question about back graduations

[Arnold Schnitzer]

I read some of the dissertation Ken M linked. What I found most interesting was the response of players to the round vs. flat back comparison. Comments were all over the place and contradictory. The author pointed out how subjective the whole subject is. I personally think there is something to having a "spring" of brace wood under the soundpost, regardless of whether the bass has a round or flat back. I have had the opportunity to add a back brace to a round backed bass on several occasions, and felt the bass responded quicker afterward. Ken S. has some experience with this as well. Your comments, Maestro?

[Ken Smith]

Originally Posted by Arnold Schnitzer

I read some of the dissertation Ken M linked. What I found most interesting was the response of players to the round vs. flat back comparison. Comments were all over the place and contradictory. The author pointed out how subjective the whole subject is. I personally think there is something to having a "spring" of brace wood under the soundpost, regardless of whether the bass has a round or flat back. I have had the opportunity to add a back brace to a round backed bass on several occasions, and felt the bass responded quicker afterward. Ken S. has some experience with this as well. Your comments, Maestro?

Well, let me start by saying if not for seeing this already in one old Italian that passed thru my hands as well as seeing it in use on New basses made by both Arnold and Jeff B. I would not have felt as confident as I did when I requested such a modification on two of my own favorite Italians.

My Candi went in for some repairs and a new Neck Graft. Due to an old repaired crack in the Back running up from the bottom to the soundpost area I suggested we put a center brace in the roundback Candi for two reasons. One, this would keep direct pressure off of the Crack from the soundpost for ever! and Two, the Candi made from soft Italian maple aka Oppio would benefit as well from this structurally and hopefully tonally.

My Martini has a 3-pc back of this same Oppio but seems to have been graduated much thicker by the maker back in 1918/19 when it was made. The soundpost had over the years pushed on the back joint that is only a few inches from the post but outside towards the C-bout, not a center joint as it is 3 pieces as I mentioned. This center brace was more of an alongated back patch but a brace no doubt joining the center and outer pieces of the back therefore once again taking the direct pressure off of that joint nearest the Post area. The Candi brace was mostly all across but did not reach all the way t the Ribs or linings. Thus a center brace/patch in one.

Results?. Both basses are louder, more focused sounding and healthier as well. I was very pleased with the outcome as I know both of these basses from before the repair.

At the ISB this summer with all of the great old and expensive basses there the Candi had quite the audience. Italian Luthier Sergio Scaramelli came by several times during the week looking it over and playing it with passion I might add. A true compliment to the bass. Sregio mentioned he owned a Candi Cello that in other words, needed his big brother back home if you get my meaning. At this same time, world renown Italian bassist/soloist Stefano Sciascia played the bass and I must tell you, this guy can make a grown man cry. He was there to play in one of the venues in which the Karr/Koussevitzky bass had been prepared for him to do so. He told me if not for the Karr bass (the one they 'used' to call an Amati) he would have chosen the Candi to play. I played the Karr bass and I must say, Sergio would have sounded much better with the Candi. It has more power and more color to the sound. If just doesn't have the Karr mojo in it. Maybe I can call Gary and have him play a few minuted on the bass and see what mojo might rub off.. You think?

There is something to be said for adding this center Brace in many cases. My Gilkes however is made from such dense wood that it was not even considered. The Gilkes is a bass made from the finest woods one could ever wish for, made by a maker with magic in his fingers and posses more power than any 3/4 bass I have ever seen matching and surpassing most 7/8ths and 4/4 basses I have seen in projection as well. This Bass needs only to be played as it was made as perfect as a Strad Cello and needs no modifications.

Modifications are good to do if it helps the bass. If it ain't broke, don't fix it!

[Ken McKay]

Well, since the meastro spoke, I might take a turn.

Regarding the players responses to the listening test being contradictory and variable. Browns summary on the subject:

• It can be seen that the opinions of bassists on the subject a spectrum of bassists contains bassists that believe the difference is clear and important and others who believe there is no significant difference. Many of the responding bassists are somewhere in between, unsure if a real difference in sound between the two types exists.

And then Brown goes on to show that there is an acoustic difference and measures it and publishes it. Interesting that players have variable views but it makes perfect sense since both types are seen in modern orchestras almost interchangably.

Martin Schleske a modern violinmaker who is alive today makes "tonal copies" of some of the finest stradivari and del Gesu violins. He charges a small percentage of what it would cost for an original. As a physicist and violinmaker he has developed some techniques to test and replicate violins. Schleske was quoted by Brown in the dissertation on page 47 to say:

• "To make an acoustal copy of a Guadagnini bass, it would cost almost as much as the original instrument. The ratio between the cost of an original violin (DM 1,000,000) and an acoustal copy (DM 40,000) is much more attractive than as with a bass (DM 150,000 and DM 75,000)"

And an interesting comment on page 48 (with and illustration by J Bollbach) regarding the static pressures on the bass.

• "The back plate of the double bass is subjected to strong forces. The back serves as the anchor for upper and lower blocks, as a platform for the ribs, and supports downward string pressure on the top plate through the soundpost. Each of these areas must be strong enough to support the static forces as well as dynamic forces during playing and transport. About 2/3rds of the downwardstring pressure is supported by the soundpost, whichmay be calculated to about 353 N. (79 lbs) According to Guth."

Seems like a perfectly good place to put a spring if you are looking to recoup some free green energy. And here is also where the graduated plate, thick in the center and thin at the recurve, works to a similar advantage. Or a sprung X brace.

[Arnold Schnitzer]

Originally Posted by Ken McKay

Seems like a perfectly good place to put a spring if you are looking to recoup some free green energy. And here is also where the graduated plate, thick in the center and thin at the recurve, works to a similar advantage. Or a sprung X brace.

Good stuff, Ken. But why put spring in any brace? To me, that's just asking for future trouble. The cross or x-brace is under spring pressure from the soundpost, so why also stress the glue joint?

While on the subject of bass back bracing, some colleagues of mine suggested installing what amounts to a single angled long brace, which I have used with excellent results. It's up to our esteemed host whether he wants to post the pics. (Nick Lloyd used this same system in his 2009 Silver Medal ISB bass.) It provides the requisite support for the soundpost, but avoids the cross-grain attachment which makes traditionally-braced flat-backs so trouble-prone.

[Ken Smith]

Originally Posted by Arnold Schnitzer

Good stuff, Ken. But why put spring in any brace? To me, that's just asking for future trouble. The cross or x-brace is under spring pressure from the soundpost, so why also stress the glue joint?

While on the subject of bass back bracing, some colleagues of mine suggested installing what amounts to a single angled long brace, which I have used with excellent results. It's up to our esteemed host whether he wants to post the pics. (Nick Lloyd used this same system in his 2009 Silver Medal ISB bass.) It provides the requisite support for the bassbar, but avoids the cross-grain attachment which makes traditionally-braced flat-backs so trouble-prone.

Arnold, do I have pics from the inside of the Bass? If I do which were sent from you then it would be best that you post them. I do currently have the Bass that has that new system and will welcome it in any other future repair as it's seen fit to do so. The Bass sounds at least as good after as it did before. This is the modern English made Lott copy I currently have made in part by the former owned of the actual Lott who is a Luthier and another older Luthier that did the main 'frame work' on the Bass. After settling in the US/NE its first winter, I gave the bass to our esteemed maestro 'Sir Arnold' to repair and he did quite the fine job as usual I must say..

[Arnold Schnitzer]

Originally Posted by Ken Smith

Arnold, do I have pics from the inside of the Bass? If I do which were sent from you then it would be best that you post them.

Sorry, posting pics is beyond my computer capability...

[Ken Smith]

Originally Posted by Arnold Schnitzer

Sorry, posting pics is beyond my computer capability...

Read this; Posting Pics Tutorial, by Mike Smith.

Or, email them to someone that knows how to post them. That someone NOT being me.. lol..

[Eric Rene Roy]

Originally Posted by Arnold Schnitzer

(Nick Lloyd used this same system in his 2009 Silver Medal ISB bass.) It provides the requisite support for the soundpost, but avoids the cross-grain attachment which makes traditionally-braced flat-backs so trouble-prone.

awww...I missed looking inside his bass...I would have liked to see that.

This was some minor inspiration for some that I have been trying...and just good work to look at. http://www.talkbass.com/forum/showpo...4&postcount=39

I will say I did try one thing Hans did, but with bad results (I had to replace a customers back). He said he did spots of glue every inch or so to allow for wood movement. I did this...and the wood moved...causing a bulge in between two of the glue spots. I won't try that again.

[Ken Smith]

Originally Posted by Eric Rene Roy

awww...I missed looking inside his bass...I would have liked to see that.

This was some minor inspiration for some that I have been trying...and just good work to look at. http://www.talkbass.com/forum/showpo...4&postcount=39

I will say I did try one thing Hans did, but with bad results (I had to replace a customers back). He said he did spots of glue every inch or so to allow for wood movement. I did this...and the wood moved...causing a bulge in between two of the glue spots. I won't try that again.

Are you totally sure it was the Bracing and not the aging of the wood? Besides commercial drying if done so, how long did the back wood sit in block form and/or at near finished dimension before it was used to make a back and put on the bass? How long id it take for the Back to fail.

And, what do you mean by Spots of Glue? Just Glue over the wood or with patches or braces? Ever seen the upper back bend of a Panormo School Bass?

[Eric Rene Roy]

The wood was plenty dry and about 8 years old. The bass was made in the fall of 08...did well through the winter, and then I saw it at the ISB (June 09) and it was fine...perfect even...I looked it over well as it is the one and only I did with glue spots. We had a record breaking amount of rain in June and July...and it was July when it failed. I suspect the owner let it sit in his house with the windows all open and 80 to 90% humidity instead of running his air conditioner to keep it at a more healthy 40 to 50%. Regardless of his care...it wouldn't have developed the problem it did had I glued the braces normally.

By glue spots...I mean take your brace (This bass had traditional horizontal bracing) and put a one inch drop of glue every 2 inches across the brace. This is a bad idea and one I will not do again.

[Ken Smith]

Originally Posted by Eric Rene Roy

By glue spots...I mean take your brace (This bass had traditional horizontal bracing) and put a one inch drop of glue every 2 inches across the brace. This is a bad idea and one I will not do again.

I have never in my life heard or that or saw that in any bass. What was the 'supposed' purpose of this idea? Glue 'outside' the joint 'on top' of the wood that's glued to the bass?

I have seen plenty of natural glue drips inside of a bass that was just sloppy work but I am sure none of it was done intentionally. My Gilkes had just about the entire Back covered in drips from seams being sloppily glued. Arnold made mention that he scraped off about 2 lbs. of glue from the back during the restoration. I am sure it was more like ounces than pounds but either way, the glue was not there to serve any purpose at all.

I have one old Italian bass in restoration with the upper and lower braces beautifully scalloped. They are slightly wider than normal but fairly shallow with a slight 'roller coaster' design from end to end. I asked the Luthier working on this particular bass (Nick Lloyd) to leave the original 'bars in place if at all possible. This way I could see if the bass sounds good with them in because we could always replace them later if 'bars are not destroyed blindly just for tradition sake.

Glue Drips? Maybe it's some sore of low cost 'sealer' to the wood that a Luthier/Witch Doctor came up with. Leave windows open in the Summer with the Rain and high humidity? Why would any human punish themselves like that and try breathing that heavy wet air. I would suspect he was at least as sick as the bass by that time.. right?