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Double Bass Bass resonate on particular note

Michal Herman

Michal Herman

May 31, 2013
242
141
#1
I've got new bass - hybrid Strunal.
It's quite even in sound, but note D resonates more than others.
When plying acoustic it is not that noticeable, but it starts ringing, when playing amplified. When I play amplified and hit D note bass starts to resonate creating "infinite sustain". No problem on other notes. It occurs as well on empty D string as on D note on A or E string.
It's not "wolf tone" as I understand this term - sound do not vibrate. It's clear note, but bass resonate more on that note.
Any tips how to eliminate or decrease this effect?
 
#2
From what you describe, this sounds like an instrument resonance frequency. That resonance is being picked-up by your PU, then amplified and converted to sound waves, and subsequently the instrument (to all likelihood mostly the bass top) acts as a microphone & picks-up the vibrations from the air, and then feeds it into the PU again. Hence a feedback loop. Questions would be: what kind PU, and where is it placed? I think this is what they call a wolf tone.

Solving may not be easy, but you can try things like:
  • do not stand in front of your speaker
  • or change the distance
  • try a 180° phase shift (often found on preamps)
  • try a different PU or placement (E-wing --> G-wing?)
Changing the actual acoustics is more difficult, you may try things like clamping a weight on your tailpiece, or maybe a very light tailpiece, a different bridge or strings (low PoS).

Before you go & change-out difficult things, another easy thing to try is clamping a small weight on the bridge. Take 2 pieces of wood (say 5x2x0.5cm), drill 6mm holes on the far edges, and use suitable length M6 bolts & nuts to clamp that contraption on for instance the legs. That will change the resonance slightly, which may improve the situation. That might help in assessing if your instrument would benefit from a heavier bridge (in which case also a lighter bridge might help.

Are you sure it is not the end-pin? (Just take it out completely & try again.) Might also be the free part of the finger board (try damping with your hand to diagnose? or if you tap that FB, is it the same note?).

Good luck!
 
#3
@Ortsom
Thank you for tips.
I think it's acoustic of bass, because even when playing unamplified D note is little louder than others.
I will try to experiment with weight of tailpiece and bridge and will see, if it is changing effect.
 
#4
If it is a resonance of the top moving the sound post might help, since it changes the modes (possible movement patterns) of the top.
But this might change the character of the sound.

But first try things that you can do yourself and that are reversible. If you are not happy with the results visit a luthier for the soundpost.
 
#5
Every acoustic instrument has resonance frequencies, but in some they are sharper than in others. And D is awkward.

I forgot to mention, the other practical help (for amping) can come from an equaliser. If you have a parametric EQ, set it to attenuate suitably using the narrowest bandwidth still effective. With a graphic EQ, suppress that tone (but then often you attenuate too much around it too).

Maybe someone else has the golden bullet for this issue (although I just saw that the golden horse has now snuffed it...)
 
#8
KUNGfuSHERIFF said:
The open D string is generally the loudest note on any bass. Just learn to compensate for it.
Click to expand...

If the problem was only open D, that would not be such a problem. But it resonates also on D played on other strings.
A luthier whom I know recommended me this kind of wolf eliminator: Invalid Link Removed
It's two magnets that add weight to chosen point on bass top.
Has anyone tried such solution? Any thoughts about would it work? It costs about $100 so I would like to hear some opinions before buying.
 
#9
I do not know if it is true that the open D (=73.4Hz) is generally the loudest on any bass. I think I find prime resonances more commonly around the a - a#, say in the 115-120Hz range. But the principle remains: the instrument will resonate most willingly around it's resonance, and that note will sound loudest & decay quickest.

I have no experience with the device you linked to, but I know the vibration patterns in a top can be influenced by judiciously placing weights. Yet I see this advertised tool more as a means to diagnose, rather than a permanent solution: if it works, you'll be left with a magnet on your top, which can move (or fall) in transit. So then you would want something more permanent, I'd guess on the inside. It may work, but my gut feel is that this is not a very attractive route to pursue at this stage, for 383 Zloty = $99. I'd rather try easier & more conventional approaches first (definitely including optimising the SP location, as DoubleMIDI suggested).

My suggestion on placing small weights on the bridge works along the same idea of the magnets here advertised. The difference is of course that the weight is only placed on a very limited location: only on the bridge. But the advantage is that it costs nothing, and will leave no marks; so its cheap to try. You can also try a small clamp.

Another possibility is this: does you bridge maybe have brass height adjusters? Those add a lot of weight, and that could also be the cause, or at least contribute to the problem. Your resonance seems low, suggesting too heavy. If you have brass adjusters, you can try taking-out the heavy adjustment wheels (or replacing that assy with a beheaded M6 (or ¼", depending on your thread) bolt going through a piece of wood with a suitable thickness). If that helps, you need alu adjusters, or a fixed bridge, at any rate: lighter. Or try something like this:
Enlightened adjusters (148g total).jpg

Of course this is a poor-boy fix, enlightened for reasons other than yours. Alu is better, hollow titanium bolts in super light wheels or with TI pins is best. This 17cm+ tall bridge weighs 148g all-in, which is still too much for my taste.

Edit/add: can you discuss your issue with a luthier?
 
Last edited:
#12
This just sounds like normal headaches caused by amplifying upright bass. I wouldn't look to any drastic measures on the bass itself. I think my old bass did the same thing when I had a bassmax in the E side bridge wing.

I found my current bass does something like this when I play a B on the G string amplified in one particular part of one song. One of the open strings takes off on me. It's one of those things that I never noticed until I was playing said tune in a full PA setting. I just mute the other strings when I play that part - problem solved.

Where are you trying this all out? If you're doing it in small room, than several frequencies are going to be causing issues IME. My practice room rattles enough when I'm not plugged in. If I turn on an amplifier, the whole place is a wash of vibrations. I don't even care what my amp sounds like at home, because I know it wont sound that way at a gig. Recently I bought a really nice pedal that sounded fantastic in my practice room, however I used it once live and figured out quickly it wasn't going to work.

Before you start dissecting what's wrong with the bass, record some acoustic stuff with a mic and see if there really is a problem.
 
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#13
You can try to move the bridge a bit up or down to simulate (to a certain point) the influence of the soundpost position.
If that helps, moving the soundpost would be a good idea.

I don't think adding mass to the bridge can help. But you can try.

The magnets will move the vibrational pattern of the top like a repositioning of the soundpost. But they need to have some more mass (except if you have a rather thin top) to have a substantial influence.

Strong neodymium magnets might work, but for about 400zl better order the MSP pickup from japan. Then you have a pickup and three more neodymium magnets to try (you can stack them for more mass). The price after customs and VAT might be about 25% higher than the magnets the luthier recommended, but it would be worth the money for the pickup function alone.

Did you ask the luthier explicitly for a soundpost move when you talked to him on the phone?
 
#14
DoubleMIDI said:
move the bridge a bit
Click to expand...
You are a clever cookie! That is the easiest trial.
On the weight on the bridge: you're right, it probably won't make much difference. But also cheap & easy to try.

I've heard good things about the MSP as a PU, but it is likely too light to be a real influence on the top vibes too. If you want to try the magnet way, there are much cheaper alternatives, see for instance supramagnets or other web suppliers. Also, the linked tool was for cello & DB, so may be light for a DB.
 
#15
Jay Corwin said:
I think my old bass did the same thing when I had a bassmax in the E side bridge wing.
Click to expand...

Wow. Thats exacly the case I have :-) But I cannot change it to G wing easily - this would need bridge shape correction for good fit.
I really only tested it in practice room - with soundproofing foam on walls - but quite small: about 20 square meters.
I have gig tomorrow on which I will be using this bass, so I can test how it performs in gig scenario.
 
#16
Michal Herman said:
Wow. Thats exacly the case I have :) But I cannot change it to G wing easily - this would need bridge shape correction for good fit.
I really only tested it in practice room - with soundproofing foam on walls - but quite small: about 20 square meters.
I have gig tomorrow on which I will be using this bass, so I can test how it performs in gig scenario.
Click to expand...

That is a small room for bass amplification. Also I'm not an acoustics engineer, but a lot of that sound deadening material doesn't knock down bass frequencies very efficiently. That's why bass traps exists.

I would see what happens when you play the thing in a room that can handle the decibels better.
 
#18
OK, so I now understand it is not so much an acoustic issue, but rather an amplifying issue, which in a stage setting is actually not so much of an issue (possibly you had a sound man). I also understand you have a K&K Bass Max in the E-wing.

The E-wing is the common advice, but again I'd recommend you also try the G-wing. Depending on instrument & bridge geometry, I often prefer the G-wing for being flatter & better balanced in output level across the strings. If the G-slot is too narrow, take a bit of the G-wing; if it is too wide use 2 thin maple or beech wedges which you push into each other to provide flat pressure onto the PU.
 
#19
Michal Herman said:
I've got new bass - hybrid Strunal.
It's quite even in sound, but note D resonates more than others.
When plying acoustic it is not that noticeable, but it starts ringing, when playing amplified. When I play amplified and hit D note bass starts to resonate creating "infinite sustain". No problem on other notes. It occurs as well on empty D string as on D note on A or E string.
It's not "wolf tone" as I understand this term - sound do not vibrate. It's clear note, but bass resonate more on that note.
Any tips how to eliminate or decrease this effect?
Click to expand...
I have this issue with both of my bass guitars with a G played anywhere on the fretboard. Oddly, the open G is the least "offensive". I've tried working this out with EQ settings, position in relation to amps and other instruments, but without success. It is a maddening problem!
 

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