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  • 1.  Adding power and tone

    Registered Piano Technician
    Posted 09-12-2014 15:44
    I recently tuned a Samick SG-172 from the 80's that has been lightly used. The middle four octaves sound like I have earplugs on: no power, no particular attack. It's not an unpleasant sound, and certainly not bright, but just wimpy.

    I haven't done any regulation yet, but the hammer flange pinning is OK. The surface of the hammers is not smooth: lightly grooved, with tiny loose strands of felt at random. They're on the soft side, but not Q-Tips (TM).

    Which is likely to have the greater improvement: resurfacing the strike point, or standard shoulder needling? (I guess I should plan for both... after traveling, etc.).


    Cy Shuster, RPT
    Albuquerque, NM

  • 2.  RE: Adding power and tone

    Posted 09-12-2014 17:48
    Hi, Cy---I have had great results many times with hammers such as you describe by treating the lower half of the hammer---from the start of the felt to 3 and 9 o'clock on the shoulders---with 6:1 acetone/lacquer solution. Wait a day, and I speculate magic will happen.
    Also, if the action has a low balance weight (DW+UW /2) you can add a .5gm mini-binder clip to the shank as close to the hammer molding as possible. This will add power and fundamental tone.

    David Andersen
    Los Angeles CA

  • 3.  RE: Adding power and tone

    Registered Piano Technician
    Posted 09-13-2014 13:28
      |   view attached
    Cy, Here is what I would probably try BEFORE breaking out the hammer stiffener/hardener- at least on a couple of hammers to see what it will do.( It may also help David's lacquer technique work even better if in fact it is still needed. --although David's post is very good, especially the binder clip trick.)

    I have attached a pic of a hammer that is labeled according to the particular voicing areas, so that we can all see what we are talking about. First I would do some deep needling low in the shoulder (area 5--maybe about 5 to 7 insertions with the 3 needles, about 1/2 inch deep. Then work your way up to about 3 and 9 o'clock--probably just above, using the same technique. It may take a fairly large number of insertions in area 4, but you can just see what effect it is having and do a little more, etc--before you make a final decision.  What this will do is release the tension from what Andre' Oorebeek refers to as the "battery" or "reserve power" area (area 5 in pic---see "the Voice of the Piano by Oorebeek),  ALLOWING the tension and power to move up the hammer more toward the strike point, greatly increasing the power and dynamic range, etc.

    From Craig Waldrop at Baylor I have found to be true): "Deep needling directly into the 3:00 and 9:00 areas (area 4) WILL increase power. It takes more needling in this area to be effective as it is less sensitive, but it works!"

    Hope this helps someone, if nothing else.
    I  had to do this on a set of Abel Naturals I just installed on a Baldwin L.- they were NEARLY in the "Q-tip" range on this piano.
    I installed another set of Naturals last month on a Steinway L and they were nearly perfect, just had to open up the shoulders a little mainly.
    (I tried a set of Pianotek's "special press" on the same Steinway L first, but they were WAY too bright for this piano prof. It seems to me the "special Press hammers are quite a bit harder than the Naturals--right out of the box. Just my limited experience so far.)

    Kevin Fortenberry
    Registered Piano Technician
    Texas Tech University

  • 4.  RE: Adding power and tone

    Registered Piano Technician
    Posted 09-14-2014 10:19
    Thanks, Kevin and David. I've taken Oorebeek's class, and he focuses mostly on preparing brand-new hammers (while these techniques should work on old hammers somewhat).

    It's interesting to contrast the two answers: one is to harden the staple area to support the crown, and the other is to soften the staple area to allow tension to move up to the crown. Standard shoulder needling should reduce string contact time and increase power, too. I've done the binder clip trick on uprights, but hadn't thought about it for grands. The hammers are rather small overall; haven't measured weight.

    Kevin, you gave one specific answer I was looking for: how effective one technique is over another. With a given time budget on a piano, I'm looking for a technique that's less time-consuming than deep-needling half of each hammer. I'm also guessing this is less effective on 30-year-old felt than on new felt.

    And what about resurfacing the strike point? No one has chimed in with a vote for that approach.

    I'm leaning toward a combined approach: lacquer for a big win, and then needling to even it out.


  • 5.  RE:Adding power and tone

    Registered Piano Technician
    Posted 09-14-2014 11:01
    Cy, YES- & you have to decide. One other idea that has worked well when under tight time constraints: chuck up a needle (I use Schaff #107 --fairly small neddle) in a BATTERY powers Dremel took - the 7.2 volt is PERFECT on low setting. The 4 er 5 volt ones work FAIR on high setting but it's wimpy & battery doesn't last). Then just do A LTTLE deep needling one the low shoulder if nothing else- so that at least some on that tension & POWER reserved in the "battery" is released, before you apply the laquer because once you apply the laquer it will be sort of "locked in" and harder to release. Adding the laquer to the shoulder WILL add strength & bolster power greatly by backing up what's up top, etc.
    Light hammer filing at least is a must (I have come to LOVE the finer papers in strips)
    So my suggestion is that some quick deep needling just MAY get you within fairly light filing range, and may not be all that time consuming.
    Hope this makes sense!!

    Kevin Fortenberry
    Registered Piano Technician
    Lubbock TX

  • 6.  RE: Adding power and tone

    Registered Piano Technician
    Posted 09-14-2014 15:48
    A Samick is likely to have had extra dense hammers to start with. Hence, the sound you describe is likely the result of voicing. What you describe about the surface felt conditions reinforces that idea, and also the notion that the voicing that was done was "stab" voicing: lots of rapid jabs, somewhat random in where they hit. This kind of stab voicing tends only to penetrate about 5 mm on average. The result is often what you describe: characterless, mellow tone, that doesn't "rise" as you play harder.

    The inner felt is likely to be quite dense. If you needle deeply, 10 mm plus, you will release the bonding of the inner fibers, so that they will press outward. This will result in a brighter tone quality, at least to some extent. Insert a single long needle (10-12 mm) into several hammers in the shoulder area. Does the needle penetrate easily through the first 4 - 5 mm, then encounter a layer that is very difficult to penetrate? That would indicate my guess about stab voicing is correct. It may be, though, that the first step should be to file, fairly aggressively, taking off 1 - 2 mm of felt from the outside. Experiment, and see what happens. 

    For the deep needling to bring up the hammers, a good technique is to start in the lower shoulder (below 3 and 10 o'clock) and aim toward the crown and toward the core (an angle in that combination of directions). That way you are releasing inner compression without compromising outer tension, to the extent that is possible. A good tool for this is the ergonomic needle tool sold by pianoforte supply and Renner, with the curves for thumb and finger. It can let you do this on the shank side of the hammer (since it is short, and can be controlled). BTW, thanks to Terry Otake of Shigeru Kawai for this technique using this tool.

    Fine surface sanding can give good attack brightness, and I have come to like the 15 and 9 micron 3M sanding film for that, though you can use 400, 600 and 1000-1500 grit wet of dry for the same basic results.

    Fred Sturm
    University of New Mexico
    "When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou

  • 7.  RE: Adding power and tone

    Registered Piano Technician
    Posted 09-15-2014 10:34
    I've often wondered about that claim, that needling the low shoulder releases tension up to the crown.  Doesn't make sense to me.  The tension around the hammer is contiguous.  if you stretch a rubber band around the hammer then by removing tension from the lower part of the rubber band the top part won't gain in tension, there will be a net loss.  The more likely explanation, seems to me, might be related to the Poisson effect (you'll have to look it up).  By needling lower in the hammer you expand the hammer outward in that region and in expanding the hammer outward the top of the hammer wants to pull down increasing the tension and density of the hammer over the crown and thus it gets brighter.  Doesn't always work, btw, we notice.  Seems that might have something to do with how much tension is actually stored in the outer layers of felt to begin with  A low tension hammer bound up with lacquer, for example, doesn't respond that way (getting brighter when you needle the low shoulder), a more highly tensioned Renner hammer will.   

    David Love RPT
    415 407 8320