modulated audio recording with digi002

i’ve been using Ardour 2.8.11 and jack 0.89 with a digi002 rack to record live concerts at my job for a few years with no problems until very recently. i did a session here with myself and another player and noticed on playing it back that depending on where i started playback there would be a very harsh ring-modulated sound to the tracks. eventually no matter where i started the playback from, the modulation was there. i quit ardour and played the session’s audiofiles separately with the mac preview and with audacity - the modulation effect is actually on the files themselves! i blamed the fact that i’d had a firewire drive plugged into the computer at the same time as the digi interface and hoped that avoiding that would solve the problem.

recorded a concert that week and everything was fine. did another one a few days later, and the same modulation was present on the tracks - bad news.

i will switch over to reaper for now, but has anyone here ever had anything like this happen? i was initially suspicious of the ardour<->jack<->coreaudio<->digi linkage, but it’s been so stable for so long …

i can put a sample of the audio up somewhere if that would be helpful.

bill sack