Following on from my thread on the sound decoder/speaker problem, I have ordered a genuine ESU 100 Ohm X 0.5 watt speaker for my BR64. Just to check I asked my Chinese supplier if they sold the same, and was told no.

I spoke to a friend about it and he made this comment in jest.

"Now we know why Marklin has no 100 Ohm speakers.. The Chinese do not sell them any more either."

Now I am pretty ignorant when it come to electric theory, but I understand why you transmit power on the national grid at very high voltages because that reduces the amperage, so smaller wires can be used.

SO!

What are the advantages and or disadvantages of the 100 ohm speaker against say the 8 ohm speaker [ and vise versa ] with reference to Marklin sound in its engines?

Dereck

Edited by moderator 12 June 2018 06:44:25(UTC)  | Reason: Took pity on the poster.. ;-)

As far as I know, the usage of 8 or 100 ohm loudspeaker is just to follow the industry's trend due to design constraint.
Before the availability of class-D amplifier (digital or PWM amplifier), Marklin used 8 ohm loudspeaker driven by class-AB (linear) amplifier chip. (e.g.: Marklin #29855, #34664, #37743, etc)
Then during 2000s era, power efficient digital amplifier (class-D) became popular in small devices and small class-D amplifier chip was commercially available. However, during that era, all digital amplifier require low-pass filter consisting of inductor and capacitor. This filter will be larger (and more expensive) whenever the loudspeaker's impedance is lower, thus designers of small devices opted to use high impedance loudspeaker such as the 100 ohm.
As technology keep progressing, filterless class-D amplifier became possible by the mid of last decade. Thus designers have the option to use low impedance loudspeaker ( 8 ohm or even 4 ohm). Lower impedance loudspeaker require lower voltage to generate the same output power as compared to the higher impedance. This is a boon to battery powered devices (which usually use 3.7V battery). Therefore most filterless amplifier chips were designed to handle low impedance loudspeaker, and operate at low voltage. The high impedance amplifier chip become more expensive as its market decrease
Although the locomotive is not battery powered, but the size of decoder is small, thus the designer will be happy to eliminate the L-C filter by using widely available (and cheap) filterless amplifier chip.

I wonder if there is any way to adapt the 8 ohm speakers. I did read that when putting resistors in circuit, the speakers dont operate correctly, as well as the resistors generate heat. What do we do when we cant get the 100ohm speakers or when they be come more expensive than the value of the loco? Eg $15.00 each from a NZ supplier and 21 Euro from Marklin, as they are now.
Dereck

You would need a transformer to match the 8 ohm speaker to the 100 ohms the decoder is expecting. You would be better off replacing the decoder for one that will drive an 8 ohm speaker ...