measures 30 mm x 15 mm by about 4 or so millimeters thick and is an 8 pin type.

I decided to try something different with this installation. As I've been playing with different sound chambers in my N scale locos, I thought I'd give this fella a big sound.  I already had a bunch of the ESU 50321 Sugar Cube Speaker and Baffle sets on hand, so I figured that since the ESU LokSound decoders can drive 4 ohm to 16 ohm impedance type speakers, that I might just see what two 8 ohm sugar cubes wired in parallel would sound like since that makes 4 ohms impedance.

I built up a seperate baffle chamber for each speaker using the supplied ESU parts. I used the 2 mm walls, the lid and the speaker on each setup. The walls and lid were super glued together and then the speaker attached to this with white glue. 

This gave a speaker size of 11 x 15 x 6.5 mm. The 6.5 mm depth just fits into the 1720 loco's fuel tank with juuuust enough room to use a piece of double sided tape - the Sellotape "Sticky Dots" type since they are nice and thin.

Now the chassis went into the vise, rubber jaws of course, so I could work on it easier than it floating all over my bench. 

Once the white glue was dry, overnight wait, the double sided tape was applied and the speakers stuck into the fuel tank. I spaced them apart for better sound reproduction, but didn't allow them to actually touch the walls of the fuel tank - less chance of stray rattles. "Rattle & Hum" by U2 was playing in the background (for real) by the way, if you were interested Scooter.

The decoder was then double sided taped to the inside of the roof as far to the rear as I could possibly get it. I used my normal old Sellotape "Mounting Tape" to stick it in place.

I then carefully soldered on my wires to the speakers. I wired the speakers in parallel first:

Then I wired this setup back up to the decoder and used some tiny heat shrink tubing over the joins to the decoder. 

I drilled a few more tiny holes in the fuel tank cover to "let out the sound" better and snapped that back into place. Here is a before and after the drill bit was used.

A few attempts of carefully putting the loco's shell back on was needed, to make sure all the wires went back in as efficiently as possible so as to not jam anything up or get in any way. The two screws to hold the shell on were then screwed into place and we were ready. So onto the test track and I fired up JMRI on the computer and opened up a throttle and turned the power on to the loco...

With the same settings as I normally used for single Sugar Cube Speakers or standard 8 ohm coil speakers... HOLY COW !!!!  Ear plugs required !!!!  But she is crystal clear - NOICE, very nice indeed... can you hear me over the engine noise?  OMG, does this steup work or what ?!!!

So I have now gone into JMRI and reconfigured a few settings on the sound chip.  I have dropped the Master Volume down from 180 down to 100  (192 is max).  Also,  Slot 1, which is the Engine Noise, has also been dropped down from 100 to 70 (128 is max).

I may have to revisit these settings and drop them lower. I'll find out once I run the loco down at the train club.

I am now very very tempted to revisit my older 1720 locos and do them with dual speakers too... we'll see.