Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Electronic tuning forks

Hi,

I'm looking to purchase an electronic tuning fork. I've done a little Googling, but I'm not finding what I want.

Ideally, the fork would be accurate to 5 "sigfigs", i.e. 440.00, 442.00, 435.00, as well as for C. Also, it should be capable of emitting a tone that I can use to tune by, as well as calibrate an ETD.

Also, nothing that will break my bank account.

This isn't a big deal. I just thought that if any of you had encountered anything like this. you could point me in the right direction.

Thanks.
-Joe

Electronic tuning fork? New one on me!

The late Dr. Albert Sanderson designed the best electronic fork I know: the Accu-Fork

see here: Inventronics

It can be set to A4, A#4, B4 and C5.

It's not cheap, but one can't have it all at once!

BTW, he's the designer of the Accu-Tuner, one of the best ETDs available today.

One issue to keep in mind in any electronic replacement for the tuning fork, like the Accu-Fork, is harmonics. A real tuning fork has almost no harmonics, which makes it very easy to hear the proper beat with the fundamental of A4. But many electronic tone generators generate a square wave, which has a very strong 3rd harmonic. This 3rd harmonic beats with the 3rd partial of the piano note A4. And since the piano note has inharmonicity and the electronic tone does not, this beat will not go to zero at the same tuning where the fundamental beat goes to zero. This could confuse you. Now it is possible to train yourself to listen for the beat at 440 and ignore the beat at 1320, but it will be a challenge. If you really want an electronic tone generator that can replace a tuning fork, then make sure it is a pure sine wave generator.

Another way, instead of learning to ignore the third partial, is to listen at the beat rate of F2 with the fork and with A4.

This beat rate is produced by the fundamental of A4 (and the fork) and the 5th partial of F2.

You can take also B1 instead of F2, in this case beats are produced between the seventh partial of B1 and the fundamental of A4 (and the fork).

I have one of Dr. Sanderson's originals called the "Hale Electrofork" sold by Tuners Supply of Boston. It remains accurate after 35 or so years. Set to A-440. Comes in handy sometimes. Grand kids love to play with it. Great teaching aid for kids.

Nowadays it's pretty trivial to download some free audio editor software, generate a 440Hz sine wave, and put it on your mp3 player or wherever.

Kees

Good point!

I can use my iPack as a reliable pitch source.

Make sure to calibrate with some (calibrated) ETD as these devices are not completely accurate. Just measure the cent offset and then generate a sine wave with this offset.
I've never seen any that are off by more than a cent, but you never know.

Kees

Hi Loren,
Yep. They exist

I see the AccuFork goes for around $165. Reyburn Cybertuner has an A fork for around $99.

According to their respective web-sites: The guaranteed accuracy of the SAF II is superior at room temperature, being within one half a cent at A-440. http://www.accu-tuner.com/AF.html

The Reyburn Cybertuner site states: CyberFork A440 calibration pitch source (+/- .01 cent to N.I.S.T) http://www.reyburn.com/rctstore/rctstore.html

Maybe the AccuTuner has features not available opn the CyberFork? I'll look intop this. Thanks, Rafael.

I thought that there might be others out there that I was not aware of.

Dr. Scott,
I was not aware that it might output square waves + other harmonics.. Thank you! I will inquire about this when I decide.

Steven, I know that Dr. Sanderson’s products have a very good rep for durability. Even so, that’s really impressive for a piece of electronics to still be dead on after 35 years!


Hey Kees and Rafael,
You could use it, but be careful. You need to verify the accuracy of your soundcard. On my last PC, I used Audacity to output a sine wave to check my forks. I used my Verituner to measure the output. I had to have Audacity output 440.376Hz in order to output an A440.00 sine wave that would fluctuate +/- 0.01 cents. http://audacity.sourceforge.net/download/


Edit: Kees,I guess we posted at the same time about verifying your soundcard

It's more the hardware of the playback device than the soundcard that needs to be corrected. If you can tune to 0.01 cent error you should write a book about it.

Kees

Use a handheld digital voice recorder to record the NIST standard over the phone. 440 and several other pitches can be recorded and you will always have a highly accurate reference tone. Google the subject and you will find a reference chart for when they broadcast the various frequencies every hour.

Unfortunately record and playback speeds are not guaranteed to be the same on some "handheld digital voice recorders".

Kees

The chart is also at Tunelab's website in their iPhone app help file.

I guess once I have stored a calibrated tone my iPack will always output the same correct pitch, won't it?

I mean, it will be stable, it won't change with temperature, moisture or anything else.

Correct. It may be simpler (unless you want to take the PTG tuing exam) though to just use the free demo version of tunelab to set A4 (or C4) and take it from there.

If you do insist on having an aural pitch source, tuning fork or electronic, what I found to work most accurately is to have a 444Hz and a 436Hz source, and make A4 equal beating between the two.

Kees

lol!

The output through my speakers would fluctuate to between +0.01 to -0.01 cents according to my Verituner. There was a slow waver where the pitch would go between +0.01 and -0.01 and back again.

I'm planning on purchasing the VT software for netbook. Since the VT is accurate to +/- 1/100th of a cent, I want to use the most accurate reference possible for setting the offset. I know I could use the phone and NIST. But, I keep picturing myself getting flustered and having to wait another hour or half-hour or whatever it is for the pitch to come around again.

Edit: Then again, it was a while ago. Maybe it WAS +/- 0.1 with Audacity.

A question to Mr. Robert Scott:

The tone generated by TuneLabPro has to be calibrated?

I´ve read in the manual that the audio has an input and an output, does that mean that we have to calibrate both?

Is it a sinusoidal tone?

Yes, this was a surprise to me when I first found out that some sound cards used separate crystals for sound-generating and sound-listening. I could think of no good engineering reason why they should be separate, but experimentation showed that input and output calibration were sometimes measurably different. If you don't do an output calibration on TuneLab, then it will assume the input calibration can be applied to the output as well. And in most cases that will be just fine. And of course it doesn't matter at all if you don't use the output tone. But if you want to be absolutely sure the output sound is correct, it should be calibrated too.

And yes, the output is sinusoidal. However playing that output through cheap speakers or at a high enough level to cause distortion will make it non-sinusoidal and thus create those undesirable harmonics.

Verituner has no tone generation. I suppose the fact of including an aural element in a visual device seemed unnecessary.

But, for learning purposes, to show clients their pianos are at 440, and many other issues, I believe it was a good idea to include this tone.