Stagepas 600i - Feedback Suppression

[Blunoze]

Hi Guys,

I recently bought a 600i, as my previous rig was giving me too many squeals on the high EQ band. I decided on the 600i purely to try to counter that issue, and give myself more dB's before I get issues.

However I have to admit I am bit frustrated by the system. Apparently, it has 7 'onboard' automatic notch filters that clamp down the offending frequency when a feedback loop is detected. However I had some issues during my last gig, so tonight I was doing some testing, and trying to understand how these notch filters kick in. It seems you have to get the system to ring with quite loud feedback for a few seconds, and then it will kill that frequency. However how the hell do I actually do this in practise? There is no way that I am going to crank the system up to feedback levels in a full bar while I am setting up, and deafen everybody while the notch filter kicks in. And apparently when you cut the power, it resets the notch filters so I can't dial it in before the gig.

Does anybody have any experience with the function of this system? Is there any way to activate it without blowing people's heads off? I have to say, I am really disappointed with this element of the system. Thanks in advance for your feedback (excuse the pun).

I too have a Stagepas 600i and I leave the feedback suppression engaged whenever I used the system. I have not had any feedback with the system, and assumed that the feedback suppression was helping prevent it. Your experience indicates that it may be that the feedback suppression has not kicked in at all. Sorry that I have no advice for you...

[El Conquistador]

I just looked at the (very limited) user manual and it seems to indicate that it is simply either an "on" or "off" feature. When "on" it will AUTOMATICALLY suppress feedback. So, if you have this feature switched "on" and are still getting feedback, I would suspect you have a faulty unit. I would cal Yamaha tech support and get their take on this.

Steve

[Nick84]

I also have a 600i and leave the button on all the time. I find it works and it's quite effective. I don't suffer from feedback issues at 99% of my gigs

[pieterh]

Originally Posted by El Conquistador

I just looked at the (very limited) user manual and it seems to indicate that it is simply either an "on" or "off" feature. When "on" it will AUTOMATICALLY suppress feedback. So, if you have this feature switched "on" and are still getting feedback, I would suspect you have a faulty unit. I would cal Yamaha tech support and get their take on this.

Steve

Not necessarily, it may be that the stage level is such that the 7 quoted notch filters have all been activated and then the noise on stage is such that an eighth frequency starts to cause trouble.

Feedback suppresses are all very well but if you have time to ring out a system then you should also have time to eq the sound on stage (and out front, standing waves in the venue will affect the risk for feedback on stage) in order to get the best conditions for your setup.

[Tomm Williams]

Where is your feedback originating............vocals I assume ? what mic are you using and have you tried different speaker positions ?

[Blunoze]

If you have never had feedback, then I imagine that the notch filters have not been activated. If I understand the system well, it analyses for a db spike on a certain frequency before the filter kicks in and cuts 20dB from that frequency alone. It can then do this 7 times.

Yes, the feedback was on the vocal mics, which we then moved which improved things slightly, but ultimately we had to reduce the gain which then left the vocals weak compared to the acoustic drum. This is rather frustrating, considering it supposedly has a built in feedback suppression system.

But you can pay more than 300 for a good quality outboard feedback suppressor, which leads me to believe that the one inside the 600i is probably not going to be that expensive, and certainly not have much processing power across the frequency range.

[lschwart]

Originally Posted by Blunoze

If you have never had feedback, then I imagine that the notch filters have not been activated. If I understand the system well, it analyses for a db spike on a certain frequency before the filter kicks in and cuts 20dB from that frequency alone. It can then do this 7 times.

Yes, the feedback was on the vocal mics, which we then moved which improved things slightly, but ultimately we had to reduce the gain which then left the vocals weak compared to the acoustic drum. This is rather frustrating, considering it supposedly has a built in feedback suppression system.

But you can pay more than 300 for a good quality outboard feedback suppressor, which leads me to believe that the one inside the 600i is probably not going to be that expensive, and certainly not have much processing power across the frequency range.

Tell us a little more about the speaker and mic placement, what kind of mic you were using, and what sort of space you were in. It may be that the unit is faulty or that you were simply overtaxing its abilities, but stage arrangement often matters much more than notch filters automatic or manual.

Louis

[Blunoze]

KSM-9, we were playing outdoors in a street with houses n both sides, so the sound was reflecting off both walls and then coming back into the mic. The volume we were trying to play at, feedback was unavoidable with the gear we had. A large rubber mat on the wall behind us would have prevented the reflection but we didn't know the venue until we got there. But if I may, the point is not to try placement to avoid feedback. What I am trying to understand is the why the system I bought specifically to avoid feedback didn't kick in. If you buy a system with that functionality, it seems odd that you still have to precisely set things up just as you would with a PA without this function.

I am indeed trying to understand if the unit is faulty, but first I need to understand the principles on how it works. I did some tests at home with some earplugs in, turned up the system until feedback started, and then the feedback started sounding like a tremolo effect was on it, then it stopped. So I assumed that was a notch filter kicking in. But it took around 5 seconds to do that. I cannot do that in a venue, because everyone will be deaf. So I am trying to understand how this element of the system works.

[lschwart]

Originally Posted by Blunoze

KSM-9, we were playing outdoors in a street with houses n both sides, so the sound was reflecting off both walls and then coming back into the mic. The volume we were trying to play at, feedback was unavoidable with the gear we had. A large rubber mat on the wall behind us would have prevented the reflection but we didn't know the venue until we got there. But if I may, the point is not to try placement to avoid feedback. What I am trying to understand is the why the system I bought specifically to avoid feedback didn't kick in. If you buy a system with that functionality, it seems odd that you still have to precisely set things up just as you would with a PA without this function.

I am indeed trying to understand if the unit is faulty, but first I need to understand the principles on how it works. I did some tests at home with some earplugs in, turned up the system until feedback started, and then the feedback started sounding like a tremolo effect was on it, then it stopped. So I assumed that was a notch filter kicking in. But it took around 5 seconds to do that. I cannot do that in a venue, because everyone will be deaf. So I am trying to understand how this element of the system works.

I think you might just be expecting too much from a feedback suppressor built into such an inexpensive piece of equipment. Although of course it might just not be working properly, and you should contact Yamaha.

If you had the speakers pointed out in front of you, right at a reflective wall opposite you, and with a reflective wall behind you, I think you'd get feedback at a certain volume even with a much better suppressor. Since you have that very nice mic with a switchable pattern, maybe in situations like this you could put the speakers to your sides, tilted in and facing across the space in front of your stage area with the mic set to the supercardioid pattern to maximize side rejection. This way the refections from the opposite wall wouldn't be coming right back at you. Also, were you using monitors?

Just thinking out loud about ways to solve this kind of problem.

Louis