Minor sostenuto problem

Posted by: g_s_223

Minor sostenuto problem - 02/09/13 10:38 AM

On my grand with Renner action, after depressing the sostenuto pedal, one or two notes when played staccato continue to sound, i.e. their dampers aren't working properly when the sostenuto mechanism is operative. I'd appreciate any input on what adjustment to make - I feel comfortable to make minor tweaks. If you could use the terminology from this diagram that would be ideal: http://www.pianoparts.com/grand/grand1.jpg
Thanks!
Posted by: BDB

Re: Minor sostenuto problem - 02/09/13 10:52 AM

Adjusting a sostenuto pedal is difficult. You can usually test it by pressing the sostenuto pedal by itself and seeing whether any dampers go up, and either pressing the damper pedal and then the sostenuto pedal, and then releasing the damper pedal to see if any dampers fall down. The latter may not work, and then you have to test the sostenuto note by note, playing the note, using the sostenuto pedal, and releasing the note to see whether the damper stays up.

Once you have tested it, adjusting it properly depends on the entire damper system working properly. I have posted instructions for doing that a couple of times, but it was a long time ago. You could do a search. But everything has to be right. Worn felt in the wrong place can keep the sostenuto pedal from being adjusted properly. Minor tweaks may not cut it.
Posted by: Zeno Wood

Re: Minor sostenuto problem - 02/09/13 11:11 AM

Since you're in the UK, and you have a Renner action in whatever sort of piano you have, then the diagram in that link is not what you're dealing with. The link depicts a NY Steinway which has the sostenuto rod mounted on the back of the keyboard. But most likely your sostenuto mechanism is mounted inside the action cavity on the belly rail. And that is good for you, because it's easier to adjust.

Take the action out, and look inside. Using your hands, knees, or feet, operate the sostenuto pedal while watching how the rod interacts with the sost. tabs. Lift the offending damper underlevers, activate the pedal, and see what happens. Also, activate the pedal, then lift the offending underlevers to see if they get caught by the rod. The rod can be moved up/down and in/out. You'll figure it out. Probably.
Posted by: Gene Nelson

Re: Minor sostenuto problem - 02/09/13 11:27 AM

Regardless of the mounting place of the sostenuto rod, the photo shows the correct relationship of the rod #14 to the tab #35.
Push the sos pedal and the rod should rotate and not contact any tab.
If it does, the tab is too far forward.
Hold down the sos pedal, play a note and the tab should not jump above the rod - making the damper hang up. If this happens the tab is too high.
If either of these happen, get a tech with experience to make the adjustment.
Posted by: Mark Cerisano, RPT

Re: Minor sostenuto problem - 02/09/13 08:50 PM

I am one of the techs on this forum that is usually the one who gives advice to owners to try and fix their own pianos, and here three have already done that and now I'm the one to discourage that. This is weird.

Anyway, I'll tell you why I don't think you should attempt this adjustment on your own.

The sostenuto pedal is bizarre beast; only the most accomplished pianists use it, or know how it works. I worked on a Steinway D in a concert setting where the sostenuto made a very loud "kerplunk" when it was pressed, but I guess it had never been used before, so nobody complained.

So, if you are one of those players who knows how it works (obviously you do) and use it, and know how to use it, then I strongly recommend getting a good grand technician to make the adjustments. He or she will probably find other anomalies that could eventually cause you grief and fix them preemptively. And if you use it properly, you want it to work right, right?

If you never use the sostenuto pedal, there is really no need to fix it. Unless of course you are the kind of person that just likes to have everything working the way it should, In that case, you will be very happy after the knowledgeable tech fixes that and whatever else he/she finds.

I hope I haven't offended you but I just think in this situation, you will be much happier after the job is done right. Of course, you can always try it on your own and then call in the tech if things get out of hand. Be warned though, I hope you have an easy-going tech. Some do not appreciate an owner trying to adjust his or her own piano.
Posted by: Dave B

Re: Minor sostenuto problem - 02/10/13 11:47 AM

I agree with Mark. Any thing that has anything to do with dampers must be approached cautiously. The needed adjustments can very likely be in the dampers.
Posted by: g_s_223

Re: Minor sostenuto problem - 02/12/13 04:02 AM

Thanks for all the replies. Having tried out BDB's suggestion of alternate use of the pedals, it clearly shows that many more of the dampers aren't correctly aligned so this isn't such a simple job as I thought so I will be leaving it alone. The sostenuto pedal is something I need occasionally, and when it works well it is very useful.

If there is an expert piano technician in London UK reading this who'd like to work on my grand piano, do send me a PM!
Posted by: Supply

Re: Minor sostenuto problem - 02/12/13 11:48 AM

Mark is spot on. Dampers are one of the more difficult parts of an action to regulate properly. Grand dampers more so than upright dampers. And sostenuto can be the most challenging part of damper work.

No technician should be advising piano owners to be pulling their piano actions and start moving the sotenuto rod around.

Unless, of course, the client is the type who likes to pay the "You Fixed It First" rate for the repair, which is usually close to double. wink
Posted by: Zeno Wood

Re: Minor sostenuto problem - 02/12/13 05:43 PM

Well, I will admit I maybe shouldn't have been so forthcoming with the advice. But, he said he felt comfortable with small adjustments, and he was quick to recognize that he was in over his depth. So it's a happy ending! Hooray!