Acoustic bass feedback

[bassingeorge]

So, I want to thank you all guys for helping me out in other topics, but the thing is that I don't own 1 bass, but I also own an acoustic electric mickael kelly 5 string bass, and I have a problem with it; when I play it with the amp, about 1/4 turn of the volume (amp) and half the volume (bass) it starts the feedback! my bass is a jumbo size cuttaway hollow acoustic, maybe thats the thing. Anyway, what can I do to fix this!! help me please

[Bob Gollihur]

ABGs feed back readily; I have a custom made fretless 5 string that I can't even take on stage. I used to own an Ovation-style ABG and could get pretty loud with it. Laminated instruments like the Kelly have a better chance of some more volume. There are some things you can do:

 

• If you have a phase switch on your bass' preamp, use it. Running out a phase can get you a couple more dB or so
  
• Get a rubber plug the seal off the sound hole, they are readily available from catalog places, maybe your local music store
   
  
• Stand to the side of your amp, you want to avoid have the speaker blowing at the instrument- the transducer turns it into a big microphone
   
  
• Cut back on some of the lows at the amp or bass
   
  

That's what worked for me.

[bassingeorge]

Thanks! I don't have a phase switch but, I'll try to find the soundhole plug thing.

I also checked fishman, and saw this "platinum bass" EQ, it's like a big console, you know what I'm talking about, would this cure the problem?

Or are there any pedals, boxes, EQ's, whatever, to cure this?

Thanx

[jeremy c]

I've given up using my acoustic bass guitar with a band, I've never been able to solve the feedback problem.

 

When playing with a few acoustic guitarists at low volume it's fine.

[Bob Gollihur]

Originally posted by bassingeorge:

Thanks! I don't have a phase switch but, I'll try to find the soundhole plug thing.

I also checked fishman, and saw this "platinum bass" EQ, it's like a big console, you know what I'm talking about, would this cure the problem?

Or are there any pedals, boxes, EQ's, whatever, to cure this?

Thanx

Yes, in fact I just added it to my web site at http://www.urbbob.com/preamp-fishman.html - the phase switch can give you a couple extra db of volume and offers some nice features. However, IME it is a challenge, and as with all acoustic bass amplification, there are limitations.

[jimbojones]

If your playing with a distorttion pedal, which I really doubt, that'll do it, cause acoustic pickups are made for be played through an overdrive or distortion pedal. Also, if your playing through a small practice amp, that may be the problem. Feedback has to do with the amp as much as the pickups or guitar.

[bassingeorge]

No not at all, I don't play it through a dist. pedal and I play it with a Carvin 200 watt amp, with a 15" speaker, and believe me, it's LOUD!

Mmmm I guess it's made for playing at low volume with their acoustic guitar cousins...Oh well...

Any more suggestions?

[JohnS]

I have been thinking about getting an ABG but have been concerned about the feedback issue. I have been looking at the Carvin AC50 fretless. I have noticed that there are feedback eliminator/ exterminator/ suppressor/ destroyers on the market and I wonder if anyone has any experience with any of these items?

[The Guy]

I have not used any of those such devices, in fact I have never used an ABG, but I have used a few uprights, and have found the volume = feedback thing to be quite frustrating. The best, low cost thing to do is to adjust your location in referance to your amp.

 

If you stand in front of your amp, it will feedback like mad, but if you stand behind it, it probably won't as much(depending on your room accoustics). Unfortunately, you won't be able to hear yourself very well. So work on finding a place off to the side of your amp.

 

For example, if your cabinet speaker is crappy, the sound will distribute in a long, narrow cone shape.(ex. 40-55 degrees) A good speaker will produce sound in a wider cone,(70-90 degrees) and an excellent speaker project sound in a 180-360 degree radius; these are surround sound speakers and are seldom, if not never, found in amp cabs. Assuming you have a good speaker, try standing a few steps infront and to the side of your amp.

 

To help you hear it, try standing to the side of the amp so that it will be the only thing, or one of the only things, coming from that side. For example, if you stand to the left of your drummer, stand to the right of your amp, so that you will hear the drummer in your right ear, and your bass in your left. In the very least, you should be able to hear yourself at least reasonably well. If possible, leave the house sound up to the soundguy.

 

Rock on

Mark

[ClarkW]

The ideal situation would be to always play through a PA that provides you with in-ear monitors and keeps the stage volume at almost null. Of course that's not a very economical solution, since each earpiece and transmitter is going to cost upwards of $1000.

 

A local bluegrass-rock fusion group has that setup, with a plexiglass shield around the drummer. They can't have very loud stage volume because they'll have 2-4 piezo'd instruments going at once (guitar, mandolin, banjo, fiddle, bazuki, bass). I stood up onstage with them during soundcheck one day and it was the eeriest thing, almost whisper quiet. But they had the earpieces and it was gravy for them.

[music-man]

Two added thoughts:

 

1. I've used a Trace Elliott preamp box with a "notch" EQ filter with some success. Basically, the notch is a dip in amplitude, set at a sweepable EQ. This works pretty well live, since you can focus on the most annoying feedback pitch. However, it's a limited solution, since at higher volumes, you get multiple frequencies feeding back, and the notch only works on one.

 

2. I've tried an "automatic" feedback destroyer ... it doesn't work very well. It either wipes out your tone, or doesn't eliminate enough of the feedback.

 

There is a very effective invention that many people use in order to eliminate the resonant feedback inherent in any hollow-bodied acoustic instrument ... it's called a solid-body ...

[Max Valentino]

In addition to the tips and comments made here already:

Placement of your amp to be serving as your monitor (as to the side of you) will help, as will some notch filtering. Units such as the Fishman have a phase reversal switch which is very helpful in reducinh some feedback. A parametric set to a small bandwidth can be dialed into just the resonant freq of yoyr bass and zap that right out, also. Yet, big hollow bodies have a problem with low end feedback as part of their design.

 

Piezo pu's have an enormous dynamic and frequency range, so if you are boosting either at the bass or amp, this will be at least partly responsible for feedback.

It is best to set the amp flat, perhaps even cut some low end, and use the on board eq to focus the tone. It is also more desireable to cut treble rather than add bass for more lows (and vice versa). In general, I never boost any freqs at the eq, but rather use it for cutting. This helps out quite a bit.

 

I am not sure where the poster got info that "acoustic pu;s are made to be fed into OD boxes". Quite to the contrary, piezo pu's have very high output impedences and plugging into a stomp box, with notoriously low input impedences, will deteriorate the tone of the bass...altho' this "loading down" will attenuate the low and high end, which can alieviate the boominess and feedback, but at a greater tonal compromise.

 

Max