8ohm Speakers

[M. Matthews]

I understand that the sugar cube speaker that comes with the TXS decoders can be replaced with a different 8ohm speaker for better sound. Is the ohm rating the only thing to look out for? I’ve seen some larger speakers that are designed for O gauge. Is it safe to use a speaker like this? I’m assuming there’s more to it as I’ve seen hi-fi speakers rated at 8ohms. I’m just aiming to get the best and loudest sound out of the decoders.

Thanks

[Bulleidboy]

I'm pretty certain most 8ohms speakers will do to replace the TXS sugar cube - the main problem may be available space. I did replace one of mine with a round 28mm High Definition speaker - I did this as I wanted it to fit in the space in the tender originally intended for the round TTS speaker. All worked and still works ok.

[P-Henny]

Look also at Wattage. Sound decoder speakers are typically rated at 1 Watt sometimes 2. If you use a much higher wattage, then the sound may not be as crisp and clear as it could be. However, that said. Higher wattage speakers tend to be significantly larger in size so the 8 ohm speakers that will physically fit in a model loco are likely to only be in the 1 Watt to 2 Watt range anyway. I shouldn't go less than 1 Watt else you risk over-powering the speaker and creating distortion.

[Bulleidboy]

I recall reading that Hornby was going to amend the "famous manual" saying that volume should be limited to 25/30%. Even at that level in a small room (10x7) it can sound excessive.

[96RAF]

If you look in the back of your home HiFi you will likely find those speakers are 8 ohm but you wouldn’t expect to drive them direct from a TXS decoder. As stated wattage goes hand in hand with the impedance.

[ColinB]

The 8 ohm determines the current that the output can source, so if you use a 4 ohm you get double the current. In the case of TTS or HM7000 this is enough to blow it up. The more expensive decoders can use 4 ohm speakers but to be honest I find 8 ohm ones work perfectly well and the output stage might last a bit longer. If the sound decoder passes more current it means its output drivers have to get rid of the extra heat generated. The very early LokSound decoders used a 100 ohm speaker so if you put an 8 ohm on one of those, you would definitely fry it, as you are passing over 10 times the current. So then you come to all the different types of speakers which the sound is dependant on enclosure type and lots of other things. Richard of Road and Rails did a really good YouTube video identifying all the speakers he sells and how good each sounds. I tend to use either his low profile bass speakers or the Iphone ones he sells.