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Thread: Final tuning - what do you listen for?

  1. #1
    Registered User fscotte's Avatar
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    Default Final tuning - what do you listen for?

    I find that fine tuning the mandolin in the white the hardest part of the entire process. Simply put, I don't have enough experience doing it.

    What things do you listen for or feel for when trying to bring out the best of the tone? Is there a particular string+fret that you play that helps steer you in the proper direction?

    As an example, I find that the G string at the 5th or 6th fret sounds too cold and hard when my back plate is too stiff. Consequently I find that the 4th string at the 4th to 7th frets sound too hard when the top needs sanding.

  2. #2
    Registered User Lefty Luthier's Avatar
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    Default Re: Final tuning - what do you listen for?

    Advancing age and less than perfect hearing have compelled me to depend on detailed spectrum analysis when making final adjustments to soundboard, nut and bridge fit. By using software overlays of a known near perfect instrument and the new one, it is fairly easy to determine where additional work needs to be done. This is not subjective judgement like hot or cold but does assure reasonable consistancy between instruments. I wish that I had started this method years ago since it removes most wishful thinking from the process.
    Byron Spain, Builder
    www.theleftyluthier.com

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    Registered User j. condino's Avatar
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    Default Re: Final tuning - what do you listen for?

    Byron:

    What software are you using for your analysis? The ears do play some tricks on all of us as we get older; some of my best customers seem to be half deaf old geezers. I can't imagine what they are hearing compared to a 16 year old.

    I'm headed over to the VSA Oberlin acoustics workshop in June and pretty excited to see how the folks combine cat scans and the rest of the Strad3D type nerdiness into hard data forms applied to instruments.

    These days, I string all my instruments up in the white with no soundholes and just a rough, oversized neck. The neck gets hand shaped while strung up over about a week of playing. After that, I may keep it strung up for a month or so, gradually playing the instrument and slowly opening and then enlarging the sound holes until one of two things happens: either things get so close to what I'm after that I'm afraid to go any farther or I just sneak past the window a tiny bit. I tend to keep the top dimensions pretty specific and constant, but the back will get thinned and worked to final specs during this process too.

    No matter how it s done, there are compromises throughout the spectrum that show up in certain zones. In the past I struggled with consistency of tone; taking an extra bit of time and working through things slowly has helped tremendously. 'Manageable with smaller outputs each year, but unrealistic if you've got a $100k bank loan on a big fancy piece of machinery ( or several ex-wives) and you are trying to crank out 30 instruments a year.....

    j.
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    www.kaybassrepair.com

  4. #4
    Registered User Lefty Luthier's Avatar
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    Default Re: Final tuning - what do you listen for?

    What software are you using for your analysis?

    I use Strobosoft for the initial collection of data that is fed into a portable hard drive that records a 30 second sine sweep from 75 to 300 Hz generated by either a software algorythm or my old HP sweep frequency oscilator and recorded from three accelerometers (one on the bridge, one on the tailpiece and one on the peghead). I then play that recording back through a filter that uses the acoustic standard as a negative input. This is the same process used to stabilize TV cameras on news helicopters and on commercial aircraft PA systems to cancel out boundary layer noise. The difference comes up on the screen as discrete frequency vs amplitude difference that can be either freeze frame recorded or just displayed on my laptop while in the shop. I have learned over the years how to roughly adjust the structure to modify the vibratory response but it isn't a perfect solution, more a cut and try exercise. But the final result is pretty dramatic.
    Byron Spain, Builder
    www.theleftyluthier.com

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    Registered User j. condino's Avatar
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    Default Re: Final tuning - what do you listen for?

    I'm currently not using anything that does a spectrum analysis; that is a big reason why I'm headed to the VSA Oberlin acoustics workshop. I've seen a bunch of it used in combination with cat scans over at Nugget's place and the results were very interesting. At this point, I'll pretty much follow anything Mike tells me! He gets incredible results and consistency.

    I believe the work at Oberlin uses Audacity for their software.

    j.

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    Registered User Tavy's Avatar
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    Default Re: Final tuning - what do you listen for?

    Lefty, what do you feed the output from your frequency generator into? It would be nice to have a solution that doesn't involve blasting the thing from a speaker (not household friendly!). I've tried using piezo elements to drive the top - but they don't chuck out enough power for the job - feels like something that would drive the top in the same manner that the strings/bridge do would be the ideal solution though?

  7. #7
    Registered User Lefty Luthier's Avatar
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    Default Re: Final tuning - what do you listen for?

    Quote Originally Posted by Tavy View Post
    Lefty, what do you feed the output from your frequency generator into? It would be nice to have a solution that doesn't involve blasting the thing from a speaker (not household friendly!). I've tried using piezo elements to drive the top - but they don't chuck out enough power for the job - feels like something that would drive the top in the same manner that the strings/bridge do would be the ideal solution though?
    Unfortunately, I have found the best results with a speaker. I too have tried other methods of excitement but found them lacking.
    Byron Spain, Builder
    www.theleftyluthier.com

  8. #8
    Adrian Minarovic
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    Default Re: Final tuning - what do you listen for?

    Quote Originally Posted by fscotte View Post
    I find that fine tuning the mandolin in the white the hardest part of the entire process. Simply put, I don't have enough experience doing it.

    What things do you listen for or feel for when trying to bring out the best of the tone? Is there a particular string+fret that you play that helps steer you in the proper direction?

    As an example, I find that the G string at the 5th or 6th fret sounds too cold and hard when my back plate is too stiff. Consequently I find that the 4th string at the 4th to 7th frets sound too hard when the top needs sanding.
    I will steer back from spectrum analysis to practical approach. I (being math an IT type) do know pros and cons of the analysis but foun them very impractical unless you have very large database of sampled/measured instruments etc. I've used Cool Edit Pro for analysis.

    I'd tell there are several steps:

    1. play and listen carefully to tone (and feel) of many (hundreds) of instruments and compare them to good and bad instruments to develop ear for what tone contains (don't listen to folks'descriptions, someones good bass is just plain tubby for someone else etc... very subjective) This may take several years. Don't forget to notice type of strings (material, age) and action/setup so you'll learn how action and strings type of bridge etc. affect tone.
    2. If possible take measurements and look inside. Notice arch shape (develop eye for "flat", "full"etc. shape of arch) style and depth of recurve (does it go around top or ends near point/scroll?), neck angle, notice thickness of top (at least at adges of f holes) and thickness and position of tonebars (dentist mirror or your pinky if it fits in the f hole). Notice woods especially cut and species of maple (softer vs harder, quartered/ flatsawn) top species (redwood vs. red cedar vs spruce - Engelmann, sitka, European, red - MAY indicate stiffness and density of top)
    3. Notice deflection of top vs f hole edges (may be unreliable on others'instruments just warped due to humidity etc...) I like to press top and back lightly with thumbs where tonebars end on both sides. Feel if it is stiff of deflects with very light pressure...
    4. Notice everything else you can that I didn't cover in 1-3 (thickness of finish comes to mind - often visible in dents/ scratches or edges of fingerboard- but don't get fooled by looks alone, thin finish may look deep), read books on acoustics but be aware that there's tons of BS on internet as well as paper. There's no instant recipe for good tone...

    5. Build your mandolins consistently - don't change too many things from one build to another, best if you stick to one good model and try to copy the main features of that. Don't build too light, there are well known typical sizes/thicknesses for given type of instrument and rather stay a bit thicker.
    6. Once instrument is strung up in white, let it settle for few days 5 or so (there's dramatic change in first hour and gradually smaller in firt day) don't let the strings go dead while you're working (clean them or replace if you notice them going dead). Always try to set up instrument to the same initial specs. Compare your tone and specs to instrument in your database (your brain) and evaluate sound. Play it up and down the neck hard and lightly... I write thickness of top/ back on the outside before gluing up the box.
    7. Generally, removal of wood will bring out bass and if gone too far may start reducing trebles. Try removing wood from different areas and listen for changes. I use thin scraper (0.3mm 3x4" with one side rouded to elliptical curve) with honed square edge and very little burr drawn so it cuts both when laid flat and used normally. Don't remove more than 0.1mm at onne step and play instrument before and immediately after. If you ar enot certain, don't continue. Don't expect huge changes in tone, more like balancing the sound. If the tone is really wrong there must be something wrong with your construction. Basicly, if you copy Loar very closely, your sound should be in the ballpark.
    There are some hints on tuning in one of my old posts (outside tuning) from few years ago... search MC
    I think your ears are not really concern unless you are really impaired (you should continue evaluating instruments and adjust your ears as you age and not try to get now the tone you heard 40 years ago)
    Best,
    Adrian
    Adrian

  9. #9
    Mandolin & Mandola maker
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    Default Re: Final tuning - what do you listen for?

    Very good advice Adrian. I would just add, (1) change one thing at a time, and (2) use a reference instrument. It is well known that the brain has a short audio memory so a mandolin with known characteristics you can refer back to is essential.
    Peter Coombe - mandolins, mandolas and guitars
    http://www.petercoombe.com

  10. #10
    Registered User David Houchens's Avatar
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    Default Re: Final tuning - what do you listen for?

    I think think the reference instument as a "standard" is very important. I'm still tring to hold onto one. A great tool.

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