I’ve heard/seen a few people mention and show electronic simplex 4903 having variants in the pitch of the horn. I know the newest one use the truealerts horn. But do these differences versions have a set pitch that changed over time due to simplex updating the series or is it more random?
yeah, the pitch differences on 4903 electronic horns are real. It’s partly due to Simplex updating the internal driver over the years — earlier models tend to sound lower and raspier, while later ones (especially when they switched to the TrueAlert driver) are higher-pitched and smoother. There’s also some slight variation between units just from manufacturing differences.
The older devices also sound different from device to device because they use analog circuitry to generate the tone rather than a digital file like the newer TrueAlert horns use.