How / where is aftertouch measured?

Posted by: electone2007

How / where is aftertouch measured? - 12/02/12 05:26 PM

Is it measured at the front of the key?
Posted by: Mark Cerisano, RPT

Re: How / where is aftertouch measured? - 12/02/12 06:24 PM

I measure it at the jack. For grands, the jack needs to be halfway between the knuckle and the rep. lever felt at key bottom. For the upright, there should be about 1/32" clearance between the hammer butt and the jack top at key bottom.
Posted by: accordeur

Re: How / where is aftertouch measured? - 12/02/12 06:40 PM

Let-off, drop, aftertouch. By pushing the key slowly without the hammer catching, the hammer not touching the strings.

If the let-off is at 1 mm from the string, the drop should be at 2mm, and the aftertouch will rise by 1 mm. It's like 1 2 3. Break 1mm, drop by a mm, and then back up 1 mm. The numbers vary enormously, I used these numbers to illustrate how I measure aftertouch.

So, aftertouch should be set by varying dip and blow distance in order for it to reach the same level as the let-off.

An upright action is altogether different.

All the best
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/02/12 07:19 PM

Thanks but I still need some more elaboration.

When they say that aftertouch is set at, say, 0.045", (1 mm) where is this measured? Is this the space between the front of the jack and the rep lever felt at key bottom? Or is this measured at the key itself?

Pardon my ignorance. I cannot find this in the books.
Posted by: accordeur

Re: How / where is aftertouch measured? - 12/02/12 07:21 PM

the hammer from the string.
Posted by: beethoven986

Re: How / where is aftertouch measured? - 12/02/12 07:30 PM

Originally Posted By: electone2007
Is it measured at the front of the key?


The method that I use:

1. Place a .045" (or whatever the desired AT is) paper/cardboard front rail punching on top of the felt front rail punching.

2. Using a 300g weight, slowly depress the key and adjust until the action goes through escapement by gently tapping the key bed. Generally, I adjust the hammer blow to achieve this, but you could also adjust dip.

For more in depth discussion, refer to "Piano Shop Trade Secrets: Measuring After Touch" in the October 2002 issue of the PTG Journal, by John Hartman.
Posted by: beethoven986

Re: How / where is aftertouch measured? - 12/02/12 07:33 PM

Originally Posted By: electone2007
Is this the space between the front of the jack and the rep lever felt at key bottom? Or is this measured at the key itself?


Just to be clear from my post immediately above this one, .045" would be measured at the front of the key. This is the most accurate way of setting after touch, IMO.
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/02/12 08:44 PM

Thank you very much!!
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/02/12 09:12 PM

Originally Posted By: accordeur
Let-off, drop, aftertouch. By pushing the key slowly without the hammer catching, the hammer not touching the strings.

If the let-off is at 1 mm from the string, the drop should be at 2mm, and the aftertouch will rise by 1 mm. It's like 1 2 3. Break 1mm, drop by a mm, and then back up 1 mm. The numbers vary enormously, I used these numbers to illustrate how I measure aftertouch.

So, aftertouch should be set by varying dip and blow distance in order for it to reach the same level as the let-off.




I understood this just now. I can see how the hammer lets off at 1 mm then drops by 1 mm, then rises 1 mm to where the let off occured. Is that correct? Thanks.
Posted by: beethoven986

Re: How / where is aftertouch measured? - 12/02/12 09:38 PM

Originally Posted By: electone2007
Originally Posted By: accordeur
Let-off, drop, aftertouch. By pushing the key slowly without the hammer catching, the hammer not touching the strings.

If the let-off is at 1 mm from the string, the drop should be at 2mm, and the aftertouch will rise by 1 mm. It's like 1 2 3. Break 1mm, drop by a mm, and then back up 1 mm. The numbers vary enormously, I used these numbers to illustrate how I measure aftertouch.

So, aftertouch should be set by varying dip and blow distance in order for it to reach the same level as the let-off.




I understood this just now. I can see how the hammer lets off at 1 mm then drops by 1 mm, then rises 1 mm to where the let off occured. Is that correct? Thanks.


Yes. Though, do note that he says "the numbers vary enormously". 1mm is probably too close for let-off in most applications; 1.5mm for treble/ 3mm in bass is a good general spec for let-off. The hammer should drop about 1mm from let-off, and then raise some when going through after-touch.
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/02/12 10:05 PM

Thanks again, beethoven!

I guess measuring at the key front will be more reproducible for me.
Posted by: BDB

Re: How / where is aftertouch measured? - 12/03/12 12:48 AM

Actually, if you put the 0.045" punching on the key pin, that is where you are measuring the aftertouch, not the front of the key. If you decide on a tolerance, that should be the point where it lets off, and if you add a punching the thickness of your tolerance, it should not let off. A 0.010" punching for the tolerance is close enough. You can hardly expect felt to be uniform enough to be any more accurate than that.
Posted by: beethoven986

Re: How / where is aftertouch measured? - 12/03/12 01:01 AM

Originally Posted By: electone2007
Thanks again, beethoven!

I guess measuring at the key front will be more reproducible for me.


Sorry if I confused you, but the measurement is not literally at the key front; it is at the key pin. I meant "front of the key" as a general term, as opposed to "the front of the jack and the rep lever felt at key bottom". It should also be noted that the mass of the weight will change your results. A 300g weight will produce different results than a 400g weight with the same .045".
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/03/12 01:34 AM

Thanks, BDB and beethoven! That's what I thought!
Posted by: Ed Foote

Re: How / where is aftertouch measured? - 12/03/12 06:05 AM

Originally Posted By: BDB
Actually, if you put the 0.045" punching on the key pin, that is where you are measuring the aftertouch, not the front of the key. If you decide on a tolerance, that should be the point where it lets off, and if you add a punching the thickness of your tolerance, it should not let off. A 0.010" punching for the tolerance is close enough. You can hardly expect felt to be uniform enough to be any more accurate than that.


Greetings,
In a performance setting, .010" is a huge tolerance for aftertouch. In a church choir room, not so much.

I set dip by setting the aftertouch, which is where most pianists gauge evenness of action. I consider aftertouch as that key travel which occurs after the jack is no longer supporting the weight of the hammer, and before the key's motion is stopped by the front punching.
After the blow and let-off are done, I set aftertouch by altering a previously set static dip, usually .390" on an older Steinway. If I have to deviate from that depth, in order to get an even aftertouch, .007" is as far as I allow the dip to vary before I start moving the hammer height. To determine the bottom limit of the key travel, I use my sense of touch to depress the key on the selected thickness of punching, ( I usually favor .035" with moderately firm pressure). Using a thicker punching to measure with firmer pressure will give a more consistent result that a thinner punching with light pressure. Whatever combo works for a given tech's sense of touch is the best way to do this. The object is consistency first and foremost.

If I am using the Crescendo punchings, I will often be using the .002" to achieve discernable differences in aftertouch. I can't tell a .002" difference in key dip, but in a regulating zone, that difference can be felt in aftertouch. And if I, as a tech can feel it, I assume my customers can, also.
Regards,
Posted by: Olek

Re: How / where is aftertouch measured? - 12/03/12 06:29 AM

we measure a bit more than 10 mm with the keyblock because it is easier to feel it when it is a hair lower from the neighboring key

Accesoirly, that way we have more the supposed 10 mm key dip 5 mm from the edge of the key.

Then one state of 1mm aftertouch as a good moderate value, and then use a .75 carboard to verify it.

All those are not so precise values. On some actions, when you have .75 aftertouch, the feel is in fact of a large 2 mm one...

As many keys are not level when they are at full dip, I cross check left and right side (but in fact I make samples on D's and A's then I even the level of the other keys at full dip, by feel. and in the end what counts is the even aftertouch sensation; If you cannot ascertain it you cannot regulate the sharps well, so the cleaner method is to use a 0.75 shim and regulate the hammer travel so it just barely begin to drop, jack is still touching the knuckle probably.

Then once you know the white keys have an even aftertouch, use that aftertouch sensation and reproduce it on the sharps, that time with paper front punchings (assuming the sharps are leveled so they dont go too low at full dip, so if you dont know the original sharp's height samples are necessary)
Posted by: Withindale

Re: How / where is aftertouch measured? - 12/03/12 07:26 AM

Originally Posted By: Kamin
... I even the level of the other keys at full dip, by feel ...

Kamin

To clarify, the resulting key dip is exactly the same for all naturals and for all sharps?
Posted by: Olek

Re: How / where is aftertouch measured? - 12/03/12 07:40 AM

No, the aftertouch sensation may be the same, for the sharps I don't measure the dip, even if I can check at large by pushing on 3 or 6 black keys together, then you feel/see if their dip is even. Checking the level of sharp at full dip vs the white keys provide also some informations)

Sharps have generally a different leverage than white keys (hopefully not too different , but there are extremes)

Theoretically what matters is that the hammer motion is the same for sharps and white keys, I have even no idea of how much is the sharps dip.

I also sometime find easier to feel letoff and aftertouch with more than one key at once, 3 white keys together for instance, but the usual and best tip is to use the 3d fingers of each hand together on one key, for after touch you feel is then twice , way more precise.

try to have the 3 fingers in a row to push on 3 white keys together (idem for sharps) I like that to check the eveness of letoff/drop, but it is regulated individually, and what is difficult there is to manage the key so you stop it before aftertouch, just wen drop begins. Standing on the back of the action allows to have the fore arm quietly installed on the hammer rail, then maximum tactile feedback from the key, but comparison with neighboring key is not good.

Working on new actions or new parts is necessary to get the feel for that, with parts that are not uneven.

The more you use your sensations for regulations the nearer you are of the pianist
Posted by: electone2007

Re: How / where is aftertouch measured? - 12/03/12 08:35 AM

Thank you, Ed and Kamin!
Posted by: James Carney

Re: How / where is aftertouch measured? - 12/03/12 08:49 AM

Originally Posted By: Kamin
No, the aftertouch sensation may be the same, for the sharps I don't measure the dip, even if I can check at large by pushing on 3 or 6 black keys together, then you feel/see if their dip is even. Checking the level of sharp at full dip vs the white keys provide also some informations)

Sharps have generally a different leverage than white keys (hopefully not too different , but there are extremes)

Theoretically what matters is that the hammer motion is the same for sharps and white keys, I have even no idea of how much is the sharps dip.

I also sometime find easier to feel letoff and aftertouch with more than one key at once, 3 white keys together for instance, but the usual and best tip is to use the 3d fingers of each hand together on one key, for after touch you feel is then twice , way more precise.

try to have the 3 fingers in a row to push on 3 white keys together (idem for sharps) I like that to check the eveness of letoff/drop, but it is regulated individually, and what is difficult there is to manage the key so you stop it before aftertouch, just wen drop begins. Standing on the back of the action allows to have the fore arm quietly installed on the hammer rail, then maximum tactile feedback from the key, but comparison with neighboring key is not good.

Working on new actions or new parts is necessary to get the feel for that, with parts that are not uneven.

The more you use your sensations for regulations the nearer you are of the pianist


I completely agree - I never measure sharp key dip. I set it so that the aftertouch coincides with that of the naturals. (This means it happens late in the game during a full regulation.) To me it doesn't make any sense to even try to set sharp keydip with a tool.
Posted by: BDB

Re: How / where is aftertouch measured? - 12/03/12 11:54 AM

Originally Posted By: Ed Foote
Greetings,
In a performance setting, .010" is a huge tolerance for aftertouch. In a church choir room, not so much.

I set dip by setting the aftertouch, which is where most pianists gauge evenness of action. I consider aftertouch as that key travel which occurs after the jack is no longer supporting the weight of the hammer, and before the key's motion is stopped by the front punching.
After the blow and let-off are done, I set aftertouch by altering a previously set static dip, usually .390" on an older Steinway. If I have to deviate from that depth, in order to get an even aftertouch, .007" is as far as I allow the dip to vary before I start moving the hammer height. To determine the bottom limit of the key travel, I use my sense of touch to depress the key on the selected thickness of punching, ( I usually favor .035" with moderately firm pressure). Using a thicker punching to measure with firmer pressure will give a more consistent result that a thinner punching with light pressure. Whatever combo works for a given tech's sense of touch is the best way to do this. The object is consistency first and foremost.

If I am using the Crescendo punchings, I will often be using the .002" to achieve discernable differences in aftertouch. I can't tell a .002" difference in key dip, but in a regulating zone, that difference can be felt in aftertouch. And if I, as a tech can feel it, I assume my customers can, also.
Regards,


Sorry, but I do not believe that. In order to maintain such tight tolerances, you would need incredible control over not just the keybed punchings, but the knuckle and letoff button as well. The adjustment would have to be checked constantly, which would wipe out the budget of most small concert venues.

What is more, I have never heard of a single concert artist stopping in the middle of a run because there is a variation in the aftertouch of more than 0.007". Anyone who does this is not likely to have a career.

Keep in mind that this topic is for a amateur in a foreign country with little access to good piano care. Being pedantic does not help.
Posted by: Withindale

Re: How / where is aftertouch measured? - 12/03/12 12:50 PM

Originally Posted By: BDB
Keep in mind that this topic is for a amateur in a foreign country ...

To interpose my experience as an amateur in a foreign country, I found that 0.010" (0.25 mm) reduction in aftertouch made a huge difference to the touch of my piano. A further 0.010" reduction made another huge difference. 0.005" would have be discernible to me if not 0.002".
Posted by: Ed Foote

Re: How / where is aftertouch measured? - 12/04/12 08:21 PM

I wrote:
In a performance setting, .010" is a huge tolerance for aftertouch. In a church choir room, not so much.
If I am using the Crescendo punchings, I will often be using the .002" to achieve discernable differences in aftertouch. I can't tell a .002" difference in key dip, but in a regulating zone, that difference can be felt in aftertouch. And if I, as a tech can feel it, I assume my customers can, also.

BDB responds:
>>Sorry, but I do not believe that. In order to maintain such tight tolerances, you would need incredible control over not just the keybed punchings, but the knuckle and letoff button as well. The adjustment would have to be checked constantly, which would wipe out the budget of most small concert venues. <,

Believe what you like, my experience is that there are artists out there that can tell. , I strive for that kind of control over the action, and yes, I have many customers that easily discern a .010" difference in aftertouch. Ronnie Milsap could feel a little over .004" difference. The adjustment is not checked constantly, it begins with tolerances that close, and gradually loosens up, like one regulation a year on our stages. At the end of semester worst, there might be a tolerance of .010", but not to start.

>>>What is more, I have never heard of a single concert artist stopping in the middle of a run because there is a variation in the aftertouch of more than 0.007". Anyone who does this is not likely to have a career.

Pardon me, but there is straw leaking out. No artist is going to stop in the middle of a run, but they will adjust to whatever irregularities there are in an action, and the less irregular the individual component settings are, the less irregular the final result will be. The more regular the action, the less effort is expended on the instrument and more attention on the music. Aftertouch is a huge part of the equation , perhaps the most sensitive dimension in the action, and I still maintain that a .010" tolerance, while perhaps suitable for a choir practice piano, is a crude margin for the performance venue, which is where I live.
Regards,
Posted by: Olek

Re: How / where is aftertouch measured? - 12/05/12 03:27 AM

When we are regulating with the smallest papers it is surprizing how the aftertouch difference is more sensitive than key dip difference.

The thin papers are 0.06 mm (silk paper) but those are for the balance, mostly even if I have seen as thin papers used. What counts in my opinion is to use papers that are not taking moisture too easily. I use the Yamaha ones in lack of better source. (not cheap)

I also use 22 mm diameter papers I still see pianos with the good large punchings installed on papers 20 mm in diameter, as originally the punchings where 20 mm.
The "creshendo" punchings are adding power but à little noise too. They are precise, but may be a little hard to the pianist articulation.
Not for all pianos, if the the keybed is not too sonorous it is better..
Regards
Posted by: beethoven986

Re: How / where is aftertouch measured? - 12/05/12 04:01 AM

Originally Posted By: Kamin

The "creshendo" punchings are adding power but à little noise too. They are precise, but may be a little hard to the pianist articulation.


The Crescendo punchings are great for stable regulation, however I agree that their extra firmness is noticeable to the pianist when playing (at least to me). It's not necessarily bad, but it took a little getting used to.