back bracing question

bcarter · #1 05-12-2009, 09:42 AM

hey guys,
my regular luthier has told me about some bracing on the back of my 200 year old french instrument on the inside. it was done by a luthier in england (J. Reiger of Arnes String Shop, Inc.) in the early 1960s so i'm betting techniques have updated since then. i'm told these huge bars (more like large planks) are muting the sound quite a bit and i should have them replaced with some new ones which would be much thinner, thus allowing a bigger sound

i am also told that my top will have to come off and i know that a small portion of your top wood is sacrificed every time it is seperated. is this correct?

my bass isn't monstrously loud, but has great volume and incredible tone. would this be worth the money and wood or should i wait until it is a necessity for the top to come off or should i do it now? the whole point would be to increase the volume and help the overall tone. how much would one of you charge for this type of procedure?

thanks!

p.s. i'll try to get pictures...

DallasStrings · #2 05-12-2009, 10:48 AM

I assume your bass is probably a flatback Mirecourt. There has been a lot of experimentation with the reinforcing braces on flatbacks. Some have had good results with X-shaped bracing. I would get as many opinions as you can from multiple luthiers.

I believe there is at least one article about this in an ISB publication somewhere. It might be worth it to research that. Perhaps someone here could give you more specifics on that.

I don't believe that anyone will be able to give you a price without looking at the instrument so I doubt you'll find that answer here.

CPike · #3 05-12-2009, 11:15 AM

+1 - If it ain't broke, don't fix it... A friend of mine has an extraordinary Florentine bass from the 1750s, and it has some really thick bracing on the flat back - it's a cannon.

Chris

bcarter · #4 05-12-2009, 01:56 PM

yes my bass is a mirecourt flatback.

i wouldn't be seeking advice if i didn't think my bass could be improved. it is relatively tight and you really have to coax the sound out. it is great in the sense that i like it... but i have played many basses with greater depth and bigger sound. if this will help and you have an opinion, please, share.

Paul Warburton · #5 05-12-2009, 03:02 PM

Thanks....clarification is a good thing.
If you had stated those other facts in the OP, I would have tried to be of more help.
(post deleted)

Mike Arnopol · #6 05-12-2009, 04:16 PM

Mirecourt basses typically had one very large brace in the center. What you have may not be overkill. Another typical detail of Mirecourt construction is VERY thick tops. A typical Parisian graduation might me 6mm across the entire top. That's a bit thin in the center but these basses typically stay in good health if properly maintained. It is not unusual to see Mirecourt basses with tops as thick as 12 to 14mm in the center. This really can make a bass thinner sounding. I had a very nice Mirecourt bass with a very thick top. Maybe 14mm in the center. Al Jackstadt graduated it down to 6mm the whole way. I'm not saying that I'm a big advocate of the center being that thin---just that in the best French basses that's how they're graduated. The difference in sound and response was astounding. Deeper, darker, easier response. Just saying that your culprit might be the top, not the back.

bcarter · #7 05-12-2009, 05:21 PM

Quote:

Originally Posted by Mike Arnopol

Mirecourt basses typically had one very large brace in the center. What you have may not be overkill. Another typical detail of Mirecourt construction is VERY thick tops. A typical Parisian graduation might me 6mm across the entire top. That's a bit thin in the center but these basses typically stay in good health if properly maintained. It is not unusual to see Mirecourt basses with tops as thick as 12 to 14mm in the center. This really can make a bass thinner sounding. I had a very nice Mirecourt bass with a very thick top. Maybe 14mm in the center. Al Jackstadt graduated it down to 6mm the whole way. I'm not saying that I'm a big advocate of the center being that thin---just that in the best French basses that's how they're graduated. The difference in sound and response was astounding. Deeper, darker, easier response. Just saying that your culprit might be the top, not the back.

can this be measured simply by a ruler or is there a more accurate way? regraduation is something i've thought was to be avoided if possible. any opinions?

Mike Arnopol · #8 05-12-2009, 05:50 PM

If you have a great old Italian or English bass (or any pedigree old instrument) regraduating will lower the value of the instrument. On other instruments if the quality of sound is dramatically improved and the work is done properly, the value can increase. There is a great repairman named Bob Daugherty who has done remarkable work with regraduation. I know of guys with different types of basses that have benefitted greatly. As an experiment Bob took a generic carved contemporary German instrument and did the top and back. The instrument doesn't even vaguely sound like any instrument like that now. I've gotten good enough to ballpark the thickness by looking and feeling in from the f holes but this is obviously not very accurate. Have a repairman check with a gauge made to measure top thickness. I've owned a lot of French basses and tops that are WAY too thick are more the rule than exceptuions as far as Mirecourt basses. When repairmen rebrace Mirecourt basses they usually stick with the same type of bracing which I think is the case with your bass. David Perlman (now deceased) was the principal with the Cleveland orchestra. He had a collection of some of the finest Italian basses in the world. He had them all restored and believed that very large bracing helped the sound projection. And they were all off the charts in terms of sound. I have seen very successful basses with dramatically different types of construction. I've learned that you can't make many absolute rules as far as successful bass construction. I'm just pointing out that in my experience that (in a bass like yours) the top is a much more likely culprit.

zeytoun · #9 05-12-2009, 07:55 PM

Have you tried other less invasive things first, like soundpost, tailpience wire, a lighter tailpiece, endpin, etc., etc.?

bcarter · #10 05-12-2009, 10:53 PM

Quote:

Originally Posted by zeytoun

Have you tried other less invasive things first, like soundpost, tailpience wire, a lighter tailpiece, endpin, etc., etc.?

my luthier fitted my bass with a new soundpost recently for the warmer season and i definitely noticed the change in playability and overall sound.

i haven't really thought of any other changes. any specific suggestions are welcome. i can at least learn about all the different products.

**Matthew Tucker** · #11 05-13-2009, 12:19 AM

Quote:

Originally Posted by Mike Arnopol

David Perlman [...] believed that very large bracing helped the sound projection.

This is a pretty common strategy used by guitar makers, where a stiff back (and ribs) is believed to assist in projection, whereas a thinner, more flexible back results in a sound that envelopes the player more. It kind of makes sense if you think about it, but I am sure for every bass that seems to fit in with one of these scenarios there is another bass that is an exception to the rule!

Now, guitar luthiers are rediscovering laminated ribs(!!) and building guitars with DOUBLE backs!

Ken McKay · #12 05-13-2009, 01:53 AM

This working model does not transfer well to bowed stringed instruments where the back must be a resonator since it is part of corpus that moves in a twisting motion. A stiff back is going to impede this movement or the instrument won't sound normal. Besides the twist motion there is the movement of widening the Anterior/postier diameter that helps with a deep bass tone (helmholtz). With a guitar, it is easy to get a lot of bass, so harvesting the precious string energy for more movement in the guitar top is going to waste less and hopefully gain more timbre where it helps projection.

Flat back instruments are braced in a peculiar way. They really don't resonate in the same way a carved plate does, yet they are successful in their own right and are not devalued. They are more viol like which has a more reedy sound. I can't say a flat back bass has that reedy timbre though so either the back doesn't contribute much to this quality or the other factors that distinguish a violin from a viol over power the back's contribution to tone.

As for the original question you might gain something and yet lose something else, or it might be all gain, who knows. I think I would do some testing on the top plate before I would mess with the back bracing. I'd want to know how stiff and its weight.

Taking the top off should not really sacrifice it much if it was glued on properly. This is done all the time and the reason we luthiers use diluted glue for the top.

**Matthew Tucker** · #13 05-13-2009, 02:47 AM

Quote:

Originally Posted by Ken McKay

This working model does not transfer well to bowed stringed instruments where the back must be a resonator since it is part of corpus that moves in a twisting motion. A stiff back is going to impede this movement or the instrument won't sound normal.

Well, i don't know. There are makers building or adding horizontal bracing to roundback basses; that would make them pretty stiff, too.
Thing is, its pretty hard to measure the flexibility of a glued-up back, so we're all talking theory here.
i suppose i should get my Chladni pattern apparatus out and start measuring the resonant frequency of my flatbacks ... if only i had the time!

I think that thinning or replacing the back braces on this Mirecourt bass would tend to darken the sound. I'm not sure it will make it any louder.

Ken McKay · #14 05-13-2009, 03:17 AM

...and how do they sound?

I don't think it is that hard to measure the flexibility of the bass body. A quick impulse test on the bridge will probably tell the frequencies most effected by the back stiffness.

...and why in the world would one want to add cross braces to a carved back? They would cause cracking down the road I would think. Maybe in an alteration, but in new construction, why not design it into the plate by thickness or arching?

Eric Rene Roy · #15 05-13-2009, 05:56 AM

Ken, you missed this post:

AES Walnut

in this thread:

AES Walnut

I'm playing with variations of this brace by Hans Johannsson and other bracing by Jim Ham:

back braces

CPike · #16 05-13-2009, 08:40 AM

Quote:

Originally Posted by Matthew Tucker

This is a pretty common strategy used by guitar makers, where a stiff back (and ribs) is believed to assist in projection, whereas a thinner, more flexible back results in a sound that envelopes the player more... Now, guitar luthiers are rediscovering laminated ribs(!!) and building guitars with DOUBLE backs!

I'm a guitarist as well as a bassist, but not a luthier, and I have done much reading in guitar forums similar to this forum. What I have to add may further complicate the issue here, but it may be useful too (well, interesting at least). Yes, many guitar makers are using thicker and heavier backs and ribs, the idea being that with less vibration happening in the back and ribs, the more vibration is reserved and used by the top (soundboard). A well-known example of this has been developed by Smallman in Australia, and his guitars are renowned for very strong projection compared with traditional guitars. I've had the pleasure of playing a couple of Smallmans, and not only is the back thicker and much heavier, but it is also slightly rounded, not flat.

There is some confusion regarding the terms "double back" and "double top" in the guitar realm, and sometimes they both can mean the same thing. A "double back" guitar has an exterior layer of traditional hardwood, for ex. rosewood - but on the inside there is a layer of tonewood (cedar or spruce) laminated to the exterior portion. I don't know if this is also true for the ribs. Guitars like this are sometimes referred to as "double top", because the interior layer is tonewood just as is the soundboard. Further confusing the nomenclature is a modern technique of laminating the actual soundboard with a layer of honeycomb material sandwiched between two very thin strips of spruce/cedar. This increases stiffness and minimizes weight. This is also called "double top", for obvious reasons.

And, if that's not enough variation for you, some classical guitar luthiers are making instruments with arched tops, but they are rare and not widely accepted.

bcarter · #17 05-13-2009, 09:06 AM

any suggestions on a new tailpiece or wire that might loosen up the sound a bit more? i know these minor adjustments don't do too much... that's why i haven't really done anything with them. i'm always thnking about trying new strings, but i have to crack my piggie bank every time for those.

Rvl · #18 05-13-2009, 10:04 AM

Regraduating and redoing bracing is expensive.....thousands
And you have no guarantee it will sound better

Personally I think these do have a big part in opening up tone
Changing strings or tailpiece or tailwire or endpin is totally reversible and the expense is minimal(comparatively) ie $100 or $200 or $20 or $150

Show some photos and we might be able to make some suggestions

Thanks

Robert VanLane

bcarter · #19 05-13-2009, 11:32 AM

Quote:

Originally Posted by Rvl

Regraduating and redoing bracing is expensive.....thousands
And you have no guarantee it will sound better

Personally I think these do have a big part in opening up tone
Changing strings or tailpiece or tailwire or endpin is totally reversible and the expense is minimal(comparatively) ie $100 or $200 or $20 or $150

Show some photos and we might be able to make some suggestions

Thanks

Robert VanLane

RVL,
do you have any suggestions as far as tailpieces and tailpiece wire or any other things that aren't as permanent as the alternative? thank you for your advice!

Mike Arnopol · #20 05-13-2009, 12:00 PM

Also the string angle over the bridge can have a big impact. Although it may seem counterintuitive, sometimes on a bass with a thick top it helps having a GREATER angle over the strings. Different tops need different loading. I've seen when the angle was increased and more pressure was thus applied to the top that the instrument actually FELT looser. A thick top with too little pressure can feel tighter because there is not enough pressure to load the top properly.