Tuning And Temperature

[PAUL GOODMAN]

I own a combination organ which is mainly digital with a pipe section consisting of Open Diapason, and Trumpet 8 extended down to give a 16 Trombone.

 

The organ is housed in a room interconnected to another with a good space for the organ to breathe - (about 32' square plus another 22' square connecting.)

 

My problem is that on a late September evening I have a concert being given by an illustrious organist and I want the pipes to sound their best, but it is hard to guess the temperature with the influx of 75 people. Should I tune without any heat, and then open the windows and hope the temp does not exceed what we tuned at, or should I turn some heating on tune at a higher temp and hope the peoples body heat proves equal the central heating???

 

Does anyone have a calculation as to how much the rise would be with +75 people?

[Guest Geoff McMahon]

I am afraid that only trial and error will give you the answer to that question. Some electronic combination organs have a facility for adjusting the pitch of the electronic section. Of course, if it were all pipes, there would be less of a problem.

 

John Pike Mander

[PAUL GOODMAN]

The organ does not have a pipes/digital regulator, and I think they are of little use, because the problem is the pipes out of tune with themselves.

 

I would love to have a pipes only organ (although I see little point in real flue 16' basses when space is short in a house) - and I do have space for an organ chamber behind the music room with a hole cut in the wall. The only problem is I don't have the money!!!!

 

If I did it would be detached console electric action and some extension/duplication - would Mander build it??????????????

[Guest Geoff McMahon]

Not an easy question to answer. In principle, I think we would encourage the customer to build the pipe organ which fits the space, but to keep it "straight" rather than to extend it. There is much one can do with a small, but honest instrument and the possibilities are not always obvious. Extending ranks does not always give the result one might be hoping for.

 

John Pike Mander

[Claviorgue]

My idea would be to tune the instrument when the room is at 25c. My rough calculations are that flue pipes sharpen by approx 0.6 Hz per degree Celsius. Therefore if the temperature at the beginning of the concert is say, 22c, your reed rank is going to be sharp by almost 2 Hz. Hopefully, by the end of the concert and the temperature perhaps as high as 27c, the reeds will be still no more than 2 Hz different from the flues. The overall pitch of the instrument has no consequence unless other instruments are involved.

This is a very rough guide and does not take into consideration the temperature at different levels in the room.

[chrisb]

My idea would be to tune the instrument when the room is at 25c. My rough calculations are that flue pipes sharpen by approx 0.6 Hz per degree Celsius. Therefore if the temperature at the beginning of the concert is say, 22c, your reed rank is going to be sharp by almost 2 Hz. Hopefully, by the end of the concert and the temperature perhaps as high as 27c, the reeds will be still no more than 2 Hz different from the flues. The overall pitch of the instrument has no consequence unless other instruments are involved.

This is a very rough guide and does not take into consideration the temperature at different levels in the room.

 

Get ready folks, here comes the stupid question of the year!

By what reasoning does increasing temperature cause pipes to 'sharpen' in pitch? Logic says that increased temperature causes the pipe to expand, and, in my primitive brain, bigger pipes equal lower notes - flattening.

And people talk of the organ going flat when it's cold when my poor assaulted reasoning says the pipes are getting smaller and sharper.....

 

Or, is it more to do with the way sound waves behave in changing temperatures, rather than any consideration of the pipes themselves?

My churches allow me two tunings a year, and I call for these mid-autumn and around Easter time, which in the buildings' unheated state, means that both tunings are carried out at more or less the mean temperature of the year. Seems to work OK but is probably nonsense. My tuner agrees, though that may be to do with having a couple of churches outside of the Christmas rush.

 

I'm already wishing I hadn't got into this

Chris Baker

[Claviorgue]

Get ready folks, here comes the stupid question of the year!

By what reasoning does increasing temperature cause pipes to 'sharpen' in pitch? Logic says that increased temperature causes the pipe to expand, and, in my primitive brain, bigger pipes equal lower notes - flattening.

And people talk of the organ going flat when it's cold when my poor assaulted reasoning says the pipes are getting smaller and sharper.....

 

Or, is it more to do with the way sound waves behave in changing temperatures, rather than any consideration of the pipes themselves?

My churches allow me two tunings a year, and I call for these mid-autumn and around Easter time, which in the buildings' unheated state, means that both tunings are carried out at more or less the mean temperature of the year. Seems to work OK but is probably nonsense. My tuner agrees, though that may be to do with having a couple of churches outside of the Christmas rush.

 

I'm already wishing I hadn't got into this

Chris Baker

 

It is not a stupid question. It is to do with the latter of your assumptions. Air density changes with temperature. Cold air has a higher density and therefore sound/frequencies travel slower. We could bring in the factor of humidity here, but perhaps we have enough to fill our collective heads for the moment? It is amusing that we are responding to a four year old post. I hope that the original writer is not offended by our tardiness? In conclusion, I am hoping that someone better versed in the laws of physics is going to give us some hard facts. In the meanwhile I will continue with my rather crude rule of thumb technique.

[pwhodges]

Full details. There is a graph showing the effects due to the speed of sound in air at different temperatures, for different humidities. Also a note that the effect of physical changes to the pipe is about one sixtieth of that due to the air.

 

Paul

[chrisb]

Paul and Claviorque, thank you for your replies. It is good, even for a brief moment, to be getting wiser as well as older.

Chris

[Claviorgue]

Full details. There is a graph showing the effects due to the speed of sound in air at different temperatures, for different humidities. Also a note that the effect of physical changes to the pipe is about one sixtieth of that due to the air.

 

Paul

Thank you very much Paul.

Ken

[Lausanne]

Paul and Claviorque, thank you for your replies. It is good, even for a brief moment, to be getting wiser as well as older.

Chris

 

The A pipe tuned to 440Hz at 20°C will change by about 0.8Hz (0.781) per °C.

 

In practice tuning problems related to heating are usually caused by unstable air conditions. Either the air temperature is changing (as a heater comes on) or there is a stream of air moving across certain pipes because the heated air is only coming from one direction. In this case, tuning anything other than the reeds during the heating period should be avoided if possible. Of course if there is a constant temperature difference between one division and another caused by the heating, it is possible to tune them together, but the 'heated' division will require tuning back when the heat is off. The full tune should really only be done during the time of year when the temperature in the building is the same as outside and there are no air currents anywhere near the organ.

 

Organs are usually built so as to limit the unstable air caused by heating, but many organs predate the heating system they now have to contend with.

[JohnR]

It is not a stupid question. It is to do with the latter of your assumptions. Air density changes with temperature. Cold air has a higher density and therefore sound/frequencies travel slower. We could bring in the factor of humidity here, but perhaps we have enough to fill our collective heads for the moment? It is amusing that we are responding to a four year old post. I hope that the original writer is not offended by our tardiness? In conclusion, I am hoping that someone better versed in the laws of physics is going to give us some hard facts. In the meanwhile I will continue with my rather crude rule of thumb technique.

 

The important thing with a flue type organ pipe is that the pipe specifically determines the wavelength of the note, not the frequency. The frequency also depends on the speed of sound in air. This is because the speed of sound in air determines the speed of travel of the pressure wave along the pipe. This in turn determines the number of oscillations of the pressure wave per unit time i.e. the frequency of the note.

 

John R

[Guest Cynic]

I know Paul Goodman's installation. In a large recreation area in his Devon guesthouse he started off with an Allen two-decker. To this he (and friends) then added two pipe ranks that play through the MIDI channel of the Allen. He has a substantial Diapason from 8' C and a (mostly) Compton Trumpet rank from 16' C. When all of it is in tune, the whole lot makes a spanking sound which has been displayed and exploited in concerts by such folks as Carlo Curley and Geoffrey Morgan.

 

It's a practical question, and one almost incapable of an accurate answer - but it's one I have had to face a number of times too. House organs because of being placed in more intimate settings seem to be much more succeptible to temperature rises as a result of an audience. In the spring I twice sat thirty-five members of The Organ Club in my organ barn which normally remains rock steady at 60 degrees. By the end of each little concert, due to the body heat of the audience alone, the temperature had gone up to nearly 70. Note, my barn is 40' long by 20' wide with a maximum roof pitch of 16'. I think the height has the most to do with it! Unfortunately, an out of tune organ sounds even worse in a small building than it does in a large one.

 

I entirely agree with an earlier comment which advises that one should leave fluework alone when the temperature swings, but in Paul's case, even the flues will be out with the Allen stops if he gets a large audience.

 

Let's be pragmatic....here's what I would do: I have an opening recital to give soon on another house organ installation of mine - December is not a good month for organ tuning, but we must do the best we can. I have arranged

1. the householder puts the heating on full first thing in the morning - this'll get the room up to about 70

2. I will tune anything that seems adrift before lunch

3. just when the audience arrives for a 3pm performance, we'll put the heat off.

 

I guess that the audience will keep the heat roughly where it is, and the organ should sound OK.

[Fingers crossed.]

[JohnR]

I know Paul Goodman's installation. In a large recreation area in his Devon guesthouse he started off with an Allen two-decker. To this he (and friends) then added two pipe ranks that play through the MIDI channel of the Allen. He has a substantial Diapason from 8' C and a (mostly) Compton Trumpet rank from 16' C. When all of it is in tune, the whole lot makes a spanking sound which has been displayed and exploited in concerts by such folks as Carlo Curley and Geoffrey Morgan.

 

It's a practical question, and one almost incapable of an accurate answer - but it's one I have had to face a number of times too. House organs because of being placed in more intimate settings seem to be much more succeptible to temperature rises as a result of an audience. In the spring I twice sat thirty-five members of The Organ Club in my organ barn which normally remains rock steady at 60 degrees. By the end of each little concert, due to the body heat of the audience alone, the temperature had gone up to nearly 70. Note, my barn is 40' long by 20' wide with a maximum roof pitch of 16'. I think the height has the most to do with it! Unfortunately, an out of tune organ sounds even worse in a small building than it does in a large one.

 

I entirely agree with an earlier comment which advises that one should leave fluework alone when the temperature swings, but in Paul's case, even the flues will be out with the Allen stops if he gets a large audience.

 

Let's be pragmatic....here's what I would do: I have an opening recital to give soon on another house organ installation of mine - December is not a good month for organ tuning, but we must do the best we can. I have arranged

1. the householder puts the heating on full first thing in the morning - this'll get the room up to about 70

2. I will tune anything that seems adrift before lunch

3. just when the audience arrives for a 3pm performance, we'll put the heat off.

 

I guess that the audience will keep the heat roughly where it is, and the organ should sound OK.

[Fingers crossed.]

 

It's a shame if the electronic tones can't be master tuned. That would help a great deal. I sometimes play an organ that uses a couple of MIDI stops to play an electronic reed (a good one). The electronic unit is tuneable and it's pitch indicator really emphasis just how much the pitch of the organ fluework changes throughout the year.

 

John R

[andyorgan]

I know Paul Goodman's installation. In a large recreation area in his Devon guesthouse he started off with an Allen two-decker.

 

Can anyone tell me roughly where in Devon this is? I'm often working that end of the country and looking for B & B or hotels. The thought of one with an organ, or at least a sympathetically organist owner quite attracts. Perhaps a PM would be more appropriate if the information is sensitive in any way.

[AJJ]

Can anyone tell me roughly where in Devon this is? I'm often working that end of the country and looking for B & B or hotels. The thought of one with an organ, or at least a sympathetically organist owner quite attracts. Perhaps a PM would be more appropriate if the information is sensitive in any way.

 

Not much help but he used to advertise (maybe still does?) in Organists' review.

 

Alastair

 

Later......Try this.