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Cheap superior quality onboard sound for 7mm


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Hi all....


For some reason (not hard to guess why), I've not had much response to my demo of a Class37 sound project using onboard Bluetooth Streamed Audio.


It uses the free JMRI DCC Virtual Sound Decoder and has cost me £15 for Bluetooth speakers plus a power supply.


It is ideally suited to 7mm as a valid replacement for a £170 sound decoder, and the sound quality will probably turn out to be far superior to what is accepted as the norm at the moment.


As fellow 7mm modellers, please take a look at the "Cheaper and better quality DCC sound" thread.




Edited to include latest video: https://youtu.be/S-Y_ONP9XuY


Please view my Youtube video project and give honest feedback....I won't take offence.

Happy New Year



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Not having seen your video/thread prior to now - but having had quite a bit of experience with bluetooth audio/streaming - I honestly can't believe I've not put 2+2 together to consider the possibility before! Genius...


Hi John....

Any advice you can give with regard to Bluetooth Audio Streaming will be gratefully received in the Cheaper and Better DCC Sound thread, in particular components suitable for 4mm scale....


My demo was based upon the Java Model Railroad Interface (JMRI)Virtual Sound Decoder (VSD).


However, the above thread started off with the idea of using a specially configured offboard 4mm sound decoder loaded with several loco projects feeding speakers hidden on the layout (resulting in a potentially big saving in terms of ££££’s).


I had the idea that the same sounds could be streamed.....and I have now been able to stream sounds from an offboard 4mm sound decoder to what would be ONBOARD Bluetooth Speakers via my laptop....


I envisage equipping my 7mm fleet for less than the cost of a single 7mm sound decoder.


Bluetooth speakers are available for as cheap as £10, so I wasn't kidding when I named this thread.


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  • 4 weeks later...

Hi again...

I wasn't going to update this thread again until I had a demonstration up and running...

However, I have to mention that Sainsbury's have the VEHO BT360 speaker currently on offer at £11.99.

If you are ever going to contemplate sound-equipping your locomotives, then I can't emphasis how ideal these speakers are for 7mm scale and above.


For that price, you can dispose of the Bluetooth module and you will be left with a pair of speakers in an ideal sound-enhancing enclosure.


I am still developing the use of Bluetooth Audio Streaming in association with the JMRI Virtual Sound Decoder... I will update on this soon....


However, these speakers will also be ideal for use with bonafide DCC Sound Decoders.





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  • 1 month later...

Hi again...

I've started a Sound for the Masses thread the Modelling and Musings forum...


The Steam Loco in the video gives an indication of the sound through speakers with panning, so the sounds follow the train.


Diesel locos sound absolutely amazing through onboard Bluetooth Audio Stream speakers too....



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Hi again....


A quickie Class 03 shunter...

Dup'ed from the Musings thread, so sorry if you've seen it before...

Needs refining, but it will be streamed from my tablet/smartphone through Bluetooth to onboard speakers...Simples!

It's easy to sync sounds and motion control, if you're wondering....

DC or DCC...



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  • 3 weeks later...

Hi again...

It's been a little while since I stated my intentions with regard to finding a cheaper alternative to extortionately-priced 7mm sound decoders. The thread opened with a reference to my trials with the JMRI Virtual Sound Decoder, and Bluetooth Audio Streaming.


I was happy with the fact that I had created a usable VSD project, (sorry... I accidentally deleted the Youtube video), and my plans to use the VEHO BT 365 M3 Bluetooth module (shown in the photos). .


I got very distracted by alternative sound production applications as I more or less succeeded in the creation of my own method of streaming sounds to the Bluetooth module, using a gamepad controller to trigger sounds and control loco motion via JMRI DCC. That's more of a longterm project.


My latest project involves the SoundByte application running on my iPad as shown in the two recent videos.


The Bluetooth speaker originally cost £18, but is currently available for £11.99 at Sainsbury's, and the SoundByte app costs £1.99.

(Other apps are available for Android devices).


Obviously, there is no motion control with SoundByte - trains have to be controlled separately, and you have to run the trains to match the sounds that you hear. This is proving to be easier and more convincing than it sounds.


The streamed sounds are of much higher quality than can be stored on a soundchip and the speaker gives excellent playback quality.


A huge benefit of using Tablets and/or Smartphones is the Touchscreen capability, avoiding countless hardware pushbuttons and interfaces etc etc


Also, SoundByte (and the others) are polyphonic, which means they can play many sounds at the same time, as the two recent videos show...


For the time being, I've decided to stay with DC control for my 7mm Costleigh layout. This makes the cost savings even greater.


The DCC system still controls my 4mm layout.


I refrained from modifying my locomotives until I had worked out a plan of attack, but I think I'm now ready.


I'll be posting progress as I go...


(There could well be a lull, as we are expecting the imminent birth of our first grandchild)


Those who saw the original Youtube video, would have seen the intact VEHO speaker module being placed into the void beneath the PCB on my Heljan Class 37.


This proved impractical, and I ended up dismantling the module and removing everything from the outer casing.


The now smaller footprint makes installation even easier, as I will demonstrate as I go along


I was delighted to find that the speaker was still enclosed within it's own housing, which means the sound quality is unaffected.




The image shows a temporary extension of the speaker cables.


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First off, I'm already beginning to wonder if the decision to use DC over DCC was a wise one....

That's not to say DC is a non-starter...but it does pose an immediate problem.


The Bluetooth module obviously needs a power source.


It has a battery, which doesn't necessarily have to be the primary power source. Indeed if the primary power comes from the tracks, the battery still has a invaluable duty to perform. It will act as a keep-alive source, so if the track has dirty spots, the sound keeps on playing.


Fully charged, the battery is capable of two hours continuous playback.


On a DC layout, juice is only available when the power is applied to start a loco moving.

This power is obviously also variable, depending on the controller setting.


Because there is no constant supply to run off, it will probably be necessary to use the battery as the primary onboard power source for the Bluetooth device, which means there also has to be an offboard power supply to charge the battery.


The VEHO device is supplied with a USB cable which is used to initially charge the battery from cold before the speaker can be used remotely from the sound source (thereby fulfilling it's design objective).


I would need to make the onboard power socket accessible, and preferably hidden or disguised....something similar to an old clockwork key. I am thinking I could maybe drill out one of the fuel tank gauges and site the power supply socket immediately behind the hole?



I have decided my primary source will be the tracks....


On a DCC layout, the supply to the loco is constant from the moment the layout is powered-up.


I therefore plan to use the onboard variable voltage power supply (that currently drives the roof fan in my Heljan Class 37) to primarily provide juice to the Bluetooth device, but also to charge the battery.


This means that the entire assembly is onboard, with no need for an offshore power supply.


I am therefore leaning back towards DCC control...no big deal as the 7mm layout was designed for it.


However, the onboard variable power supply could also be used by DC to maintain the charge in the battery once the loco is running.


For locos that don't come ready-fitted with an onboard variable voltage power supply, I have already successfully built and tested the small kit available for £10 from Maplin....thereby maintaining the low-cost brief.


No news yet on our new grandchild's imminent arrival....



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Hi again...

I'm struggling to get time to progress the installation of the Bluetooth module and speaker into my Heljan Class 37, so here's a quick pic of the speaker out of it's casing, with a size reference. The speaker enclosure is double-ended.


You may still be able to pick them up for £11.99 at branches of Sainsbury's...




They are (or were) £18.00 in Tesco.


I think the speaker would fit neatly into many a 7mm boiler too... the Bluetooth module located in the tender connected to the speaker in the boiler....imagine.... top quality sounds coming from the right end of the loco.


Purely in the interests of research, anyone care to donate a steam locomotive?





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Hi again...

Back on track following the birth of our first grandson.....


The images show the install sequence for the VEHO BT360 M3 Bluetooth module into the fuel tanks of the Heljan Class 37.


I did decide to go down the route of installing the module for a DC setup.


I chose this method purely to demonstrate that cheap (£15) quality sound is available for DC modellers.


You will see that I've drilled out one of the fuel tank gauges to allow the charging plug to connect to it's socket inside the fuel tank (hopefully the images will make sense of the steps necessary).


I will also be connecting the onboard variable voltage power supply to allow charging via the tracks when used on DCC.


The module and speaker are now held in place by a touch of hotmelt glue.




Edited: extra image included













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Hi again...

Grandfatherly reponsibilities prevented me from providing a more detailed explanation yesterday, so thanks to Flexible_Coupling for filling in the blanks....


Additionally, another pair of cables (not added when the pic was taken) now runs from the module to the Heljan variable voltage power supply to provide onboard power when running on DCC.


The square mounting plate with the large hole is simply the Heljan blanking plate pushed into service. A couple of plastikard packing pieces are there to maintain the level. The curved piece comes from the original VEHO casing. It's there to act as resistance when the power cord is plugged in. The casing is made from a similar material to Plastikard, so solvent was used to fix it in place.


The first image shows the additional pair of holes in the chassis block for the cables to pass through.


Not visible in the photos is the access hole I made underneath the fuel tank where the ((( ))) grill is in the photo...this allows me to access the module's on/off microswitch.


However, I've since discovered that the device can be left active....it re-establishes connection to the active Bluetooth host (my iPad) automatically when power is applied.

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  • 3 weeks later...
  • 2 weeks later...

Hi again....


Soundbyte and Bluetooth Audio Streaming had a recent outing at the Swansea Railway Modellers Group meeting and I think reception was quite positive.


On arrival, I unboxed and railed up my 7mm Heljan Class 37 with the onboard VEHO Bluetooth module and speaker. After a few soundless circuits of the large O gauge test track, I started up the Soundbyte App and observed....


The initial reaction was that someone had a locomotive with sound...Big Deal!


It then began to dawn on some members that I was controlling the sounds from my iPad.


Several came over to watch and ask questions....


Others remained indifferent (but leaned over to check as the Class 37 went by)...


Around the far side, I started up the sounds of a Steam locomotive and watched as the loco passed-by along the front of the test track.... Trigger inquisitive looks...


Finally, I did a run past with the sounds of a Mr Whippy Ice Cream van...trigger laughs all round....


Admittedly, I was surprised by the lower fidelity in the large room compared to the close confines of my loft. In fairness, there were other trains running on the 4mm and 2mm tracks, plus the general hubbub of the clubroom....probably a validation that amplified sounds can increase the annoyance factor at exhibitions....


There were also several signal drop-outs when the loco was on the far side of the tracks, behind several members who were within the central operating area.


However, several members (especially the younger clan) came over and asked many petinent questions and I demonstrated how things worked.


I was absolutely chuffed to note that not one person commented on the fact that I was controlling the motion and the sounds separately.


Not a bad debut for 7mm sound that cost less than £15....





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  • 1 year later...
  • 6 months later...


I gave a brief outing to my Heljan Class 37 with Bluetooth sounds on the DC test track at the ALSRM show in Reading today.

I was very pleased with the reaction of those who took the time to watch and listen.

I was especially pleased by the encouragement and positive comments of the test track Steward who accompanied me for the twenty minute stint. He asked many questions and was amazed when I told him that the cost was negligible. He suggested that I should take it to other shows to demonstrate how effective it is. I was able to show him that it was simple to synchronise the sounds with the movement of the loco, especially halting the loco with the accompanying brake squeal....

I played several seriously thrashing Class 37 tracks - with ramps and spool downs - very effective indeed to my mind. I also played tracks for other diesel classes such as 52 and 25. I played an extended steam track that raises a few quizzical looks and smiles from passers-by. The steam sounds coming from the loco were sublime and I'd love to be able to have a go with bluetooth steam sounds on a garden railway.

The room was quite busy and I gauged how many were actually listening when I played Mr Whippy Ice Cream van sounds as the loco circled the room.

Everyone smiled.


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Just to clarify things in case you are struggling to make sense of my ramblings...

It's important to realise that I'm not constantly pressing buttons on my iPad to generate appropriate sounds for each speed step.

For some movements, yes..but pressing buttons is not the be all and end all.


I adjusted the speed control (DC power remember) with one hand and pressed iPad buttons with the other...all quite simple.


Some of the soundtracks last for several minutes and the Class 37 circled the test track several times during the demo before I switched to different sounds just to demonstrate other features...

actually, I spent most of my time pressing the horn buttons....


I think this is eminently suitable for the modeller who enjoys playing trains...just watching trains go by....although shunting is easy because there may only be one or two buttons to press.


These are HIGH QUALITY sounds that may not be 100% authentic to the movement, but neither are horrendously expensive (inherently inferior quality) sound chips.


At home, on my end-to-end layout, I barely get beyond speed notch 1 so all I have to concentrate on is pressing the brake squeal button when the loco comes to a halt.....

The Soundbyte app does the rest....each button-press fades the preceding sound resulting in a smooth transition.


My biggest mistake today was the fact that I forgot to video the damn thing.

I could go on, but it's getting late...except to say CHEAP!


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Randy, I have just read through this thread & I love what you are doing. I have been searching for a suitable sound system for my radio controlled loco's & also some DC loco's.


I am completely in love with my radio controlled loco's since switching to non track power on my garden line....but I have to say I have been glancing  enviously at DCC sound since it first came along...to the point where I have even been considering switching yet again to DCC, but the only advantage for me would be sound & I think the return to being reliant on track power would be detrimental for me.


Your brilliant idea could hopefully give me the best of both worlds with on board sound & power.


Could you give this very un-technical person an idea of what would be a suitable app that I could use on my Samsung Galaxy S6 phone as a starting point into the wonderful world of Bluetooth sound?

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