Pianotech

  • 1.  Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-30-2020 18:49
    Greetings and Happy New Year in advance,

    I will be seeing a Korean-made 6' Knabe soon (I haven't seen it yet). The owner sent the following comment/request:

    "The sustain pedal has a very strong thump on release. It's been that way since I bought the piano (used) and I'm hoping there's a way to calm it down."

    Thanks for your collective suggestions about potential trouble areas to be aware of, and possible fixes - I'll hope to be prepared to take care of the issue(s) immediately.

    David Trasoff

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    David Trasoff
    Whatcom Piano Service
    (360) 389-2158
    david@whatcompianoservice.com
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  • 2.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-30-2020 18:57
    This could be the collective drop of all the dampers on the string.  You can either remove each damper and soften up the felt, or replace all of the dampers. Cost wise it's six of one, half a dozen of the other.  I would opt to replace the felts and get it over with.

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 3.  RE: Knabe/Samick sustain pedal thump

    Member
    Posted 12-30-2020 19:23
    Check the damper lift from the pedal to see how high the dampers are lifting as well as the damper upstop rail height. Check the lost motion in the pedal as well as the trapwork felts/leathers/ capstan adjustment and springs.. There may be a strong assist spring on a pedal trap work lever.

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    James Kelly
    Owner- Fur Elise Piano Service
    Pawleys Island SC
    843-325-4357
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  • 4.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-31-2020 06:37
    In at least one case I was able to determine that most of the thump was emanating from the bass dampers, and replacing only the bass dampers reduced the noise considerably with much less time and expense than would a complete set. I used the sostenuto to hold all the treble dampers up (with these strings damped with a clean towel) then worked the sustain pedal to hear the isolated bass damper thump. Then I reversed the sostenuto/blanket to compare to just the treble thump. The difference was quite obvious.

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    Mark Dierauf
    Concord NH
    603-225-4652
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  • 5.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-31-2020 12:44
    Hard(ish) dampers, mostly bass dampers, all coming down and hitting the strings at once can cause a thump. Softening the dampers may help. The damper lift tray may also be causing the thump when it comes to rest. However, more often than not, I have found that it is the player releasing the pedal too quickly, like by lifting up their foot faster than the damper pedal is actually returning, that allows the damper pedal to thump against the damper pedal slot (upstop) felt with all the force of the return spring, causing the whole lyre box to go thump. Watch them play and see if it is not simply poor pedal usage from the person playing before making other changes. I see this more in uprights than grands but it's because the player treats the pedal as an on/off switch instead of a variable control. Also, unless it's an old Knabe it's a Samick. And... well...

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    Geoff Sykes, RPT
    Los Angeles CA
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  • 6.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-31-2020 13:03
    New info: the owner just informed me that the piano has a Pianodisc system installed and that there’s “a lot of extra hardware under there.”




  • 7.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 12-31-2020 13:35
    The newer PianoDisc systems have refined the pedal operation, but older ones pretty much treated the pedals as on/off switches, with all the expected clunks as trapwork was allowed to slam back into rest position. May not be a whole lot you can do if the clunk is PD related.

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    Geoff Sykes, RPT
    Los Angeles CA
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  • 8.  RE: Knabe/Samick sustain pedal thump

    Member
    Posted 12-31-2020 14:11
    I am certified in PianoDisc and just upgraded an old PDS128 diskette player to the Prodigy wireless system. The pedal solenoid calibration is actually a multiple step process the first step being manually adjusting the damper lift from the pedal with the action out making adjustments on early and late risers. The felt on the dampers needs to barely clear the strings. With the action in and the player activated the pedal solenoid needs to be observed and adjusted using nuts on the solenoid that control lift and return. There is a pedal calibration setting in the calibration software that controls pedal force/strike and hold times. If done correctly the dampers can be very quiet . Before doing or suggesting anything observe that the player system is working and if the pedal solenoid is firing at all. The solenoids can burn out from too much heat being generated, improper calibration, corrosion or tarnish on the shaft. Wiring can be bad and the circuit board in the bass that drives the solenoid can be bad. Best to refer this work to someone trained in PD . The older systems tend to have more action noises and difficult to control volumes. It is a good idea to get model and serial numbers to date the system

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    James Kelly
    Owner- Fur Elise Piano Service
    Pawleys Island SC
    843-325-4357
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  • 9.  RE: Knabe/Samick sustain pedal thump

    Registered Piano Technician
    Posted 01-01-2021 10:00
    Hi David.  Reduce damper lift to just clear of the strings.  Some noise is unavoidable.  It's gravity doing it's thing.  You can reduce the noise by limiting the distance the dampers fall.

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    Larry Fisher
    Owner, Chief Grunt, Head Hosehead
    Vancouver WA
    503-310-6965
    Working the gravy zone for the rest of my days.
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