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Feedback Suppression Questions
by litesnsirens on 2013-04-07 14:23:35

I'm really digging the feedback suppression on the M20d and the Stagesource Speakers.  I've found that so far I can crank the volume up beyond what I need and make the mics feedback on purpose.  Then I just listen as one by one different frequencies start to build up feedback and then then just go silent.  Then I just roll back to the level I'm actually going to play at and I'm good to go.  I like to do it this way because if you have that frequency that just on the edge and really just kind of rings as you sing, then it doesn't get built up enough for the M20d or the speakers to recognize it and notch it out.

But it brings up a few questions,

1) I read in the stagesource manual that if you turn off the feedback suppression using the feedback suppression on/off buttons that it resets itself.  But what about when you turn off the speakers themselves?  When you turn them back on are they "remembering" the frequencies that they notched out? 

2) What is the reccommendation regarding using the feedback suppression on the speakers and the M20d?  Are they both active?  Does one supercede the other or is there a physical priority in the order in which they work? 

3) As in question number 1, I'm wondering about how and when the feedback suppression parameters get saved or how to reset them and when they are lost on the M20d.  And I guess depending on these answers do they get saved with a setup?

All I found in the manual on the feedback suppression for the M20d was that it's in the input tab of deep tweak and that there is vocal and universal settings.  I'm also familiar with the feedback suppression reset button in the deeptweak but I'm more interested in what happens when I don't touch that but turn off the system and or load new setups or save current setups.  I really want to understand as much as I can about this so that I can use it to my advantage.  Obviously if I'm using the technique as described above, what we always called "ringing out the room", I don't want to go into a bar and do that when it's full of people, if possible I'd want to go in at a time when there isn't anyone there, setup, ring out the room, maybe a quick sound check and then just come back later and play with no worries.  So then I need to know if I shut down the system will I still be good to go when I fire it back up?  Also if I were to ring out the room in a certain club at one gig, if I was able to save that setup with the feedback suppression settings, as long as I set up the speakers the same way the next time we play there maybe I don't have to ring out the room again I just load up that preset and I'm good to go.



Re: Feedback Suppression Questions
by ArneLine6 on 2013-04-08 09:35:16

Hi,

To answer your questions:

1) The FBS always resets itself when the FBS or the speaker is turned off- on.

2) If you have an M20d the FBS in the mixer should be active and the one in the speaker inactive. The M20d can analyze the signals with more detail since every input has its own FBS. On the hand if the both are on the speaker FBS will most likely not do anything because the mixers FBS would kick in first.

3) At the moment the FBS settings are not saved.

The best way to deal with this situation might be to press the "Mute All" button and leave the mixer on.



Re: Feedback Suppression Questions
by litesnsirens on 2013-04-08 10:26:24

Thanks for that explanation Arne, now that I understand how it works I can certainly employ a strategy that will not defeat any efforts that I undertake to ring out the room.  The fact that you say "At the moment the FBS settings are not saved" gives me some hope that maybe line 6 feels this might be something worth looking into.  I think it would be a great feature, you could still make it so that when you turn off the M20d the FBS resets, then you would have to manually load the setup to get those FBS settings back, even if it was the last setup loaded when you turned off the M20d.  That would allow you a way to start from scratch if you wanted to.



Re: Feedback Suppression Questions
by litesnsirens on 2013-04-11 04:34:57

Sorry, thinking again... I should probably stop that.  But this has all brought up another question in my mind, despite the fact that it may in real world terms be hypothetical.  So, as I understand it each device, each L2t, L3t and the M20d all have up to 12 bands of FBS.  So theoretically, if you had the FBS on the M20d and for whatever reason you used up 12 different frequencies of FBS on the M20d and some more frequencies started feeding back, the built in FBS on the the L2t and or L3t speakers could pick up the slack.  Is that correct?  Also just to be clear the 12 bands on the M20d are shared across all the channels, right?  Again, it's just curiousity.  To date, I have yet to exhaust the 12 frequencies of FBS and the reality is all the old physical placement methods of reducing feedback don't necessarily need to be thrown out the window just because we have this technology.  It's just cool to know these things.



Re: Feedback Suppression Questions
by ArneLine6 on 2013-04-11 17:03:14

Theoretically yes. Very theoretically. Usually the first  3 or 4 filters do about 90% of the gain before feedback advantage. So, the 13th filter may gain another 0.5 dB but practically there would not be a noticeable difference. The 12 filters are not shared across all channels. Every channel has its own filters. The detection algorithm is shared across channel 1- 5 and 5- 12. In theory you are right, you could get a bit more gain before feedback by leaving the speakers FBS on. Practically the real gain happens in the first few bands. 



Re: Feedback Suppression Questions
by litesnsirens on 2013-04-12 08:40:42

Thanks again Arne,  all I can say is "WOW"!!!  This stuff is deeper than I thought it was.  And I was pretty well aware, as I haven't yet done it, that I wouldn't need to get to 13 bands.  It's just cool to know.  I'm pretty stoke about my new gear and when other musicians ask me about it, I want to be able to explain the magic.  And I guess theoretically I could end up in that room that is giving me more problems than I bargained for, so understanding the gear gives me more options for trouble-shooting.  But if I am understanding right if a mic frequency is notched out on channel 1 then channel 2, 3, 4 & 5 wouldn't need to notch that frequency out for themselves?  But channels 6 to 12 would.  I'm guessing that's allowing for 5 vocal mics that may share the same issues to work on the same detection algorithm.  Which is a cool idea and will make me re-think how I structure my stage setup on the M20d.




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