Summary: used to be the best, but PitchLab now leaves it in the dust!
Pros (in decreasing order of importance)
Sound output as well as meter (needle-type, cents deviation)
User-selectable reference note
Calibration by sampling external reference tone
User programable temperaments in steps of 0,1 cents
Selectable sound wave form:
sine, square, triangle, and sawtooth waveform (i.e. use sawtooth!)
Frequency display of the selected note in both sound and meter modes
Cons (in decreasing order of importance)
No manual entry of reference pitch values for notes other than A
Inaccurate reference display with user-selected reference note other than A
The default temperaments
Cleartune is very cleanly designed and easy to understand. The basic interface is easy to see and manipulate. My tests indicate that its internal frequency generation is very precise, especially compared to the Korg, which is an unmitigated disaster in this respect .
Two very important improvements have been made in the latest version of ClearTune:
1. The device no longer insists upon keeping A locked to the programmed reference pitch. In other words, if you have programmed your temperaments in an historically-informed manner, that is, with a constant C or F (0 cents deviation for this note), the chosen constant note will now indeed remain constant, and A will float (as the old German texts literally say: schweben) according to its programmed offset value. This is a major improvement, one which makes Cleartune eminently practical for Historical Performance Practice. But this is not all…
2. You can now calibrate the device to a sound using whatever note you want, so you can use ClearTune to duplicate the method ubiquitously described in 16th, 17th, and 18th century tuning instructions; take your C or F from a wind instrument (flute, oboe, bassoon etc.), and then keep that note constant no matter what temperament you select. What’s the value of A? Who cares! Not important!! The wind instrument is the arbiter, not some pointless abstract standard.
To use this feature, select the microphone just to the right of the “A4 Calibration” box in the info menu. Then select the note you want to remain constant, have your wind instrument play that note, select “Start” and wait for the device to sample the sound. When it has determined the pitch, it will display both the measured frequency for the specified note as well as the value of an Equal Tempered A in reference to this note. Click “Apply”, and you’re ready to Go Historic! The note your wind player played will be constant in all temperaments! Fantastic!!
For example, you have to tune a harpsichord at Cornetthon (approximately a half-step above modern pitch). Your reference instrument is in fact a cornetto (from which the name comes!) in C. Your cornetto player warms-up for a few minutes, and then gives you a C. You select the microphone calibration, select the note C, and then select Start. Cleartune listens to the note played on the cornetto and determines that the frequency is 277,17 Hz (on another day, in another room with a another temperature, it may well be different!). This translates into an equal-tempered frequency for A4 of 466,14 Hz, but this information is no real value precisely because A in all historical systems is not a fixed note.
You now select Apply, and Cleartune will maintain a constant C = 277,17 no matter what temperament you select! The frequency of A will float up or down as needed to meet the requirements of whatever temperament you select. In this case, I’ve selected Werckmeister’s Continuo temperament with a 1/5th Syntonic comma base (user programmed), and we can see how the frequency of A has been lowered while C remains constant – exactly as things should be!
There is a minor flaw in the App in this respect, however, is that the Calibration menu always displays the frequency of the Equal Tempered version of A only, rather than the actual frequency of the selected fixed reference note. This conceptual “bug” is but a minor irritation which is easily ignored, but the user must be aware of this false indication in order to avoid misinterpretations. Hopefully it will be corrected in a future version. (Note: the latest version has eliminated the A reference value from the pitch wheel page. The screenshots shown here were taken from the previous version. This is already a significant improvement in that it removes a possible source of confusion when using reference pitches other than A.)
Now for the negatives. The most bothersome aspect for use in historical performance situation is the inability to manually enter a frequency for a reference note other than A. You can, of course, lock the program to another value using the microphone calibration method, but it would be great if one could simply enter the frequency as well. For example, maybe you know that when the temperature is a bit on coolish side, your oboist prefers a C of 244. If you don’t have your oboist at hand to play a note for you, as it stands now, the only way you can tune at this pitch level is if you know the equal-tempered A for a C at 244 Hz.
By the way, here’s a handy trick to figure it out: simply multiply the difference between the standard value (261,6 @ A=440) and the desired custom C value by 1,68 and this will be the amount to subtract from 440 to get the new value of A. For example, in the example given here above:
261,6 – 244 = 17,6
17,6 * 1,68 = 29,6
440 – 29,6 = 410,4
If you manually enter 410,4 in the calibration setting, your C will be constant at 244 no matter what temperament is selected (that is, if your temperaments have been correctly programmed with 0 cents deviation for C!).
Additionally, the pre-programmed list of temperaments unfortunately appears to have been drawn from the writings of Owen Jorgenson, and the temperaments are labeled using Jorgenson’s quirky arcane names. No information is provided about the structure of the temperaments, and there is no way to view the cents deviation for each note, so if you don’t happen to have Jorgenson’s Great Red Tome, you’re screwed; there is no way of knowing what curious sort of temperamental beasts might be represented by “Aaron-Neidhardt”, “Almost-equal”, “Shifted Vallotti-Young”, “Homogeneous French”, “Early French”, etc. Luckily, the latest version of Cleartune now places the user-programmed temperaments at the top of the list, so the pre-programmed temperaments can simply be ignored. Even better would be to give the user the option to simply trash them, as they are undoubtedly programmed with constant A reference.
By far, the least desirable aspect of this program is also the least important, because it is something you shouldn’t be using anyway: the meter. While it is noticeably better than a Korg, it still has the drawbacks of all the various dedicated devices with meters: needle jitter, false readings, and slow response. Your ears are far more precise than any cents deviation meter can ever be, and the aural processing part of your brain understands and responds far more quickly to the changes you are making with the tuning hammer than your visual processing center can ever do.
Cleartune used to be the best solution, but it now appears limited and primitive when compared to PitchLab. I used to give it 4 3/4 out of 5 stars, but now that the bar has risen so much, I’d demote it to about 2 stars. Unless you have an Android or Windows device and can’t wait for the temperament capable version of PitchLab to appear for your platform, I’d say don’t waste your money.
Cleartune is available through the iPhone App Store or from the Bitcount website
Note: all reviews of all apps are kept up-to-date, that is, whenever a new version of the app appears, I check to see if any major changes, either positive or negative, have been made. Since iPhone apps are automatically updated, it is safe to assume that at any moment the review refers to the most recent version. The same holds true for the iOS version. Currently, I have an iPhone 4 and an iPad mini retina. Latest update: 31 July 2014.