Six years ago, tap tuning was a big "secret" and many builders thought it was a lot of bunk. Luthiers read that Gibson performed tap tuning on its heralded F5 mandolins under the guidance of Lloyd Loar and that legendary violin makers were masters in their tap tuning, but the lack of information about the subject shrouded tap tuning in secrecy. When The Art of Tap Tuning was published, luthiers were slow to adopt the process, but now it is well understood; manufacturers like Peterson make equipment for it, and the true art of tap tuning is well on its way to being commonplace.

Questions still abound, and I get a regular flow of emails and calls from folks regarding tap tuning. I would like to share some answers to a few of the most common questions.

What octave?

Many folks wonder about the octave they are shooting for and my typical answer is "don't worry about the octave." I go on to say that if you are an octave too high or too low, the part will be so ridiculously thick or thin that you'll know about it long before you tap tune it. Listen for the note - don't worry about the octave. Whatever note shows on the strobetuner or on Strobosoft will be the right one.

I can't get to an A#.

If you have tried to tune a soundboard or backboard and can't get to the target notes, first use your judgment about whether the board or tone bars are the right size. If they are, go to the next nearest note you can arrive at. Just make it a whole note that is neither zero cents sharp nor flat.

I don't get the C=256 thing.

There are 12 notes in the musical scale and each note has a specific relationship to the note above it and below it. Today, concert pitch tuning is based on A, but at one time the concert pitch was based on C. It could have been any of the other 11 notes, but C was selected. So, if one knew the frequency for C, one knew how to adjust all the other notes to be in the proper relationship to C. But C was really a clumsy note to use, especially for the grand orchestras where the violinist was selected to sound the first note for all instruments to tune to. The choice fell to the violin's open A string, and the world's orchestras agreed on concert pitch being based on A rather than C. And, when A is 440Hz, C is 261Hz. However, when Lloyd Loar was specifying the tunings for the bodies of F5 mandolins in the mid-1920s, C was then 256Hz, not 261Hz as it is today. (A=440 officially became 440Hz in 1971, 28 years after Loar's death.) To make a long story short, using concert pitch C=256 sets all 12 notes of the scale to be one quartertone off from the notes of the A440 scale, and this is a good thing for tuning the body parts of instruments. In this way, the air chamber and body will resonant equally for all notes played and not pop or be overbearing when playing a specific note of the A440 scale.

No matter what I do, the note does not change.

This is usually the case of tapping too hard or having the microphone too close to the part being tapped. The microphone will get overloaded if you are too close and you will just get a lot of noise. Hit lightly enough to just evoke a tone, and work about 2' to 3' from the microphone.

I'm not really clear on how to set up the Peterson 490 strobetuner or how to use Peterson's Strobosoft.

There is a free download instruction document (written by me) for each of these units on our web site.

I keep getting different readings with Strobosoft.

Peterson's Strobosoft is VERY sensitive and will most likely give a slightly different reading in CENTS each time you tap. This is because it is very difficult to tap in the exact location with the same intensity every time you tap. Being accurate and consistent in how you do this is very important. However, you should be using the Strobosoft Tap Tuning function and set the "averaging" selector to anywhere from 3 and 5 taps.

I'm removing wood from tone bars but don't see a change.

Each removal of wood should reveal a change in the frequency of the part. As you remove wood from a brace or tone bar, the pitch will drop (i.e., frequency will get lower). However, this will only happen if the soundboard is supple enough to be sensitive to the change you have made. Here is an extreme example: If you have soundboard that weighs 5 pounds (i.e., very stiff and very heavy), and you remove a 1 ounce shaving of wood from a tone bar, the relative change you have made to the soundboard is very small relative to the mass of the wood, and the frequency/pitch change will be minimal. On the other hand, if you have a soundboard that weighs 2 ounces (another extreme) and you remove the same 1-ounce shaving from a tone bar, you will have changed the soundboard's mass by 50% and will see a huge change in frequency/pitch. So, sometimes you will see a small change because the entire soundboard is still too heavy in which case you need to remove wood from the soundboard. In the case of guitar soundboards, you will only recognize a change in pitch once most of the braces and tone bars have been reasonably lightened.

I've done everything you said, but the note still doesn't change.

Background noise can be your worst enemy; if you have a refrigerator, air conditioner/heater, fan, loud fluorescent lights, or other ambient noise in the shop, Strobosoft will hear it. And in some cases, it will overpower and/or interfere with the signal. Several months back I was demonstrating Strobosoft at a luthier association meeting, and during our tests I kept getting the same reading. My associate Ken said that he thought there was too much noise from the air conditioner. Sure enough, when we had the AC shut off, our readings stabilized!

There are two pitfalls that rear their ugly heads when spraying the finish on a mandolin: the dust that is inside the instrument that finds its way outside when spraying (yuck), and any over-sprayed finish that finds its way to the inside of the instrument.

Many guitar makers have tricks to seal the air chamber of their instruments; some use balloons, and others - like Martin - use plastic cups held in place by sponges. The mandolin's irregularly-shaped f-holes make it a bit more difficult to seal easily, unless, of course, you simply tape them shut from the inside.

You can easily prepare some blue paint-masking tape by using one or two little pieces of tape as a handle. Position the tape sticky side up, attach the handle(s), push the tape into the f-holes and then when it is all inside, pull it back up so that it sticks to the inside edge of the f-holes. If you are unsure of how well it will hold, you can fabricate a small piece of wire bent into an "L" shape, stick it into the f-hole before you pull all of the tape up, and use it as a stick from within the mandolin to push the tape to the inner surface of the soundboard.

It works well, it is really easy, and it costs practically nothing.