Mallet QSI Install


I added a QSI DCC motor/sound unit to my Mallet, it is in the boiler. (newer versions might have it in the tender)

Here's the QSI in place, no great shakes, takes longer to remove the boiler than to install it!


If you have read my Mikado install, you know I used one of the 2 sets of wires between the loco and tender to bring track power to the loco, and the other to send the sound from the loco back to the tender.

The Mallet has a working backup light, so making the sound "go" from the QSI in the boiler "back" to the tender would have required another wire, since I am using one wire for the power pickup from the tender, and the other runs the backup light.

I really did not want to add yet another wire and connector set, and also, the QSI is a 5 watt output, the stock Aristo speaker in the tender is 1 watt, so I would wind up replacing it, it does not have a lot of bass and distorts easily.

More importantly to me, the mallet is the first loco where the the sound coming from the tender just sounded silly.

Since the smokestack is VERY far forward from the tender, you could notice this from 20 to 30 feet away. I tried the tender speaker and it seemed very  unrealistic.

While installing the QSI, I noticed a large open spot in the very front bottom of the boiler. I simply took a 1.5" hole saw and cut a hole through here, and put in a small speaker with a big magnet. I did not bother to make an enclosure. I do not get as much bass as the larger speaker in the tender, but the sound comes from the right place now, and I liked it much better.

Here's the speaker held in place with some double sticky "tape" This stuff is moldable and sticks to itself. I found it at Home Depot, used for sealing windows, etc.

I figured I'd make a better mount later, and possibly look at a larger speaker, but this sure was quick and easy! This is a 2" speaker from Jonathan Belieze, who owned Electric & Steam Modelworks. Jonathan always found great speakers at good prices, and this speaker has a very long throw, big magnet, nice surround.


Here's the measurements to make sure the speaker would clear the smoke unit:


Well, that was nice, but thought maybe I would try a larger speaker for a bit more bass, since I had the loco open. I tried a 2x3 oval from Jonathan, it just fit, had to notch the frame:

That was an improvement, but since it was 4 ohms, I put 2 in series, and put one back by the backhead:

I still did not have an enclosure. While I was contemplating what to do, my friend Leonard Kerns took 4 of the 2" speakers and made enclosures for them:

One goes where I put it before, the other points up into the boiler right next to it, and the long tube (which has a speaker at each end) lays on the weight in the boiler. Do it right and everything fits, including the stock smoke unit.

This sounds even better. Leonard had a site and made these up for you. (Excuse the look of mine, mine were prototypes, and I gooped up a bunch of silicon on the outsides.

QSI install and settings

Original sound file: 7.0.50 soundset 0, 8/24/07

loaded version 7.18.2 on 12/22/2007, type# 4000, sound# 0

needed to set reverse direction

cv56.12 = 44 (autochuff scale interval)


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