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Double Bass Dead D-Flat

Benthoven

Benthoven

May 26, 2009
76
112
Charlotte, NC
www.facebook.com
#1
I've got a really nice Eastman 305 carved bass, set up for jazz, with Fishman pickups an adjustable-height bridge. It's warm, it's got all the sustain and ring I could ever ask for (that's why I chose this bass,) except for D-flat, played in any position, any string. That note (played piz) just dies on this bass - almost no sustain. What can I do to solve this? It's got to be an acoustic anomaly of some kind, I would think, but what?
 
#2
Good question-I hope that some sound experts can help you. Seems interesting that it is happening on just one note, rather than at a location across the board, like around one area. Since it dies at the pitch of one note, then, I would think,that it would have to be related to the set up in some way. I would start by checking the general set-up to include the wire side adjuster(it is on the E side-right?)of the Fishman to make sure that the E side adjuster is solidly fit to the bridge with no space between the non-threaded stem where it fits against the bridge leg . Also, make sure that there is some thread is showing on the adjusters. I am sure that you have checked the bridge location -centered between the f hole notches.

Since it dies on every string at D flat, complicates finding the reason-In my opinion. I am assuming that it doesn't die when you arco. You might try pressing harder with left hand and playing the note with more force since(play with rest stroke pizz) As you know, that is what happens when the bow crosses the strings causing the string to vibrate more than what pizz causes. If the strings have those cushion washers at the tailpiece, remove them and see if changes the D flats. You might also try, not only moving the sound post, but change the diameter. It should be around 19mm. I doubt if making it larger would help, but making it smaller might.

Have you tried it with adjusters other than what comes with the Fishman? Have you tried moving the sound post?. I would just start trying difference things with the set-up; tailpiece wire length and maybe a lighter wire. Sorry, but I really don't know specifically what it could be, and I am mostly just thinking outloud here of the things that I would try. Maybe someone has experienced the same thing. I'll be interested in finding out how it was corrected. Hope you find out what is causing it. I have never had this one note issue, but have had a particular area that died out sooner than the rest of the scale(from D on G up to about F.) Shortening the tailpiece wire corrected it. Good luck.
 
#3
Yeah, I always anticipate having to play D-flats more forcefully, and that can be distracting and it's enough of a problem that I'm posting here. No cushion washers; it is a 19mm soundpost and moving it changes all kinds of other tone qualities and right now it's in a sweet spot for what I like to hear. The Fishman BP-100 pickup I have is the one with dual piezos with the fussy little metal clips. (I like the sound but it's a constant maintenance situation.)

I like the Tailpiece wire-change approach you mentioned, and the more I think about it the more it seems like the solution. Bill Traeger's chapter on "Mode Matching" goes into great detail on this but I'm a little lost on finding A0, W, B0 etc. This chapter is really complicated, really technical, but it makes sense. For 25 years, I was a church organ builder, pipemaker and voicer. Finish-voicing an organ in the church involved finding the natural (hot) pitch of the sanctuary (as if you could pick the room up and blow it like a coke bottle to get a note). That resonant note, once found, defined the harmonic series of the room, and the pipes had to be balanced with it. For instance a "B-flat" room required that I soften all the B-flats and usually F pipes a little bit, and louden the E and B pipes (a tritone away) to achieve an even volume up and down the scale. There were many other variables involved, like surface finishes, wall and ceiling mass, soft surfaces, standing waves etc, but the bass avoids most of those problems naturally.

Bill Traeger really goes much, much deeper into technical detail with his chapter on this and I'm still a bit overwhelmed with it, even with my organ voicing background. Does anyone have experience with Traeger's Mode Matching? Pros, cons, were the results worth it, not worth it, etc.? Did it address an issue similar to mine? It's a pretty steep learning curve and will require some investment to do properly, so I'd be interested in any feedback you guys might have.
 
#4
You have a wolf note on the Db. Often, the more responsive the bass is, the more likely it will have a wolf note somewhere. If you bow that note, it will seem to fight you, or oscillate wildly. Unfortunately, wolf notes are often hard to eliminate altogether, although you can usually improve them or move the frequency a bit. I would ask your luthier to have a look at it and start by doing non-destructive adjustments like tuning/changing the tailpiece or tuning the afterlengths, changing the soundpost position. It may take a while to find the solution!
 
#5
Thanks, Matthew. I just read Traeger's technical definition of "wolf note" and your description of its symptoms and they seem to mesh perfectly. The Db really fights my bow as you described. I'm going to start with changing the tailpiece wire and tuning of the afterlengths. If I could just move that frequency off the Db a bit I am sure it would help some. I'm reluctant to move the soundpost much because I really like the sound where it is. This is a very responsive bass, (really great for playing jazz) and it only makes sense what you said about the greater likelihood of a wolf note somewhere. Thanks!
 
#7
Ha! I'm tempted... I'm also tempted to take another piece of Traeger advice and make a shorter, "winter" soundpost for it. (it is winter here, you know) However, in the extremely dry, arid, desert climate of Las Vegas, where the humidity rarely exceeds 20% year-round, I sorta doubt there's much to be gained there. Any thoughts on that?
 
#8
You are right about Traeger's chapter-I have read it, pondered it at least 3 times and each time I just shake my head and wonder how anyone could figure out what is being said there. Matthew may have something with the wolf-thanks Matthew and thanks Benthoven for what you shared about the organ and finding the "natural hot pitch of the sanctuary"--very interesting. I know a very busy pro bassist in Canada who does not use a tailpiece at all- He says if you use what he does, you will never go back to a tailpiece. PM me if you want his email. I wonder what an angled tailpiece would do for it.

I wonder what just changing the sting lengths would do with an angled tailpiece

Arnold- help us out here! Can't you see that we are wondering aimlessly, except for the wolf and wire possibility.
 
#9
It is a wolf note as Matthew said. You can buy a little brass wolf eliminator from International violin company. Or even make one perhaps. It goes around the string between the bridge and tailpiece. You can slide it to and fro to change the resonance of the vibrating string afterlength. This usually takes care of the wolf by moving it in between the notes.

No need to understand AO BO matching really, which is a different subject altogether. This has more to do with trying to gain some power in the AO frequency region by making the neck and fingerboard vibrate in sympathy with the air in the bass body.
 
#10
I wonder how many have run across this before (assuming it is a wolf)having a wolf at the same note on all the strings. Just trying to learn something here. If you take Ken's suggestion which sounds sound, you might want to order one from Int Vio 800-542-3538 even though they would take them back if you got four and didn't need them. They are kinda on the expensive side.I think Ken is making a lot of sense, but unless you have tool and Dye tools, making a GOOD ONE` would not be that easy.
 
#15
The wolf note is something pretty instrinsic to the whole of the bass. Like the "sanctuary" note, there is often a single pitch that is either boosted or attenuated by the particular combination of wood, string, soundpost, afterlength etc that makes up a bass. And yes, the note will occur wherever you play it, and to a degree on the harmonics of that note as well. By altering the dynamics of the bass, you can often move the pitch of the wolf around, but eliminating it altogether is a hit or miss affair. You might get lucky.

My own feeling is that the wolf usually has more to do with the graduation and shape of the wood of the top, and the shape of the cavity of the bass, than anything else; at a certain frequency, the top will vibrate in a way that produces standing waves that can cancel or amplify each other - like an internal echo - and that is a hard thing to correct.

It would be interesting to look at whether basses with parallel edge ribs have a greater propensity to wolf notes than those where the ribs are wider at the lower block than at the top. But it's probably impossible to generalise.
 
#17
That pretty much mirrors my own "mechanic's intuition" on it Matthew. Let me sorta think aloud here, relating the bass to what I know of organ pipe acoustics. The 'cavity' of the bass, or the "vibrating air column" as we refer to in pipes, that is formed by the top, back and ribs, acts precisely like a stoppered wooden organ pipe, primarily with respect to determining the cubic volume of air contained inside it, which directly determines it's pitch. A stoppered organ pipe is tuned by pushing the stopper inward- reducing the cubic volume and raising the pitch, or pulling the stopper outward, increasing the cubic volume and lowering the pitch. (a capped metal pipe is precisely the same thing, tuned by moving the cap up and down) The cubic volume alone, in organ pipes anyway, determines the frequency of that "single pitch that is either boosted or attenuated" as you described above.

The shape however, of an organ pipe really only affects the tone quality, i.e. the harmonic series produced by the pipe, perceived as either a "brighter" or "darker" or "flutier" tone, and I think this relates to basses as well. The most critical factor in determining its tonal character, is the ratio of a pipe's length to its diameter. An A-440 can be produced by a pipe that is 54" long and 1-1/2" diam (producing a Viol De Gamba sound), or one that is 40" long and 3" diameter (producing a Bass Flute sound), or any ratio in between as long as the cubic volume remains the same. Similarly, different degrees of tapered pipe bodies are used for different tones, and this taper is expressed as a ratio, such as 1/4 or 1/3, meaning that the top of the pipe is 1/4 or 1/3 the diameter of the pipe diameter at it's mouth, and this is manipulated to achieve certain tone qualities. I think this directly relates to the tone produced in a given bass, by the size of the shoulders, the width of the ribs, and other factors that form the overall "taper" of the body of the bass, attenuated as well by the size and location of the F holes and C bouts, and the internal curvatures of the various walls of the bass. Darker, bassier orchestral basses are far less "tapered" than my brighter, more mid-rangey Eastman bass with its narrow shoulders and tapered ribs, in my somewhat limited experience with orchestral instruments. Am I far off with that assessment?

(The volume and projection of a bass I would think are more a function of the hardness, thickness, and mass of the woods used to build it, among other lesser factors, if the physics of organ pipe sound production apply to the bass as well. Low frequencies in sufficient volume to fill a church sanctuary can only be produced by pipes of hard, thick walls with lots of mass, whether made of metal or wood. Lower mass = less volume.)

But getting back to the wolf notes - if, as I am proposing, the cubic volume is the primary, but not the sole determinant of the natural resonant pitch of the bass cavity, and a wolf note is a frequency that's in direct physical conflict with the natural frequency or harmonics of the bass cavity itself, the cubic volume would really have to be changed to affect the resonant pitch significantly, right? Hence the extreme difficulty of eliminating it altogether. To truly "eliminate" it, and change the resonant frequency of the bass cavity, you'd have to add a rather large piece of wood inside the bass somewhere to reduce the cubic volume, I would think. But how and where?, and how to do it in such a way as to not adversely affect some other aspect of the bass' tone?
 
#18
Any alteration of the "cavity" will result in more than just the wolf tone elimination. That great resonant sound you're praising is likely to go away as well.

I sell Eastman basses in mass quantity here in Dallas and work on them all the time. Wolf notes are more common on A than Db though in my area. I use the Invalid Link Removed. They come in different weights. I start by putting a heavy one on the A string and find the spot that alleviates the wolf. Then I'll remove it and install a suppressor of less weight until the suppressor is too light to make a difference. The least amount of weight, the less it will affect your resonance and sustain. That's the unfortunate side effect of wolf suppressors..
 
#20
yes, I would do that first also. loosen the strings, protect the top where the tailpiece flops down onto the the top. Mark the spot on the back with a long pencil(pencil taped to a small dowel, or another pencil taped together)since it is in "the sweet spot" already. If after the tension is off the top and it doesn't fall and is hard to move, then it is too tight-use fine sand paper and take some off the top of the post.(no more than 1mm at a time till it slide over to postition without a lot of pull. You will need a sound post tool and a grabber(auto parts store/home depot for the grabber-it's not necessary but makes everything much easier--)IMO, every bassist needs to have a sound post setter in their gig bag.If you want to do this yourself and don't have the tools. I would either get them or take it to a bass luthier- with your experience of working on organs, you could do this yourself in my opinion.PM me if you needs detail instructions on how to make a setter-very easy. Good luck- with all the post, you will get to the bottom of this for sure.
 

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