Hi Dmitry,
as promised, I filmed a video for you wherein I tune my 10" tom to your personal tuning values for your drum, as shared in your email to me.
It's a quite long movie. First, I explain how I get stable lug pitch detections. (... and I go on about that.)
I figured this type of interference may have been what you referred to, so that's why I spend so much time on illustrating it.
At some point in the movie I show, on 2 different TB's, and also on the app, how sometimes you can detect the fundamental tone instead of a lug pitch while hitting near a lug.
This phenomenon occurs when the drum heads are tuned in a way whereat the fundamental tone is so 'present' in the drum sound, that even a hit near the bearing edges excite it sufficiently to show up in the readings.
In such a case, you can see that the app, and also the TB's, will sometimes display a reading of the fundamental tone, instead of a lug pitch.
Whether it happens or not, just depends on the specific tuning of the drum.
As soon as the fundamental tone is too preset in the sound, you'll risk that it interferes.
(In Drumtune PRO, there's preset tuner mode, with a CENTER/EDGE switch that solves this type of interference.)
In drum tuner EZ, if the fundamental tone interferes and thus prevents the app (or a TB) from reading a lug pitch successfully, you can mainly do two things to get perfect lug pitch readings all the time.
Here they are:
1) Just detect a lug pitch from a lug that gives a good reading and press 'set'. Now, the app will prevent the fundamental tone (and also higher order overtones) from being detected, so that you can successfully detect the lug pitch of lugs that were previously showing a reading of the fundamental tone. (BTW: On a TB, you could use the same approach and then press its 'filter' button. That way, with the filter mode activated on a detected lug pitch, also a TB won't suffer from an interfering fundamental tone anymore, and it would also display the lug pitches correctly.)
2) Alternatively you could 'mute' the fundamental tone physically. To do so, simply place the drum on a flat surface. Now, the fundamental tone can't be produced by the drum, thus there's no more risk of it interfering with the lug pitch readings anymore and you'll successfully detect the lug pitches. You can combine solution 2, and 1 as well to further eliminate higher order overtone interference.
Only in the mid of the vid or so, I started tuning the batter head to a lug pitch of 210 Hz, and the resonant head to a lug pitch of 275 Hz, which were your values*.
Those resulted in a fundamental tone of about 139 / 140 Hz, really close to a C#.
Note:
*Those values are not remarkably giving you a nice tone, and nice decay. That's because of how they proportionally relate with the fundamental tone, and with one another in a consonant manner. Their ratios (B/F= ~P5, R/F = ~P8, B/R= ~P4) are following rather consonant intervals that introduce some harmonics in the timbre, and beat frequency which are promoting the perceived tonal harmony in the timbre and our (psycho-acoustic) perception of definite pitch in the drum sound.
Keep in mind that such a tuning sounds much different when captured/heard from above the heads, than how it projects from the sides of the drum into the surroundings.
I may make another video showing you that aspect, later on, if I find another moment to make it.
You can see me tune to your values.
During that fine-tuning process nothing of interest occurs.
I follow the tuning flow, exactly like how I would do it normally.
At least, you can see me use 'set' target, and/or refresh it and set it again when needed.
Perhaps it's still interesting to observe, and you may get some insight by what I tell while tuning.
(FYI: It's a DIY drum, with cheap hardware that I recovered from a entry-level kit. I sanded the bearing edges manually. They are not as perfect as machined ones, and thus the drum fine-tunes a bit less fluently.)
The tuning goes relatively smoothly, nonetheless fine-tuning that drum with those heads to 1 Hz accuracy takes a couple of minutes per head to get it really right.
In general, fine-tuning a drumhead to a specific lug pitch and clearing it with a precision of +/- 1 Hz, is obviously more time consuming than clearing to a precision of +/- 2 Hz.
Still clearing with a tool beats me tuning by ear to that same degree of precsion.
Of course, you decide for yourself how precise your drums must be tuned, before their sound serves your needs.
If you're fine with a drum sound coming from a head that's cleared to lug pitches in each other's ball park range instead, you can also stop earlier with fine-tuning.
Overall, I hope it helps to clarify stuff. If you have any further questions, please feel free to ask'm by email.
I stay put!
Best regards,
Bram