[LAU] no sound from zyn

I'm relatively new to Arch, and tried to use zyn through jack for the first time last night but couldn't get any sound from it. I've mostly been an Ubuntu user in years past and never had this issue. Had to install a2jmidid to get midi note data to it from my midi keyboard, and that worked fine. Verified that my volume settings were OK by playing sound through jack from other programs. The level meters in zyn made it look like it was outputting sound, but nothing through my speakers. No error messages in qjackctl. I tried starting zyn from a terminal to see if it would print any errors, and saw nothing. I can't think of what to try next. Any suggestions?