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Acoustic Bass Feedback!!!!!!!!!!!!!!!!!

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panic_striken

Oct 13, 2005
562
3
#1
I have a very nice Michael Kelly Dragonfly Rose that I CAN NOT use at practice or gigs!!!!!! The thing will feedback the moment we start to play. What can I do??? Will a complete soundhole cover remedy this???? I want to either use it or loose it!!!!!! Please help :bawl:
 
#2
Try a soundhole cover. You may want to hook up a phase reversing cable as well. The phase reversing cable may be a bit odd to work with due to some creative wiring, but it could solve your problem.

Also, you could find a good single rackmount 31 band EQ, and cut at the feedback frequency (that is, if you amp doesn't have a notch filter).
 
#3
There is a limit to how loud you can go with an ABG before it feeds back. You can try a soundhole cover, stuffing some foam into the body, notch filtering, other kinds of EQ, ... but it will only work so well.

One way to improve the situation is to not stand in line with your amp. Getting off axis to it will help a lot.
 
#5
You may have a tough time with getting truly off axis with a bass amp though, because the radiation pattern is much more omni-directional than it would be with a higher frequency guitar signal. That is why I suggest the phase reversal. Reversing the phase will put the acoustic output at an exact opposite to what is coming out of the speakers. When this happens, the nature of sound is for the opposing waves to cancel each other out. Feedback is the opposite of this.

With the phase reversed, you won't be able to hear the bass' acoustic output, due to the cancellation. But, this will give you a truer sense of what is coming out of the speakers. Anyone outside of the earshot of the bass' acoustic sound won't notice any difference at all (except for a lack of feedback). You may not even realize an audible difference.
 
#6
Get an external amp with a parametric or semiparametric mid-EQ. Turn the level control all the way down and sweep the frequency control until the offending feedback is gone.

Note though, that some instruments feed back at multiple frequencies. You may be able to tame feedback at one frequency only to have another type of feedback pop up.
 
#7
Use a solid body.

Seriously. Heavy notching will damage the tone. And if you are playing at such a volume that feedback is happening, I doubt you would get any serious tonal advantages from an ABG. Nuances get lost in the mix.

One question, does it feedback when no on else is playing? Or when the guitarist starts? If so, perhaps the guitar could usefully lose some bass or low mids.......you top may be vibrating in sympathy to his invasion of YOUR sonic space.
 
#8
The concept of phase-reversal is not universal. By that I mean that it doesn't work in a predictable way. My Tacoma came with a Fishman Prefix Plus w/ phase reverse switch and it didn't do a whole lot to reduce feedback. The idea is that if your distance from the amp is at X, reversing the phase will put you 1/2 wavelength further away. That means that you have equal chances of it being better or worse for any given playing position. Having a phase reversal switch will let you compare. Even then it won't be a cure all.

Getting off axis can help. But like I said, it will only work to a point. Depending on the cab, the stage, the room... it can make a difference. A lot of players stand in front of their amps, and that causes problems with ABGs. Stand to the side, or go direct if you have a PA system and have the sound guy watch your fader like a hawk. You can also use a vol pedal and try to control it from your end.

Stuffing the body will dampen the bass, but if you wanted all that nuance then you should not be trying to play over a loud band :) My first ABG was a Ferrington and when I bought it there was a load of foam in the body! I thought "that's odd, I'll just ditch that", but I'm glad I held onto it because without the foam it was a nightmare plugged in.

I still play my Tacoma often, but I know its limitations. In the right place it is like the mini-URB that I always wanted. Otherwise I bring a volume-friendly bass like a defretted Dano DC, or even my J with flats.

Here is my Tacoma through my AI/Epifani rig:
[Invalid or Expired Link Removed]

Just thought that I'd share....
 
#9
Guess I'm gonna sell it, and maybe add a fretless to the arsenal. We are a loud band. I mean **** who likes quite rock and roll!!?? I just thought it would be a good touch for acoustic sets or songs. It is great for home practice because I don't have to plug in.............I just grab it and go :bassist: Oustside of that though it's a paper weight.
 
#13
panic_striken said:
Guess I'm gonna sell it, and maybe add a fretless to the arsenal. We are a loud band. I mean **** who likes quite rock and roll!!?? I just thought it would be a good touch for acoustic sets or songs. It is great for home practice because I don't have to plug in.............I just grab it and go :bassist: Oustside of that though it's a paper weight.
Click to expand...

You see you've just defined the problem. The fact that you can hear it unplugged means that it's very resonant. And that fact means that because its a good sound producer it's also a good microphone. And the resonance just enhances its ability to produce heavy feedback!

However you do have the right idea of an ABG adding a nice touch to some songs. That's why I bought my Carvin AC50 semi-hollow acoustic bass. And it's that semi-hollow that makes all the difference! You can't hear it unplugged for crap, which is why you can't get it to feedback either!

If you do decide to sell your ABG (personally I'd keep it for coffee house gigs and unplugged practice. Rule: you can never own too many bass guitars!), I'd look into a semi-hollow body bass. My big gripe with the Carvin is it doesn't have a magnetic pickup to mix in, but it nevertheless gives great acoustic tone.
 
#14
fretlessrock said:
Stuffing the body will dampen the bass, but if you wanted all that nuance then you should not be trying to play over a loud band :) My first ABG was a Ferrington and when I bought it there was a load of foam in the body! I thought "that's odd, I'll just ditch that", but I'm glad I held onto it because without the foam it was a nightmare plugged in.
Click to expand...

How much foam inside?. I'm guessing a lot perhaps close to the entire cavity filled?

I have a performance in a large room in NYC tomorrow. I built a custom sound hole cover from leather layered with a plastic backing and then foam. It fits snugly and I'm able to play up to about 80 db through an Eden Traveler 400 with 15 and 210 cabs without feedback in my rehearsal space. Of course that's by myself. Not sure how relevant that test is. I have no idea how loud we will be. The performance is an "unplugged" type event but there is a drummer and the acoustic guitars will be be amped. I'm bringing along a solid body as backup.

As I got up in loudness I noticed the tone went out the window but was functional

I suspect loading foam will be more effective than the sound hole cover.

Here is the sound hole cover:
Custom leather and foam sound hole cover for Ferrington ABG

Custom leather and foam sound hole cover for Ferrington ABG

Used contact cement to layer a thin plastic onto the leather, then glued the foam to that.

Custom leather and foam sound hole cover for Ferrington ABG

Custom leather and foam sound hole cover for Ferrington ABG

Used contact cement to layer a thin plastic onto the leather, then glued the foam to that.
 
#15
You seem to like the ability to grab the ABG and practice. I'd say keep it for that.
There are plenty of inexpensive solid body basses that should meet your budget and address the R&R need. I picked up my Silvertone LB11 for only $50 and it is a killer P-bass clone!
 
#17
This one from Dunlop is pretty good I lower the volume and keep everything flat it helps me with feedback.

51lb5MSQwgL._AC_UL320_SR318,320_.jpg
 
#20
Sorry for thread resurrection.

I originally searched the internet for anyone discussing how the Ferrington behaves in a band setting as volume increases and found nothing. Yesterday I looked up ABG feedback and found this thread. Good thing too, fretlessrock's story about purchasing a Ferrington used that was loaded with soft foam in the cavity answered my question.

I like the Ferrington for playing unamped and for "coffee house" situations. As it gets louder if first morphs into a fairly typical electric bass tone, especially if you play closer to the bridge. Any louder and the tone becomes a mix of the normal sound and what I call pre feedback tone layered over it.

I'm going to start testing semi hollow body basses to find one that has some of that woody, shades of upright sound yet punches through the mix.
 

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