Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Petrof magnetic action ... any good ?

Has anyone tried or serviced the Petrof magnetic action ？

Is this a recent invention ?

Any real advantage or just another gimmick ?

I reviewed one several years ago in the Piano Buyer, which you can find somewhere in the archives. I seem to recall one of the primary motivations was to completely eliminate lead from the action.

Some years ago there were new international laws concerning lead so manufacturers looked into magnets instead of springs and weights. Then either the laws were relaxed or found to be not as stringent as first thought and so interest in magnets seemed to evaporate.

I still have two bags of keyleads buried under my patio along with a particularly delicious but unpasteurised cheese.

Shh!

I remember when that came out, then was surprised as time went by that I never heard anything about it anymore. I thought it was a pretty neat idea though.

Pwg

Seiler used magnets in upright actions - not sure if they still do or if they used them in grand actions.

Did you try a Petrof with the magnetic "accelerated action", Fazioli-Yang? What did you think of it?

I'm pretty sure applications which used them in vertical pianos were more concerned with increasing repetition speed, if memory serves. Have not played one.

Yes, I think that's right - that's what I recall reading.

Fazioli-Yang, have you tried a Petrof with the magnetic action? What did you think?

If it is only speed, it is well known that an upright can repeat faster than a grand.

It is control at all speeds that is sought after for uprights.

Yes. Uprights have a kind of resonant repetition speed that works well at certain rapid rates, but fails if the speed slows.

Magnets have been tried by several companies and inventors. The issue is the inverse square law as applied to magnetic attraction. The closer the magnet gets to another magnet, their attraction multiplies exponentially. As a result, it is a real challenge to use magnets in a fashion that is truly controllable. Again, one of those instances illustrating that static measurement doesn't predict dynamic experience.

I googled and found out it was invented by a Dutch guy. I have not touched a magnetic action before. I was near a Petrof grand @ Music China, but I didn't know about magnetic action until after the show. I missed the opportunity. I am also wondering how the inventor counters the sudden surge in the magnetic attraction and repulsion when 2 magnets are brought too close with each other.

Very interesting - I hadn't thought about the inverse square law in connection with magnetic attraction!

Keep in mind... I'm not saying that such a concept is impossible -- just that there are extreme challenges to deal with. In the world of physics, there's no such thing as a free lunch. In the piano action world, that generally is manifested either as unintended-unforseen consequences in the downstroke or completely forgetting there may be consequences to the upstroke.

I do recall Rick Voit, inventor of the Keyforce 1, analyzing a magnetic action and pinpointing the issues that it had even though static parameters were within the orthodox static limits.