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Double Bass To Re-graduate or Not?

richhansen

richhansen

Oct 2, 2006
312
130
Utah
Disclosures
Endorser of the KSM Foundation Bridge.
#1
I have a Bulgarian made 5-string from Bob Gollihur (fully carved "Kremona" factory), which I've been considering having the top plate re-graduated. Its tone is quite good, but is not as resonant as my 1930's Bohemian carved bass. The tone seems a bit "choked", and this could be because its top is pretty thick (about 8-9 mm at the ff holes).

Has anyone here done this job on one of these basses, or is familiar enough with them to know if this would be something worth pursuing?

Thanks
 
#2
Before you make a decision about regraduation, you need accurate measurements of the entire top and back plates. This can be done with a Hacklinger gauge or one of the newer electronic ones. Keep in mind that regraduation is time-consuming and expensive, and your bass will also need a new bass bar if the job is done correctly. You can certainly expect an improvement to the resonance and response if the plates are currently over-thick. You could also pay as much or more than the bass cost. Good luck!
 
#3
Thanks for the response Arnold. Your expertise on these forums is very much appreciated. So you say that the bass bar needs replaced. What would be the reason it would need replaced? Also, because this is a five string, for reasons of structural stability, what would you recommend for a target thickness from the bridge area to the top and the ff holes? Chuck Traeger's book recommends between 9-12 mm at the center near the bridge and soundpost, and 7-6 mm at the ff holes. Also, what is a good electronic gage for measuring thickness? My luthier has not worked on a fiver before, so we are both searching for guidance before starting the process.

Thanks again.
 
#4
I'd thought of doing this to my bass too to help relieve some of its tightness but I decided against it because my money is simply nowhere near being disposable enough to afford it (besides, there are simpler ways of doing this, some of which are free.. like rearranging how where the strings are strung in the scroll, making sure the bridge is tilted slightly in the right direction, etc).
 
#5
richhansen said:
Thanks for the response Arnold. Your expertise on these forums is very much appreciated. So you say that the bass bar needs replaced. What would be the reason it would need replaced? Also, because this is a five string, for reasons of structural stability, what would you recommend for a target thickness from the bridge area to the top and the ff holes? Chuck Traeger's book recommends between 9-12 mm at the center near the bridge and soundpost, and 7-6 mm at the ff holes. Also, what is a good electronic gage for measuring thickness? My luthier has not worked on a fiver before, so we are both searching for guidance before starting the process.

Thanks again.
Click to expand...
Firstly, you will need to remove the bass bar to do the regraduation properly. I have encountered a few basses where the bass bar was carved around, leaving the bar sitting up on a shelf. This creates a stress riser which can cause cracking next to the bass bar, and prevents the luthier from being able to carve and level the area right next to the bass bar in a professional manner. Also, the bass bar will have gotten taller in relation to the top table surface. And many bass bars are placed wrongly to begin with.

Secondly, Traeger's suggested thicknesses are quite a bit thicker than one generally sees in the real world. But no one can make recommendations for your graduations until he has assessed the flexibility and weight and arching of your instrument's top and back. Most makers I'm aware of carve their tops about 1mm thicker for a five-string bass (compared to a four-string).

Thirdly, there are two electronic thickness measurement devices on the market that I am aware of. The less-expensive one is sold to professionals by Metropolitan Music in Stowe, VT. I can't remember the name of the other one, but James Condino was showing one off at the Oberlin workshop, and it was way cool.
 
#6
arnoldschnitzer said:
Thirdly, there are two electronic thickness measurement devices on the market that I am aware of. The less-expensive one is sold to professionals by Metropolitan Music in Stowe, VT. I can't remember the name of the other one, but James Condino was showing one off at the Oberlin workshop, and it was way cool.
Click to expand...

Liam's Magic Probe is a very useful device at a pretty reasonable price. I put off buying a Hacklinger Gauge for years because it seemed too primitive and inaccurate for its very high price but the Probe is accurate and useful.

Highly recommended.
 
#7
Jake deVilliers said:
Liam's Magic Probe is a very useful device at a pretty reasonable price. I put off buying a Hacklinger Gauge for years because it seemed too primitive and inaccurate for its very high price but the Probe is accurate and useful.

Highly recommended.
Click to expand...


Having used a hacklinger guage almost daily for about a half dozen years now, I can comfortably say that I'd gladly pay for its weight in gold. We are all in agreement that the two decade price of $400+ for $1.50 worth of parts has had a stranglehold on luthiers worldwide, but it is neither primitive nor inaccurate; just a little old school tool. Accuracy within 1/10th of a millimeter is fine for me, especially on a double bass. I also still use a couple of shop made devices and I have a Majic Probe. They all do the job very effectively. If you are a luddite; the 'Hack is probably for you. If you are one of the latest I-gadget geeks, then the MP is the one for you. Either way, just get something and start making educatied decisions with a solid number base to go on.

The Guild of American Luthiers has published several articles by Mike Doolin on how to fabricate your own device that works very reasonable for just a few dollars worth of scrap parts and there is also an old bootleg copy of an article that showed how to crack the code on the Hacklinger device that is still floating around the web. Funny thing is that it was everywhere for about three weeks and then seemed to disappear off the face of the planet.

Here is the link to the Majic Probe website:

http://www.magicprobe.net/


If anyone wants a nice early Christmas present price on a very slightly used Majic Probe, email or call me.

j.
www.condino.com
 
#10
MostlyBass said:
I had the top of my carved Rumano Solano Rogeri copy thinned out / re-graduated by Aaron Reiley of The Guarneri House. The bass became much louder, responsive, and open. Money well spent.
Click to expand...

That's really interesting, I sometimes kick around the idea of having my Solano re-graduated. When you had the work done, how long was your bass out of commission?
 
#14
I must caution about over re-graduating. It's easy to get it thinner, louder, and speak faster, but it must still be thick and stiff enough to last a decade or hopefully more. I have seen overly thinned tops, especially at the edges, have serious problems in a very short time.
 
#17
Schoolhouse said:
I must caution about over re-graduating. It's easy to get it thinner, louder, and speak faster, but it must still be thick and stiff enough to last a decade or hopefully more. I have seen overly thinned tops, especially at the edges, have serious problems in a very short time.
Click to expand...

Excellent point. Take it to a trusted pro with experience.
It is an expensive process and luthier's charge anywhere from 1,000 to 4,000 dollars.
 

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