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Here you can discuss details about instruments, equipment and all those other bits that non-musicians won't understand !

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TimH
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Feedback

Postby TimH » Sat Oct 11, 2008 5:35 pm

Gordon (and the gang),
You never seem to struggle with what is surely the acoustic guitarists nemsis - feedback :twisted: . Do you have any gadgets that you use during soundcheck to help eliminate it? I've been thinking about the L.R. Baggs Feedback Master but it's £120 and don't want to shell out if it doesn't actually work. I've tried to eliminate feedback with a Boss GE-7 graphic eq but it doesn't seem to be accurate enough to eliminate the precise frequency or be able to cut the frequency bands enough (it doesn't work is what I'm saying!)

Any views gratefully received.
All the best
Tim.

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Mike Stranks
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Postby Mike Stranks » Sat Oct 11, 2008 8:25 pm

Hi Tim

Please forgive a non-guitarist pitching in first on this. However, I do a lot of live-sound engineering and the guitarists I work with are almost all of the acoustic variety.

Before I give any opinions on what might be causing problems a bit more information would be helpful. For instance, are you using pickups or mic-ing the guitar? In either case, makes and model numbers would be helpful. Are you using an acoustic guitar anp or putting the signal through a sound system - "speakers on sticks"? Again, makes and models would be helpful.

I'm sure that between us we'll be able to come up with some hints and tips, but we really need more info so we don't suggest stuff that's completely inappropriate.

Mike

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TimH
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Postby TimH » Sat Oct 11, 2008 11:40 pm

Hi Mike,
Several guitars: Fylde GG Signature prototype; Fylde Alchemist; Ovation Celebrity bowl-back. Fyldes have Fishman Rare Earth Blend (set roughly 50:50 mic:magnetic) and the ovation has a Fishman piezo undersaddle. All go into an Award-Session GG-10 pre-amp and thence into a desk and out to powered PA speakers and to stage monitors. The Ovation has a feedback reducing soundhole baffle but not the Fyldes as the Rare Earth Blend is soundhole mounted. Usual venues are pubs and hotel function rooms (low ceilings usually a feature) and always in competition with drums, bass, sax, keyboards and vocals! Drums and bass don't go through the PA but everything else does.

Any info and views gratefully received.
Cheers,
Tim.

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Mike Stranks
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Postby Mike Stranks » Sun Oct 12, 2008 8:30 pm

That's very helpful Tim.

With that information others who are players will probably join in. Their perspective as players will be very useful.

A few suggestions:

As long as it doesn't compromise the sound quality too much for you I'd try altering the ratio of mic to pickup on the guitar - less mic and more pickup.

I presume that you've done the obvious stuff like making sure you're behind an imaginary line drawn between your two PA speakers? Also be careful where you stand in relation to the backs of these speakers - it's surprising how much lower-mid sound comes out of the back of some speakers.

Try to ensure that your foldback speaker isn't pointing directly at the soundhole of the guitar(s) if possible. I suspect with the other sounds you're working with then you need the foldback quite high to be able to hear yourself. That sound could be resonating inside the body of the guitar and being picked up by the mic element of the pick-up.

Have you thought of going with in-ear monitors? That could make a huge difference.

I presume that the gain structure from the guitar through to the speakers is set up OK? That is, you've got as beefy a signal as possible without overloading any input stage right through the process.

In terms of the PA itself, try to ensure that the speakers are not pointing directly at hard walls at the back of the room. It doesn't sound as if you're troubled with high ceilings/roofs which bounce the sound around and cause all sorts of problems, but with difficult acoustics and/or hard rear walls I try to get the speakers as high as possible (Studiospares do some 3m ones, but you have to be very careful of health and safety!) and angle then down at about 5 degs or so - it'll depend on the venue. don't tip the stands - very dangerous - you can get purpose designed adjustable pole tilts - about £35 a pair.

In terms of the graphic EQ and the feedback destroyer - the L R Baggs - I think you won't see much improvement. The graphic you've been using is operating over far too broad a frequnecy band on each slider to do much without ruining your sound. I'd go for a 15-band as an absolute minimum and ideally a 31-band. I've used feedback destroyers in the past, with a degree of success, but they're not 'magic bullets' for feedback problems. These days I tend to spend more time EQ-ing the foldback using graphic equalisers. That's paid huge dividends.

So that's an engineer's take - now over to the guitarists! :D

Mike

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TimH
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Postby TimH » Tue Oct 14, 2008 12:23 pm

Many thanks Mike, very useful info. I will be hiring a 31 band eq for the next gig to give that a try and I'll report back.
Cheers,
Tim.

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Russ Gannicott
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Postby Russ Gannicott » Sat Oct 18, 2008 10:56 pm

Hi Tim,
Just a thought, and in addition to Mikes excellent advice already given; Do you have someone opperate the PA for you, or is it 'self run' from the stage?
Also, I take it you are using one monitor mix...?
The biggest likely cause of your feedback is not going to be your guitar, but something else dominant in the feedback mix that is causing a sympathetic resonance in your guitar. With this in mind, it is almost impossible to eq this out at the guitar end of things and must be addressed at the moniior send from the desk. You may well find that you have to put up with a rather unpleasant guitar sound coming out of the monitor to cure this unless you can split up your moniitor mixes.
An obvious sugestion would be to use a small dedicated amp as a nearfield monitor just for your guitar and them reposition the floor monitors away from you. The sax you should be able to hear 'acoustically' and hopefully the keyboard player is using some backline which you would pick up as well. That just leaves the vocal and a small amount of your guitar in the mix for the others to hear as reference. Pushing too much through the PA is a classic mistake that is made by many bands playing small venues. If their is no need for an engineer to take control of your mix in 'real time' out front, then you should be able to do it from where you are on stage using backline. You'll also get a far better sound as you wont get a dead spot in front of the stage where the audience can only hear the drummer!!.
If you are using a Session pre-amp, you dont even need to by an expensive acoustic amp. In fact, if you can find a small (30watt) bass amp with a 'direct in' you will find it works really well with acoustic guitar. You can still use the Session as a DI out to the PA, but at least with your amp 'in your face' you'll be able to hear yourself at a suitable level without having to have the rest of the band shouting into your guitar!
Good luck and please keep us posted.
Russ

Trevor Raggatt
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Postby Trevor Raggatt » Wed Oct 22, 2008 5:01 pm

TimH wrote:Hi Mike,
The Ovation has a feedback reducing soundhole baffle but not the Fyldes as the Rare Earth Blend is soundhole mounted.


It might still be worth getting hold of one of the rubber "Feedback-buster" soundhole plugs and experimenting with it and a stanley knife. Certainly with the Rare Earth pickup you can't just bung it in the sound-hole. However, it could be worth trying slicing the bung into two appropriate sized pieces (being very careful with finger, of course!!) which would still fit snugly into the sound hole either side of the pickup and butting right up to it.

Cut right they should fit nice and snugly and still work to cut out a significant amount of feedback.

I had to do a similar job for my very sensitive and very feed-back prone Brook. Not a full slice in half job but it has an LR Baggs dual source pickup with a sound-hole mounted vol and blend control. I had to carve out a space to accommodate the control and it works pretty well.

With cutting the plug in half or more you may need to strengthen the edge along by the cut but this can be easily done by sticking some sort of stiffener on the back of the bung.

Of course, it may not work but trying would be much less expensive than splashing out on a feedback seeking pedal or the like.

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GORDON
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Postby GORDON » Wed Oct 22, 2008 9:20 pm

Hi Tim.

Sorry about the late reply. Fortunately I rarely get feedback, mainly because I work at pretty low levels and also don't like the monitors too loud. Obviously if I were in a rock band situation it would be a different story. Acoustic guitars are notorious for feedback, and I'm sure that all the expert advice you have been given here will certainly help towards eliminating the problem.

Be Well sir.

G.

Trevor Raggatt
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Life is full of compromises...

Postby Trevor Raggatt » Thu Oct 23, 2008 1:47 pm

Just thinking about Mike's blend comment. It could be also worth living with the compromise of using less mic blend. Realistically you're playing in non-ideal listening conditions (same as the function band which I play in so I know the type of set-up) and the level of differentiation in sound that your audience gets between a 50/50 mix and a more magnetic heavy mix may simply not be audible to them. The good thing is the Rare Earth mag sound is a lot more "acoustic" than older mag pickups for acoustics used to be. Not ideal, of course, as we are always on th ehunt for that elusive ideal live tone but better than rampant feedback,


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