DCC Sound in Brass Locos

On my Key PRR 2-8-0's I mount a 1.2" QSI hi base speaker and snap on enclosure in the smokebox pointed up the stack.  At a slight sacrifice of volume I gain the advantage of the sound coming from the right end of the locomotive.  I used Soundtraxx Tsunami decoders for motor control and sound.  Their small size fits nicely above the factory lead weight inside the boiler.  The chuff is triggered by a bronze wiper I installed to run over the factory cam on the 4th driver.  For locomotives without factory cams I'm planning on using split axel cams offered by Grizzly Mountain Engineering in a wide variety of axel diameters.  The Tsunami decoder reliably handles the smallish Canon motors in the Key H's.  For larger motors with higher current draw one can purchased Tsunami decoders modified for heavier duty service by Protocraft, or go with QSI Solutions Titan's.  A secondary advantage of mounting the speaker and decoder in the boiler is that it minimizes the number of wires (and connector size) between engine and tender to just that needed for lights on the tender.

Ed Rappe

I have not put sound in a brass steamer with DCC.   But I have done over 20 for straight DC.   

First I check the current draw under load and stall.    If the current draw is less than specified for an "HO" sized decoder Iuse one.    Some of my newer Sunsets were OK with this.   I had a stack of Digitrax DH123 decoders that were dirt cheap.   They worked fine in these and have a 2 amp stall.   Very basic decoder with only motor and light functions.

If the loco draws more than an amp running and the stall is higher, I use an NCE D408SR decoder.   This supports 4 amps running and 10 or so stall.   It will handle any O scale motor I have including old Max Greys and do it well.   

I try to fit the decoder into the boiler if possible, because is saves the number of wires I need from the tender.   If this works, I have 2 for the tender light, and 1 for the track pickup.    Easy to get 3 prong plugs.    I have found on many steamers I can get the big 408 decoders in above the weight in the boiler.

I installed DCC/sound in two Sunset brass locomotives. This was 3-4 years ago and I used what was then the state of the art QSI Magnum G/O scale decoder. Both engines sound good but not great to my ear. Both are PRR engines. One is a Consolidation and the other a High Iron K4. The K4 had some holes in the tender from the factory so I didn't use the tender as a speaker box. I made a speaker box out of wood. I mounted a speaker from QSI in the box and used double sided tape to stick it to the tender. The only thing I did not do was make some kind of cam like Ed did. There is a way to program the chuffs if you use QSI decoders but you need their programmer to do this which I do not have. I am going to look into Grizzly Mountain Engineering. Thanks for the heads up Ed. 

Thanks for your advice guys. Much appreciated.