Page 2 of 3 FirstFirst 123 LastLast
Results 26 to 50 of 54

Thread: Tuner for tap tuning

  1. #26
    Professional Dreamer journeybear's Avatar
    Join Date
    Aug 2007
    Location
    Northeastern South Carolina, west of North Carolina
    Posts
    15,346
    Blog Entries
    2

    Default Re: Tuner for tap tuning

    Now this I can help with. There are at least three choices here: https://gfycat.com/gifs/search/deer+eating+pop

    Say, where in the Great State of RI are you?
    But that's just my opinion. I could be wrong. - Dennis Miller

    Furthering Mandolin Consciousness

    Finders Keepers, my duo with the astoundingly talented and versatile Patti Rothberg. Our EP is finally done, and available! PM me, while they last!

  2. #27
    Registered User Mandoborg's Avatar
    Join Date
    Sep 2002
    Location
    RI
    Posts
    346

    Default Re: Tuner for tap tuning

    Thanks Journeybear. I'll have to check that out. Not very computer literate, but if it's easy enough, I'll grab it. I'm currently re-locating from Tiverton to Portsmouth R.I.

  3. #28
    Registered User Mandoborg's Avatar
    Join Date
    Sep 2002
    Location
    RI
    Posts
    346

    Default Re: Tuner for tap tuning

    ...

  4. #29
    Professional Dreamer journeybear's Avatar
    Join Date
    Aug 2007
    Location
    Northeastern South Carolina, west of North Carolina
    Posts
    15,346
    Blog Entries
    2

    Default Re: Tuner for tap tuning

    Ooo-wee! That's a big move! Clear across the Sakonnet River. (For those who don't know, it's a whole 5-6 miles.) I'm from way over to the other side of the state, Moonstone Beach. (For those who don't know, it's really far - like over an hour. )

    That's enough of that, I'm sure. As to your gif, I'm pretty sure if you go to that site, and click or right-click on the image, it should give you the option you want. Or do that on this image - might be simpler. Sorry for the derail, folks. As you were.
    But that's just my opinion. I could be wrong. - Dennis Miller

    Furthering Mandolin Consciousness

    Finders Keepers, my duo with the astoundingly talented and versatile Patti Rothberg. Our EP is finally done, and available! PM me, while they last!

  5. #30

    Default Re: Tuner for tap tuning

    It was mentioned that this thread has been beat to death yet I see new builders who don’t get it, in my opinion anyway. And some longtime builders. That’s why I post.
    Last edited by Jim Hilburn; Dec-15-2021 at 9:40am. Reason: Kant spel

  6. The Following 3 Users Say Thank You to Jim Hilburn For This Useful Post:


  7. #31
    Registered User
    Join Date
    Jan 2014
    Location
    Farmington, MN
    Posts
    280

    Default Re: Tuner for tap tuning

    Quote Originally Posted by Jim Hilburn View Post
    It was mentioned that this thread has been best to death yet I see new builders who don’t get it, in my opinion anyway. And some longtime builders. That’s why I post.
    Exactly Jim. That's why I post. These questions keep coming up. I wasted a lot of time and frustration chasing that ghost. I'd like to save others the hassles.

  8. #32
    Registered User Tom Haywood's Avatar
    Join Date
    Oct 2008
    Location
    PTC GA
    Posts
    1,348

    Default Re: Tuner for tap tuning

    I'm in the process of graduating a back plate and top for an A model new mandolin. I have the original Siminoff book and notes from my previous builds to use as reminders and general guides to stay in the ball park. Being in the ballpark is what all the recommended numbers and musical notes are all about. The actual final numbers, etc. will be different for your particular build. I find that Siminoff's numbers in the first edition book are mostly accurate for final carving but not for final thicknessing. The same seems to apply to his "target notes". I think what you learn from all that is the process of determining what will work best as a balance for strength and sound.

    I use any clip-on tuner at hand to see how the "note" is changing with further graduation of the plate. That is useful information but not determinative. I aim for thicknesses close to what can be found in many posts of measured Loars and others, but again that is not determinative. What is determinative is what my ear hears when I tap the plate, and what the stiffness feels like. Also, I've had the backs off of a number of old Gibsons for repair, and there is a fairly common look and feel to them even though the "numbers" vary a lot. That is the best clue that the numbers are just goals to get you close.

    For a first build, you can build a good sounding mandolin without going deep into the measurements and without tap tuning toward specific notes. As others have said, it is a big enough elephant to learn without going there. If your goal is to do better than the basics, then I think it is worth exploring tap tuning as you thickness your plates.

    You can see a photo I posted on my FB luthier page a week or so ago where I drew the thickness areas and wrote the target numbers on the back plate. Those numbers are claimed to be from a mandolin built by a former Gibson employee and based on the Loar specs. All they really are is useful goals. My back plate is working out to slightly different thicknesses. You can save the photo and enlarge it to read the numbers.

    Good luck and have fun!
    Tom

    "Feel the wood."
    Luthier Page: Facebook

  9. #33
    Registered User John Bertotti's Avatar
    Join Date
    Oct 2002
    Location
    SD
    Posts
    3,658

    Default Re: Tuner for tap tuning

    Anyone currently using deflection to help decide when to stop carving and fine tuning your tops?
    My avatar is of my OldWave Oval A

    Creativity is just doing something wierd and finding out others like it.

  10. #34
    Registered User Tom Haywood's Avatar
    Join Date
    Oct 2008
    Location
    PTC GA
    Posts
    1,348

    Default Re: Tuner for tap tuning

    I think somebody pointed out up above that deflection tuning presents similar issues. Once you have your own set of data for similar woods, arches, etc, then it is certainly useful for achieving similar results. Suggesting that a specific number should apply in all situations might be a general ballpark guide, but it might also be useless. I find it more useful to flex the plate in hand, because it varies according to the pieces of wood used.
    Tom

    "Feel the wood."
    Luthier Page: Facebook

  11. The Following 2 Users Say Thank You to Tom Haywood For This Useful Post:


  12. #35
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    3,462

    Default Re: Tuner for tap tuning

    Quote Originally Posted by John Bertotti View Post
    Anyone currently using deflection to help decide when to stop carving and fine tuning your tops?
    I do not but several known makers use it - Don McRostie, I think Tom Ellis just to name few. I know some top tier violin makers measure deflection to gauge their bass bar stiffness.
    Adrian

  13. The Following 2 Users Say Thank You to HoGo For This Useful Post:


  14. #36
    Registered User j. condino's Avatar
    Join Date
    Nov 2005
    Location
    Asheville, NC
    Posts
    2,758

    Default Re: Tuner for tap tuning

    Those people all have a reference library of dozens and or hundreds of instruments that they measured on the exact same deflection device. That is how they are able to consistently reproduce reults. They do not just arbitrarily suggest numbers to a novice who will in all likely build a very different jig that will require its own individually adjusted deflection measurements.

    There are many other variables involved with building a good mandolin than just the plate thicknesses or deflection alone...

    Use high quality, well seasoned materials. Pick a simple design that can be well executed without a lot of needless "fluff or bling". Try your best to mimic a known good mandolin; Adrian's plan's are the best. A fast, comfortable neck, an excellent setup. Keep things simple and don't be impatient. Turn off your computer. If you give it your best effort, you'll likely build a nice mandolin. When you build 10 more, there will be obvious improvements. A similar thing happens after 100......If your end goal is to emulate a Loar, find the best one you can get access to and clone it. Like most things in life worth doing, there is no fast track or substitute for putting in the time and effort.
    www.condino.com

    Crafted by hand in a workshop powered by the sun.

  15. The Following 2 Users Say Thank You to j. condino For This Useful Post:


  16. #37
    Adrian Minarovic
    Join Date
    Oct 2003
    Location
    Banska Bystrica, Slovakia, Europe
    Posts
    3,462

    Default Re: Tuner for tap tuning

    +1 on what James said. You can search teh internet and find several deflection jigs in action and you can build your own but unless you reproduce their arching shape and their wod selection and they provide you with their database of deflection measurements, all you can do is start your own and try to build as repeatale as possible. Starting with good proven model and learn to build it consistently is always the safest way.
    Adrian

  17. The Following 3 Users Say Thank You to HoGo For This Useful Post:


  18. #38
    Registered User John Bertotti's Avatar
    Join Date
    Oct 2002
    Location
    SD
    Posts
    3,658

    Default Re: Tuner for tap tuning

    Yea this has been said so many times. I do take it to heart. I just if this conversation was going to be brought it it would maybe pay to bring it up. The reason is there is one underlying concept that the pros who help here always bring up. Data, the people who do this seem to have an ongoing data base they have built on for many many years and instruments. Others go a lot on feel it seems. They find wood combinations they like to work with and learn by feel. I doubt there is any perfect way and in the end you have to start somewhere. It seems if you want a solid instrument that sounds good you first need to build an instrument. If you want repeatability you need to build a lot of instruments.

    I have Hogo's plans! They are artwork in and of themselves! I have plans I have cut apart to make jigs with no worries about saving them but these plans I will either need to trace onto paper I can cut up or go to a big printer and try to make a disposable copy because once I finish this ongoing nightmare go making a shop They are getting framed and hung on a wall.
    My avatar is of my OldWave Oval A

    Creativity is just doing something wierd and finding out others like it.

  19. #39
    Registered User sunburst's Avatar
    Join Date
    Nov 2003
    Location
    Kentucky
    Posts
    15,863

    Default Re: Tuner for tap tuning

    While I've had a set of "Hogo drawings" for years I only used it for reference on certain Loar "things". Not until last year did I follow the drawing and build a mandolin "to Loar specs" as 'they' say. When it was done it sounded a little different from my usual mandolin in the details of sound, but overall very much like my mandolins sound in general.
    Most things are very similar or only slightly different from what I do anyway after building and tweaking things for 30+ years, with the exception of back graduation, which I deliberately do differently. I can say I learned some things from the experience, but I didn't change anything in my usual building.
    I can say this: if you faithfully follow the Hogo drawing using good quality materials and good building techniques, you will build an excellent mandolin.

  20. The Following 4 Users Say Thank You to sunburst For This Useful Post:


  21. #40
    Registered User Steve Sorensen's Avatar
    Join Date
    Sep 2009
    Location
    Santa Clarita, CA
    Posts
    2,461

    Default Re: Tuner for tap tuning

    For a while, I matched taps to notes on my piano. Now, I just listen for a brightness, focus, and shift in tones from treble to bass sides that matches what I've found created great results in the past.

    I also spend several hours cleaning and shaping the internal join of the top to the sides since I've found that a lot of crappy response is caused by the random junky vibrations as the moving top sloshes against the sides.

    Siminoff's tap tuning approach misses the most important aspect of the top -- the ability to provide consistent, balanced, powerful, and clean response to each and ALL of the forces of the plucked notes across the neck. I think the point being repeated here is that the tap tone buckets are far too much like taking a shotgun to wedding -- you may get a rough result that hits near the required target, but not the real balance and finesse of tone that is truly desirable.

    Steve

    PS -- a highly annotated page of HoGo's top view is hanging on at the entrance to my shop. I still check back to it regularly.
    Steve Sorensen
    Sorensen Mandolin & Guitar Co.
    www.sorensenstrings.com

  22. The Following 3 Users Say Thank You to Steve Sorensen For This Useful Post:


  23. #41
    Registered User j. condino's Avatar
    Join Date
    Nov 2005
    Location
    Asheville, NC
    Posts
    2,758

    Default Re: Tuner for tap tuning

    One last thing: know that none of you are alone on an island with all of this. All of the folks contributing here visit and hang out and talk with each other on a regular basis, exchanging ideas and laughter. I've been to visit Don and Mike and John and Dale and the rest of the crew, and everyone likes to visit Asheville and hang at my place; my open house Wednesdays are a veritable party for all of the young guns and apprentices. Steve & I were laughing it up just yesterday afternoon. The hundreds of blueprints, drawings, and numbers notes that I have made over the decades are readily accessible to all of my students.

    All of the season OG luthiers went through this same process. Each of us has a slightly different approach that suits our different personalities, yet works for us. When Roger hit upon his plate tuning, something went off and worked for him. When Don started the deflection, something similar happened. When I switched to the removable plate jig that allows me to make changes under tension and play and hear the results, it was like a grenade of happiness went off in the shop and my instruments became much more consistent.

    Find a good mentor and follow their lead. Not the internet or mandolincafe or you tube; a real human with live interaction. It will save you a decade or two of reinventing the wheel for mandolins and also so much more in life. We are humanity. Every bit of our life and experience and personality comes out when we build these funny small little instruments. As my good friend & mentor Eugene Clark once said to me around his 80th birthday, "Why would I need to take up yoga or fly fishing when I get everything they offer from a good day of French polishing???"
    www.condino.com

    Crafted by hand in a workshop powered by the sun.

  24. The Following 5 Users Say Thank You to j. condino For This Useful Post:


  25. #42

    Default Re: Tuner for tap tuning

    A nice bit in this video showing Don McRostie's tap tuning process. A short bit, but very informative for me -
    https://www.youtube.com/watch?v=TzrmDUgKWh4

  26. #43
    Registered User sblock's Avatar
    Join Date
    Mar 2009
    Location
    Redwood City, CA
    Posts
    2,335

    Default Re: Tuner for tap tuning

    Quote Originally Posted by LKN2MYIS View Post
    A nice bit in this video showing Don McRostie's tap tuning process. A short bit, but very informative for me -
    https://www.youtube.com/watch?v=TzrmDUgKWh4
    (Sorry) An important correction and distinction: Don McRostie does not perform tap tuning. He uses deflection tuning. This is different in fundamental ways.

    In most instantiations, tap tuning is based on adjusting the note (i.e., the fundamental frequency) produced when the free top plate is set into vibration by tapping it -- hence the name. Wood is then removed from the top plate until the desired note is achieved.

    Deflection tuning does not rely upon hearing any notes. Instead, the top is subjected to a downward force of known, reproducible amount, and the corresponding deflection of the top is measured using a micrometer -- this measurement is usually carried out in several different places on the top. Wood is then removed from different parts of the top until the desired deflections are obtained in all the measured regions. Very often, the deflection of the top is measured not on the free top plate (as in tap tuning), but instead with the plate attached to the ribs (sides) of the mandolin assembly. Top deflections can also be measured with a fully assembled mandolin -- which is something that tap tuning cannot do. Measurements on fully functional mandolins of high quality (e.g., Loar F5's and suchlike) can therefore be used to provide a useful baseline of information, providing target values. With the right jig and equipment, it is straightforward to make a non-destructive measurement of numerous great mandolins, and thereby build up a database. This is a key advantage, because you sure can't do that with tap tuning!

    A comment on some of the physics: the "note" provided by tap tuning is a holistic property of the entire top plate, and it does not provide information about different regions (unlike deflection tuning). The fundamental note achieved while tapping the top plate is not related in any simple way to the "note" that it produces in the assembled mandolin, once its edges are attached to the ribs and a resonant cavity is formed inside the instrument. The note of the free plate depends not only on the plate geometry (i.e., shape and thickness and graduations of the plate), but also on the mass of the plate (and the spatial mass distribution) and the top plate stiffness (and the spatial stiffness distribution). Tap tuning is sensitive in a complex way to all of these properties. For example, a top plate made from stiffer wood will sound a higher note, but so will a top plate of lighter wood with the same stiffness.

    In contrast, deflection tuning is not sensitive to the mass (nor the mass distribution) of the wood in the top plate. It is just sensitive to the stiffness (and to the spatial stiffness distribution) and, of course, to the plate geometry (for example, to the size and locations of ff or oval holes, and to the tone bars). This feature is both good and bad, depending on your point of view. On the one hand, deflection tuning isolates the contributions of stiffness, and it does so in a way (albeit somewhat crudely) that reports on the actual locations and graduations. On the other hand, top stiffness is not the only contribution to a mandolin's tone, which is produced by the fundamental and harmonic series of the assembly, including the top, and also by the air cavity. Presumably, the mass distribution matters, as well, but it is not really being considered. You can view this as a glass half full or half empty!

    Anyway, tap tuning and deflection tuning involve fundamentally different kinds of measurements, and they are not sensitive the same things. They therefore provide distinct, alternative ways of monitoring a build, and making decisions about top thickness graduations.

  27. The Following 2 Users Say Thank You to sblock For This Useful Post:


  28. #44
    Mandolin & Mandola maker
    Join Date
    Sep 2002
    Location
    Bega NSW, Australia
    Posts
    1,425

    Default Re: Tuner for tap tuning

    I hesitate to say "tap tuning", so will rename it measuring the modes of vibration, which is a more accurate description. So, the frequencies of the modes of vibration are a function of the stiffness and mass of the object, and also the size and shape. Deflection testing only measures stiffness, but the size and shape remains the same. That leaves the mass, and mass is important. These things vibrate, and mass and stiffness both determine how it vibrates. You CAN measure the modes of vibration in a competed instrument ready to play with the strings on it. Cohen and Rossing has done it using laser interferometry, but you can also do it using FFT or Chladni patterns. It is just plain wrong to say you can't measure "tap tones" in a completed mandolin, or any other instrument for that matter. One could easily argue that the modes of vibration of the completed instrument are the most important thing to be able to measure since everything changes when the free plates are glued up. What you need is a correlation between the free plate frequency measurements (tap tones) and the completed instrument for it to be at all useful. That requires a database of measurements. From my database there is a correlation, but it is not what most people think it might be and that is why everyone fails at "tap tuning". The correlation is quite different for archtop vs flat top mandolins, and is different for different instruments so gets complicated. It is not a close correlation, there is a fair bit of scatter, which is to be expected if you understand all the factors that will change the mass and stiffness and thus alter the frequencies. Things such as the mass of the sides, mass of the tuners, mass of the tailpiece, mass of the bridge, how the pickguard is attached and so it goes on and on. Heck, the correlation is probably different between A type mandolins and F type mandolins because of the mass of the scroll. I dunno, I don't make scrolly bits. So it gets even more complicated. Using a tuner that just picks up one mode of vibration (usually the lowest frequency) which is actually very poorly correlated to the modes of vibration in the finished instrument is a sure fire way to failure. Just read the failure posts in this thread!

    These sorts of measurements have limitations in that you are only measuring the lowest frequencies. According to Gore and Gilet, these modes contribute to most of the sound of a guitar and mandolins vibrate like a guitar so the same applies. However, there are many more modes of vibration at higher frequencies that can't be separated out because they merge together, and there are also limitations to the measurement techniques at high frequencies. These higher frequencies do contribute to the overall sound. So even if you build so consistently that the modes of vibration you can measure are identical, different instruments will still sound different. Not as different if you don't build consistently, but still different.
    Peter Coombe - mandolins, mandolas and guitars
    http://www.petercoombe.com

  29. #45

    Default Re: Tuner for tap tuning

    Quote Originally Posted by sblock View Post
    (Sorry) An important correction and distinction: Don McRostie does not perform tap tuning. He uses deflection tuning. This is different in fundamental ways.

    In most instantiations, tap tuning is based on adjusting the note (i.e., the fundamental frequency) produced when the free top plate is set into vibration by tapping it -- hence the name. Wood is then removed from the top plate until the desired note is achieved.

    Deflection tuning does not rely upon hearing any notes. Instead, the top is subjected to a downward force of known, reproducible amount, and the corresponding deflection of the top is measured using a micrometer -- this measurement is usually carried out in several different places on the top. Wood is then removed from different parts of the top until the desired deflections are obtained in all the measured regions. Very often, the deflection of the top is measured not on the free top plate (as in tap tuning), but instead with the plate attached to the ribs (sides) of the mandolin assembly. Top deflections can also be measured with a fully assembled mandolin -- which is something that tap tuning cannot do. Measurements on fully functional mandolins of high quality (e.g., Loar F5's and suchlike) can therefore be used to provide a useful baseline of information, providing target values. With the right jig and equipment, it is straightforward to make a non-destructive measurement of numerous great mandolins, and thereby build up a database. This is a key advantage, because you sure can't do that with tap tuning!

    A comment on some of the physics: the "note" provided by tap tuning is a holistic property of the entire top plate, and it does not provide information about different regions (unlike deflection tuning). The fundamental note achieved while tapping the top plate is not related in any simple way to the "note" that it produces in the assembled mandolin, once its edges are attached to the ribs and a resonant cavity is formed inside the instrument. The note of the free plate depends not only on the plate geometry (i.e., shape and thickness and graduations of the plate), but also on the mass of the plate (and the spatial mass distribution) and the top plate stiffness (and the spatial stiffness distribution). Tap tuning is sensitive in a complex way to all of these properties. For example, a top plate made from stiffer wood will sound a higher note, but so will a top plate of lighter wood with the same stiffness.

    In contrast, deflection tuning is not sensitive to the mass (nor the mass distribution) of the wood in the top plate. It is just sensitive to the stiffness (and to the spatial stiffness distribution) and, of course, to the plate geometry (for example, to the size and locations of ff or oval holes, and to the tone bars). This feature is both good and bad, depending on your point of view. On the one hand, deflection tuning isolates the contributions of stiffness, and it does so in a way (albeit somewhat crudely) that reports on the actual locations and graduations. On the other hand, top stiffness is not the only contribution to a mandolin's tone, which is produced by the fundamental and harmonic series of the assembly, including the top, and also by the air cavity. Presumably, the mass distribution matters, as well, but it is not really being considered. You can view this as a glass half full or half empty!

    Anyway, tap tuning and deflection tuning involve fundamentally different kinds of measurements, and they are not sensitive the same things. They therefore provide distinct, alternative ways of monitoring a build, and making decisions about top thickness graduations.
    THAT was incredibly enlightening and well explained. Thank you for that! GOD, I love this forum......

  30. #46
    Registered User sblock's Avatar
    Join Date
    Mar 2009
    Location
    Redwood City, CA
    Posts
    2,335

    Default Re: Tuner for tap tuning

    Quote Originally Posted by peter.coombe View Post
    I hesitate to say "tap tuning", so will rename it measuring the modes of vibration, which is a more accurate description. So, the frequencies of the modes of vibration are a function of the stiffness and mass of the object, and also the size and shape. Deflection testing only measures stiffness, but the size and shape remains the same. That leaves the mass, and mass is important. These things vibrate, and mass and stiffness both determine how it vibrates. You CAN measure the modes of vibration in a competed instrument ready to play with the strings on it. Cohen and Rossing has done it using laser interferometry, but you can also do it using FFT or Chladni patterns. It is just plain wrong to say you can't measure "tap tones" in a completed mandolin, or any other instrument for that matter. One could easily argue that the modes of vibration of the completed instrument are the most important thing to be able to measure since everything changes when the free plates are glued up. What you need is a correlation between the free plate frequency measurements (tap tones) and the completed instrument for it to be at all useful. That requires a database of measurements. From my database there is a correlation, but it is not what most people think it might be and that is why everyone fails at "tap tuning". The correlation is quite different for archtop vs flat top mandolins, and is different for different instruments so gets complicated. It is not a close correlation, there is a fair bit of scatter, which is to be expected if you understand all the factors that will change the mass and stiffness and thus alter the frequencies. Things such as the mass of the sides, mass of the tuners, mass of the tailpiece, mass of the bridge, how the pickguard is attached and so it goes on and on. Heck, the correlation is probably different between A type mandolins and F type mandolins because of the mass of the scroll. I dunno, I don't make scrolly bits. So it gets even more complicated. Using a tuner that just picks up one mode of vibration (usually the lowest frequency) which is actually very poorly correlated to the modes of vibration in the finished instrument is a sure fire way to failure. Just read the failure posts in this thread!
    ...
    Dear Peter,

    Thanks for adding your perspective on this, which I appreciate. And I find much that I agree about. With all respect, though, I think you have confused the terminology just a bit. Hopefully, MC readers will follow all this. You have chosen to rename "tap tuning" to something else, which it isn't. You wrote: "I hesitate to say "tap tuning", so will rename it measuring the modes of vibration, which is a more accurate description. So, the frequencies of the modes of vibration are a function of the stiffness and mass of the object, and also the size and shape."

    Measuring the acoustic modes, for example, by using an FFT = Fast Fourier Transform (that is, measuring the frequency components of the full acoustic spectrum by mathematically transforming the temporal amplitudes of a digitally recorded tone), or by using Chladni patterns to reveal the spatial mode node lines (the old fashioned way, by using sand or other small particles, or the modern way, by using laser light interferometry) is a valid approach. But it is NOT tap tuning. Tap tuning for the purpose of carving graduations, as defined in my previous post, is performed on the free top plate.

    Later in your post, you claim that "It is just plain wrong to say you can't measure "tap tones" in a completed mandolin, or any other instrument for that matter." With all respect, this is both untrue and misleading. Yes, it is certainly possible to measure the note produced by tapping the top of a completed mandolin. But if you do that, the dominant note that you'll hear is the air cavity resonance, and not the plate resonance! Also, for the reasons you laid out perfectly well in your post, the free top plate and the attached top plate behave quite differently. Tap tuners, as I have already pointed out, work with free top plates and not with attached ones. Yes, it is possible to get more information than just the fundamental "tap" note frequency, but doing so requires using the other methods that you've described, involving either full spectral analysis or spatial mode analysis. And not just listening for a tap tone, or by using an electronic tuner to "hear" the tapped note. I don't want readers to get confused about these things, which is why I'm chiming in now.

    Writing for myself, I think that full spectral analysis, which is now widely available thanks to software tools that are comparatively easy to use, holds real potential for aiding in carving mandolin tops. However, unlike deflection tuning, spectral analysis provides no guide about WHERE any top the wood needs to be removed in the plate! It can therefore be hit-or-miss. And using laser interferometry to reveal spatial modes is simply not a going possibility for most builders, because the technology is expensive, not widely available, and quite difficult to implement reproducibly. Finally, as you've pointed out yourself, there is no simple relationship between these properties (or simple tap tunes, for that matter) measured on free top plates and those in the completed mandolin. Your own database, as I understand it, took a long time to develop, and even then, the correlations you described are not straightforward. Also, your database doesn't include any F-style instruments (or the like), which have f-holes, longitudinal tones bars, and points and scrolls. It's therefore not clear whether any of the empirical relationships you've found will carry over. So, it's of little help to those folks building these instruments. Maybe yes, but probably no, is my guess.

    I think we both agree that tap tuning is a rather crude way to measure progress, and it can even be downright misleading, at times. But it's probably better than nothing, no? Or perhaps better than simply measuring graduation thicknesses? As for deflection tuning, we agree that it is responsive to stiffness but disregards variations in mass (wood density), and therefore poses its own issues. But at least deflection tuning can report on the spatial distribution of stiffness, and therefore provide at least some hints as to where wood needs to be removed when carving -- unlike tap tuning, which provides no spatial information. And neither does full acoustic spectral analysis, for that matter!

    Yup, it's really complex! Building a mandolin is both science AND art. The physical tools improve every year, but we are still pretty far from the place where measurements can guide us unerringly to the timbres we seek in the completed instrument.

    I suppose something similar can be said about modern medicine. It's both science and art, and the science is slowly gaining, but not all there.


    Last edited by sblock; Jan-04-2022 at 2:16pm.

  31. The following members say thank you to sblock for this post:


  32. #47

    Default Re: Tuner for tap tuning

    Quote Originally Posted by sblock View Post
    But it is NOT tap tuning. Tap tuning for the purpose of carving graduations, as defined in my previous post, is performed on the free top plate.
    To mix things up further, Siminoff's instructions for "tap tuning", that most of us were first exposed to in the Mandolin Construction Manual, instruct the reader to fix the plate to a rigid rim, and illustrates a fixture for doing this.

  33. The following members say thank you to Marty Jacobson for this post:

    sblock 

  34. #48
    Mandolin & Mandola maker
    Join Date
    Sep 2002
    Location
    Bega NSW, Australia
    Posts
    1,425

    Default Re: Tuner for tap tuning

    I am not going to argue about semantics, you are basically measuring the same thing (frequency of modes of vibration), just doing it in different ways. Is tap tuning better than nothing? Not really, because the correlation between taps on free plates and sound is poor. It is too crude. A tuner won't pick up the frequencies that are important.
    Peter Coombe - mandolins, mandolas and guitars
    http://www.petercoombe.com

  35. #49
    Registered User j. condino's Avatar
    Join Date
    Nov 2005
    Location
    Asheville, NC
    Posts
    2,758

    Default Re: Tuner for tap tuning

    One thing I think we can all agree on is that tappity, tappity, scratch, bend, flex, glitter sprinkling, & rubbing a (un-)lucky rabbit's foot all have one thing in common. They give us some kind of insight (real or perceived) that- hey- something is happening and I can at least rationalize it to be something positive rather than spending 150 hours (im-)patiently waiting to find out what the damned thing sounds like before I decide it sucks and light another one on fire!!!!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	DelayedLimitedGrouper-max-1mb.gif 
Views:	46 
Size:	374.3 KB 
ID:	198552  
    www.condino.com

    Crafted by hand in a workshop powered by the sun.

  36. The Following 2 Users Say Thank You to j. condino For This Useful Post:


  37. #50

    Default Re: Tuner for tap tuning

    Quote Originally Posted by j. condino View Post
    One thing I think we can all agree on is that tappity, tappity, scratch, bend, flex, glitter sprinkling, & rubbing a (un-)lucky rabbit's foot all have one thing in common. They give us some kind of insight (real or perceived) that- hey- something is happening and I can at least rationalize it to be something positive rather than spending 150 hours (im-)patiently waiting to find out what the damned thing sounds like before I decide it sucks and light another one on fire!!!!
    Right - I think it doesn't matter exactly what you do, what does matter that you do the same thing every time, and keep records of what you did. The more relevant and reproduceable the "things" you do are, and the better records you keep, the more useful they are likely to be. But whatever you choose to do will work for you after you build a few dozen instruments.

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •