RailPro User Group

RailPro => RailPro Specific Help & Discussion => Topic started by: Smoke on September 29, 2023, 11:10:55 AM

Title: Under Table Sound Possible?
Post by: Smoke on September 29, 2023, 11:10:55 AM

I have recently been wanting to do some research into higher fidelity sound from our models and came across this DCC solution from Lance Mindheim: https://lancemindheim.com/about-us/wireless-headphone-sound/

With DCC this is a little easier as you can consist the two decoders together and since they don't talk to each other the locomotive you are running won't change how it operates. How feasible would this setup be with RailPro? I see two possible issues:
1. The stationary module would mess with the locomotive module and the load sharing wouldn't work.
2. If I change locomotives, I would have to update the stationary LM-3S with the correct sound file(s).

I don't have allot of experience with RailPro, and I'm wondering if consisting two modules together with only one of them being an actual locomotive would mess with the load sharing capabilities. Does anyone have any thoughts on this or better yet experience with a setup like this?

A couple notes:
1. I would only be running one actual locomotive at a time.
2. This would be for a small shelf layout, so multiple operators wouldn't ever be an issue.

Thanks for any thoughts/suggestions!!

Title: Re: Under Table Sound Possible?
Post by: Smoke on October 09, 2023, 03:32:06 PM

I have been doing some testing with a LM-3S in a locomotive and a stationary LM-3S sitting on my desk.

So far in my testing, if you MU together a moving and a stationary LM-3S, there are no issues. When you crack the throttle, the stationary LM-3S ramps up rather quickly to the full output to try and match the load of the moving loco. As far as I can tell, the moving locomotive isn't affected by this behavior, and still runs and responds to the throttle as expected.

I've also been playing around with the speaker outputs from the LM-3S and believe I have figured out a couple things:

• I hooked up the two speaker wires to my disassembled Jabra 510 speaker, and my goodness the sound is fantastic!! The printing on the back of the speaker says it is 4Ω, so I was able to hook it up directly without an audio transformer inline.
• I hooked up an audio output transformer in line with the output (273-1380, same one as Lance Mindheim), and connected it to my Sony headphones, and the sound is FANTASTIC!! The sound is super loud even with the volume at 20% however. I think the sound is super loud as the audio transformer is impedance matching to 1KΩ, and the headphones have an impedance of 32Ω so there is way more power coming from the LM-3S than required.

I think the next step is to order a couple different impedance matching audio transformers to see if I can get the sound to the headphones down to a reasonable level. I also need to do more reading on audio transformers as I only understand about 10% of what I'm doing at this point and would like to greatly increase that percentage.

Title: Re: Under Table Sound Possible?
Post by: G8B4Life on October 10, 2023, 07:03:33 AM

I'll be interested in seeing what you find out. I've had headphones hooked up to an LM before on my testing board and the sound was very good. I don't think I'll need to do the same as you but seeing the results of a good experiment is always fun.

- Tim