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Eromlignod:

I still have two questions.
1. How does this devise compensate for the substantial drop in pitch that occurs with newer piano wire? and
2. How much electric power is used to maintain all the string warmth?

Sorry if I seem a little skeptical here. B

Hi Ben:

The power consumption is directly proportionate to the tuning range: the more range you want, the more juice it takes.

Theoretically you can have any range you want...just feed it more watts. But practically, you are limited by how much power is commonly available from a household outlet.

The amount of power it consumes obviously depends on how far it is out of tune. The worst case would be when all the strings are all at full flattening power and that is what the power supply is sized for, though the piano will probably never use that much in normal operation.

The prototype's power supply can provide up to 1500 watts. This is about the same as an ordinary steam iron. This should provide a tuning range of about 50 or 60 cents for all strings.

Don
Kansas City

Is your system installed in a piano of your choice exclusively at your factory or can it be installed by anybody on any piano? How much is the price?

JUNMER

It's not out yet. It was supposed to come out on Story & Clark Prelude grands in 2005, but as I mentioned, QRS never got around to it (though they still had to pay me minimum royalties).

I have designed it as a universal kit for any piano, but the installation is a little tricky. Ideally it would be installed at the piano factory, but it could also be installed in the field by an experienced tech.

Once I have completed the final prototype (in a couple of months) I will be looking for a company to manufacture, or possibly even install, the kits. The big problem with installation is that a piano has to be shipped to the installation facility and stored while it awaits conversion. If I got an order for 500 of them in a month, I'd have to unload and store 500 pianos, then reload and ship them when they're done...ugh!

The price will depend on sales and on margin. The more units that can be made at a time, the lower the cost (this is particularly true of electronic items). Whoever the main manufacturer is will decide what kind of profit margin the market can bear. I have no way to know what the demand will be like. I'm assuming it will be brisk at the beginning and taper off after a while. How "brisk", I don't know.

If they sell like hotcakes, I could see them selling for as little as $500; maybe lower. Only time will tell.

Don
Kansas City

Hi Don:

Perhaps your device would be used best in conjunction with an occasional ear tuning to keep the strings tight enough at room temperature so the power consumption would be kept at a minimum. I'd be very curious to see one of your devices in action.

Thanks for the info
Ben G

@Don

I understand - the power you supply to the strings is never greater than the dissipation of the system at the operating temperature.

Don, for this to be commercially viable, I think the 24/7 average power consumption will need to be 100 Watts or fewer (comparable to what a Dampp-Chaser consumes). What sort of numbers are you seeing from your prototype?

At 1.5kW, the system would cost over $1000 per year to operate, just for the electricity. That is also quite a lot of heat to dissipate in one room- like running a hair dryer 24/7! That would be enough to affect one's heating/cooling expenses.

At 200 Watts, it would cost about $140 annually for the electricity. I'd feel a little environmentally irresponsible using even that much power just to keep the piano in tune 24/7. But a system that only uses power when making adjustments and is otherwise turned off would be very attractive.

Mark:

The system only functions while it is turned on. You switch it off when you are done playing (or it switches itself off automatically if no playing is sensed for ten minutes).

Using my local electricity rates, it would cost 32 cents to practice for three hours.

Don
Kansas City

Ah, that changes things a lot, thanks for clarifying. I assumed it had to be on 24/7 because it seemed like adding and removing extra string tension for all the notes at once on short notice might adversely affect the piano.

Mark:

No, I've never really had any trouble with changing the tensions. You have to remember that when you turn it off, it doesn't take *all* the tension out of the strings, like if you were re-stringing it (I have talked to people who have thought this). It just goes a little sharp when the strings cool to room temperature.

Don
Kansas City

Seems that turning it off wouldn't take *any* of the tension out of the strings, since it tunes from that cool/sharp slightly over-tensioned state down to correct pitch by warming/expansion when operating. (Just to be clear.)

(Still patiently waiting for a nice Universal Retrofit Unit to hit the market. Thinking it might be available before aging arms and ears tire of quarterly self-tuning. :p )

I'm sorry to have to say this, but this self tuning sounds like one of those ideas that has not been properly thought through. Do I need a warm-up time before I start to play? What's the effect on the damper felts? How is the humidity of the instrument affected, particularly the soundboard? Dried out bridges start to crack. Hide glue starts to soften at about 60 degrees C. Bridge pins might expand and become loose. Non-uniform warming could well put new stresses on the pinblock and plate, etc, etc
For the last hundred years, many have tried to improve what is a fantastic empirical design. You only have to imagine those little bits of bushing cloth taking the full force of every keystroke millions of times to realise what a miracle of engineering a piano is. No one has yet succeeded in improving it (remember Steinway's teflon?), and I can't imagine that heating up its strings is going to do it any good either.

It doesn`t get that hot. He said that already not 10 posts above...

The average string temperature is around 95 F. The keys in your pocket are warmer than that.

Don
Kansas City

Don, I think I saw an article with a diagram a couple of years ago. I seem to remember that your system involves clamping the strings somewhere near the tuning pins. Is that correct?
Have you installed your system in a whole piano from top to bottom yet, or just done tests in the "lab" so far.

Don, if your system can be a retro-fit in my M&H RBB, count me in! Look forward to seeing and hearing it. All the best!

The idea to clamp the strings was abandoned long ago. I wrote that article for the Piano Techicians Journal in July of 2002. Since then I have joined the PTG and had the much-appreciated assistance and advice from several seasoned piano techs. They assured me that 99% of the detuning of a good piano is due to environmental effects on the soundboard and frame, not slipping pins. This has turned out to be absolutely true.

I started out to prove the concept with just a few strings tuning at once. This was enough to get a contract with QRS. I then tested a complete system using a massive PLC, which is what is used to control factory machinery (my vocation). An electronics design firm was chosen by QRS and they were supposed to convert the controls to embedded microchips, but they never got very far as the project was constantly put on hold.

Finally I decided to design the circuit myself. I'm a mechanical engineer by trade, so there was a considerable learning curve, but I have eventually gotten everything running.

Now I have designed a printed circuit that does everything on a 3.5" x 10.5" board that is hidden in the cubby hole behind the action on the treble end. I have also redesigned the sustainers to be much smaller, easier to adjust, universal for any piano, self-exciting and with a volume adjustment.

I still plan to have the complete, embedded system working in the next few months. There have been a lot of delays and it seems that I spend more time waiting on parts than actually working on the piano.

Thanks for your interest!

Don
Kansas City

Very interesting.

How does the circuit know when to stop heating each string? What's the "tuner" element?

So a piano in the field could be tuned 5-10 cents sharp and the retrofit could then take over?

Each string has a "sustainer" under it. It is an optical sensor that detects the vibration of the string by how it blocks a tiny beam of light (sort of a minature version of the thing that trips your garage door opener). This signal is conditioned into a square wave that transitions on and off at the fundamental frequency of the string. This wave is fed to a magnetic coil that causes the string to vibrate freely, as if drawing a violin bow across it.

I do not "count" the waves, like a frequency counter does. I use the square wave to turn a high-speed counter on and off. The counter is counting the waves of a 50 MHz oscillator. So, in effect, I'm counting how many "ticks" of the oscillator occur during each vibration of the string. So, for A-440, a correct reading would be

50,000,000 / 440 = 113,636 ticks

So 113,636 ticks occur from the oscillator every time the A-440 string vibrates one time.

You can see, since the number is so large, there is a very high accuracy and resolution to the reading. For example, one "cent" sharp for A-440 is 440.254 Hz, so its correct count would be

50,000,000 / 440.254 = 113,571 ticks

That's a difference of 65 ticks just for a single cent off. So basically, at A-440 it can be as accurate as about 1/65th of a cent.

What I have found, though, is that a string naturally fluctuates as much as 1/5 cent, so this resolution is much finer than it needs to be.

Don
Kansas City

Don, does the system scan the strings continuously while it's being played, or does it maintain the same temperature it would set at the beginning of the session. Do you have heat sensors as well? Do bigger, longer strings (tenor and bass) require more or less current?