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| fixing compensation at bridge for flamenco guitar http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=54326 |
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| Author: | wbergman [ Wed Aug 18, 2021 5:26 pm ] |
| Post subject: | fixing compensation at bridge for flamenco guitar |
Guitar is a 50+ year old Marcelino Barbero cedar flamenco, which is internally fan braced and externally a Ramirez copy with 660mm scale. The top is dished and the bridge rotated, so that the compensation at the bridge is way off. The saddle has been raised a lot over the years and now slants towards the fingerboard. I have a thought, but I want to run it by to see if maybe I am just going to break the guitar. I visualize making a new saddle that overhangs above the slot towards the tie block. The crest of the saddle would be shaped behind the bridge slot, and therefor not aiming the force of the string straight down towards the bridge slot. So, am I likely to snap the bridge apart or any other pitfalls? |
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| Author: | Clay S. [ Wed Aug 18, 2021 11:08 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
You may be better off replacing the lower transverse brace to put the top back where it belongs. When the tornavoz lost favor and were removed from Torres's guitars a lower transverse brace was fitted to strengthen the top and keep it from collapsing. |
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| Author: | Hesh [ Thu Aug 19, 2021 5:29 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
1). Is the guitar worth repairing there were tons of inexpensive Ramirez copies produced and distributed in the past 50+ years or so and many of them are cheap junk made with unserviceable glues. 2). When we move the break point over the saddle crown aft we also inadvertently reduce the downward pressure on the back edge, the edge that locks the strings in place... of the tie block. If you are not moving much no problem if you are moving the break point a lot the strings may not stay tied for lack of sufficient downward pressure on the wraps. 3). We would consider this approach, deeper saddle over the bridge toward the tie block to be addressing the symptom and not the problem and therefor it would not be our approach. Either the instrument has the residual value or even sentimental value to the steward to be wanting to pay for the repairs and if so then we would address the top distortion and bridge rotation. For us though if this is a cheap guitar not intended or built to be serviced we would decline because of the uncertainty and unpredictability of it's build quality and the dozens of people waiting on our wait list. Now if this is yours and you want to fix I would also address the internal issues with it and in doing so at the very least reduce the excessive bridge rotation. Lastly if you have high tension strings on it you can reduce bridge rotation by reducing the tension of the selected strings you use. Sometimes combinations of approaches get us where we want to go such as address internal structural issues and go with lower tension strings. Please also recognize that I am not discussing how to fix this I am discussing what we would do if we encountered it and we are commercial in nature and that greatly changes our approach and always brings us back to concepts such as what is appropriate for this instrument in this condition as it sits right now, is the client willing to pay, what is our work load and is this a science project better suited to be listed on Craig's list for sale as a "project guitar." All these things are in play with a commercial shop. |
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| Author: | Alan Carruth [ Thu Aug 19, 2021 9:46 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
Hesh wrote: "2). When we move the break point over the saddle crown aft we also inadvertently reduce the downward pressure on the back edge, the edge that locks the strings in place... of the tie block. If you are not moving much no problem if you are moving the break point a lot the strings may not stay tied for lack of sufficient downward pressure on the wraps." As I see it, moving the break point back toward the tieblock should increase the break angle, and therefore the down pressure on the saddle. It also increases the tipping force on the saddle top that is trying to break out the front of the slot, so I'd be careful about that. My own experiments suggest that anything more than about 12-18 degrees of break angle is unnecessary for sound, and probably harmful mechanically. I can't see how it would make any difference in the tieblock geometry. Aside from the back overhanging saddle, you could also try compensating the nut with small pieces glued to the fingerboard surface at the front face of the nut. This will reduce the amount you'll need to move the saddle back, and might be just enough to get the G string more or less into tune. Different brands of nylon strings require different amounts of compensation because they use different types of nylon that stretch differently. I find the moving the take-off point for the G string at the nut a mm or more toward the first fret usually helps the intonation in the lower positions a lot, and reduces the need for as much compensation at the saddle. WRC is, in general, a less dense wood than most spruces, and since the long-grain stiffness at a given thickness tracks the density pretty well, making a cedar top as thin as you would a spruce one tends to end up too weak in the long run. That may well be the situation here. Lowering the string height off the top will reduce the torque load, and could help, but in this case it may be that the damage is done. |
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| Author: | wbergman [ Thu Aug 19, 2021 10:02 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
The dishing down does not project into the rosette, so I think there would be minimal help by trying to make the transverse bar a bit more arched. It seems that the original fan bracing and top thickness cannot withstand the twist. It is a valuable guitar. I have seen them listed 20 years ago used for ~$2,000, though recently I saw one listed on ebay for a bit less. Plus, it is sentimental and very good sounding. It is all solid wood (Spanish cypress ?). Someone more skilled that I would retop it and be ahead, I think. That is a last option for me, because it is not really worth paying someone to retop it. I do have a cheap Ramirez copy (plywood) that I used for a travel guitar so I do not worry if it is lost or crushed. |
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| Author: | Clay S. [ Thu Aug 19, 2021 10:35 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
An interesting thread on Del Camp about Marcelino Barbero guitars and Sherry- Brenner: https://www.classicalguitardelcamp.com/ ... 11&t=27827 I think the guitar is worth repairing based on what people have said, but I would try fixing the top dishing and bridge rotation rather than making an overhanging saddle. If the intonation is still off once those items are corrected, you could either move the bridge or (if it doesn't need much correction) fill the old slot and recut a new one. |
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| Author: | Clay S. [ Thu Aug 19, 2021 10:42 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
Before going to the point of retopping I would install a bridge doctor to reduce the bridge rotation and see how negatively it impacts the sound. One nice thing about bridge doctors is they are relatively easy to install or remove. |
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| Author: | Barry Daniels [ Thu Aug 19, 2021 11:57 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
I don't think a Bridge Doctor would work very well in a classic. You would have to drill a hole through the bridge and top. And the device would probably really compromise the sound. But I could be wrong. |
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| Author: | jshelton [ Thu Aug 19, 2021 1:21 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
wbergman wrote: The dishing down does not project into the rosette, so I think there would be minimal help by trying to make the transverse bar a bit more arched. It seems that the original fan bracing and top thickness cannot withstand the twist. It is a valuable guitar. I have seen them listed 20 years ago used for ~$2,000, though recently I saw one listed on ebay for a bit less. Plus, it is sentimental and very good sounding. It is all solid wood (Spanish cypress ?). Someone more skilled that I would retop it and be ahead, I think. That is a last option for me, because it is not really worth paying someone to retop it. These guitars were made in Asia (Japan I think). I bought one new back in the 80's (70's?) for $750 which was serious money in those days. The top is indeed cedar and back and sides are some kind of softwood (spruce?) not cypress. They tended to have very oversized necks which made them a little uncomfortable to play and many had flaws in construction (fretwork, finish, etc.) which required lots of time spent in the repair/setup shop. I don't think it's worth as much as you think but I could be wrong. I'd listen to Mr. Carruth about correcting the intonation. |
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| Author: | wbergman [ Thu Aug 19, 2021 2:29 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
I agree that it not worth $2000. I just mentioned that for history. There are two one ebay now for under $1000, though both look to me to be rather damaged--one more than the other. |
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| Author: | Clay S. [ Thu Aug 19, 2021 4:51 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
Barry Daniels wrote: I don't think a Bridge Doctor would work very well in a classic. You would have to drill a hole through the bridge and top. And the device would probably really compromise the sound. But I could be wrong. I am not a huge fan of the Bridge Doctor, but I have used them on a couple of occasions when they were a reasonable option to restore playability on an otherwise unplayable instrument. On instruments with thin tops they can sometimes improve the sound, but no guarantees on that. They do help with bridge rotation. They are a fairly simple to make device - a small block of wood, a short length of dowel, and a hex drive softwood threaded insert can be used as the "worm" If they don't work out they are easily removed and the small hole they make patched. Breedlove uses them on their lightly built tops (which I am also not a fan of) straight from the factory: https://www.youtube.com/watch?v=4tWo_KihoaA Life in the trenches, when you're in the last ditch...... https://www.youtube.com/watch?v=nxJpM4xoXg0 |
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| Author: | guitarjtb [ Thu Aug 19, 2021 5:24 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
https://reverb.com/item/37650065-marcelino-barbero-l882-classical-1969-natural I can't help much on the repair info, but here is one on Reverb for value comparison |
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| Author: | Barry Daniels [ Thu Aug 19, 2021 7:09 pm ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
Clay, you used them on a classical? How did they sound afterward? wbergman, have you made sure that the fan braces are not loose anywhere, especially the upper ends? If all else fails, you could always flatten the top with a bit of heat, moisture and clamping to a flat caul, then maybe add a couple of small short fan braces. I did that to a cheap old parlor and it saved the guitar from being a wall hanger. I also agree with the low tension strings. |
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| Author: | Clay S. [ Fri Aug 20, 2021 6:22 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
Hi Barry, No, I've never used a bridge doctor on a classical. That doesn't mean I wouldn't. It wouldn't be my first choice to correct the problem, but it might be a practicable solution when all things are considered. If made of light weight woods (tulip poplar?) it might not hurt the volume too much (and possibly improve the tone). You don't know until you try. If it makes the instrument sound terrible it can be removed by unscrewing one small screw and the hole plugged. Normally (on the 2 I have done) I countersink the screw head and cover it with a pearl dot, however when testing it's efficacy on that particular instrument the screw head could be left proud so in the event it doesn't help or hurts the sound too much, plugging the screw hole left by it's removal could be done fairly inconspicuously. One thing I noticed on the Breedlove device was the lightening of the Bridge Doctor by drilling holes in it in noncritical areas. |
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| Author: | wbergman [ Fri Aug 20, 2021 11:58 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
The bridge itself is only 7mm or less at the thickest parts. Probably IRW. The bridge is concave itself. I wonder if replacing the bridge with a bit more substantial one and the saddle slot better situated might be an answer? |
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| Author: | Clay S. [ Sun Aug 22, 2021 1:40 am ] |
| Post subject: | Re: fixing compensation at bridge for flamenco guitar |
On a typical classical I think the bridge is normally about 8 mm at the tie block, so for a flamenco 7 mm might be reasonable. You could probably get away with making the tie block 9-10mm and making the "spine" of the wings 5-6mm which would add a lot of stiffness. One thing to keep an eye on is how it affects the action - you may be changing it from a flamenco into more of a classical. |
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