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| The violin, the mandolin, and acoustic optimization copyright 2005 Stephen Perry No reproduction allowed |
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| Development of mandovoodoo (tm) optimization |
Spear’s Work I’ve long been tuning bridges and so on by pretty much standard methods (to the numbers, then by response) and trying to understand Hutchins’ mode tuning chart. Deena Spears’ book, “Ears of the Angels” really opened my eyes to the possibilities of fine tuning the acoustic response of instruments. The main aspects of the process Spears outlines (at least the physical process - read the book) is directed to violins: # 1. Check for loose or weak seams # 2. Set up and adjust instrument completely # 3. Set B 0 to the “singing pitch” by adjustments to fingerboard # 4. Set tailpiece resonance frequency to a certain distance away from the “singing pitch” # 5. Adjust ribs to even response via slight scraping of the interior of the ribs or blocks in critical areas # 6. Tune bridge to symmetry by very slight scraping along the sides # 7. Adjust bass bar by fine scraping of heavy spots # 8. Balance response of F hole edges on each side # 9. Repeat until stable I’ve expanded and modified this approach on violins to include more extensive work on the bridge. How does this process work? Energy seems to go into production of nice sound rather than noise. The amount of wood actually removed is none to very little. Just burnishing the bridge with a fingernail can be enough to clean up the tone a little if done in just the right spot. Maybe something to do with constructive and destructive interference. Regardless, the system consistently smooths and improves response and tone. Working Model for Mandolins Not every part of Spears’ process applies easily to mandolins. For example, setting B 0 is difficult. I’ve experimented with clay stuck to the headstock to lower B 0. Good results, but the required mass is too great for easy permanent attachment. In mandolins I find the most powerful adjustments deal with the relationship between tone bars and ribs. Working on the ribs changes the tone bar response and vice versa. To a lesser extent, F hole and bridge work influence ribs and tone bars. The effect is one of cleaning up the sound and improving response. I think of the process as looking for lumps or dead spots. Small areas that are interfering with the even transmittal of vibration around the instrument. Thinking this way gets quick results. However, I have no scientifically defensible explanation. The exception to the general pattern is the bridge. The bridge I always tune the same. The bridge behaves differently from ribs and bars, which behave very similarly and in a strongly interrelated manner. Process My mandovoodoo™ process addresses the ribs, bridge, tone bars, and F hole edges. I don’t find it very difficult, but I find others can’t tell what is going on. While I listen to tapped notes or changes in the character of a plucked tone I’m not actually listening to the pitch. More like listening for slow beats, for perfect intonation. Very much like setting the final unison in tuning a piano, which I also do. A subtle settling or deadening versus a clear liveliness. I suspect years of tapping violin plates and bridges brings skill in this type of listening. Here’s the process in moderate detail with observations. # 1. Check basic setup and structural integrity. Substantial adjustments later can throw the acoustic blueprinting out of whack. I’ll gladly do minor future adjustments without charge, but it is needless trouble if adjustments are needed at the time of adjustment. # 2. Test and adjust rib balance. This generally increases clarity and opens up the sound quite distinctly. Only a small amount of powder is raised in this step. I find the general area of spots to scrape by a combination of touching and feeling the mandolin ribs while playing a single open string. I locate the exact spots requires light scraping by gently skating the scraper along the inside of the rib in the general area located from the outside. I only remove a tiny bit of powder. I find that there’s usually one major dead spot on each rib and one substantial live spot. Adjustment often moves these closer. Further adjustment makes them merge and disappear. Sometimes a second less pronounced pair of spots remains and I adjust those. On an F style I adjust all three ribs. # 3. Test and adjust bridge balance. The testing process is similar to that for ribs. I work along the edges of the bridge base and top, initially concentrating on 8 specific points. After the major balance is good I work along the saddle between the string pairs. Again, only a very tiny amount of wood gets removed, barely a dust. The sound generally gets much more clear and open. Players frequently report a substantial apparent increase in volume. I frequently make small adjustments with a fingernail as a demonstration, which is a bit spooky. # 4. Test and adjust tone bars or bracing. I use two approaches. First I play an open string and find spots that generate a dead or muffled tone. I remove a small amount of wood from the dead areas. A very small amount, just a couple of light scrapes. This always gives better clarity, especially on the lower strings and sometimes on the A strings around D. Then I use a taping technique on the back to find front/back interference. Final scraping is very light and generally gives a luminous edge to the tone. Tone bar work generally puts some imbalances in the ribs. I work back and forth from ribs to tone bars until they stabilize, then check the bridge, which is almost never out any. # 5. Tune F hole edges. This process involves working around each F hole, testing one side in relation to the other. The effect is quite subtle, but very helpful in bringing out the overtones and increasing apparent projection. Luminosity and clarity improve. I use a knife to very lightly work the F hole edge. I don’t do this on oval hole mandolins. I can continue to work using the same techniques on the interior surfaces of the top and back, the sides of the neck, and so on. The big interference in mandolins is the finish. If the sides of the neck were unfinished ebony I could shave fine amounts of dust off without trouble. This works very well on violin fingerboards and on the edges of tailpieces. The typical area for final adjustment on fingerboards is about 1/4" long and takes a couple of light scrapes. Effects At this point I consider the mandolin “acoustically blueprinted.” Further playing lets the instrument settle into its final tone and response. Words are somewhat difficult to use in describing the effects. I feel more rapid response to the pick and a notable lack of "beats" in the instrument (like the beats between two notes just a little bit apart). The basic sound is more free and open. The notes are more even from string course to string course. There's much less "noise" in the overall tone. Notes stand out, and the space between the notes is more empty. Like a well tuned piano versus one just a bit out. Dynamic range and the ease of using that dynamic range often increase a bit. The overall effect is often quite striking. The mandolin becomes more of what it is already. Most players merely think the instrument sounds “better.” Here’s a quote: "Setup is also such an important factor. Funny how we buy a mandolin, only to send it off immediately for setup. This is where things get interesting! I played the Eastman for a few minutes at a time, and Steve would ask to see it. He would then seemingly remove imperceptible amounts of wood from the bracing, perhaps other places inside the top, and even the bridge. EVERY TIME he handed it back, it sounded better. Being a bench-builder of violins, Steve is in tune with the properties of violin building, and realizes the similarities with mandolins." Roscoe Morgan on Mandolin Cafe about his Eastman MD615 mandolin No. 166 Or this quote from David Bromberg, a well-known musician: “Eastman makes violins, and I’ve been dealing with their violins for a long time. To me, the mandolin is amazing - and I’ve had three Lloyd Loars at different times. It’s Chinese. Mandolin players talk about how an instrument does or does not ‘bark.’ Well, the only new mandolins ever played that barked – with the exception of one Gilchrist that’s better than any of the Loars I ever had – are a couple of Eastmans. They’re really good. The one thing about it that was not wonderful was that it was very trebly sounding. So I had Stephen Perry in Tennessee do his MandoVoodoo thing on it, and it’s now much deeper and richer sounding. It’s a better mandolin that I am a mandolin player.” David Bromberg, quoted by Dan Foste, Vintage Guitar, July 2007 If you're still curious, give me a call 866 884 6546 toll free |
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| The mandovoodoo™ process was invented by and is only performed by Stephen Perry of Gianna Violins, the world's premier seller of fine Eastman Mandolins. Copyright © 2005-7 Stephen K. Perry. No use without written permission. By viewing you agree to all site terms and conditions. mandovoodoo.com (tm) is a division of Gianna Violins. |
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