Wow, I think I'm currently working on the same exact project Larry was working on when he made this thread. Small world.
Currently, the system technically 'works', but there's a pretty loud echo that occurs when you talk. This manifests itself in two ways:
1. When your Push-to-talk is off, the mic line is not completely isolated. It seems like other headsets can still barely hear you, but very quietly. You can't hear yourself. This isn't really an issue, but it may be an important clue in finding the culprit of the problem.
2. This is the bigger one. When you push the PTT key, other headsets can hear you, but you can also hear yourself. Your voice comes back to you slightly quieter, but extremely distorted. I've noticed that the problem is proportional to the gains on the headsets & microphones. I've tried tuning them to bring it to a tolerable level, but can't seem to hit that point, which is why I really want to identify the root of the problem.
Some background real quick, the eight headsets connect through a module to VOIP, which let you access the channels through other headsets on the network. When using a network headset to talk to a single headset connected to the module, everything works fine, and there are no distortions or echoes. However, as soon as you plug in a second headset into the new module, the signal starts to return a corrupted echo to the transmitting user (per bullet 2).
Does anyone have any experience with audio systems that might have ran into something similar before? I thought it might have been a groundloop issue, but so far none of my attempts to improve it have been effective.