Gladys Hydrophone Kit

Nice little kit. I bought two for stereo. Built them up and tested them. They were sensitive to ‘mains hum’ but guess they’ll be ok when used outdoors away from any cables. Sadly one of the hydrophones failed during the potting process. I was listening as the resin set. Suddenly a loud hiss appeared. I guess the setting compound disturbed a dry joint in my soldering or on the PCB. The other one works fine and once I’ve fully tested it outdoors I’ll probably order a second one to replace the one that failed.