Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Half-pedalling with the una corda/soft pedal

Hello!

There is a discussion on other PW forums regarding "half pedalling" with the soft/una corda pedal. The soft pedal is often used as an on/off switch (fully depressed or fully released). With the term "half pedalling" I mean using the soft pedal in a way similar to how the damper pedal can be used, i.e. only partially depressing it to an intermediate point or depressing/releasing it gradually. Btw, this discussion only applies to acoustic grand pianos with a contemporary design and not to historic pianofortes/hammerklaviers or uprights.

Could you please provide some insights on what is the impact of half pedalling with the soft pedal from a technical perspective, especially when it comes to regulation and voicing? In my limited knowledge, I am aware that partially depressing this pedal can be used to slightly shift the hammers so that all strings are still struck but with a softer (ungrooved, less used) part of the felt. However, in a concert-grade piano that is properly prepared, why would partial una corda be used?

For example, this video shows an overview of voicing the hammers for una corda. What would be the effect of partial/half pedalling if a piano is voiced and regulated in such a way?

Many thanks for any input!

I think you answered your own question when you said that half pedaling with the una corda would mean that all three strings strike the hammer but in a softer part of the felt. That would create a different sound than when two strings either hit the grooves or the softer part of the felt(I think the una corda can, depending on setup work either of the last two ways).

If I remember correctly, my tech told me that for pianists who want to half pedal with the una corda one can voice the hammers separately for both full and half una corda.

Couldn't this occur naturally as the hammers are played in based on how much the piano is played at full vs. half una corda?

But is it technically possible to voice the hammers in such a way? The hammer is ca. 10mm wide. That gives ca. 3mm width per string on the treble regions. Three different voicings on the same hammer (no soft pedal, half soft pedal, full soft pedal) require hardness changes to hammer felt every 1mm or so. Is this feasible? Is this a common request from pro players? Can such fine voicing be systematically controlled by the player?

Remember that some pianos are set up so that full una corda would have the two strings hitting the hammer in the deep grooves used for regualar playing. At least that's what my tech said although in an earlier thread some knowledgeable dealers disagreed. But, assuming that's the case, only two different tunings would be required.

Two different voicings. It all depends on what you are willing to pay for, and you have to remember that it will not work the same on other pianos.

Pressing the una corda pedal down less than fully results in the hammers moving less far to the right and will result in some of the felt of the hammer head making contact with the left most string. Only the pianist's ear can determine the effect on the sound (IMO).

While it is useful to know the mechanism by which the una corda works on a grand piano, i.e., shifting the action to the right so that (usually these days) just two strings are struck instead of three (so it's really a due-corda pedal?), in my opinion, what is important is the pianist's ears and hearing and musical taste and judgment. I routinely use the damper pedal in gradations other than full ON or OFF. The differences are, to my ear, clearly audible. I've never used the una corda pedal other than ON or OFF though I will now experiment with using it that way to hear what the results are. How I use those pedals depends on the sound I want based on what is written in the music, the hardness of the hammers, the size and acoustical character (live to dead) of the room where I am playing.

In theory, using the una corda in the way described by the OP should afford the pianist more fine grained control of the quality and volume and color of sound. Would this be perceptible to an audience in a small hall? a large one? in a recording? I won't know until I try.

Much of Horwitz's sound was due to his clever use of shift pedal. (That is the proper term in my mind since no modern piano can shift over to only hit one string except in the lower two string notes because the first 10 or so notes are "una-corda" all the time.)

Some makers usually regulate their pianos not to clear the third string when the shift pedal is fully engaged. (Bosendorfer comes to mind).

Steinway has traditionaly regulated the action so the hammers are spaced to hit the strings with just over a string diameter of hammer on the bass side of the unison for all the trichords. The bichords hammers are spaced so when the shift pedal is fully engaged, and the third string is cleared on the trichords, the bichord hammers still strike both strings.

Regulated that way the pianist has a half-shift which moves the hammers over just enough to hit the less worked, softer felt between the string grooves which makes for a softer tone. And then on full shift the trichord hammers do not strike the third string and this causes the unstruck string to behave as a passive coupler.

The passive coupler vibrates 180 degrees out of phase with the struck strings. This is because it doesn't start vibrating until the first half-wave from the hammer strike begins to move the bridge. This reduces the volume of the impact sound and keeps the musicaly audible sustain envelope similar in duration or even a bit longer depending on how well the soundboard and string terminations function compared to striking on full shift.

If a piano maker uses heavy hammers with too dense felt and/or if they are hardened too much, the tone on full shift is not good because the edge of tha hammer is "crusty" and weird "twangy" sounds are created.

Almost all contemporary piano makers use too heavy, dense hammers to enable reliable regulation for full shift to clear the third string. This limits the musical expression available to pianists and is a very poor choice. The older pianos had lighter, softer hammers and they sounded best in the bass and middle regions after they acquired some grooves from playing. This increases the tone changes possible from both half and full shift.

Most modern hammers sound too shrill with significant string grooves.

My advice to pianists? Register your complaints at your nearest piano dealer! Manufacturers are much more prone to listen to what retailers report about pianist expectations. They don't listen to me!

Also, if you have a piano with the traditional wood hammer shanks, exposing your piano to extreme humidty changes will warp the hammer shanks enough to undo this kind of careful regulation over time. That is why the W,N&G composite shank is such a tremendous value. (NOTE, I am not paid or compensated to say this).

[quote=Ed McMorrow, RPT

Steinway has traditionaly regulated the action so the hammers are spaced to hit the strings with just over a string diameter of hammer on the bass side of the unison for all the trichords. The bichords hammers are spaced so when the shift pedal is fully engaged, and the third string is cleared on the trichords, the bichord hammers still strike both strings.
Regulated that way the pianist has a half-shift which moves the hammers over just enough to hit the less worked, softer felt between the string grooves which makes for a softer tone. And then on full shift the trichord hammers do not strike the third string and this causes the unstruck string to behave as a passive coupler.
The passive coupler vibrates 180 degrees out of phase with the struck strings. This is because it doesn't start vibrating until the first half-wave from the hammer strike begins to move the bridge. This reduces the volume of the impact sound and keeps the musicaly audible sustain envelope similar in duration or even a bit longer depending on how well the soundboard and string terminations function compared to striking on full shift. (quote)


Ed thanks for the 180 degree out of phase info., a very clear explanation of the unique sound of a "true" full unacorda shift. The only piano I have found to have only 2 strings play on full una-corda have been Steinways. I increased the right throw as much as possible on my Estonia (C8 was just about hitting the right cheek block). I then had to put a small bevel on the left side of the hammers to get to a place where when I muted off the middle and right string and engaged the una corda pedal completely there was no sound from the left string. At full u-c depression I now get that wonderful almost eerie full u-c sound. I of course can still half pedal and just get a softer sound from all 3 strings. I think it's a shame that almost all pianos come from the factory with the u-c pedal just able to give a softer effect. They are not regulated for pianists to be able to have at their disposal a "full' una-corda shift sound, and this is a tonal loss.

Sanfrancisco, Your welcome and thank you for noticing. Most of the grand pianos made today have wider unison spacing than older onbes. The agraffe string holes are slightly wider now than the American Steinway and Chickering used to do it. (Although some old D's and C's had wider trichord agraffes which I dump for narrower ones when I rebuild them).

The European scale design standards are for wider unisons, wider hammers and wider scale sticks overall. And all the Asian makers follow the Euro pattern. And most modern makers use harder, denser hammers that creat full shift tone problems, so they don't bother to try to build the piano to function with full shift.

EVER WONDR WHY THE PIANO BUSINESS IS GETTING WEAKER IN THE FACE OF DIGITAL COMPETITION!

I just explained some of the reasons.

Ed McMorrow RPT
Seattle, WA USA
Much of Horwitz's sound was due to his clever use of shift pedal. (Quote)

I would extend that to his advanced use of all 3 pedals in various combinations (sometimes all 3 at once!). Which is one reason why it is important to have the amount of initial free play and engagement point regulated evenly on all 3 pedals. It seems to me that many of the professional pianists I've heard keep their right foot resting (not engaging) on the sustain pedal and their left also resting on the una-corda most of the time. For me it allows me to immediately adjust the amount of depression I place on either pedal in response to aural feedback. I do find that keeping my left foot resting on the uc pedal does slightly throw off my balance, but I'm sure it is something that I will adjust to with practice. The increase in tonal palate is worth it.
Perhaps some of the piano teachers here could comment on why pedal technique/foot position is not taught at the same entry level as hand placement/position. It seems to me that if learned early it would become second nature.

Most students don't use any of the pedals in the very beginning stages of study probably because there is plenty of other things to keep their attention and one cannot focus on too many thing at once.

Many professional pianists don't keep their left foot on the UC unless perhaps if the particular piece uses that pedal extensively. I also don't think many pianists are constantly adjusting the amount of depression on the una corda when they do use it. Even in master classes with top conservatory level students I have extremely rarely(basically never) heard the teacher discuss using or use of the UC.

I think the overall amount of use of the una corda varies a lot for professional pianists with some using it very infrequently. Using the UC, except in a few pieces where it's a clear choice, would be inappropriate for most pianists during the first 3-4 years of study especially because it's important to learn how to play pp without the UC. I think use of the UC is quite minor compared to so many other things in learning to play the piano.

Sanfrancisco;
Horowitz usually did not keep his left foot on the UC. If he was playing loudly his left foot often went clear back under the bench and he used it to lift himself up a little higher to allow for more forceful arm motions.

Pianoloverus:
I think the reason so few pianists today use the shift pedal is the fact that tonal gradations have been reduced by so many makers not designing and tone regulating their pianos for full shift capability. Shift playing is dying a slow death because most newer pianos are not made to work properly.

This is an interesting discussion I didn’t initially read until now!

I make a lot of use of the shift pedal (with different levels of depression) and am keenly aware that nearly every piano I’ve played responds differently. Before I perform I always check the sound at different levels of pedal depression, because a softer tone might be right in the middle and further down might get bright again (or just plain weird sounding). One piano I commonly play has 3 very distinct sounds with the shift pedal.

Sanfrancisco, as a teacher I rarely teach any pedalling even to very advanced students. Just suggestions here and there. Pedalling is such a personal thing. I’ll tell my students when it’s bad or problematic pedalling, and I’ll show what I do just as a general part of demonstration (including shift pedal), but I deliberately let them explore it themselves. It just naturally develops as long as they’re nudged in the right direction.

Soft pedals are never going to work on uprights the way that they work on grands, so right off the bat, you have one reason why soft pedal technique is not taught. (They do not work the same way on all grands, for that matter.) One can spend a lot of money on careful alignment and voicing to get special effects with the soft pedal, but few people are willing to do so, particularly if you cannot be assured of playing on a piano where those effects are obtainable.

BDB don't you think if one is regulating a piano that has a shift pedal it would be unprofessional to not make it work as the design intends?

Just on the off chance a pianist of Horowitz's caliber is anywhere around?

Horowitz's piano did not sound very good. Most people would prefer theirs to sound better than his. As to whether it works as the design intends, the designers have two ways that that it is intended to work, which is not exactly definitive.

I think that most people prefer not to spend thousands of dollars extra on pianos for features that they are not likely to use. In the amount of time that it would take to make one grand piano soft pedal work slightly better I could make half a dozen Kimball Artist Consoles sound and play markedly better, so I think that my time would be better spent doing that.

BDB,
I agree Horowitzs' piano was less than stellar sounding. But Horowitz sounded really good most of the time in spite of the piano and he required full and half-shift operation of the left pedal.

I will remember that the next time Horowitz comes to town!

If a pianist wants to pay me to set up the soft pedal exactly, I can do it. Whether they would want to pay me is a different matter. I do not go around trying to sell services my customers do not want or need. There is plenty to do without that. There are lots of pianos that can stand a few hundred dollars worth of work instead of the thousands that others want to do a job that is not necessarily going to make the piano play any better.

BDB your opinion of pianos is rather pedestrian. I enjoy when one plays wonderfully and has a wide palette of expressive capabilities.

I can get a digital piano to work well enough if I give up the lofty goals, and I don't have to tune it!