Violin Forum/Message Board

Mat Roop · Posted: Sat Nov 23, 2013 3:01 pm Post subject: bass buzz etc

I have not worked on very many basses... but a 1/2 size, apparently with a buzz, showed up in my shop yesterday... 3 questions... because if the problem buzz is with the bass bar it will not be worth it to open up the instrument.

1- This bass is a student Pfretschner plywood bass and the client got it as a donation from a school who said they thought that the bass bar was loose causing a buzz. I have inspected the bar thoroughly with good light and mirrors while tuned to tension. There is only one short area where the glue seems to have a small crack, but it does not seem to move under pressure and it is near the center of the bar on the bass side. The ends seem firmly fixed. It seems unusual that the bar would be loose in the middle and not the ends.... is it likely or even possible that the buzz can come from here. There are lots of loose slivers and pieces of ply around the edges that to my mind are the source of the buzz.

2-Do all tailpieces follow the standard sizing?... ie this unit has a Thomastik 4 adjuster style tailpiece that looks monstrous... but it is only 287 mm long compared the the standard 1/2 size tailpiece length of 310mm. The standard length of a 1/4 tailpiece is 290mm. I could not find sizing info on the underside of the tailpiece. so I am wondering what size of tail piece is this?

3- The tuning gears are in serious need of lubricant... what is appropriate to use?

Thanks for all your help!.... Mat

Michael Darnton · Posted: Sat Nov 23, 2013 4:42 pm Post subject:

There are a lot of things on an instrument that can buzz, but in over 30 years, though I've heard a lot of people blame the bass bar I have yet to see one that caused a buzz, even detached ones. I'd look elsewhere.

Be aware that something that vibrates at a certain frequency can be heard somewhere else, far away, that happens to resonate at that frequency. The worse I've seen of this was a cello that sounded like it had a can of dry beans taped to the inside of the top, up near the neck. There were a whole bunch of cracks there, loose, and loose studs, so I took the top off and glued it all up, with new studs, and when it was back together, the buzz was still right there. When I finally found the cause it was a screw on the endpin socket, to hold the ring in place. I tightened the screw, and the buzz disappeared!
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L P Reedy · Posted: Sat Nov 23, 2013 7:47 pm Post subject:

As Michael said, buzzes can be very strange. I, too, have never encountered a bass bar buzz, even after a violin had been dropped and one end of the bar split. It sounded terrible but didn't buzz.

One bass buzz that I had was fixed with a new bridge. I couldn't pinpoint the reason but some genius had hollowed the feet. One cello buzzed on the D string because of a strange buildup of rosin, but only when bowed, not plucked.

I suspect that your loose pieces of ply are not the problem but you should be able to check that with masking tape.

DonLeister · Posted: Sat Nov 23, 2013 10:40 pm Post subject:

I would get someone to make it buzz while I poked and prodded things.
I have had a buzz occur from a 'soft' string groove at the bridge.
My experience of pfretzners is that the factory was very fond of white glue that doesn't want to let go.

Mat Roop · Posted: Mon Nov 25, 2013 12:51 am Post subject:

Thanks folks for all the good replies.... found a rattle in the tuning gears and a separated seam at the back center bout that opens up when the instrument is tensioned.... I am counting that these will fix the issue once the instrument is back together.
I plan on using beeswax for the gear lubricant.... any reason why not?
Cheers, mat

DonLeister · Posted: Mon Nov 25, 2013 9:13 am Post subject:

It's a sticky wax?

Mat Roop · Posted: Wed Nov 27, 2013 12:17 am Post subject:

Hi Don ... Sticky is a relative term, but I would judge bees wax as fairly dry... not much different than paraffin, but it seems to have more body.
In the old days bees wax was used to polish the tops (cooking surfaces) of the old wood burning kitchen stoves. It kept the iron top nice and dark and shiney and did not burn off easily.
I used beeswax latest on a hammered dulcimer with 58 steel tuning pins that were well rusted and corroded. I wire brushed all the rust off, rubbed on the wax and melted it with a torch. The wax melts nicely and infuses into the metal reducing any rusting in humid conditions. I had done another dulcimer similarly about 5 years ago and saw it agian a few weeks ago... the tuning pins were in as good condition as the day it left my shop.
I'm just not sure of its qualities as a lubricant for bass tuning gear.
Cheers, Mat