Digitrax Sound decoder in a Kato F7 B unit?

[Flagler]

Has anyone installed the SDN144KOA in a kato B unit. How did you do it & what did you learn?
I always run consits with my F3 & F7 and plan to put a sound decoder in some of my B units.
I hope i dont have to make any frame modificatons by doing this.

[Flagler]

I guess I am the first to do this.

[Roger Holmes]

Flagler -- I have installed SDN144KOA's  in Kato E8A's and a Kato E8B.  The Digitrax website lists them for that application along with PA's and P42's.  They also say, "similar locomotives" but I would think that this board would be too long for the F7 you mention.

In the E8 the rear of the frame runs the full height of the carbody and is about 3/4 inch or so long.  The instructions call for boring a hole deep into the weight and recessing the speaker so it fires downward.  That large rear weight are doesn't exist on the F7 so you would need to find a place for the speaker.

I hope this helps.

[Flagler]

The job is complete and it works with no milling.
First I removed the Lights from the decoder on each end. The decoder board fits perfectly in the F3 & F7.
next I put the speaker and the capaciter in the cab end of the B unit and did not put the molded plastic cab back in.
I then put the shell back on and it works just fine. I wish it was louder r.but considering how cheap and simple I will do it again.

[Cajonpassfan]

That's great, so now the real question is, how's the sound???
I've pretty much given up on the early Digitrax sound decoders, but don't have experience with this particular one. Is it still generic sound?
Thanks for any input, Otto

[Flagler]

I think its week when compared to Tsunma that I just got preinstalled in my Intermountain cab forward,but it adds a little fun with bell & Horn.I need to do some more running

[Roger Holmes]

Surprised but good to know that it fits.    I'll have to try that out.  Any room for a small speaker enclosure since that generally improves sound quality?

[ram53]

Have you tested the engine with the decoder installed?  I know, I sound like Bob Downer of the Byron Pessimist Club, but on every Digitrax sound decoder I have ever used,  there is a very annoying slowdown when you activate any sound function other than the prime mover, ie.  you are moving along at 30 s.m.p.h. , hit the horn, bell or any sound function and the engine immediately slows down to 15 mph, then when you let go it speeds back up.  Tremendously annoying and the only solution is to disable all BEMF CVs, which makes for a less than stellar running engine, ie hard to get smooth starts and slow speeds.   This is one reason I've given up on Digitrax sound decoders, the other being the need for added keep-alive capacitors, the necessity to mill most engine frames and just the generally poor quality 8-bit sound.  In many cases, the sound files are raw and need audio editing at the assembly code level, which is just way beyond me and I don't see why a company can't provide properly edited soundfiles as a consumer product. Ultimately, the novelty wears off too, and after two years of struggling with sound that is usually too quiet and always lacking in low frequency, I'm ditching onboard sound and trying the stationary decoder to wireless transceiver to wireless headphone route.  I am amazed at how much better non-sound decoders perform at basic motor control after using Digitrax, MRC and Tsunami sound/motor decoders!   I like the sound of idling engines, but once they notch up, it sounds like white noise after a few minutes-the teeny speakers just can't move enough air.

[Flagler]

I would like the volume to be much louder.I have maxed all the CV's and its not enough.Does anyone have any ideas. What would it take to be as loud as my AC-11.Maybe a Tsunumi  & speeker in a dummy  B unit .It only cost a lttle bit more too upgrade the decoder to sound. I guess its a good way to develop a base line for sound  knowledge in n scale.Maybe Kato would make dummy b units with sound.

[bc6]

I would like the volume to be much louder.I have maxed all the CV's and its not enough.Does anyone have any ideas. What would it take to be as loud as my AC-11.Maybe a Tsunumi  & speeker in a dummy  B unit .It only cost a lttle bit more too upgrade the decoder to sound. I guess its a good way to develop a base line for sound  knowledge in n scale.Maybe Kato would make dummy b units with sound.

How about a sound car, most of the time youre hauling a boxcar behind the loco anyway. As far as the loco goes wouldnt vents in the loco help sound escape. Im talking fan grills, windows etc.

[robert3985]

I would like the volume to be much louder.I have maxed all the CV's and its not enough.Does anyone have any ideas. What would it take to be as loud as my AC-11.Maybe a Tsunumi  & speeker in a dummy  B unit .It only cost a lttle bit more too upgrade the decoder to sound. I guess its a good way to develop a base line for sound  knowledge in n scale.Maybe Kato would make dummy b units with sound.

Flagler, I've installed the Digitrax SDN144K0a's in all of my Kato E9/8 A units.  Having a Sherline mill made the process pretty easy, but I wouldn't have wanted to do it without a mill to create a precise pilot hole, then drill the 13mm hole with a sturdy drill press.  The speaker hole has to be drilled precisely in the middle of the rear chunk-0'-metal on the chassis, and the walls between the hole and the outside of the chassis are thin.  I could give you a precise measurement, but I don't wanna go down to my workshop to do that right now. Also, whatever metal Kato is using for the chassis doesn't like to be machined, or drilled.

The sound that's coming out of my E's is very loud, until I take the body shell off...then I can barely hear it.  The difference is extreme and I designed the installation so that the Kato E unit body would form a basically air tight speaker enclosure, and the 13mm speaker fires down to the track.  The hole is directly over the rear axle of the rear truck, and it is just slightly smaller than 13mm in diameter...so, it's a pretty big hole and allows a lot of air to move.

I wasn't sure if the body would form a tight enough enclosure, so I made the hole so the speaker went clear down it and left a big space on top for me to plug to form a smaller enclosure if the body shell wasn't tight enough.  Luckily it was tight enough.

So, on an F-unit, you have to have some way for the sound waves to get out of the shell, and you MUST put a speaker enclosure on one side of the speaker, or the sound waves will nearly cancel each other completely out. 

You've got two problems going on (1) No vent, and (2) No speaker enclosure.

I've got one of my DCC'ized Kato F3 B-units sitting here, and after I opened it up and took a look at the room inside the body, I frankly cannot see an effective speaker mounting method without some grinding and drilling/machining of holes, except for one possibility.

First, I'd use a 10mm speaker instead of the supplied 13mm speaker (I don't think there's room for a 13mm speaker and enclosure too) and I'd put as short and airtight a speaker enclosure on the back of it as you can find.  I'd mount it firing upwards exactly where you've got yours mounted now.  Then, I'd remove the black plastic "filler" on the bottom "front" of the chassis, which will create a vent so the sound waves can escape the body.

That might work.  It will certainly be much better than what you've got now because of the addition of the air tight speaker enclosure, and creating a vent to let the sound out.

If it's still not loud enough for you, I'd mill (or file) the "cab" end of the chassis so that it's flat, which will open the "vent" up by .080" spanning the width of the body.  That's a pretty easy metal removal job.

With a speaker enclosure, you're also going to get quite a bit of venting coming out of the truck mounting points.  You can increase the venting by drilling several holes in the plastic covers over the mounting points.

If you want ultimate loudness, then the place to mount the speaker (10mm again) is in the fuel tank, firing down, with the 10mm hole you've drilled and press-fit your speaker into, acting as a speaker enclosure, with either a big hole or several small holes in the cosmetic plastic fuel tank cover to vent the sound out. Make sure you don't drill the mounting hole all the way through, but as far as your clearances will allow.  This is the way I'll be mounting the speakers in my F3 A units, since A's don't require a B unit, but, B units are almost always paired up with an A unit.

Here's a photo of my E-unit install.


Good luck...but I think my suggestions will solve your loudness problem.

[robert3985]

Otto, The sound quality of the Digitrax decoder is not as good as either SoundTraxx or ESU Loksound, especially the horn, which "clicks" when it sounds.  However, as opposed to SoundTraxx, I can re-program the sound if files become available, and the decoders are waaaay cheaper than either SoundTraxx or ESU Loksound.  So, I'm living with their weak points and I'm pretty happy with them, 'cause any sound is better than no sound in my book.

As opposed to other's experiences with Digitrax sound decoders, I get absolutely NO slowing when activating the horn.  It's not a problem I've seen.

[peteski]

Robert,
I realize that you are happy with the sound but that hole is a good candidate for a prefect speaker enclosure!  Yes, the shell partially seals the hole but have you tried to actually create tight seal on the top of that hole?  I would use a plug made from lead roof flashing (which is about 0.045" thick).  Assuming that the speaker is sealed all around and the top plug is sealed air-tight, I wonder how much better it would sound than just having the shell cover the open hole.

I said that this is a perfect speaker enclosure because the chassis metal will not vibrate like the thin plastic speaker enclosures usually used in models. Then the lead plug would also not be prone to transmit air vibrations from inside the enclosure.  Also, there is quite a bit of air space inside that "speaker cabinet" to allow the speaker cone (almost) unrestricted movement.

If you're willing to plug up the top part of the hole and make the thing air-tight I would really be interested in how much even better the sound would be. Basically I would be interested if it is worth it to go that extra step of really sealing the top of the hole.

[robert3985]

I wasn't sure if the body would form a tight enough enclosure, so I made the hole so the speaker went clear down it and left a big space on top for me to plug to form a smaller enclosure if the body shell wasn't tight enough.  Luckily it was tight enough.

Peteski, yup...I am aware that the hole with an airtight cap on top would be a nice speaker enclosure (see above quote).   I have not attempted to machine a cap yet because I am happy with the volume and quality of the sound using the fairly tight Kato E-unit body as the enclosure.

However, as per your suggestion, it would be an interesting experiment to see what capping the hole would do for the sound.  Maybe I'll do that sometime this week if I can find the time to get off the drawing board for an hour or so and chuck a piece of brass into my lathe for a press-fit cap with a clearance cut for the wires...which I'll seal with a dab of caulk.

I'll report back on this thread.

[Flagler]

Thanks for all the replies. I am thinking of installing a sound decoder in a kato Bagage car.Has anyone done this?