Strikeline issue

[tomsrob]

Hi All,

I've been experimenting with my '78 MI 73 for the past year or so to get the optimum sound. I moved the strikeline once and it helped a bit. I did it again and it really improved except the lower couple of octaves were thunky so I moved it back. After many months I put it back to this spot and this is really where it needs to be. The middle and upper registers sound great. I've got most of the lower octaves to play at least but not great. There are a few that are really thunky: D and D flat below middle C and F-F# below those. I've adjusted escapement to try to improve it. I also have the bass end shim removed and tried putting it back in to no avail. I checked the really thunky notes and the tines are the proper length.

Thanks for any thoughts or suggestions!

[David Aubke]

Are the tuning springs on the bad notes set farther back (forward? towards the tine block, anyway) than on other notes? If too heavy of a spring is used, it will need to sit farther back to make the correct pitch. I think this either changes the tine's "sweet spot" or at least just deadens it.

[voltergeist]

You may just have fatigued tines in those places.  When all else fails, try replacing the tine. 

[pianotuner steveo]

No, if the bass notes sounded better and the treble notes sounded worse before, I think the screw holes on the bass side may need to be moved so the harp can be at an optimum angle for both sides.

[tomsrob]

Yes, let me clarify...the whole range from D (below middle C) to the bottom is not right, although the lowest few notes are pretty good. So I don't think it's tines or springs. The strike line for the bass end is not right. However, from the top down to the Eb just above that D it's perfect. Seems weird to me that the Eb can sound so good and the next note down is awful but maybe that's not out of the ordinary.

I left one screw in the treble side to find strikeline, maybe I'll set the bass side and adjust the treble and see if I can get the same results from the mid and treble.

[Tim W]

You will notice that the transition point you are mentioning is exactly where the hammertips also change from soft black to red (if your piano was not modified).

The height of the hammertips changes here as well.  If the height of the hammertip increases by a step, the strike point moves back towards the player by a step as well.  In a piano with graduated height hammertips, the strikeline changes at each breakpoint in the hammer height (as well as the escapement).

Welcome to late Rhodes production optimization (actually it started a little earlier, but really became noticeable in '76 when the angled tips came into fashion). 

In pianos from the early 70s, all the hammertips were basically the same height.  The escapement was set by shimming the bass end higher than the treble end.  You had a linear gradation of escapement from bass to treble.  The strikeline was then set, and viola, you had a good sounding instrument or great instrument with proper voicing.  The shimming and strikeline setup was time consuming and took someone who had an ear and an understanding of the instrument to properly align.  You also had to then make individual adjustments to all of the dampers to get proper response and stopping.  The mysterious Buz Watson was particularly good at this.

Later, to save time on the production line they shimmed the bass and treble ends identically, and used the changes in hammertip height to save having to shim for escapement.  In fact, in most MK2s, they never even set individual strikelines- just bolted the pianos together using the pre-punched holes in the harp endblocks. 

With all these factors at play it was now impossible to get a linear strikeline across the piano, because the strikeline shifted in steps for each increase in hammer height.  HOWEVER- in most pianos, you could find a sweet spot that was 'good enough' for all ranges of the piano.  They may not have been optimal, but they were good enough to get the pianos out of the factory, quickly... without shimming and without messing with dampers too much.  Big time savings, big labor savings, and ears and understanding of the instrument was not as necessary to get them out the door.

Some pianos are more stubborn than others, and the point at which the whole piano plays evenly is still far off from optimal- the sweet spot for strikeline just isn't good enough.  Moving the harp one way makes the treble sound great, and the bass thunk.  The other way makes the bass sound great and the treble clanky.   Or (at least in my case), the tech is more stubborn, and wants excellent, optimal response in all ranges of the piano.  The only way to get this ideal setup is by having a linear strikeline, and this means either hammertips that are the same height across the keyboard with appropriate shimming of the harp for escapement, or equal harp shimming on both sides with a linear increase in hammertip height for each  individual note from left to right for proper escapement (a real pain and not a realistic way to approach the problem).

And you will occasionally find shims in later pianos etc. etc. but it was more the exception than the norm- and probably last ditch efforts to get a 'good enough' piano leaving the factory.  Remember you've got tolerance stacking:

1. Endblock punching tolerance and shim thickness tolerance.
2. Harp metal frame punching and alignment tolerance.
3. Tine 'pinblock' registration and alignment into the metal harp frame.
4. Tine pinblock curvature and cut tolerance.
5. Tine swaging taper tolerance.
6. Tine metallurgy, processing, etc. from lot to lot...
7.  Hammertiip height and shape tolerance...

The list goes on and on- and we haven't even addressed keybed and action issues.
A mouthful, I know... and that is just the tip of the iceberg...

So, what do you do? 

1. Live with a less than optimal piano that is acceptable in all ranges but not as great as it could be.
2. Try also shifting the treble end with the possibility of drilling new holes in the treble endblock.
3. Angle the harp on the bass or treble or both ends front to back by using a wedge shaped shim.
4. Get all your hammertips to the same height, shim the ends for proper escapement, and set an optimal linear strikeline.  This will also require significant damper adjustments.
5. Bring it to us, and let us deal with it.

Again, not all pianos are uncooperative.  Sometimes the sweet spot for the tines across the piano is wide enough that you can get an optimal response with graduated height hammertips and even shims without all the nonsense.  You can have a great sounding and responsive piano with just a few optimizations.  Most times they are not-- there are a lot of variables at play.

Hopefully this helps shed some light on the issues...

Tim
retrolinear.com

[retro-mike]

dude! get back to work!

[tomsrob]

Ha! Thanks for screwing off work to respond with such an informative post. I would gladly bring my piano to you if time, money and driving distance were not factors. Instead I'll have to see what I can do to not have to choose between having a 73 key muddy sounding piano or a 50 key (or so) great sounding one.