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What is the biggest deviation a unison can have to be considered out of tune?


martin

I think a unison is either in tune or it's not. Unless it's perfectly clean, it's out of tune. Very slow roll? Out of tune.

From the perspective of the PTG tuning exam, being within one cent in the midrange gets you "no deductions" from the exam score. More than that, and you lose points at a rate of 2x the number of 1-cent errors.

Which is not to say that's good enough for practical purposes, but it is something to measure by.

It depend on who's askin' so I looked up your profile. My answer to a tuning student has to agree with your initial answers... Zero Tolerance. In fact, for a note that only lasts 5 seconds an advanced tuner can sense that there is a beat coming in the 6th or 7th second and tune accordingly even though the beat will never be heard. The possibility of a beat can be sensed immediately after the initial attack. a really skilled tuner can use this to advantage and vary the quality of a beat free unison.
Now. In the real world, most peoples experience of live piano music is on a piano that is out of tune to some degree and it is my guess that you are really asking what that degree is. One of my contracts is to look after many pianos in a limited time and, in the times when the weather is changing I have to make this judgement call every day in establishing my priorities. It might be thought that my experience of this might produce an answer to your question but, in all honesty, i don't make these decisions in terms of beats per second but on general first impressions.
Early in my carreer as a recording technician on constant attendance over several days of recording, I once heard a general enlargement of tone In the monitor speakers as the piano drifted slowly so I left it that way. Suddenly, the piano began to sound merely out of tune. That lesson was learned. I was discussing this phenomenon with a more experienced colleague and he told me to always keep the tuning clean in these circumstances so that any slight drift is to my advantage. Of course, I am speaking of subtleties that are not noticed in home tunings not under the scrutiny of a microphone. I do know what you are getting at but it is so subtle that I cannot express it in terms of beats per second. It will also very with the accoustics, the voicing of the piano and the tolerance of the listener. Just concentrate on tuning unisons as clean as you can and youwill find that the delicate motor skills you develop in making tiny changes will help you to develop a more and more solid tuning. They go hand in hand.
I wish you well in your endeavours.

Of course when you tune a unison to zero tolerance it will stay there for only zero minutes.

Can we come up with something like "the time between beats should be less than a factor x of the duration of the note". Maybe x = 8? In that case assuming A4 will sound 5 seconds an accuracy of about 0.1 cent is required. Does that sound reasonable?

Kees

I don't think it does; I think it sounds complicated! I think "the note should have 0 beats in it" sounds reasonable.

But that is impossible.

Kees

It's impossible to tune three strings so that they are all at the same frequency?

edit: and all those years, I thought I was putting pianos in tune...

Kees, so, by extension would a unison that beats once every 6 years stay there 6 years? I'm being silly but I take your point. I once saw a sign that read 'absolutely nothing will be tolerated'.
Also when we begin to speak of how long a note lasts in finite terms we are getting into deep waters. Could I ask you to express your formula in beats per fathom?

I think a unison is in tune if the beat is overwhelmed by the decay.

That's precisely what I tried to quantify with my too complicated post.

Kees

Exactly? Yes that is impossible.

Kees

No the other way around. A unison that beats once every 6 years would stay that way for about 10 milliseconds I would estimate. A fathom is a unit of length, not of time, so I can not accommodate your request I'm afraid.

Kees

This is about one of the funniest threads yet. Either it is in tune, or it is not. It is possible to tune something beatless. If one person cannot do it, that doesn't mean that another can't either.

Nobody can tune 2 strings to have exactly the same frequency, if only because of Heisenberg's uncertainty principle. So I would like to know (in numbers) what is your tolerance for being "in tune". I am guessing 0.1 cent.

If you give me a recording of one of your "in tune" unisons I think I could measure how much it is off.

Would be interesting to know...

Kees

Of course I was being flippant. I naturally assumed this excessive pedantry to be humorous. It is?, isn't it? Just a reality check.

Well, I put in a smiley didn't I?

Kees

Of course nobody can, but Heisenberg has nothing to do with it!

Firstly, Heisenberg's principle applies to the subatomic scale, and secondly it is about measuring (determining) two properties simultaneously, of which the accuracies are mutually exclusive (disruptive) , e.g. position and momentum. The more accurately you try to measure the one, the more uncertain the other one becomes.

Neither is a piano string subatomic (to the contrary, the physics that are involved are macroscopic and purely classical), nor are there any such mutually exclusive accuracies in tuning a string or unison.

Getting a unison into tune is a question of
1) auditory distinction of frequencies to identify any "rolling"
2) mechanical accuracy in pin-setting
3) hammer to string mating, to avoid out-of-phase strings
4) material (no two strings and termination points are perfectly equal, hence their partial envelopes won't match perfectly, so you have to decide on the best compromise - including the issue of false beats)
5) ?

Those four or five issues are by no means mutually exclusive. Each of them can be improved independently of the others. And if you get each one of them "close enough", the unison is in tune - without invoking quantum physics.

While some of you are venturing into sub-atomics, the rest of us are tuning beatless unsions.