Manual confusion... can you grasp this?

Emp_Fab

I'm reading the manual for a Behringer Feeback Destroyer and I'm scratching my head at this section about connecting it with the mixer...

Read Section 5.2 and look at Fig 5.2 (please!)... (on page 10)

http://www.pdf-manuals.com/pdf/behringer-feedback-destroyer-pro-fbq2496-feedback-fbq2496-b-h-38973-user-manual.pdf

(I tried to post a picture of the page but I'm on an iPad and wasted the past hour twatting about trying to get a direct jpg URL out of a Flickr image before giving up!)

As luck has it, the mixer they've used in Fig5.2 is the exact one we have.

I get the explanation about using it with the mixer subgroups and how to feed the output of the FBQ2496 back into the mixer via an unused channel strip - IF your mixer doesn't have any subgroup inserts (ours does not).  BUT... what's doing my head in is Fig 5.2!!!  It's showing insert leads, one coming and going to/from a channel strip, the other where the subgroup outputs are located on that (our) mixer.  There are no subgroup inserts, so WTF is that insert cable doing on the right??
Also, what the hell are the mixer main outs doing going into the side of the FBQ2496?????  There is only L & R inputs and outputs ?  That illustration has SIX connections to it!

I'm wondering if they are just using that particular mixer as an example of "a mixer" without realising that the one they've used doesn't have any subgroup inserts, and that the main outputs are supposed to go to the power amp above, which isn't connected at all??

jpfamps

The other thing they don't tell you about the FBQ2496 is that it comes set from the factory in graphic eq mode! 

This defeated myself and 2 BBC sound engineers!

Danny1969

All you need to know is that it needs to go inline between the mix bus and the power amp. So out of main left and right into the graphic and then out of graphic and into power amp

If you had inserts on the main left and right or subgroups you could use it on those but there's no advantage to doing so if your using it for global FOH correction 

EricTheWeary

He's my favourite Spanish punk rocker. 

Emp_Fab

@Danny1969 This isn't the graphic mate, it's the feedback destroyer and I want to send only the vocal mics through it via a subgroup.  I want to keep everything else away from it. I know how to wire it up to do what I want, I was just asking if anyone else could make sense of the diagram, because it doesn't make sense to me!

Danny1969

Ah sorry my bad .... you would normally have it in your vocal channel insert ... the picture i'm looking at of the UB2442FX  rear panel doesn't have inserts on the channels but you could go out the direct out on your vocal channel - into the FB destroyer and then back in the line input of another channel ..... if the direct outs on the channels are pre fader then you just keep the fader down on your vocal channel and up on the return channel .... that will keep the unit in series rather than parallel 

Emp_Fab

It does have channel inserts - they're on the top, in the channel strips.  I know how I'm going to wire it; assign the vocal mics to the Sub 1 bus only, take the output from Sub 1 to the FBQ2496 and send it back to the mixer via an unused channel input.  Then that channel can feed the main L&R busses as normal.

It's just that diagram - what they've drawn is impossible with the mixer they've used in the diagram and the main-outs are going back in to the FBQ2496 - which is also impossible, as you've already filled all the sockets on it anyway, as well as being logically incorrect.  I'm pretty sure he diagram is wrong, after sleeping on it, but I just wanted to check in case anyone else disagreed.

Roland

Emp. Have you already bought the feedback destroyer? We tried one, but found that the EQ bands it blocked were too wide. In the end we replaced it with a 31 band graphic which was much more effective.

Emp_Fab

The drummer has had it for years, so...  According to the manual, the filters are just 1/60th of an octave wide, whereas a 31-band graphic will be 1/3 of an octave, making the FBQ's filters twenty times narrower.  You sure you weren't having the same problem @jpfamps had ?

As for the diagram in the manual, Behringer support have just confirmed they've got it wrong.  The main outs should be going to the power amp in the drawing and the placement of the Right channel insert is misleading.

Brownie point for me! 

ESBlonde

Emp_Fab said:

It does have channel inserts - they're on the top, in the channel strips.  I know how I'm going to wire it; assign the vocal mics to the Sub 1 bus only, take the output from Sub 1 to the FBQ2496 and send it back to the mixer via an unused channel input.  Then that channel can feed the main L&R busses as normal.

It's just that diagram - what they've drawn is impossible with the mixer they've used in the diagram and the main-outs are going back in to the FBQ2496 - which is also impossible, as you've already filled all the sockets on it anyway, as well as being logically incorrect.  I'm pretty sure he diagram is wrong, after sleeping on it, but I just wanted to check in case anyone else disagreed.

That will work. The diagrams are generic and not to scale etc.
I would do the lead vocal to one ch of the DSP and all the backing vocals to another if you can (spare aux and input chanels being the limiting factor). That way the keyboard players cheap mic badly placed won't hack holes in the freq response of the lead singers tone which will just be cut by it's own filters. Does that make sense?
Also: for heavens sake don't use more than two or max three auto filters on each chanel of the DSP, and once you've sound checked and rung out the system change them from auto to fixed to lock the settings and turn the volume down a touch for a nice stable decent sounding rig. If you leave them in auto they keep deepening and widening the hole carved in the frequency response making the whole thing seem quiter by the second set! Used correctly they can be useful, but over used or badly used they will make the sound awful and progressivly worse as the night wears on.

Emp_Fab

@ESBlonde I like your thinking.  I do have a spare channel I can route the backing vocal mics through as you suggest.  I'll definitely do as you suggest.  Thanks for the advice mate.

wayneirie

Just use a graphic, Those things are horrible. If you want more level out the vocals without feed back put them in a subgroup.

ESBlonde

wayneirie said:

Just use a graphic, Those things are horrible. If you want more level out the vocals without feed back put them in a subgroup.

The problem with graphic eqs is that when you cut a certain frequency with a slider the octave and harmonics also see a movement/artifact. Cheaper models are worse but even the big expensive brands suffer the effect. Also a DSP filter can be right on the exact frequency, very narrow and hence shallow cut. a graphic slider is somewhere near and slices out a big chunk.
In the 70s and 80s a 32 band graphic was the best tool available to handle the problem unless you had a bunch of parametric eqs and knew how to use them! But as a valve amp loving guitar nut I have to admit in PA audio, digital is king. Big learning curve but Oh so well worth the benefits.

Danny1969

Ah I see what your trying to do now, instead of having it on just one vocal channel you trying to process all the vocal mics through it ...... that's probably not a good idea as a notch filter biting for one guy is going to cut out a notch of someone else even if the other person isn't having any feedback issues .... gonna be like sticking an auto wah on a vocal

As tempting as it is to buy racks full of Behringer outboard  (I see a lot of this with hobby PA) it generally causes more problems than it solves. With decent PA. correct mic placement and speaker placement you should be able to achieve more than sufficient gain before feedback without any feedback destroyers etc

If you do like playing with a lot of toys then your average entry level digital desk has everyone you need and non of the hassle of patching in .... plus you get iPad mix ability, IEM phone control, multitrack recording etc ..... Trying to take an old analog mixer and a bunch of outboard to achieve the same level will probably work out more money than buying a QU-SB or similar

wayneirie

Not having it, Those things are shit. If they were good they would be built into digital consoles but their not. M7, PM5, Cl5, Profile, Midas pro series none of them have a built in "feedback destroyer" Its down to the operator, theres no feedback destroyer in any of the drive racks/Monitor racks for any of the PA companies. I work for. When I mix monitors i just us whatevers in the desk I'm given. I'm well aware of the effect of Harmonics and Octaves when pulling frequencies out of a graphic. A KT/BSS Graphic would be infinitely more useful then the feedback destroyer. Of course theres a variation in quality My wedge EQ on say an PM5 is more hacked than a pro2 for example.

Also put everyone on the same vocal mic, your life will be considerably easier.

Emp_Fab

@Danny1969 ;Oh I'm definitely with you on that!  I'd love a digital mixer specifically for those reasons.  Maybe in the future, but for now, seeing as we aren't gigging yet, a total investment of £100 for the graphic and a MDX 4 channel limiter for the wired IEMs is enough.  The drummer already had the feedback destroyer, so it seems a shame not to wire it up.

ESBlonde

wayneirie said:

Not having it, Those things are shit. If they were good they would be built into digital consoles but their not. M7, PM5, Cl5, Profile, Midas pro series none of them have a built in "feedback destroyer" Its down to the operator, theres no feedback destroyer in any of the drive racks/Monitor racks for any of the PA companies. I work for. When I mix monitors i just us whatevers in the desk I'm given. I'm well aware of the effect of Harmonics and Octaves when pulling frequencies out of a graphic. A KT/BSS Graphic would be infinitely more useful then the feedback destroyer. Of course theres a variation in quality My wedge EQ on say an PM5 is more hacked than a pro2 for example.

Also put everyone on the same vocal mic, your life will be considerably easier.

I agree with much of this. Pro quality gear properly powered will always piss on the MI standard stuff as far as clarity, even response and outright punch without feedback. But with average speakers in a small club that has a stage built into the end wall and no ceiling height then you need to be reasonably talented to get the best from it. A well set (not just turned on) feedback destroyer can get your vocals over the drum kit and in the dodgy monitors. Truth is few people that buy a FBD learn how to use it and most that would know how to use it don't have the need becuase they have decent gear. It's a bit like people dissing Peavey gear, it's not so much the gear as the level of talent that uses it.
Give me a Lab Gruppen PLM ticking over into Radian/EAW Micro wedges and well placed Beta 57a mics and you can have loud and clear stage monitors and not resort to outboard processing. But thats enough capital to buy a family car.

wayneirie

ESBlonde said:

wayneirie said:

Not having it, Those things are shit. If they were good they would be built into digital consoles but their not. M7, PM5, Cl5, Profile, Midas pro series none of them have a built in "feedback destroyer" Its down to the operator, theres no feedback destroyer in any of the drive racks/Monitor racks for any of the PA companies. I work for. When I mix monitors i just us whatevers in the desk I'm given. I'm well aware of the effect of Harmonics and Octaves when pulling frequencies out of a graphic. A KT/BSS Graphic would be infinitely more useful then the feedback destroyer. Of course theres a variation in quality My wedge EQ on say an PM5 is more hacked than a pro2 for example.

Also put everyone on the same vocal mic, your life will be considerably easier.

I agree with much of this. Pro quality gear properly powered will always piss on the MI standard stuff as far as clarity, even response and outright punch without feedback. But with average speakers in a small club that has a stage built into the end wall and no ceiling height then you need to be reasonably talented to get the best from it. A well set (not just turned on) feedback destroyer can get your vocals over the drum kit and in the dodgy monitors. Truth is few people that buy a FBD learn how to use it and most that would know how to use it don't have the need becuase they have decent gear. It's a bit like people dissing Peavey gear, it's not so much the gear as the level of talent that uses it.
Give me a Lab Gruppen PLM ticking over into Radian/EAW Micro wedges and well placed Beta 57a mics and you can have loud and clear stage monitors and not resort to outboard processing. But thats enough capital to buy a family car.

In addition, It also seems the OP is trying to mix the gig with IEM's in. From behind the PA which is never helpful!! 

I've done gigs in the kind of rooms you describe, With no graphic etc when i was younger, fortunately its not something I have to do anymore. As you say the key to the feedback (fidelity)destroyer is probably setting it up properly. I Don"t know how he sets up his speakers but if he's getting feed back from FOH. I would suggest theres an issue with gain staging or speaker placement. Any way I would suggest the following:

Start with graphic flat

Engage hi pass filter @120 hz ish possibly higher, depends on singer

Get said singer coming into console with channel PFL'd. Aim for a level of around +3/+6Make sure their providing you with a level close to the one they'll be perfoming at. not mumbling 1-2. Bring fader up to 0db. 

Is there feedback? If so bring fader down a touch, until feedback stops. Now go through the graphic and Boost frequencies where you think the problem is if it starts to feed back again then you're there! try a 3db cut then bring fader back to Zero. 

If you're not sure where to start, Crossover points and Octaves/harmonics from there ie if the horn crosses over at 1.6k have a look at 12k/6.3k.3k/800/400/200.

Mute Keyboard players Mic until he gets the same one as everyone else. Or hack the life out the channel

Other feedback creators cupping mic, pointing in wedges idiocy in general. Also you can use the subgroup to get more level with less feedback. YMMV