Dave Zucal posted:I've noticed with a bluetooth set up, there is a slight delay, giving an echo effect which sounds kind of cool with whistle and horn. Is there a delay with Fm? Also, how can one keep the speaker from becoming a microphone? The speaker in my engine is picking up track noise. If I remove the bluetooth speaker and take it up stairs I can even hear the TV that's on near the layout.
The tolerable delay will depend on the application. Clearly for Bluetooth speakers for home theater, there will be lip-sync issues if the audio delay is too large or if the video system does not allow delay compensation. Actually I think the video delay adjustment was for the digital delay for external Dolby decoders which has to work pretty hard. OTOH, Bluetooth mini-amps for playing MP3 audio-only from an iPod or whatever seem less demanding on delay. The FM transmitter and receiver are 100% analog (no digital processing/memory) so no perceptible delay.
I understand what you're saying about the speaker becoming a mic, but is there actual signal "gain"? In other words if you are sitting in the room with TV, does the Bluetooth speaker make the TV louder? What's implemented here is a brute-force "splitter" with a Y connection. In other words the two outputs (the speaker and the transmitter input) are just tied together. In an engineered-splitter as used in communications systems, the outputs have some electrical isolation so they do not affect other loads. I don't think it's worth the bother in this case.
