AFS224 Dual Channel Advanced Feedback Suppression
Hi, I have an AFS224 installed for my foldback (stage monitors) via the AUX 1&2 sends on my Allen & Heath mixer and it works brilliantly. Recently I purchased a second AFS224 to work on the main PA (FOH) and have that connected via the L&R main output inserts. What seems strange to me is that despite each AFS224 being on entirely separate "circuits", I have noticed that the new main PA (FOH) AFS224 is eliminating feedback which originates in ONLY the foldback (monitors). There's no question in my mind that this is happening as I even tried shutting down the PA speakers so no feedback could occur and continued "ringing out" the foldback and what happened was that the foldback AFS "LIVE" filters started to eliminate new feedback (as you would expect) but at the same time the second AFS (connected only to the Main PA output circuit) started using up its fixed filters to eliminate the SAME frequencies as the foldback AFS was dealing with. I've spoken to Allen & Heath and they seemed to think that this is because the AFS224's are getting their "reference" from the individual mics even though that signal then gets split between AUX 1 & 2 and Main L&R. That's not how I thought it would work - I assumed that as the feedback was occurring in (say) just one of the foldback channels that only the AFS channel connected to that particular circuit would "sense" or "see" that particular feedback occurrence. I can now see some logic in what Allen & Heath are saying but it still seems odd to me. Allen & Heath suggested that I just ditch the second AFS224 and just have one operating on the foldback only. Does anyone have any experience of this and if so is there any way to run two AFS224's separately on foldback and Main PA/FOH? Hope this makes sense. As you can probably see I'm not an expert Sound engineer, just trying to get the best I can out of my smallish PA!