Batboard

Has anyone tried parallelling the audio out on 2 x9000's to drive one 4 ohm speaker?

Chris
N9LLO

NO.
You would have to use two isolation transformers, one on each radio's audio/speaker output.

I guess I should have asked has anyone but me tried it. The x9000 audio amps ARE transformer coupled and completly isolated. My dual drawer setup works fine with the audio leads in parallel driving a 4 ohm speaker.

Chris
N9LLO

If it works, it works. But not a great idea because you're backfeeding the opposing radio with audio from the active one. A transformer hybrid between the two radios and the speaker would have prevented that from occurring.

The only hybrid transformers I have seen were designed for two wire telephony circuits (600 ohms).
Probably too expensive for me even if avaliable for lo z circuits. I know there will be increased current in the amps under certain conditions but at typical volume levels I dont think it will be a problem. I seem to remember a lengthy discussion of this a long time ago but it may have been on the old board before the move to PHPbb. My search turned up nothing. Mabye someone else remembers or was involved in that discussion.

Chris
N9LLO

The hybrid that I spoke of would have to be a custom one because I've not seen a commercially available low impedance one. A less expensive idea involves using an external power amp in inverting configuration with summing resistors on its inverting input fed from the audio outputs of both X9000s. Gives you the isolation between radios to prevent the backfeed situation while summing the outputs.

Hook them up and go to it. Nothing bad will happen.