Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Repetition rate of a grand piano

Hi,
Over on the digital piano thread we are having a discussion about the repetition rate of acoustic pianos. (so we can relate it to the behaviour of digital pianos)
The discussion starts at this post:
https://www.pianoworld.com/forum/ubb...X%20130,%20PX%20330,%20.html#Post1382409

So far, the only specs that we have found are for the Seiler pianos, and the specification is 400 repetitions per minute:
http://www.seiler-pianos.de/eng/technik/daten.htm Apparently Seiler pianos have been designed for a high repetition rate.

Now, when I analyse a recording of Billy Joel playing "Angry Young Man" (e.g http://www.youtube.com/watch?v=ErPywgiMb4k ), I get about 800 reps per minute. (I may be a bit off, but not by a factor of 2!)

It has been suggested that Billy's playing may be much faster than typical, and he may be relying on the mechanical resonance of the action to achieve that speed. If he attempted to play it a bit slower, it may not work.

Questions:
Do you think that 400 reps per minute (6.7 reps per second) is realistic for a grand piano, or do you think this specification is, somehow, wrong in some way?

Do you think that Billy Joel is indeed relying on resonance, and if the repetition speed was a bit lower, the action may not repeat properly?

Does the repetition rate vary greatly across the keyboard, in general?

Thanks,
Greg.

I analysed a short group of four repeated notes in this recording: http://www.youtube.com/watch?v=PcsRl_LIJHA
( martha argerich - scarlatti, sonata k. 141 ) and got a result of 683 reps per minute. She is playing the repeats with one hand, using the rotating fingering method, as far as I can tell.

Greg.

Ah, according to this post it's 16 per second (960 per minute), although no reference is given:
https://www.pianoworld.com/forum/ubb...20Repetition%20questions.html#Post608331

Greg.

I do not think that a piano's action is necessarily the limiting factor in repetition. A note does not need to be played through let-off to produce sound. Merely tapping a key can cause a note to be played. I can see how a skillful player could coordinate the rebound of the hammers and the striking of the keys to repeat notes without the jack tripping and resetting. There is probably a name for this technique. There seems to be a name for everything else, even those two ridges of flesh that go from the nose to the upper lip!

The unsubstantiated number floating in my head is about twelve to sixteen reps per second on a grand.

High-speed video has shown that on a hard blow, the key comes to rest on the front punching *before* the hammer starts to move from its rest position! There's that much "latency" or flex in a wooden action -- part of it necessary to protect the player's hands from stress.

--Cy--

If you are repeating quickly, you are not usually playing very hard. On a grand, an artist would not let the key come up all the way in a quick trill - or even during the three finger method. The key might not bottom out either.

As with anything else in music, the moment someone sets a limit, the next guy will surpass it.

There is a trick sometimes used when possible depending on the use of the note in the piece.
It is to detune the adjacent note to match the one needing repetition so the artist has two notes next to eachother at the same ptich to take advantage of.
As was pointed out, typically during very fast repetition it is softer playing, hammer shanks and key sticks are not flexing so much.
If the letoff is set at say 1.5mm or about .060" then if the note is regulated well the key only needs to come up off of the front punching .060" for a repeat blow. This should allow repetition as fast as the artist can make it happen.
I have never counted but it is obvious if there is a malfunction.

Gene, are you saying that the aftertouch is 1.5 mm?

Gershwin's Concerto in F requires this kind of fast repetition in the third movement.

As I had said in another post some months back, a properly regulated vertical action, even a good quality spinet such as an Acrosonic can also have amazingly fast repetition. When the let-off and checking are fairly close but the blow distance is long and the aftertouch minimal, the jack pops back under the butt immediately upon lifting the key. It isn't necessary for the key to travel as far has it can and it isn't necessary for the key to return all the way for to repeat. Therefore, very fast repetition is possible.

The limitation is not the action. A player piano can repeat at a very fast rate, whether it is a grand or an upright.

Jeff, if the let off was set at 1.5mm, the aftertouch would need to be less than 1.5mm - I know you are making a point but I am missing it.

But you're worng. *Somebody* had to make a recording of the piece so that it could be played on a player piano. Consider the following:

One cannot play faster than the action, i.e. if the recording has repetitions that are faster than the player piano's action can allow, the piano can not just *magically* make its acion repeat faster.

And whoever made the recording was most likely a very good pianist (99% of the time) and we can infer that a very good pianist can repeat only as well - but at the maximum rate possible - as the action can repeat.

Player piano rolls were never made live. Not only that, the speed can be changed by moving a lever.

If the let-off and after touch are both 1.5mm and then 2.5mm of front punchings are removed, the aftertouch will be 4mm while the letoff is still 1.5mm.

The point I am making is that it is the aftertouch that determines how far the key must be released for the jack to reset, not the let off.

After watching the video ...

Billy Joel is using two hands and bouncing the hammer between the top of the jack and the string .... Sure, the more you practice that one the faster that "Parlor Trick" goes.

A simple Rock and Roll production song at that.

Not a sophisticated classical piece. Or Gershwin for that matter.

Also, once something is recorded you can play it back and exaggerate the speed faster or slower. I honestly don't know if the Joel piece is that and I am not saying it is.

Some might define repetition as a complete cycling of the action. Something different than what Joel is doing.

The repetition speed is determined by who is playing, HOW they are playing it and how that action is regulated.

In my experience, the actions are more capable that the people playing them.

In the Joel thing, considering HOW Joel is playing that repetition, Joel is the limiting factor, not the piano.

According to the online Chang this can be seen like a bouncing basket ball.

The Ball bounces faster, when the bouncing distance is shorter.
If this theory is correct, it would require that the key and the hammer has an elastic bouncing behavior and it would mean that every bouncing distance has its own "resonance frequency".

Possibly Seiler measures this under some normalized conditions and so these values are only meant as typical values for effortless repetition, and the values can be exceeded drastically with special playing technics and on the upper keys.

This would also mean that there are large differences between piano models. Especially between digitals and acoustics. And for the acoustic it would mean that the repetion rate is heavily dependant from regulation which was made by the piano technician or piano tuner.

Edit:
Did you see that Billy Joel has a bandage at his left hand thumb? So this playing style is risky.
At another site I have readed, that the Scarlatti sonata cited above is often used as repetition training for advanced pianists and that the pianist will fall into ecstatic trance states at these rates ;-)
So this seems to be near top of the roof and it needs a lot of training and carefully selected and regulated instruments to reach that.
Sorry could not resist to post that ;-).


Peter

So when depressing the key, let off happens. Drop screw and jack tail are contacted by rep lever and let off button, it takes just a small amount of key travel to get drop and the remainder is aftertouch. Easy to observe when regulating. During play the hammer is contacting the string and it is not quite the same. The jack does not need to completely reset to get repetition.
Also, I have found that the height of the rep lever plays a roll. It can be set correct so the jack fully returns with the trip the jack test but it can be set higher and improve repetition without introducing lost motion. Now we get into rep spring tension but that is for another time.

Further to this, often times extra notes were added to rolls that could not be played by a player performing the piece of music.