tap tuning w/strobe

[Martian]

Hi. First let me say that I am a newbie by any measure. Both as a builder and as a user on this site. I have completed 1 A model, 2 F models, and have a third F almost ready for assembly. I am having an awful time reaching Siminoff's target tuning for bars. I even had one read higher on the bass side, which I had to remove and start over.I own a Petterson 490. I also have all the printed materials I can find by Roger. Also I have two local builders that I can turn to however they both believe doing anything to the tone bars besides shaping them like the picture is pure voodoo. In fact one went so far as to ask me if I threw bones on the floor and tried to interpret them. Big laughs there. I need someone to help me in finding my alternatives when the "target tunings" don't just end up right. Too thin, too thick, bars in wrong spot? In any case I love this forum, ( have leaned much already), and I really appreciate all of you for your unselfish help to others.

[Lefty Luthier]

You mentioned having a Peterson 490 but not that you are using a compressor. It is nearly impossible to tap tune without a compressor and takes tons of practice even then. One major thing is that the soundboard must be edge constrained to get an accurate reading. Contrary to Siminoff's suggestions, I find it better to use a fixture that clamps the soundboard edge than gluing it to the rim. I suggest that you practice on a test board before damaging more tone bars. Just a wild guess but if you have not uniformly trimmed the flex area just in from the rim to 0.125 or a bit less, tap tuning will be a waste of time. If you have access to a laptop computer, buy the Peterson tuning software, it has a lot of options that the strobe doesn't.

[buddyellis]

I think you're going to find that most of the luthiers think tap tuning in general to be a waste of time -- at least tuning to 'specific notes' anyway.

[billhay4]

Forget it. Make it sound right to your ear.
IMHO

[labraid]

Learn to tap the free plate.
You won't need any devices but your ear.
There is no hard and fast, it's all intuition baby.
There can be specifics even in intuited methods.
You will have to learn what they are, and what they're not, over time.
No one's going to give away a golden goose,
But they may sell you feathers.

[Gail Hester]

I’ve found that I get real close with F-style instruments by ear but have started using Roger’s method recently with all the equipments he recommends. I have to say I like the results and until I become the smartest luthier in the world will continue to try to have an open mind about these things. I can’t think of any negatives or reason not to experiment with tap tuning. I’m certainly not willing to summarily dismiss the guidance of a person that has done so much to teach a generation of builders and who has forgotten more than most of us will ever know.

[Lefty Luthier]

I could not disagree more with those who think tuning by ear is better. I routinely get with 3 cents of perfect tune on both tone bars and when voicing the completed mandolin. That skill is what separates the true professionals from wannabes. Keep trying, it comes with practice. I have been at it nearly 50 years and am still learning.

[Roger Skipper]

I used to drive myself crazy trying to tap tune; whittle away, whittle away, check my hearing aid batteries, then replace the bars. Not until I built a deflection gauge that measures the actual deflection--thus stiffness--of the top under weight, did I come to peace with physical tuning. The old Loars, from what I understand, were all over the place with tap notes, but were very consistent with deflection under load--a balanced .028 deflection on both bass and treble sides under 25# of down pressure evenly distributed on the bridge feet. An old AMERICAN LUTHIER magazine (I don't know the issue, but could find it if anyone needs it) shows a mechanism to measure the deflection.

I've also been doing some editorial work for The Guild of American Luthiers, and I recently transcribed a lecture given by Dana Bourgeois in which he details his theory of not tuning to a particular pitch, but tuning to eliminate dead spots and phase cancellations.

I don't know if you recall your Physics 101 classes, or if you had a wave generation display, but the effect is this: two sources of vibration create separate waves; where they support one another, the waves are twice as high; where they conflict, the water is calm amidst the storm. The calm is where we, as luthiers, don't want to go. Look for the article soon.

Roger Skipper
www.skipperstrings.com

[buddyellis]

Not to start a war but this subject comes up multiple times a year, and I think you'll find there are plenty of professionals on here that think tap tuning to specific notes is a bunch of hoodoo. They may not chime in here this time because this is a well-traveled subject, but if you do a search you'll find that more of the pro builders say that they DO NOT tap tune to specific notes than say they do. Some wood defies being 'tuned' to a specific note. If you want to tune plates read up on chandli plate tuning or deflection measurement. For the first one, forget about it, just carve to spec.

http://www.mandolincafe.com/forum/sh...t=plate+tuning
http://www.mandolincafe.com/forum/sh...t=plate+tuning
http://www.mandolincafe.com/forum/sh...t=plate+tuning
http://www.mandolincafe.com/forum/sh...t=plate+tuning

Just build the thing.

[sunburst]

I tried tuning to the Siminoff notes early on, was successful a couple of times, unsuccessful more times, and eventually abandoned the process completely and started just carving by feel and by sound; tapping, listening, flexing, listening to my tools cutting the wood, but always keeping track of the measurements to stay within "normal" dimensions. I continued to record the notes that I got when I "bonked" the bars, though, and as I got more consistent in my mandolin building, guess what?, the notes were starting to end up about the same every time. They're not Roger's notes, and I don't try to tune to them, but they're pretty consistent these days.

I fully believe that there are almost as many ways to carve tops and backs and tone bars as there are luthiers. Some tune by ear, some with electronic equipment. Some deflection test and some feel the flex, some just measure and work "by the numbers",...it's all good. Whatever works for you. Find what that is and develop that!

[labraid]

John, forgive my repetition, but "Amen".

I use chromatic tuning forks (John Walker) for reference work. You can hear and judge the tone differentials by the same reverberations you use to tune strings.

[Lefty Luthier]

One thing that I have not seen mentioned is thickness control of the flex ring. I have found through many frustrating tries that uniformity of the flex ring is the key. I never use spruce that has less than 12 rings per inch, hold the soundboard up in front of a bright light and check for light penetration through the ring and carefully sand for uniformity before putting the soundboard in my deflection fixture. For a sharp bark, I put 30 pounds of load on the bridge point and adjust the ring for 0.030 inches of deflection. Then and only then do I commence to tap tune the tone bars.

[Yellowmandolin]

One thing that intrigues me about all of Siminoff's work is that I have never seen one of his instruments. Has anyone played a batch of his mandolins to see how they sound and if his method of tap tuning produces consistent results? I am not meaning to stir up trouble, just curious...

[Lefty Luthier]

Siminoff's instruments are OK but in my opinion not world class. Compared to Stan Miller and Lynn Dudenbostal, they come in way back. Roger's real contribution is his writing, his handbooks are a true gift to us all. When you build many mandolins, you occasionally get a real winner or a true dog so one must be very careful if you are evaluating a sample of one. I have built more than 100 mandolins over the past 50 years and if I had stopped with #22 back in 1972 I might be more famous since that instrument is truly a masterpiece. Unfortunately, we keep building and just try our best to make each instrument special.

[Yellowmandolin]

Lefty, I guess I was more curious about consistency. They may be just OK, but were the ones you played similar sounding? There are builders who are able to build instruments that sound the "same" from batch to batch, as Collings seems to be able to do. If Roger was tuning each instrument to the "right" notes, according to his method, they should be all be about the same sounding, right? Was that your experience?

[Lefty Luthier]

Yes, the two that I tried were both quite consistent. I have found that one thing he must do is set his strobe to A430 rather than A440 as most others do. When I do that, mine sound similar to his, not necessarily better, just different. The real key, in my opinion, is soundboard flex ring consistency all the way around. The only way that I have found to do this repeatably is to hold the soundboard up to a very bright light and sand carefully until a clean ring glows through.

[labraid]

Talking A440 and flex rings sounds so much more intriguing and concrete than artists flailing their arms in fits of animatory jubilation. These forums really do favour the lefties among us -- we need some new emoticons. May I suggest the Léo Ferré smilie...

[Geoff B]

My issue with tap tuning (or anything) as a sole criterion is the 'one-size-fits-all' undertone (pun! ha!) of it all. Kind of like buying a suit from Target, vs. one that has been fitted by a tailor--may fit may not vs. will fit. There is no reason not to try and quantify as you go and keep records, but to say from one luthier to another that X must be something, and Y something else just rings (ha!) illogical to me. I finally have 4 instruments around that are all very similar in sound and have found my own sort of intuition based on many levels (flex, tap, deflection, thickness, the light test, etc.). It is almost as general as asking "what's the best mandolin tone?" Different strokes... Some of the best advice I ever received was just to "keep building".

[Timbofood]

Nice analogy, Geoff! Sooner or later the tailor gets it right but, it is most often with several "Fittings"

[Lefty Luthier]

Building mandolins on speculation for sale gives one the flexability to play whatever games one desires with tuning, finish, trim, etc. But when you build custom for a specific and demanding customer, being able to exactly fit their expectations requires a different level of technical discipline and repeatable processes.

[labraid]

Folks will be happy to agree with you Lefty, if you don't qualify your point with the need for guages and readouts and machinery to find "the zone". Hey, "magic" is nothing more than using a well practiced set of skills to accomplish things that the viewing public cannot grasp. Now put a big machine on stage, and get a rabbit to vanish night after night with that, you've accomplished the same goal -- just in the context of scientific repeatability. There is also a fuzzy line of where science ends and where "the art" begins though. It's no use saying that folks who tune by ear are highly questionable, it's just that your ears aren't up to snuff. My physics ain't up to snuff (ain't that right Dr. C!), so let's not intrude on each others territory if we could...

[Lefty Luthier]

Regretably you are correct about my hearing. At 70 my ears ain't what they used to be. If it weren't for a spectrum analyzer, recorder and computer, I would likely have to hang it up.

[labraid]

Well I'm very happy you haven't Lefty! Keep up what you're doing, no one here's critical of your method. We just don't want to hear critiques of our own... unless they are very precise, not general, and lead to some positive discussion.

[laddy jota]

To build consistency into mandolins is a great accomplishment for any builder but it is also pleasing to build mandolins that sound different. If you understand why they sound different, you have mastered the craft.

[Lefty Luthier]

The real challenge is to record a scale and several key chords and then replicate that sound exactly in a new instrument. I can occasionally get very close but such things as moisture content of the soundboard, lacquer thickness and tailpiece flex are very tough variables to overcome.