the A floats

[Don]

Hi David,

Most electrical utilities have a charge for the "surge" as the 50 kilowatts
for the lights come on. It's not cheap (or so I was told). So your
calculations do *not* include that cost. You notice I said "tuning cost"
not "concert prep". The hall also has to pay for a lighting tech to be
around for those hours, not to mention the lifespan of the bulbs.

The outside air brought into the halls is very humid--at the out door
temperature, but *very* dry at the 20 degrees C. it ends up at.

I don't know how long before the 30% drop in humidity causes the pitch to
react. I do know it is not a gradual curve, but a sharp drop. I also know
that for every 5% change in humidity small pianos (Yamaha p2 and similar)
will change about 4 cents at A4. What I don't know is how fast this change
happens.

I have measured changes of 14 cents at A4 on a Steinway 7 foot when a
Dampchaser system without bottom cover was plugged in for 12 hours when the
RH was 4% (measured with a pyschodyne) in the room. (It had been unplugged
for several days)

At 01:04 AM 31/08/2004 -0600, you wrote:
>
>----- Original Message ----- 
>From: "Don" <pianotuna@accesscomm.ca>
>To: "Pianotech" <pianotech@ptg.org>
>Sent: Monday, August 30, 2004 11:36 AM
>Subject: Re: the A floats
>
>
>> Hi,
>>
>> Temperature wins out in the short term particularly the intense heat from
>> stage lights. This can be ameliorated to some extent by "pre heating" the
>> piano before it is tuned. It does require several hours for the piano to
>> reach "steady state". If all the performance lights are on to do this the
>> electricity costs far exceed the tuning costs.
>
>    Really?  I've done a lot of stage crew work in full-fledged,
>fully-equipped theatres, and came up with, very roughly, 50 kilowatts
>beating down on the stage (but not all directly on the piano) with almost
>everything except the follow spots burning.  Let's take even twice that, 100
>kilowatts.  Electricity averages about 10 cents per kilowatt-hour.  So 100
>kilowatts for an hour would be $10.  If they're all burning for 4 hours to
>warm up the piano, plus 2 or 3 more hours for concert prep, that's 7 hours
>times $10 equals 70 bucks for the juice, certainly less than the cost of the
>concert tuning and prep.
>
>> Air conditioning in halls in temperate climates in the winter time is
>often
>> done using "outside" air. Humidity can drop 30% in 15 minutes. It behooves
>> the piano technician to find out "when" the air dampers will be opened and
>> finish tuning before that event occurs.
>
>    Good idea.  But air conditioning isn't used in the winter much.  But
>even if outside air is pumped in for ventilation, it can be quite humid if
>it's snowing or raining.  And even worse in the summer.  But as a rule,
>doesn't air conditioning tend to dry the air, rather than make it more
>humid?  (I know that swamp-cooler-type cooling makes it humid).  Yeah, air
>conditioners drip water, so they must be removing it from the air.
>
>  But no matter, the main question I have is:  how long does it take the
>soundboard to react to that 30% drop (or rise) in humidity?
>
>    People have asked me on rainy days if it's a bad idea to tune the piano.
>I've always told them that just one rainy day isn't enough to throw the
>piano out of tune.  Unless all their doors and windows are open.  In
>general, I don't experience many customers all calling because their pianos
>have gone out of tune unless we've gotten 2 or 3 weeks of rain almost every
>day.  And when people turn on their furnaces in the fall, the pianos don't
>drop in pitch in one day.  It takes a few weeks.
>    You'd think there'd be scientific charts available, what with all the
>research and technology going on nowadays.  Heck, even since the beginning
>of the industrial revolution -- not much longer after the piano was
>invented.
>    David Nereson, RPT
>
>
>
>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives
>
>

Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.

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