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Double Bass Taming feedback/booming on open D string
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Do you have this issue in all rooms you play or just some?
I used to have issues of either the open E or open D feeding back and started using a high pass filter, either one built into one amp (AI Coda) or an fdeck Series 2M used with other amps. I adjust the filter to the point where the open E starts to fade away, then roll it back a bit. Some people have used notch filters and parametric EQs with some success. I always found them too fussy to dial in.
If you are able to invert the polarity (often called “phase”) of your signal either on a preamp you might be using (fdeck has such a switch) in one position the feedback usually will be stronger than in the other.
Other tricks that may help by reducing the amount of low end coupling between the room, the amp and the bass:
Change where you are standing relative to the amp if there’s enough room. Move around until the feedback subsides.
If the amp is in a corner, move it out of the corner.
Get the amp off the floor, on a chair, a stand or something makeshift like a milk crate.
Stuff some foam under the tailpiece, some people I know use Nerf footballs (seriously).
Dampen the strings between the bridge and tailpiece. I use a small piece of foam anchored by a velcro strap.
I used to have issues of either the open E or open D feeding back and started using a high pass filter, either one built into one amp (AI Coda) or an fdeck Series 2M used with other amps. I adjust the filter to the point where the open E starts to fade away, then roll it back a bit. Some people have used notch filters and parametric EQs with some success. I always found them too fussy to dial in.
If you are able to invert the polarity (often called “phase”) of your signal either on a preamp you might be using (fdeck has such a switch) in one position the feedback usually will be stronger than in the other.
Other tricks that may help by reducing the amount of low end coupling between the room, the amp and the bass:
Change where you are standing relative to the amp if there’s enough room. Move around until the feedback subsides.
If the amp is in a corner, move it out of the corner.
Get the amp off the floor, on a chair, a stand or something makeshift like a milk crate.
Stuff some foam under the tailpiece, some people I know use Nerf footballs (seriously).
Dampen the strings between the bridge and tailpiece. I use a small piece of foam anchored by a velcro strap.
If the problem is a really low frequency, try rolling up a towel and wedging it between the tail piece and top panel.
For higher frequencies, the best solution is typically a notch filter. If you don't know, a notch is a narrow and deep cut centered over the problem frequency. Many acoustic preamps have one notch filter. A few have two. In my experience it would be helpful to have about 6. Usually you hit the point of diminishing returns somewhere between 4 to 6 notches.
I haven't tried one with upright bass, but some sort of feedback suppressor in your signal path could be helpful. These devices sense and analyze the signal, and the apply notches when they conclude feedback is present. Years ago I used Sabine FBX solos for PA and they worked pretty well. The Sabines could be configured to set how may filters locked down at a fixed frequency and how may were allowed to roam. Each time you set up, you train the Sabine so the fixed notches are tailored to the playing environment. Not sure if anyone currently makes a compact model for 1/4"...everything I have found appears to be rack based
.
Most pedal EQs are not really good for notching. The Empress ParaEQ Deluxe II would be a good choice, but they are not cheap or a perfect solution. The PareEQ Deluxe has three bands of fully parametric EQ that allow you to adjust the center frequency and bandwidth. The limiting factor: Although the three bands overlap, the center frequencies cannot be adjusted over the entire audio spectrum. So essentially you get a low control (35-500hz), a mid control (250hz-5k), and high control (1k-20k). It's likely the low and mid control will be helpful for feedback suppression. The high control would probably be most useful for contouring the high mids to get rid of piezo quack.
The ParaEQ Deluxe also has a variable HPF (10hz-330hz) and Variable LPF (1.5k-22k) and includes Bass and Treble shelving and a switchable boost circuit.
The regular PareEQ uses a 3-way toggle for bandwidth rather than a rotary. It also lacks the Bass and Treble controls, as well as the HPF and LPF.
Anything you can do to reduce the amount of energy your amp puts into the bass ca help. I feel that elevating the amp helps, but some players like the resulting sound and others don't. Try and judge for yourself.
If the bass over-emphasizes the open D when playing acoustically, having a luthier make some adjustments could be helpful. This could involve adjustments to the bridge, sound post, or after lengths.
For higher frequencies, the best solution is typically a notch filter. If you don't know, a notch is a narrow and deep cut centered over the problem frequency. Many acoustic preamps have one notch filter. A few have two. In my experience it would be helpful to have about 6. Usually you hit the point of diminishing returns somewhere between 4 to 6 notches.
I haven't tried one with upright bass, but some sort of feedback suppressor in your signal path could be helpful. These devices sense and analyze the signal, and the apply notches when they conclude feedback is present. Years ago I used Sabine FBX solos for PA and they worked pretty well. The Sabines could be configured to set how may filters locked down at a fixed frequency and how may were allowed to roam. Each time you set up, you train the Sabine so the fixed notches are tailored to the playing environment. Not sure if anyone currently makes a compact model for 1/4"...everything I have found appears to be rack based
.Most pedal EQs are not really good for notching. The Empress ParaEQ Deluxe II would be a good choice, but they are not cheap or a perfect solution. The PareEQ Deluxe has three bands of fully parametric EQ that allow you to adjust the center frequency and bandwidth. The limiting factor: Although the three bands overlap, the center frequencies cannot be adjusted over the entire audio spectrum. So essentially you get a low control (35-500hz), a mid control (250hz-5k), and high control (1k-20k). It's likely the low and mid control will be helpful for feedback suppression. The high control would probably be most useful for contouring the high mids to get rid of piezo quack.
The ParaEQ Deluxe also has a variable HPF (10hz-330hz) and Variable LPF (1.5k-22k) and includes Bass and Treble shelving and a switchable boost circuit.
The regular PareEQ uses a 3-way toggle for bandwidth rather than a rotary. It also lacks the Bass and Treble controls, as well as the HPF and LPF.
Anything you can do to reduce the amount of energy your amp puts into the bass ca help. I feel that elevating the amp helps, but some players like the resulting sound and others don't. Try and judge for yourself.
If the bass over-emphasizes the open D when playing acoustically, having a luthier make some adjustments could be helpful. This could involve adjustments to the bridge, sound post, or after lengths.
^^^^^^I was going to reply, but Brian saved me a whole lot of typing.
The only other thing I’ve done in the past to tame an amplified open string is to place some muting material around the string right at the nut. I’ve used different things, but the most successful was a piece of cloth covered elastic hair tie. One or two wraps around the string with a small knot dampens the vibration of the open string, but leaves all fingered notes alone.
Need more info, @lurk
...FOH? Amp'ed? Piezo, mounted mic or stand mic? Other instruments in the mix? Crazy, loud, sensitive volume? Rough estimate of venue size/shape? Etc.?
Does your open D string produce a lot of "mwaaaaa" acoustically?
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The new Tonedexter has a useful anti-feedback function which works well to tame a boomy string. It senses the booming frequency and lets you dial out as much or as little of it as is necessary to tame it. If you bring its amplitude down to the level of the next highest amplitude note, it then lowers the amplitude of those two notes.
Thanks everyone. I've always had this problem with my bass, a 50 year old Pollmann, with various piezos in moderate to loud settings with drums. Elevating the speaker and high-pass filters help, but what I mainly do is just try to avoid that note and finger it on the A if I can. I haven't tried the hair tie trick which seems a little weird but pretty cheap if it works! I never thought - duh - of mentioning this to a luthier; I'll do that. I thought I was looking at an expensive preamp with a parametric equalizer as suggested, and that might be next. I really want to limit the number of wires, boxes, and knobs, but last night's gig, with a wonderful but aggressive drummer was tough.
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It depends on whether the feedback is high or low frequncy. You could try the electronic approach to remove the offending frequency, but I would first check whether your bass might have an acoustic prevalence to produce that frequency more than others. Wolf notes are similar but opposite ie reluctant to sound. Bowing will demonstrate this.
I would be inclined to move the sound post slightly south under the bridge foot. That should lower the tension and even out the sound a bit. I'm familiar with doing this to my own bass but you can take it to a pro if you are not.
You can get unpredictable results but IMO it's worth experimenting to solve a problem at source rather than fix it further down the chain.
I would be inclined to move the sound post slightly south under the bridge foot. That should lower the tension and even out the sound a bit. I'm familiar with doing this to my own bass but you can take it to a pro if you are not.
You can get unpredictable results but IMO it's worth experimenting to solve a problem at source rather than fix it further down the chain.
Most of my experience is with really high volume gigs. I agree with the post above. With a good setup you don't need to mess with EQ or other gizmos as much. I can stand about a foot from my 500 watt amp with no feedback. I used to run a 1000 watt amp and no feedback.
In my experience, a low to low mid feedback can be the soundpost. On my main 2 basses I put the soundpost a little closer to the bridge and it helped immensely.
If this is only happening with your open D it could also be a sympathetic vibration coming from somewhere like string afterlength or the wire going from the pickup element to the jack. But that's usually a higher pitched ringing (harmonic) in my experience.
If you mute the afterlength of the strings and adjust how your pickup wire is lying with no change, I would almost bet on it being the soundpost position or fit. Honorable mention goes to the bridge feet (but less likely).
If you're comfortable scooching the soundpost around, I'd try that first. I put the master volume and gain on my amp at about 12:00 and stand about a foot or two away (with the back of the bass facing the speakers). Keep moving the post around until you get a feel for what it's doing. You should be able to attain Woodstock volume in most cases.
I do that to all my basses and now I can leave them lying in front of the amp with no feedback if I forget to hit the mute switch between sets.
In my experience, a low to low mid feedback can be the soundpost. On my main 2 basses I put the soundpost a little closer to the bridge and it helped immensely.
If this is only happening with your open D it could also be a sympathetic vibration coming from somewhere like string afterlength or the wire going from the pickup element to the jack. But that's usually a higher pitched ringing (harmonic) in my experience.
If you mute the afterlength of the strings and adjust how your pickup wire is lying with no change, I would almost bet on it being the soundpost position or fit. Honorable mention goes to the bridge feet (but less likely).
If you're comfortable scooching the soundpost around, I'd try that first. I put the master volume and gain on my amp at about 12:00 and stand about a foot or two away (with the back of the bass facing the speakers). Keep moving the post around until you get a feel for what it's doing. You should be able to attain Woodstock volume in most cases.
I do that to all my basses and now I can leave them lying in front of the amp with no feedback if I forget to hit the mute switch between sets.
If your piezo is mounted on the g string side of the bridge, try moving it to the other side. Also make sure it's not wedged in too tight. Those things are real sensitive.
