hammers and magnet length

[pnoboy]

Hello everyone.  I'm new on this forum, and hope I'm not asking about things that have been already answered.
First, does anyone have any definitive knowledge as to when Rhodes switched to the 1/2 inch magnets?  I've found conflicting information.  For example, I had a 1972 or 1973 Mark I stage piano, and based on its pickups being wired in parallel groups of 6, and also based on the fact that decreasing the pickup-to-time gap to less than 1/16th inch caused detuning, I assume that it had the long magnets.  Nevertheless I ran across information that the shorter magnets were introduced with the mark I.  I believe the pianos with shorter magnets always had pickups wired in parallel groups of 3.  Is this correct?

Second, does anyone know which is lighter, the wood/plastic hammer or the all-plastic hammer?  I have never seen this discussed, but would expect that hammer weight would have an effect on tone.  Other things being equal, a lighter hammer will bounce off the tine more quickly, and this would favor the excitation of more harmonics, creating more of the ping when the hammer hits the time.

Thanks to all for any responses.

[pianotuner steveo]

I don't know about magnet length, but the different hammer material has no effect on the tone. The different hammer tips alter the tone. Felt or rubber tips, and different hardness of rubber will change it. Here's an analogy - in acoustic pianos, the hammers are large in the bass and very small in the treble, which means the weight is very different on notes 1 and notes 88. The tone, however is consistent unless someone alters the felt either making it harder or softer.

[pnoboy]

In the acoustic piano, hammer weight has a profound affect on tone.  You can find lots of info on this topic with some searching.  One reason treble hammers on acoustic pianos are small is to bring their weight done.  Heavy hammers in the treble region cause a loud thunk without much other sound.

[Max Brink]

For three hybrid hammer (minus the mounting hinge) and three plastic hammers that I grabbed at random the weight come in at an average of 12.13g for the wood and 12.41g for the plastic.

[Ben Bove]

I could probably locate when they actually switched to smaller magnets, but I do know for a fact that 1970 Mark I pianos still had the larger magnet pickups.  Off the top of my head I believe it was some time in 1971.  You can tell them visually apart with the plastic housing being much larger.



The detuning you're talking about with the pickup magnets having an effect on the tines, happens with all Rhodes pianos but definitely more substantially on the larger magnet, early pianos.  It does reduce when the pickups are farther away from tines.