Speaker selection

[Tim Brien]

My intention is to use a Massoth "S" decoder on my current Garratt project. This decoder has a 3 watt sinus output, so I would expect transient outputs exceeding this figure. My speaker location is a problem as most suitable speakers, by dimension only, are only 2 watt output. For a 3 watt decoder, I would anticipate a speaker of around 5 watts to avoid 'overpowering' it. The Visaton 50mm round speaker (5 watt output), would be ideal, however, its 33mm height is a problem.

Now, my question. If I wired, in series (16 ohms impedence), two 8 ohm speakers, then would the total wattage output, say two by 2 watt speakers, be suitable. The higher numerical impedence would reduce volume somewhat, but I am hoping that it would also take care of the decoder wattage as well.

I was thinking of a 2 watt speaker (40mm X 40mm) in the rear tender and a similar 2 watt speaker buried inside the loco boiler. A double throw toggle switch would be needed as I would need continuity when programming the decoder/s. In one selection it would power both speakers (normal operation). In the other selection it would only power the speaker in the tender (for programming). Any thoughts?

 

[Doug]

You won't be running the decoder output at 2watts, that would be very loud. Your average home hifi is running at less than 0.2 watts

 

[Tim Brien]

I have done some research and it appears that doubling the impedence results in only one-quarter wattage available for each speaker. Now this would result in lower anticipated 'maximum' volume, but then, are two speakers driven at less wattage quiter than one speaker at full wattage, considering that the speakers are not usually driven at full volume? Basically, for twice the 'cone area', half the total wattage is 'wasted' (not produced). Also, would sound quality suffer, given that quality is not total volume?

Driving two 4 ohm speakers in series still retains the original 8 ohm impedence and I assume no drop in volume.

Also, it appears that the 'S' module is not so 'user' friendly when used in conjunction with a motor decoder. Basically, the decoder needs to be programmed prior installation and not as I had hoped in conjunction with the motor decoder. I intended using the SUSI cable, but CV's below CV840 (approx.) are not transferred via the SUSI cable. Also decoder address CV has to be written on a programming track and not on the main.

 

[Tim Brien]

Doug,
home sound units may be driven at low wattage, but generally have larger speakers than a typical decoder installation and have amplifiers that have more power available to drive the larger speakers. I feel that a loco speaker installation driving around 0.2 watts would be very quiet and not suitable for outdoors. I would be interested in just how much wattage is actually consumed driving our speakers.

 

[Tim Brien]

After further consideration I have decided that a single speaker will be used, buried inside the boiler. Massoth require a minimum 1.5 watt speaker be used with the 'S' decoder.

Considering that the 'S' cannot be programmed insitu, when utilising the SUSI interface, there is no point in me to use two speakers. The decoder would need to be removed and programmed separately on a programming track. Massoth protocol restricts programming CV1, CV17 and CV18 on the main (POM). Thus an address change is not possible on the main. If track power pickups were used to power the decoder (not using SUSI interface), then the decoder could be isolated insitu for programming. I will be using SUSI, so any programming would entail removing the decoder, unfortunately.

 

[KeithT]

Tim you lost me somewhere after the word "Considering" :bleh:

 

[Tim Brien]

Keith,
I am aware that a motor decoder will 'pass on' CV inputs that are above its specs, say CV240 and upwards by way of the SUSI interface. An 'S' decoder has most of its CV's starting around CV840, thus any CV's that are shared with the motor decoder will need to be accounted for.

If you have successfully programmed an 'S' decoder while using the SUSI interface then please advise.

 

[bunnyrabbit03]

Keith,
I am aware that a motor decoder will 'pass on' CV inputs that are above its specs, say CV240 and upwards by way of the SUSI interface. An 'S' decoder has most of its CV's starting around CV840, thus any CV's that are shared with the motor decoder will need to be accounted for.

If you have successfully programmed an 'S' decoder while using the SUSI interface then please advise.

Hi Tim,

Please read page 30 and pages 59 onwards in the emotion S instruction manual for the CVs that are applicable when using the emotion S via SUSI. They differ from the normal CV settings to avoid the problems you have outlined, i.e. they are not shared with the motor decoder CVs when the SUSI interface is used. When connecting a sound decoder via SUSI, you do not need to programme the loco address, as you 'talk' to the sound decoder through the loco decoder. Any programming can therefore be done in situ 'on the main' as if you would programme the motor decoder, just writing higher CVs that the motor decoder will simply 'pass on' to the sound decoder.

Marc

 

[Tim Brien]

Marc,
many thanks. I have read the manual several times but was not aware that the decoder only responded through the motor decoder address.