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Aug. 31, 2019

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Aug. 18, 2019

(con't from Part VII)
[Photo: courtesy of Kimball organ at Saint Louis Scottish Rite Cathedral in Saint Louis, Missouri; taken 15 feet in the air in Main chamber facing northwest corner, pipes of Harmonic Trumpet (center, metal), English Diapason (right, metal), Concert Flute (Pedal Bourdon, wood, right), Principal Diapason (wood, left), Pedal Contra Bombarde & Clarion (wood & metal, background)]
Organists often complain about tuning; the pipe organ is a wind instrument, and it's affected by temperature and humidity (See blog, Temperaments & Tuning, Part VII).
When it's warm the organ will go sharp; when it's cold it will go flat; normally this is not particularly noticeable, except that the reeds are NOT much affected by temperature; their pitch is determined by the length of the brass tongue that vibrates.
If the whole organ was tuned in winter at 68 degrees Fahrenheit, in the summer heat the flues will go sharp and leave the reeds behind, sounding flat to everything else.
In some voicing styles, notably by Schantz, reed pipe pitch is determined as it is with flue pipes, by the length of the pipe; in others, such as used by Fisk, it's determined entirely by the length of the tongue.
It's important to understand this when tuning reeds.
Schantz reeds, for example, are almost all tuned with a scroll at the top of each resonator (photo); Fisk reeds, on the other hand, have no scrolls -- most are "dead length" and must be tuned at the wire.
The basic tuning concept is simple, but in practice it's rather complex; every pipe has a means of changing its length -- and this feature is built into it by the organ builder.
Flue pipe pitch is determined by the number of air molecules inside the pipe, measured from the mouth to the tuning device; this is why pitch goes up when it's hot; the more active air molecules contain more energy, and they bounce around more than when they are cold, reducing the air density and therefore the number of molecules excited into vibration by the pipe.
Metal pipe length can be changed by fine tuning the position of a movable tuning slide constructed at the top of the pipe, by slotting (photo) or scrolling the end of the pipe, by bending large ears on each side of the pipe mouth, or by using a tuning cone to physically bend the top of the pipe in or out; the pitch of wooden pipes may be adjusted by means of a sliding piece of metal or wood (photo) near the top of the pipe or a movable stopper or cap inside the top of the pipe.
If we can tune the thermostat, we can tune the organ without changing the pipes; it will be in tune with itself whenever the temperature is the same as the last tuning temperature (unless dirt of some foreign object is present).
In extremes of outside temperature the organ reeds will NOT be in tune; in the heat of summer, we simply avoid the reeds; when the temperature drops to normal, they will again be in tune.
If there is a budget for seasonal tuning we will want the reeds (at least) tuned for winter when the furnace is running, and again for summer after the furnace is off.
We should try to avoid spot tuning, if we can; this is when someone tunes a couple of octaves of a reed we plan to use; now the rank is out of tune with itself, and no amount of thermostat tuning will bring it back.
If we proceed to do any tuning ourselves, we should tune the entire rank at one time; a complete tuning from top to bottom (every single pipe in the organ) usually is needed only every 20+ years in an organ's early life; most tunings deal with reeds, wood pipes, high-pitched flutes, and perhaps a few other stops that are known to be unstable.
To budget for tuning, we compute a "worst case," which is tuning EVERY pipe; this should be at a rate of about 3 ranks per hour, times the tuner's hourly rate, times the number of visits anticipated.
In a 15 rank organ, for example, 15 ranks @ 3 ranks per hour = 5 hours.
5 hours times $100 per hour = $500.
$500 times 2 tunings per year = $1,000.
The technician may also charge for travel time or may have a different charge if one or 2 people are involved; we may also have to budget for repairs that may be more extensive than can be covered in a standard tuning visit.
When the building is heated all week in the winter without any humidification at all, moisture will be baked out of the wood causing pipes and wind chests to split; a split wind chest will hiss as air escapes, and a split wood pipe will not speak.
Electronic tuners are a handy way to set or check a temperament quickly, but in general they should NOT be used for most of the tuning (unless the organ is from the early 20th century and its pipes are large scale with little harmonic development); air temperature changes constantly, so the pipes continually change their base pitch; the tuner however will not change; this means that a pipe organ entirely tuned to an electronic tuner will be out of tune -- guaranteed.

Aug. 18, 2019

The most frequent problems found in pipe organs are dead notes and cyphers; the latter are pipes which sound when they should not (See blog, Cyphers).
In the case of dead notes, if we can reproduce the problem from multiple places we can pinpoint that the problem is at the pipe and not in the relay.
This is called triangulation, and it's a helpful skill.
If, for example, we discover a dead note on the low F6 on the Great 8' Concert Flute, and we find that the 16' Bourdon in the Pedal is also dead on tenor F18, and if it's the same stop, same pipe, we've triangulated where the problem is.
It's a good idea to keep a notebook where a record can be kept of issues like this for the organ technician.
By far the simplest of systems for communicating to the technician which note or pipe is the problem is to count keys from low C; in this system middle C is #25 and there is no confusion about which key on the keyboard is intended.
These written notes should be clear and specific; if we write "D is dead," or "D3 is dead," the technician will not know exactly what we mean, where to look, or which stop to check -- but if we write "Swell D27 8' Oboe Horn is dead" there will be no confusion; the problem is middle D on the Swell Oboe Horn 8'.
From the builder's perspective the organ has only sharps; key #4, for example, is low D#, never low Eb (E flat); this system should be used when leaving notes for the technician; vague messages such as "Viole is out" requires the technician to do a fair amount of detective work just to locate the offending pipe, which results in poor time management, delays, and additional expense.
A pipe that worked yesterday or last week and does not speak properly today might also have a foreign object in it, such as flies, boxelder bugs, Lady bugs, or even gum wads, rubber bands, birds, bats, or paper airplanes.
If possible, we try to find the foreign object and remove it, being careful not to bump the tuning slide or scroll; when the pipe cools from our body heat, it will be in tune once again.
Reed pipes are notorious for flying off proper speech from dirt; often the whole rank is affected, and usually the technician will need to clean them.
Cleaning all the pipes from top to bottom should be budgeted at least every 30-40 years.

Jul. 8, 2019

A pipe organ can attract all sorts of friends who want to BEE around it (photo).

Jul. 4, 2019

Recording the King of Instruments well is always a challenge but, when well done, it can be extremely rewarding.
This is a complex subject, thus only the most general information and pros and cons as it relates to nice sound are described here:
When contemplating the type and arrangement of microphones used to undertake such a task, one needs to bear in mind that no two pipe organs, even from the same builder, are ever exactly the same, and certainly no two halls, auditoriums, theatres, chapels, abbeys, churches, cathedrals, or residences are the same, so no exact information can be offered in that respect; in each unique situation it really is a case of experimentation and using the ear.
Since one would want a stereo recording in this case, the use of a spaced pair of A/B omni's (omni-directional microphones) are usually the first choice for the main pickup (photo).
Omni-directional microphones are microphones that pick up sound with equal gain from all sides or directions of the mic; this means that whether an organ pipe speaks into the mic from the front, back, overhead, left or right side, it will record the signals all with equal gain; this is very useful when the sound needs to be recorded from multiple directions, as when organ pipes are positioned in different locations within the room.
Big pipe organs are among the few instruments with a real low end worth capturing; for recording any organ which can sound 16-foot stops on low C, the sensitivity of the mics used should be able to capture frequencies at least down to 32Hz; for capturing sounds in the 32-foot octave, one would try to use a mic with a sensitivity down to as close to 16Hz as possible to minimize any non-musical ambient rumble; this will be possible because certain mics (albeit the most expensive ones) are sensitive down to 5Hz.
Tall mic stands can be helpful when recording a pipe organ, but since professional builders and voicers make their final voicings to sound good from pews/seats, not 20 or 30 feet up in the air, such stands should be positioned to pick up the signal in the room from where people are seated.
While finish voicers "tune" the organ for what it sounds like down at the listener level in the installed space, it's also the case that the best omni-mics don't hear sound with quite the same complex directional sensitivity that our brain-ear-pinna system does; we often "cheat" the mic much higher than listener level because it "creates" the same sound (as heard by the mic) that we hear with our ears down on the ground -- an added benefit being that getting the mics higher off the ground puts more space between the mics and any audience noise that may occur in a live recording.
These omni-mics would need to be positioned far enough away from the pipes that they take in the acoustics; the room is the dictating factor here; one should NEVER close-mic the organ, as it's not voiced to be heard from right up on the facade or from right in front of the tone grilles.
The capture of the room's ambience is ABSOLUTELY necessary for bringing the sound of the instrument together.
Beyond that there is no formula for mic placement, only good judgment by LISTENING on site for both clarity and room capture; the idea with mic placement is to arrive at a good balance between direct sound from the organ and natural reverb from the building.
The term Critical Distance describes the point, measured from the sound source, at which the direct signal and the reflected or reverberant signal are of equal intensity.
To find this Critical Distance requires a long tape measure, a sound level meter, and some means of generating a reasonably constant level of sound in the room which, in this case, should come from the area where the pipes are located.
One would start by measuring the noise level of the sound source at close range and making a note of the reading; this distance is then doubled and measured again; the noise level will have reduced by a certain amount because one would be in the direct field where a doubling of distance results in a halving of level.
One would then keep doubling the distance and measuring the drop in level from the previous position; while one is in the direct field, each doubling of distance results in a level drop, but as one nears the point where the direct and reverberant fields are equal in level, the level drop will get much smaller.
A change of only a decibel or two indicates that the Critical Distance has been found; further increases in distance will result in no significant change in level at all, because one is now in the reverberant field.
In general, organ lofts and pipework are built fairly high, and so a very tall mic stand or boom helps to get the mic(s) more on axis to the pipework; it's then a case of moving the mic around to get the best balance between the different divisions or sections.
If the organ is large and the pipework is installed in multiple locations, it may be necessary to use several mics to cover everything to attain the best balance; in the case of a pipe organ one may well be able to achieve an acceptable stereo effect using separate, panned, mono mics instead of (or in addition to) a stereo pair.
This is important because as one moves away from the pipes, the closer the mics are placed to the Critical Distance, the more reverberation will be picked up, and moving the mics closer to the source will result in a drier sound.
Recording engineers tend to go for a main stereo pair of mics to give the best overall balance and acoustic impression of the room, and then add additional (usually) mono mics if needed to reinforce a particular section or type of sound just to provide a little extra clarity or definition.
While the premise may be good, with pipe organs these additional mono mics, by giving certain sounds or voices a boost, will change what the listener actually hears from the instrument on site.
In an interestingly dry space where the reverberation may be less than one second, it's tough on the organist who has to adjust many things (touch, tempo, values of chords and intervening rests, possible release of final chords, etc.) to get the music to "sound"; it could mean abandoning for the time being the entire system of touch under which that organist was trained; the performer is faced with changing the score mentally to make the music the composer wrote on the page to come across; it's also tough to figure the Critical Distance for mic placement because the reverberation field is so small relative to the direct field.
The room is very much the "sound board" of a big pipe organ, thus the organist plays the room right along with the instrument; any time the acoustics are sufficiently dry like this, one would want all the hall one could get on the recording; sometimes a smaller spacing between mics improves the stereo picture a bit, but one would have to listen to know for sure; one might also experiment with an even more distant spacing from the chamber grille just to generate as much ambient reverb as possible.