Double Bass Kay Sunken Top on Treble Side

[bassjc]

Hi all,

Not sure if this is the right place to post this, but any help would be appreciated. I recently bought my first double bass. It's a '58 M-1 Kay. I noticed that it wasn't sustaining particularly well, wasn't as "bassy sounding" as I had in my head, and that it was harder to play than I expected. After looking for answers, I measured the scale length and realized the previous owner had moved the bridge closer to the neck so the scale length was 40 inches. I checked the soundpost and noticed that it was further away from the treble-side bridge foot than what I read was recommended so concluded that the previous owner had moved the bridge but hadn't adjusted the soundpost. I moved the bridge back so that it was approximately centered between the inner f hole notches, and now the bass sounds like what I was expecting, is a delight to play, and I'm having a great time with it.

The only issue now is that it appears that because the soundpost was not adjusted, the top is sagging on the treble side because the soundpost wasn't moved, so there's slope into the f hole. Because it sags, the treble bridge foot isn't perfectly fit against the top anymore. The bridge was already warped--I boiled it to straighten it out as best I could--so I was planning on having a luthier install a new one when one is available.

All of this to ask; it is possible to just install a new bridge partially fitted to the warped top if I'm happy with the sound (I'm an enthusiast with no professional ambitions), or does the top need to be fixed because the sag could lead to longer term problems? What would the process look like to fix the sag? I understand that top repairs can be expensive--my bigger concern is just not having my bass around waiting for the repair.

Thanks! Apologize in advance if I misused any terms of art. Photos are a bit distorted by the wide angle lens but I hope they can provide some context.

 

[dperrott]

The soundest was probably in too tight, and pushed up the area at the post. Makes that part lower. Yes get a bridge fitted to the top and post fit correctly. Its hard to press out a plywood top

 

[Greg Clinkingbeard]

The soundest was probably in too tight, and pushed up the area at the post. Makes that part lower. Yes get a bridge fitted to the top and post fit correctly. Its hard to press out a plywood top

I’ve had success with this. Visit a good luthier.

 

[dperrott]

I’ve had success with this. Visit a good luthier.

If I ever have to do it...I'll send them to you

 

[Steven Ayres]

As a temporary measure I would try adding a shim to that bridge foot and cutting it to suit the slope of the top. When it comes time to repair the top, James Condino is another expert who does this frequently.

Kaybass.com

 

[bassjc]

Thanks for the helpful replies!

 

[KUNGfuSHERIFF]

It’s not at all hard to press out a ply top. Plywood is floppy. Getting it to stay in round is the hard part.

OP, you should get that looked at sooner rather than later. The bridge looks like crap, and that isn’t normal top deflection. Something sketchy happened to your bass.

 

[bassjc]

It’s not at all hard to press out a ply top. Plywood is floppy. Getting it to stay in round is the hard part.

OP, you should get that looked at sooner rather than later. The bridge looks like crap, and that isn’t normal top deflection. Something sketchy happened to your bass.

Appreciate everyone's advice. Definitely planning on getting the bridge replaced as soon as a local luthier is reasonably available. It's only the area approaching the G-side f hole that's depressed. The top is even and uniform until you approach that area, in case the photos weren't clear. It doesn't seems to be spreading and I shimmed the bridge foot last night as a temporary measure, so hopefully nothing catastrophic happens between now and the doctor's visit.

The bass seems to have gotten a lot of work done in the past. There's glue on a lot of the seams and a patch where the soundpost meets the back. The last owner was a guitarist who never got around to really playing it before he needed to sell it so he couldn't tell me much about its past. Regardless, the neck is intact and it's still a blast to play.

Will post an update. Thanks again.

 

[Steven Ayres]

There's glue on a lot of the seams and a patch where the soundpost meets the back.

The post reinforcement disc is a common original Kay feature.

 

[fdeck]

I got my 1962 Kay M-1 in pieces when a high school threw it out, and I restored it myself. At the time, no luthier in my area would touch it, and there was no Internet to consult on how to do things right. We found an old violin making book from somewhere. So at least we knew about hide glue.

With that as an introduction...

The top was sunken when I got it, and I had no idea about correcting that problem, so I left it as-is. I cut a soundpost to fit, with help from my dad. We reasoned that since the plates of a plywood bass are of constant thickness, we could figure out the angles of the post from outside measurements, and cut it to the correct dimensions using a compound radial arm saw. After a couple tries, success. We started with an old spruce board, so the post always had a square profile.

But still...

I bought a bridge blank and whittled at it until it fit. Adjusters came later.

The useful information is that whatever caused the top to sink was a done deal once we had corrected the root cause in its unknown history. I owned that bass for more than 35 years, and it was dimensionally stable over that time period. At least nothing noticeable compared to the original damage, that I couldn't manage with minor bridge height adjustment.

My bass had no patch on the back, and there was a bit of a bulge.

 

[Derek Kay]

Sounds to me like the soundpost is incorrectly positioned, or possibly a replacement of the wrong length.

If the bass is round backed it very easy to position it wrongly, less so with a flat back. Both ends need positioning so that it comfortably stays in place without the full weight of the strings above it. You can relieve some of the sag of the top here, before full restringing.

Tip: tie some string around the post before you adjust it, so that you can easily retrieve it should it fall over.. The grain of the post ends should be 90 degrees to the grain of the body.

There is a tool luthiers use to position it but I've only ever used the string and tapped the post gently with a metal ruler thru the f-holes.

I needed several adjustments to get the optimum.

A usrful diagram

 

[bassjc]

Thanks for the additional replies.

Just an update: I'm lucky to live near a luthier, who was kind enough to take some time to take a look at my bass despite being swamped. He confirmed that the soundpost was beating the heck out of the bass and adjusted it. He also adjusted the bridge so that the feet were solidly on the top. We plan on replacing the bridge in October when he's not swamped, but everything's in working order for now. Bass sounds great.

Thanks again!