Pianotech

  • 1.  Split bass bridge, lousy tone and sustain elsewhere

    Registered Piano Technician
    Posted 06-09-2020 13:53

    Hello All

     

    I recently brought a Kawai UST-7 into my shop.  It belonged to a customer who said the bass had suddenly gone out of tune.  I found about half the bass bridge split along the upper line of bridge pins.  The customer only played occasionally and could not afford the repair, so I bought the piano for a small sum.

     

    I was delighted to discover that Kawai sold an off-the-shelf replacement for much less than it would cost to duplicate the bridge and I ordered it.  I was really not delighted last night when I played the piano for a bit and discovered the tone in the mid-range and treble was lousy, very thin, and the sustain weak.  I did play all the notes at the customer's home and found everything functioning but I must have breezed through it and not noticed the tone and sustain.  So my question is, Is there any way that the broken bass bridge could affect tone and sustain elsewhere?  I am vainly hoping that if I fix the bass bridge, it will fix the tone in general, wishful thinking I'm sure.  But I thought I would ask.

     

    If someone had asked me to inspect this piano, and I found the tone throughout to be what I heard last night, I would advise them not to buy it, and judge its value as maybe $0-300.  If the tone doesn't change, I cannot ethically advertise the piano for a price one would normally expect for a similar piano for sale in a store.  I am actually considering not even doing the repair, but probably will just because I've ordered the part and will get the experience of doing a repair I've only done once before.

     

    Live and learn.  Fortunately not a big financial loss.



  • 2.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Posted 06-09-2020 14:02
    A huge percentage of tone throughout the instrument,  comes from the sympathetically activated partials, which originate in the bass wrapped strings. Kill the bass, and the overall voice of the instrument is seriously altered, even when damped. If the bass terminations are really bad, you are losing a huge amount of the belly's potential. Spend serious time on terminations, both on the bass and long bridge, and you will have a better chance at getting more of everything from that beast.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 3.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Registered Piano Technician
    Posted 06-09-2020 16:00
    Loren,

    I trust you have carefully looked everywhere for separations/deterioration etc. 

    I trust also that you have a plan for making sure the downbearing will be correct when you install this new bridge...

    If it was me, I'd probably experiment FIRST by epoxying some or all of the pins and see if my problem was largly solved. If so, this would be circumstantial evidence that the problem is solely with the bridge pins. If still lousy...then something else is going on. 

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 4.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Member
    Posted 06-10-2020 10:39
    It seems to me that if it sounded ok with the old bridge, the new down bearing is too much and the extra tension on the board is inhibiting the board in the tenor section. Drop the tension on the bass wire and see if the sound in the tenor returns. You can also shim the back scale,, sometimes depending on the maker.
    Otherwise I would go with the epoxy on the pins of the long bridge. 





  • 5.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Registered Piano Technician
    Posted 06-10-2020 15:14
    I get the idea that he has yet to install the new bridge. I could be wrong though. 

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 6.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Registered Piano Technician
    Posted 06-11-2020 04:57

    I haven't installed the new bass bridge yet – it's on its way.  The old bass bridge is still in and the strings are all at full tension.  But perhaps the damaged bridge has somehow changed the stress on the soundboard overall and is affecting the tone in the rest of the piano.

     

    Thanks for your comments and suggestions.






  • 7.  RE: Split bass bridge, lousy tone and sustain elsewhere

    Member
    Posted 06-11-2020 11:39
    Oh my mistake,
    If the cracked bridge released tension and it moved into the tenor bridge, the extra tension will increase power but you lose sustain to a certain point where the board doesn't work at all. 
    Weak tenor is usually bridge pins or bridge to board connection. in pianos that have cracked bass bridges, there is a good chance the glue joint is no longer a positive connection. The screws may seem tight but they put them in with fresh glue.
    And as usually, it is a combination of problems. 
    Up here in the mountains where humidity levels range from 8% to 90%,, the bridge pins hydraulic out of the hole. You can tell by the difference in height. You know they came out of the factory all the same height. They may look like they have a pattern but the ones on the edge of the bridge usually are taller.
    Another tuner in town called me to look a piano with similar problems. He did everything but drive in the bridge pins. They were all different heights. I went through a section of easy ones to get to and what a difference. the owner said it had never sounded that good.

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    Keith Roberts
    owner
    Hathaway Pines CA
    209-770-4312
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