Thumper Sound Decoder

[Butler]

Hi

I have a Bachmann Thumper fitted with a sound decoder by Rails. It is not very loud. I have the volume turned up fullon the function number, but is there a cv value that can increase the volume. I didn’t get any more info other than the main functions when I bought it. It is fitted with an ESU loksound V4.0 Class 205

B

Edited May 2, 2021 by Butler

[charliepetty]

The original Kernow Sounds which are from South West Digital are sadly poor and not ultra loud, assuming its their sounds to following needs to be sorted:

 

If its the original Kernow/SWD  the file & the speaker is the issue.

If it has been fitted by Rails then probably its SWD file and a speaker issue.

If its got a horn you can play (Not just 'dee-doo') then its a Legomanbiffp sound file which is far louder, thus you simply need to make a box to fit behind the speaker, this then needs every hole sealing with PVA glue to make it airtight.  And this should solve your problem.  Charlie

[charliepetty]

With Reference to our Legomanbiffo Thumper project, here is the original Kernow Class 2H with a fully sealed 20X40 ESU Speaker,  not bad I think:   

 

[Butler]

Thank you, excellent sound. I will investigate. I don’t understand why the speaker needs to be airtight, I always thought( with music anyway) that the speaker needed air to drive it! Is the box supplied by Bachmann in the Thumper no good then? 

B

 

[roundhouse]

1 hour ago, Butler said:

Thank you, excellent sound. I will investigate. I don’t understand why the speaker needs to be airtight, I always thought( with music anyway) that the speaker needed air to drive it! Is the box supplied by Bachmann in the Thumper no good then? 

B

 

The box supplied by Bachamnn is fine but its not sealed. I used canopy glue to seal where the wires pass through and around the edge of the speaker . This does make quite a noticeable difference in the sound.

[charliepetty]

This is from a Hi-Fi Website:     Charlie

 

People also ask

Should speaker boxes be sealed? (Sealed Enclosures)

When the speaker moves out, the pressure inside is decreased. When the speaker moves in, the pressure inside is increased. A sealed cabinet is considered a punchier, more accurate sound. ... This is one reason why they sound punchier and more accurate.

[Butler]

Well thank you both, you live and learn, I can remember back in the 70’s salesman boasting about the large air vents for the speakers, but tech has moved on so much. You probably get a better sound out of a small train sized speaker than you did from your Amstrad Hi Fi 10” speakers. Lol! 

Does the fact that there are no holes in the floor of the coach, under the speaker, to let the sound out matter? Guess I’m being dim, just using my ancient tech to reason it through.

B

[charliepetty]

A way out for the sound is better but sometimes the frequency of the sound waves are louder if they are within a echo chamber. Other lower frequencies are quieter.

[Butler]

Wasn’t life simpler when you had a Triang set with one track, battery controller, and I had, ( and still have got) a Triang EP record with train sounds. Brill.

[Butler]

I think I’ve sorted the problem. On removing the body, and the speaker, I found that Rails hadn’t fitted the speaker over the hole in the floor, because the wires weren’t quite long enough. I extended the wires, cut a bit more plastic out of the floor, and refitted the speaker sealing as best as possible. 

Its 100% better sound, every bit as good as Charlie Pettys Video earlier.

thank you everyone.

I used to live about a Mile from Botley in Hampshire, before they electrified the Fareham to Eastleigh Line they had Thumpers, and you could here them all that way. My neighbour reckoned that when he heard the train, he could get up, get dressed and still catch it. Not sure about that , but it is a distinctive sound.

B

 

[Nearholmer]

Considering all the limitations of mini-speakers, whatever it was recorded on, and my laptop, that is pretty blooming good.

 

TBH, I think attempts to get this absolutely right are thwarted by absence of real-world accoustics, and especially the differential attenuation of frequencies over distance. These units produced a wonderful array of low frequencies that travelled miles, bouncing off the hills, when presumably the higher frequencies were damped-out much nearer to source*.

 

I grew up near Crowborough Cross, with the railway about three miles away and 500ft lower than us, but when things were quiet, we could hear trains emerge from Crowborough tunnel, stop at the station, then progress all the way round the bottom of the hill to Eridge. We could also hear Cromptons, but only the horn blast and "concrete mixer noise" as they started a train, they "disappeared" between stations.

 

The cinema at Tunbridge Wells was a bit of a laugh too, because it was situated right over the tunnel (I think it shut years ago). Although there must have been tens of feet of solid sandstone under the cinema, every time a train departed for London, you would hear four power cars in sequence, thumping the heck out of the tunnel roof as they chugged through - it was about the only thing that relieved the tedium of "Gone With The Wind" when my them girlfriend and I decided to go and see it on re-release!

 

I wonder if a key to realism is to record the sound from the real thing at a distance similar to the scale distance away of a person looking at a layout, rather than close-up to the real thing. This ought to get the spectral mix more "right", which is especially important when there is a wide spectral range, and high amplitudes at low frequencies, in the source. But, it would bring greater problems in ensuring that no extraneous sound source got captured accidentally.

 

*Attenuation over distance in air is proportional to the square of the frequency.

Edited May 5, 2021 by Nearholmer