Double Bass Chasing a brutal body buzz - is this idea totally nuts?

[BluegrassBasss]

I have such an annoying body buzz that rears its ugly head every summer. No open seams or cracks and it's not a soundpost, endpin or bass bar buzz. A total mystery that seems to be tied somehow to humidity.

It's an old German plywood shop bass.

The only thing that seems to help is adding pressure to the front and back while playing. I've used ratchet straps in the past, but tension is hard to regulate (doesn't require much to kill the buzz, and I don't want to add undue pressure).

I'm considering putting a small rod from the front to the back, fitted with rubber washers and a wing nut on one side for soft tightening/loosening as needed. (Green dotted line in the sketch below for reference).

I'm aware this is a hack and not the way a luthier would approach this, but I'm hoping to think outside that box with this.

1) what do we think of this idea?
2) has anyone tried anything similar to chase a buzz?
3) any idea where I can find an appropriately threaded thin rod to make this happen?
4) Does anyone have a line on a resourceful and creative repair person (Toronto area) that might be interested in taking this on?

 

[Steven Ayres]

Have you shown the problem to a luthier?

 

[BluegrassBasss]

Yes, it's been to a few Luthiers, but the buzz either disappears when I'm trying to show it or they simply haven't been able to find it looking for the usual culprits (splits, cracks, loose bass bar etc.).

One luthier found that the buzz was slightly improved by adding a second sound post near the top of the f-hole on the treble side.

It's a bit of a frankenbass honestly but I love the tone and am reluctant to give up and start playing a bright orange Chinese bass.

 

[Steven Ayres]

And what sort of bass is it? Who made it?

Has anyone checked for a loose piece of lining in the upper bout?

Something somewhere has to be rattling against something else. Your proposed solution is inventive, but the bottom line is that it can only disguise the problem while impairing the voice of the instrument to some extent. Better in my book to find that rattle and kill it where it lives.

 

[Sean Riddle]

This happens about once a year to my Shen hybrid. My luthier figured out a wolf tone eliminator helps out a bit with making it buzz less.

 

[unbrokenchain]

Bass players always chasing a buzz eh, just don't be driving

I spent an hour looking for the source of a buzz one time and it turned out to be the output jack that was zip-tied to the tailpiece. I've also had tuner hardware come slightly loose and buzz. It's likely something small and totally fixable. One fairly simple way of diagnosing is to bow a note that causes the buzz and have a friend go around the bass with their ear very close, or squeezing different parts of the bass to see when it goes away. You can also run a flashlight around the seams and look in through the f-holes to determine if there is any separation.

 

[AGCurry]

Nice artwork!

I'm with Stephen and unbrokenchain. The effect of that steel rod will likely affect the sound of your bass in a not-good way.

You might try the auto mechanic technique - something akin to a stethoscope. A thick dowel rod with one end to your ear and the other end to the possible source of buzz.

 

[Fretless55]

Seems you could end up with three buzzes...

 

[Dr. Love]

Is the bolt in your digram on the outside at the edges, or inside the bass like an adjustable soundpost? I’m assuming the outside?

 

[John Le Guyader]

Tuners clipped to the bridge very often buzz on my Juzek and my Englehardt.

 

[KUNGfuSHERIFF]

Odds are it’s a delamination issue causing the buzz. Seemingly everything else has been eliminated.

The buzz goes away when you squeeze the bass because your touch is robbing the corpus of energy.

 

[Reiska]

Don`t hotrod stuff before you`re absolutely sure where the buzz is coming from! Do you have a buddy that could play your bass in different rooms while you`re addressing the problem?

Beautiful drawing BTW.

 

[BluegrassBasss]

Thanks everyone for the thoughtful replies and suggestions on this. I'm intrigued by many of these ideas.

As for the provenance of the bass, it's pretty old (pre- 1950s), but definitely not a fine, or valuable bass. No label other than a fairly generic 'copy of a antonius strad.. blah blah - made in Germany' inside. It has a pretty major Romberg bevel and had a suspiciously thin soundpost when I bought it. Definitely plywood, but has some very nice purfling (which two separate luthiers have actually been surprised by). It also, strangely, has a rather small block and narrow bass bar, which has been dyed black on the f-hole side (never seen or heard of that before).

I bought it from a retiring violin collector, and it had apparently been standing in a corner for 50 years.

To say the least, it's a likely candidate for some buzzing but I am certain this is a singular buzz, and not a collection of them - I must be able to find it/kill it.

Arco doesn't seem to trigger the buzz - it's very much a pizzicato problem. Does that tell anyone here anything about the nature or type of the potential buzz I'm dealing with?

 

[GretschWretch]

Have you considered putting something like a rolled-up towel or t-shirt beneath the tailpiece to see if that downward pressure affects the buzz? If it works, that may be the least intrusive "fix" available.

 

[Jay Corwin]

Another question worth asking is, does said buzz occur on every string? every note?

 

[Don Hergert]

My main band's former bassist has recently developed a buzz in his double bass that has been similarly bothering him, it was found to be the bass bar loose at one end. This is an Asian ply bass (not Shen), and it's been worked hard outside for over a decade in many weather situations (bluegrass). It was a good and loud sounding bass at least before the bass bar let loose -- I'm not sure if the top table is also sinking as a result of the loose bass bar.

He's figuring to either glue and clamp it through the bass F-hole himself or buy a new bass, as he doesn't want to have the top removed; it would probably cost more to be repaired properly than he paid for the bass new. He's the former owner of my Alcoa (which has had a trap-door installed in the driver-side C), and he has toyed with the idea of installing an access door on his bass for this repair.

 

[Hoyt]

I agree with the likelihood of it delaminating somewhere, but I just got done chasing a buzz on my ‘53 Kay and it ended up being that the glue was starting to separate by the neck block under the fingerboard. I seeped some hide glue in and clamped it for a couple days and now it’s gone.

Just figured I’d throw that out there because it was fine with arco, but pizz and slap only brought it out occasionally.

 

[KUNGfuSHERIFF]

The thrashed ‘51 I had was staring to separate on the back a third of the way across. It wasn’t buzzing yet when I sold it to a New School student whose father kicked my butt on the price, so it’s his problem.

Kays were not meant to last. It’s amazing that many have.

 

[unbrokenchain]

Arco doesn't seem to trigger the buzz - it's very much a pizzicato problem. Does that tell anyone here anything about the nature or type of the potential buzz I'm dealing with?

Really? If it buzzes pizz then seems like it should really buzz arco... I'm sure that indicates something but nto sure what. If you can get a friend to play the bass and reproduce the buzz, that would free you up to search it out with your ear/hands.

 

[David Potts]

How long does the buzz last? Does it last as long as the string is vibrating and then decay as the sound dies or is it shorter, at the beginning of the note? Can you make a distinction between the sort of buzz? For instance, a loose bass bar or open seam will give a clatter. An end pin can resonate and rattle. A loose string end in the peg box or a loose thumb plate in a machine gives a rattling sound up there. A loose patch (or inside lining strip, I suppose) will buzz and stop when you press down. Are the feet of the bridge fitted nicely? Has the bridge rocked forward ever so slightly? Try slacking off the strings a little and pushing the top of the bridge slightly towards the tailpiece before re-tuning and plucking again. The only other things I can think of are string windings pulling apart over the bridge and maybe hidden loose purfling not apparent from the surface.

I like the idea of a delamination in the layers of ply because even plywood is affected by seasonal changes in humidity combined with temperature. If you can see an area of the belly that is easy to press down and identify as a delamination you might be able to inject glue through tiny holes and rest something like a pile of books (or old socks filled with sand????) to press everything together until it dries.

Good hunting!