Members wesg Posted July 21, 2014 Members Share Posted July 21, 2014 Hey, all -- I use a powered speaker as my keyboard amp. Specifically, a Yorkville NX55P with the keyboard plugged into the internal mixer. I then feed "link out" to the snake, providing a feed for the FOH. Last night, I was playing with a big band and the sound tech plugged into my speaker which made a LOUD pop. I figured out immediately that the pop happened because Link In and Link Out are connected together in these speakers, and the phantom power from the mixer was turned on (I doubled checked with the tech, he said, "Yep - condensers overhead"), providing plenty of input voltage. So - powered speakers are a common recommendation to replace keyboard amps nowadays. Is the hookup I described generally safe or generally risky when the mixer has phantom power turned on? I got through the gig without letting the smoke out, so I guess Yorkville must have anticipated this.....but, studying the schematic, I don't actually understand why everything worked and nothing blew up?? There are no blocking caps on the inputs to the first stage op-amps; wouldn't the 48V from the board completely overwhelm the outputs of the mixer? I know this is the place where somebody points out that the safe way to hook to the board is through a 1:1 matching transformer. But if we are giving keyboard players the go-ahead for using powered speakers as keyboard amps, should we be recommending a transformer in case of phantom? Wes Link to comment Share on other sites More sharing options...
Members agedhorse Posted July 21, 2014 Members Share Posted July 21, 2014 Some powered speakers provide such protection but some of not because the link out is not generally intended to go to a mixer, just another powered speaker. Rule of thumb is to always transformer isolate if there is any doubt. Link to comment Share on other sites More sharing options...
Members wesg Posted July 22, 2014 Author Members Share Posted July 22, 2014 Thanks, Andy. I think I will be tempering my advice to other keyboard players about going with powered speakers: make sure "Link out" can handle phantom power, or buy an isolation transformer. FWIW - I checked with Yorkville tech support, and they confirmed that phantom is safe with the NX55P - but the speaker should be turned off when connecting to avoid pops. Of course. Wes Link to comment Share on other sites More sharing options...
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