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I just purchased a new 440 Hz tuning fork. But several different computer, iPad and iPhone tuners say it's almost half a percent sharp (around 442) of Concert A.

Is there any way to adjust the frequency of a tuning fork?

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Are you sure it's a 440 fork? It is not uncommon to find one pitched at 442. And I'm curious what others have to say, but I don't think it's possible to tune a tuning fork. –  Reina Abolofia May 23 '12 at 6:29
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personally, computer/mobile/tablets tuners have never accurate for me. have you try on the actual tuner? –  Phelios May 23 '12 at 8:52
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What iPhone tuner app did you use? –  iddober May 23 '12 at 11:26
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Certainly possible the wrong fork got in the wrong box. Or, manufacturing wasn't calibrated properly. Any number of human factors could have led to a improperly boxed fork or a bad batch. –  wadesworld Jun 5 '12 at 21:21
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There should be a frequency marked on the tuning fork itself. Trust that, not the box. –  slim Nov 17 '12 at 14:59

6 Answers 6

OK. I found a quick-and-dirty temporary solution.

As an online education forum suggested, a interesting school science experiment might be to see if adding weights and changing their position on a tuning fork will change the frequency of the fork. So I played science student, and tried the experiment.

Two big rubber bands on the tines clearly lowered the frequency... by way too much. Next I tried a couple strips of masking tape wrapped around the very end of the each tuning fork tine. That also lowered the frequency, by only a bit too much, to 20 cents flat. So I removed those pieces of tape and carefully measured them. Then I cut some tape strips about 9/29ths as long (actually a few mm longer). Wrapped the new lengths of tape on the fork tines, and the fork rang 3 cents flat. A little more fine trimming of the length of the tape with some sharp scissors, and I got the fork to measure within +-1 cent of 440 Hz, as measured against several calibrated iPhone tuners (both dial and strobe). The fork also now sounds good when played simultaneously with an mp3 of a 440 Hz tone to check for beats.

The tone probably isn't as pure, and tape will eventually age and wear, but this quick fix should work well enough until my next trip to a good music store for a better quality tuning fork.

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The position of the tape along the tines should also affect the pitch. They make adjustable tuning forks using this principle. fishersci.com/ecomm/servlet/fsproductdetail_10652_1618854__-1_0 –  Caleb Hines Jun 3 at 18:26

You could tune it up if you have precision tools that can grind off just the right amount of metal from each tine (this would increase the frequency; to decrease the frequency you would need to add metal!) - but practically speaking that means no, you can't do it.

Does it look damaged? If not it is probably supposed to be a 442 tuning fork. If you need a 440 you'll need to just buy one.

Update based on the comment that you had bought a 440 fork:

Take it back to the shop, get them to check it. If their check shows it is a 442 then they can replace it. If they show it to be a 440 then maybe your tuners are out.

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OP's comment from about a minute after you posted your answer: "The package said 440, which is what I wanted." –  jadarnel27 May 23 '12 at 13:31

It is defective. Return it for a refund. There is no practical way to recalibrate it. The reason people purchase a tuning fork in the first place is to get something that is exactly calibrated already.

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Interesting question! No-one's mentioned temperature, so far. I'm off to put one in the freezer and another in the oven! I'll report back!


Just got back from hospital with frostbite on one hand and burns to the other... but surprisingly the tuning fork stayed in pitch! My theory stemmed from the British Yard which lives in London. It is exactly a yard long at a given temperature. Longer tuning fork = lower note, shorter = higher, surely?

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LOL :D Did it damage the forks or alter the pitch? –  American Luke Nov 17 '12 at 21:15
    
Please register for an account to keep all your posts and privileges working! –  Matthew Read Jan 2 '13 at 21:00
    
What's 'an account' ? –  Tim Feb 27 at 11:16

As someone else stated, grinding off material from the end of the tines will increase the pitch.

However, grinding material off at the base bend of the fork will lower the pitch: there the material contributes much more to the fork's stiffness than to its inertia.

But it may well affect the purity of tone.

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A bit of solder at the tip would lower the frequency. But to get both tines exactly right, that's tricky to do.

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This is rather impracticable. First, few people have the resources to solder. Second, just getting that little bit soldered would cost way more than it's worth, and third, filing it down to the right amount would take forever. If you look at hotpaw2's answer, you can see how little needs to be added. –  American Luke Jun 2 '12 at 0:36

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