This page is the gateway to many complete articles which describe completed studies and research.  They cover both pipe and electronic organs, and the titles are listed in the following two tables.

The first table is the "classic" chronological listing of articles in the order in which they were posted on the site.  This is the original version of the list as used on this page since the site was founded.  It is retained for those who prefer to continue using this format.

The second table is a newer subject index of articles where they are listed alphabetically by subject.  This was added in 2008 in view of the large number of articles now available on the site.

Note on updating policy : most of the articles remain substantially as they were first written on the posting date specified.  All articles were updated at the end of 2009, but this does not mean each one has been revised in its entirety.  Thus statements such as "last year" in the text of an article are usually relative to the date it was first posted.  Nor is there a guarantee that all external links referenced will still work today, though they are usually checked at the most recent update. Likewise, CD's, books and the like which are mentioned might not be available now.

Note on navigation :  when you have linked to an article from this page, you will find a button marked Up on its navigation bar.  Clicking on this will return you to this gateway page.

CHRONOLOGICAL LISTING

This is the original version of the listing as used on this page since the site was founded.   In each of the columns the most recently posted article is the first entry.  By clicking on the title you will be taken to a summary of that article lower down this page, whence you can then access the full version if desired.  The same titles but classified alphabetically in various subject areas are in another table below.

SUBJECT INDEX

In this table the articles are classified by subject.  Note that an article will often appear in more than one subject area.  By clicking on the title you will be taken to a summary of that article lower down this page, whence you can then access the full version if desired.  The same titles but listed chronologically (i.e. in the date order in which they were posted on the site) are in another table above.

Either browse the table just by scrolling down the page, or click on a subject area in the list below to skip directly to it:

Action, Construction & Mechanism

Electronic Organs (all articles)

Musicology

Organs (specific instruments)

Organ Builders & Other Personalities

Organ Building History, Trends & Styles

Perception & Subjective Effects

Physics of the Organ

Pipe Organs (all articles)

Tuning & Temperament

Voicing

SUMMARIES

This article discusses two issues which arise when preparing waveform sample sets for virtual pipe organs: the recording bit depth and how to remove noise from them.  The dynamic range of organ pipes extends from that with the greatest SPL to the weakest harmonic of that with the smallest.  An example is given of an organ whose dynamic range lies within 16 bits but without much of a safety margin.  Therefore it is suggested that at least 20 bits would be a realistic working minimum, though this could be reduced by judiciously varying the gain to match the level of the sample being recorded.

Noise on the samples is dominated by the organ blower.  Three ways of reducing it are high and low pass filtering to reduce outband noise, conventional subtractive noise reduction, and the application of VPO-specific tools.  A custom tracking comb filter is described which capitalises on the different power distributions of noise and signal as a function of frequency - noise exists at all frequencies across a significant part of the audio spectrum whereas the wanted signals have their power confined to well defined harmonics.  This difference enables the amplitude and frequency of each harmonic or partial to be tracked automatically from the start of the attack transient of the sound, through the sustain phase and then to the end of the release transient including room ambience.  Because power at all other frequencies is ignored, the result is completely noise free.  

This article describes the 'infinite speed and gradation' method of controlling swell shutters invented by Henry Willis III and Aubrey Thompson-Allen in the 1930's.  The system was different to any other in that the amount the swell pedal was moved forwards or backwards from a spring-loaded central position affected the speed of shutter opening or closure rather than shutter position itself.  Therefore it required organists to develop a specific technique for controlling it effectively.  Beyond the original patent, descriptions of how it worked are rare and therefore misapprehensions are not uncommon.  The most widespread is that the system offered a continuously variable speed of shutter movement depending on how far the swell pedal was moved from its central position, whereas in fact only five discrete speeds were available for closing the shutters and six for opening them.  Thus despite what its name implies and the claims made for it, the system offered coarser speed control than most conventional methods.  

It is possible that the systems actually made differed from the descriptions in the patent, in which several essential aspects were explained inadequately or not all.  For example it was necessary to brake the motion of the swell shutters suddenly when the swell pedal returned to its neutral position, yet the means to achieve this were incompletely described.  There was no description at all of the claim that the swell shutters were accelerated or decelerated automatically when they were near the fully closed position.  Nor was there any attempt to illustrate the electrical circuitry involved, or the essential requirement to provide a visual indication of shutter position at the console.  An effort has been made to remedy these shortcomings in this article.  Some potential improvements are also outlined which would bring reality closer to original intention, including one which would provide much finer control over shutter speed.

Whether the system worked as intended or how reliable it might have been are questions which are difficult to answer at this remove in time, particularly as so few working examples now exist.  For instance air leakage would have led to major defects, illustrated by at least two essential features of the mechanism (rapid braking and holding the shutters tightly closed) depending on the integrity merely of a flimsy diaphragm which is subjected to constant flexing.  At several points the patent rather overstated its case with claims which are at best not self–consistent and at worst simply untrue.  Examples include “a perfect crescendo and diminuendo … as quickly or slowly as is desired”, whereas in fact the speed of shutter movement was limited to just a few discrete values.  Moreover one is rendered speechless on learning that “there is no tendency of the operative parts to bind or stick”!  

As it is now unusual to find an organ still fitted with a system in proper working order, players and perhaps some organ builders might find the article of some historical interest.

The current status of both pipe and digital organs are examined in this article in terms of their respective businesses.  In the UK, that for pipe organs is characterised by three well defined groups of organ building firms (‘large’, ‘medium’ and ‘small’) in terms of the number of staff employed.  Most fall into the ‘small’ category in which firms with only two staff are the most common.  Firms in this category undertake mainly tuning and maintenance activities.  The digital organ business largely lacks this category because these products have a shorter life than pipe organs, therefore they tend to be replaced rather than maintained over very long periods.

The future of pipe organs is uncertain in the medium to long term because the industry possibly faces a ‘critical mass’ scenario in which it could cease to exist if the number of instruments falls below a certain level.  If this happens it is unlikely the industry could be resurrected because the necessary skills would have been irrecoverably lost.  This is unlike the digital organ, which could be built at will any time in the future using standard techniques and components common across the digital audio industry much as it is today.

Therefore the organ in one form or another has a long term future, but it is quite possible that only the digital instrument will be robust enough to survive indefinitely.  

This article addresses the physics of resultant bass stops on the organ.  Such stops are often erroneously regarded as a low frequency case of the so-called difference tones which are widely believed to exist in music.  It is shown that difference tones are never generated in the air when two or more organ pipes speak simultaneously, thus they cannot arrive at the ears.  Occasionally they are perceived at higher frequencies, but only if the generating tones are especially loud.  Therefore difference tones, if heard, are purely an artefact of the auditory system.

It is a mistake to confuse difference tones with beats, which are used in resultant bass stops.  Beats are always produced in the air when two or more pipes of different frequencies speak, but they possess no acoustic energy at the beat frequency.  This paradox is because a beat is merely a periodic volume variation of a sound wave at higher frequencies which does possess acoustic energy.  Only if significant nonlinearities exist in the ear will energy be transferred from the generating tones into the beat frequency, and then we might occasionally hear beats as difference tones at medium and high pitches.  However the nonlinearities of the ear are too small to result in perceptible difference tones in everyday musical experience.  Otherwise we would always hear difference tones between each frequency and all others simultaneously present.  Granted that such cacophonies do not occur, it is curious that difference tones are widely believed to exist in music.

Another aspect of beats is important for resultant bass stops - the ear’s temporal  resolution capability.  The beat frequency between two pipes speaking a fifth apart lies at the desired resultant or suboctave frequency of the longer pipe.  However the beats exist as a periodic sequence of discrete bunches of acoustic energy, each bunch having a much higher frequency.  Below about EEEE (20 Hz) the bunches begin to be separately perceived in time by the ear and it is this which gives rise to the illusion of a resultant bass for the lowest few notes.  However there is no acoustic power at the ‘bunch frequency’ itself, even though it lies at the desired suboctave frequency.  Above EEEE the ear begins to hear only the two generating tones, with progressively less perception of a resultant frequency because we no longer resolve the bunches temporally.

Notwithstanding the above, it is possible subjective aspects of aural perception might vary between individuals, thus too much dogmatism might be unwarranted.  Nevertheless, this does not affect the fact that difference tones are not generated as sound waves in the air, and that they are not the same thing as the beats which are generated.  These issues are important if one is to understand the matter properly.

This article shows that the subjective effect of a tremulant can be modified by the ambient acoustic of the room in which the organ resides.  The phenomena are demonstrated by sound clips which show that, at one extreme, the perception of certain types of tremulant can vanish in some circumstances.  It is explained in detail how this effect arises, and it is concluded that in less extreme cases it is nevertheless  likely that the subjective character of a tremulant will vary because of the different reverberation times of different rooms.  These effects seem not to be well known and it is thought to be the first time they have been reported and demonstrated. 

Although the effects might be of interest to pipe organ builders, they have particular implications for the digital simulation of pipe organs using tremulated sound samples. This is because, when the simulation is played subsequently in a different room with a different ambience, the subjective effect of the tremulant will likely be different also.  Therefore, unless the characteristics of the tremulant can be adjusted, it may not be possible to re-create its subjective character satisfactorily.  This will assume importance for the digital simulation of theatre organs whose tremulant characteristics are usually regarded as critical.  

Describing a personal technical and musical journey spanning some 35 years, this article illustrates how advances in digital technology have influenced the way organ pipe sounds are analysed and embedded in electronic organs.  It begins with the huge and expensive batch-processing bureau computers of the 1960's which were largely inaccessible and irrelevant to the majority of those in the electronic music field, and ends with today's personal computers which can host cheap virtual pipe organs whose sound quality can exceed that of commercial products costing many times as much.  The article concludes by pondering on how this might affect a trade already suffering from the impact of a contracting market.

This article surveys a range of reed stops having either conical and cylindrical resonators in terms of their different acoustical physics and tonal characteristics.  Some important aspects are emphasised, including the fact that half-length conical resonators do not enhance the fundamental frequency at all, yet this is often scarcely noticeable to the ear.  To prove this, audio clips are included showing that even the complete removal of the fundamental in the sound of a reed pipe does not necessarily affect the way it sounds, and it explains why half-length pedal reeds can be so effective.

The fractional-length cylindrical resonators used in stops such as the vox humana are also discussed in detail.  Development of this stop over several centuries has been driven by a desire to imitate the human voice, and this was investigated to see if an objective basis for the attempt could be found.  An analysis of the sounds produced by a Wurlitzer vox humana rank shows that it possesses a relatively constant formant frequency over the considerable range of four octaves centred on middle C.  This frequency lies between the second formant of a child singer and the ‘singer’s formant’ of an adult male.  Therefore it is possible this Wurlitzer formant does indeed contribute to a similarity which the best stops of the genre are said (by some) to possess. 

This article was commissioned by Organists' Review and published in the November 2009 issue.  It updated a previous one published some years ago in the same journal and discusses the pros and cons of the main types of digital organs currently available, in particular the newer techniques of physical modelling and so-called virtual pipe organs.  Neither were part of the digital organ scene when the earlier article was written.

This article considers the two main techniques for recording (sampling) real organ pipe sounds when creating waveform sample sets for use in digital organs.  These are either recorded 'wet' so that the ambience of the recording room is captured, or 'dry' so that it is not.  The pros and cons of both methods are discussed in detail by considering room ambience including reverberation and colouration, ambience conflict between the recording and reproducing rooms, various aspects of phase interference during recording and reproduction, differences between signals recorded by a microphone and those perceived by a listener at the same position, and artificial reverberation produced by commercial effects processors.  It is concluded that, although there seems to be no overall winner for all applications, one technique will sometimes be better than the other in particular situations.  Therefore, as with other aspects of digital organs which can only imitate the real thing at best, only the user can decide which of the two options is most attractive for a given application.  Hopefully this article will assist in making the choice.

Robert Hope-Jones is best known as an innovative organ builder of the Victorian era in Britain, and subsequently in America.  However, his clear vision of a pipeless organ which he described to the College of Organists in London (later the RCO) in 1891 is one of the earliest, if not the earliest, milestones in the codified history of that instrument.  This aspect of his lecture was remarkable because it occurred some two decades before the first primitive triode valves (vacuum tubes) appeared, which was about the same time that the word 'electronics' itself was coined.  It is historically important that the transcript of his lecture was published both by the College and by the musical press, because the date is thereby fixed unambiguously and because of the level of detail which was revealed.  The latter demonstrates that he had devoted much thought to his ideas, which arose largely from his background and experience as a telephone engineer.  This article examines the confident claims made by Hope-Jones in his lecture, and suggests various ways in which the limited electrical technology of the late Victorian era might have enabled him to realise them in practice.  In particular, the embryonic state of the art in pre-electronic spectrum (wave) analysis, oscillators, amplifiers, loudspeakers and signal mixing are discussed in detail in this article.

Hope-Jones never seems to have built a working prototype, that mantle thereby falling a few years later on Thaddeus Cahill in the USA with his Dynamophone or Telharmonium which was probably conceived independently.  Nevertheless, his lecture to the College of Organists gives him indisputable precedence as the probable originator of the idea of a pipeless organ using additive synthesis.  This was twenty years before the slightest vestige of the appropriate electronic technology became available, nearly half a century before Hammond and Compton succeeded in realising the technique commercially to a limited extent, and nearly a century before it was finally implemented digitally at Bradford university in the 1980's.  Therefore, as a fascinating case study in sophisticated and accurate technical forecasting, his lecture of 1891 is hard to beat.  

Hope-Jones included Quintadena stops in many of his organs, and conventional wisdom assumes that he intended them to replace mixtures.  This article examines this assumption together with the characteristics of the stops themselves.  It demonstrates the wide range of quiet and mezzo-forte effects which are endowed by Quintadenas in conjunction, not only with other speaking stops, but with the large number of couplers on Hope-Jones’s organs.  Some of them are decidedly attractive and useful in works from the conventional repertoire such as those by Bach.  It is suggested that this might be set against the general condemnation which his organs have usually attracted.  Some actual sound examples are included to assist readers make up their own minds on the matter, and in this the article is thought to be rare if not unique in the literature dealing with Hope-Jones. 

The problems posed by tremulant simulation in digital organs are discussed for synthesisers using the techniques of sampled sound, additive synthesis and physical modelling.  It is shown that the regular and smooth pulsations in the wind supply of an organ generated by a tremulant are transformed into complex and unpredictable frequency and amplitude modulations impressed on the pipe sounds largely because of air turbulence.  These effects become more pronounced the greater the modulation depth, and the effects differ from one beat of the tremulant to the next and for every pipe.  This feature endows a well-adjusted pipe organ tremulant with a richness comparable to that of the pipe sounds themselves.

Simulating all this at a detailed level is only possible for sound samplers which can capture the actual sounds of tremulated pipes, because turbulence and other random or chaotic effects are impossible to model realistically.  Therefore other types of synthesiser using any form of modelling, and this includes additive synthesis as well as physical modelling, can only approximate the effects of tremulants.  However even with samplers there are some practical difficulties which degrade the effectiveness with which the captured sounds can be reproduced.

The upshot is that shallow, gentle tremulants can be simulated quite well by any form of synthesis.  However the more complex effects of fast and deep tremulants can only be captured by sampling the sounds directly, notwithstanding the difficulties of reproducing them.  Moreover, because the effect of a tremulant differs for every pipe it is not surprising that simulating a theatre organ satisfactorily is especially difficult as far as its tremulants are concerned, regardless of the type of synthesis used.  Thus tremulants reveal the limitations of current synthesis techniques quite starkly, thereby providing yet another case study showing that digital organs can only approximate to real pipe sound.  In the last analysis only individual users can decide for themselves which of the imperfect options offends them least.  

This article shows that Hope-Jones’s organ of 1889 at St John’s, Birkenhead was the first in the world whose action was designed from the outset as an integrated system by a gifted professional engineer, using electricity to control not only the key action but the speaking stops, couplers, pistons and swell shutters as well.  One of the key elements facilitating the integration was Hope-Jones’s action magnet, whose design was subtle and which is discussed at length in the article. 

The article also traces the evolution of Hope-Jones’s subsequent thinking and practice until he left for America in 1903.  His key actions remained fairly static, consisting of pneumatic amplifiers controlled by his action magnet.  However his speaking stop actions evolved progressively from organs in which all stops were on slider chests to those in which some ranks were conceived on the unit principle.  The progression was nevertheless fairly slow considering that Hope-Jones had completed his paper design for the fully unified organ by 1890 at the latest, and the article suggests that this was due to a mixture of technical and commercial considerations.  There is little doubt that the power supply limitations of the day prevented him building the power-hungry unified organ with its hundreds or thousands of individual pipe actions, and he was probably not in a position to have manufactured them economically in any case.

Hope-Jones introduced several techniques for coupling, of which his electropneumatic ladder relay was undoubtedly the prototype for that used in the Wurlitzer theatre organ many years later.  The article discusses the design features of this in detail.  However he must also have used electromagnetic (direct electric) relays in his mobile consoles because wind would not have been available.  Likewise he must also have used both electropneumatic and electromagnetic stop combination actions which are also discussed. 

Although the organ at St John’s used a dynamo to supply the action current, Hope-Jones devoted much subsequent effort to minimising the power consumption of his organs and some of his techniques are described in the article.  This was forced on him because of the need to establish a customer base in the majority of the country which did not enjoy access to mains electricity, town gas or high pressure water for blowing the instruments and thus for driving a dynamo also.  In these cases he had to use accumulators and some of his later organs would also have run for limited periods on a battery of dry cells, though definitely not on a single cell as he loudly and frequently claimed.  In all of this he was at a disadvantage because of the low resistance of his action magnet and thus its high power consumption relative to those of his competitors.  It is unfortunate that he degraded himself by the shrillness and mendacity with which he insisted the opposite was the case.

With the exception of unit chests and their means of control which he introduced only a few years later, the 1889 organ at Birkenhead contained all of the action, switching and circuit techniques which were immediately taken up and applied in electric actions worldwide.  They were not displaced until electronics began to appear in organ building in the 1960’s.  That remains the measure of Hope-Jones’s legacy and achievements.

Synthesisers using physical modelling have been commercially available for about 15 years whereas digital organs using other synthesis methods have been around for about 40.  However it is only recently that physical modelling is now appearing in digital organs.  This article explains physical modelling in simple terms by describing the commonly used technique of waveguide synthesis applied to organ pipes.  In addition it covers the wind system and acoustic coupling models which are also necessary for successful modelling of the organ.  However, because these can also be incorporated in conventional digital organs using sampled sounds or additive synthesis, these instruments have been able to simulate pipes to a high degree of realism for some years.  Therefore it begs the question as to what additional advantages physical modelling can bring to simulating a pipe organ.

Although manufacturers continue to emphasise the small variations which occur in pipe speech, these are negligible compared to the vast range of expression which any orchestral instrument is capable of.  The corresponding effects on the simulated pipe sounds are limited to small variations in pitch and amplitude, which can both be rendered by modern sound sampling and additive synthesis techniques.   Although it is not disputed that physical modelling is capable, in principle, of simulating pipe organs to a high degree of fidelity, it seems reasonable to view it as another way to do the job rather than an intrinsically better one. 

This article discusses the sound producing mechanisms involved in the organ reed pipe in detail but without recourse to mathematics.  The breadth and depth of the treatment are thought to be unique if only because it seems to be the first time that this quantity of material has been gathered together in one place.  Examples of waveforms and frequency spectra of real reed pipes are included and their details explained in terms of the physical processes described in the article.  The variable quality of organ reed work is remarked on, and it is considered likely that further research could improve the situation and reduce costs, as it has for some other instruments.  However it is concluded that the prospect is remote that this will occur in view of the continuing decline of interest in the organ, at least in Britain.

Winston Kock was and remains well known to niches of the global science and engineering community for his work in several areas, including acoustic holography and meta-materials.  He occupied a number of senior positions during his career in industry, academia, NASA and Bell Telephone Laboratories.  

The Baldwin electronic organ which appeared just after the second world war was and remains well known to many in the global electronic music community.  It pioneered a number of entirely new techniques which were used in the majority of electronic organs for half a century until analogue technology was eventually superseded by digital.

However the link between the man and the instrument is less well known.  In fact Kock invented the Baldwin organ as a young engineer before moving into other areas.  Therefore the purpose of this article is historical and twofold: it summarises the life and work of Kock in electronic music, and it also describes the important features of the Baldwin organ which resulted from his early research.

An earlier article on this website surveyed the historical context of tuning and temperament, concluding with some remarks about the sanctity of the octave in terms of its tuning purity.  This article continues the story by asking why tempered octaves have seldom been considered in the long history of tuning keyboard instruments.  Although a definite answer is elusive, a probable reason is that temperaments with impure octaves are difficult to tune by ear, and therefore it is only recently that the advent both of electronic tuning devices and digital musical instruments have made them more accessible for study. 

Various temperaments with impure octaves are described, with the octaves tuned both sharp and flat from pure.  The work focuses exclusively on temperaments appropriate for the organ, because a temperament suitable for this instrument might be less attractive for others, and vice versa.  This is partly because of the sustained nature of organ tones, as well as the availability of stops at many pitches which other instruments do not possess.  The fact that most stops constituting an organ chorus are octavely related makes the study of temperaments with impure octaves uniquely interesting for the instrument.

Three temperaments are discussed in detail, one using offset octaves and another using Cordier’s recipe where the octaves are sharpened and the fifths pure.  The third temperament is called “Flat Octave 1” and it uses flattened octaves.  This has the advantage that the significantly sharp thirds in conventional Equal Temperament and the even sharper ones in Cordier’s temperament can be brought closer into tune.  Some mp3 sound clips are included.

Some interesting generalisations are mentioned which appear when using impure octaves, an important one being that an infinity of equal temperaments become available instead of there being just one as in the case of pure octave tuning.  This fact, that impure octaves enable the exploration of more than one equal temperament, is exciting both in theory and in practice.  It opens a door which has been locked for centuries.  All of the temperaments with impure octaves discussed in the article are equal temperaments, which means they can be used in all keys irrespective of their different characters.

Age-related hearing loss eventually affects most of us, including those who think they are immune. Many people do not even think about the possibility that they might have hearing defects, and others seem in denial about them. It is probable that there are organs which have shortcomings related to defective hearing on the part of the builders and voicers who made them. Even when this is not so, some players or listeners might still find them unsatisfactory because of their own defective hearing. Moreover, an organ expert with imperfect hearing who criticises the tonal quality of organs is the musical equivalent of an art critic with flawed vision.

It is shown that easily measurable hearing loss occurs frequently by the time people have reached their 40's and certainly once they are into their 50's and beyond. Those who make a living at music can be more badly affected than the population at large. Uniquely, some mp3 sound files have been included which demonstrate how the same organ might sound to people ranging in age from 20 to 80.

The article contemplates the curious phenomenon that, while glasses are acceptable and widely used to correct defective vision, hearing aids seem to imply to many people that their wearers are past it. Until this societal mind set changes it is unlikely the problems discussed here will recede.

This paper was originally published in the open literature in Wireless World as two articles in 1980.  It is rather a technical museum piece nowadays, as it was an attempt to raise the standard of analogue electronic organs in an era when most were utterly dreadful.  The paper is the only one known which showed how to design analogue tone-forming circuitry based on acoustic measurements of real organ pipes.

The articles proved rather difficult to post on this site for reprographic reasons so they were only available on request until March 2008.  However in view of the obvious amount of interest, they are now available as a PDF file (about 450 kB) - click on the paragraph heading above to download.  Thanks to Stefan Vorkoetter, they are also available in HTML format with reworked diagrams.  Please email me if you prefer this option (see the Contact Me page for my email address).

Gottfried Silbermann's organs have always been famed for their “silvery sounds”.  This article reports the results of research which focused on some characteristics of his fluework in an attempt to see what this might mean and how his results were achieved.  Using acoustic measurements made on a surviving Silbermann organ, details of how his Principals and Flutes were probably regulated are presented.  They demonstrate how the acoustic power output of individual Principal and Flute stops varied across the compass, and how it compared with the other ranks comprising these two varieties of chorus work.  These data are original, detailed and made available in the public domain for the first time.  Suggestions are made as to how the results might be used in practice when voicing organs which are intended to have Silbermann-like tonal characteristics.

This article is a transcript of an invited address given to the Salisbury and District Organists' Association at its Annual General Meeting on 12 February 2000.  The title indicated two of its principal themes, namely the desirability of having a holistic organ in the sense of one which has a unity and integrity of design, and whether or not we are moving towards that goal today.  It was pointed out that a holistic instrument is not necessarily one which would always meet with favour.  For example those by Robert Hope-Jones had far more of a unified sense of style than many, yet they would scarcely be the sort of organs we would wish to build now.  So if a holistic approach is not always sufficient in itself, we need to ask what sort of styles should we be aiming for, and are we actually progressing in these directions?  Among the conclusions of the address were some unpalatable facts relating to some of the largest,  most expensive and decidedly un-holistic organs built in this country in recent years, facts which in some cases seem to have been swept under the carpet.

Voicing and, particularly, regulating a pipe organ is fraught with difficulty.  Not infrequently the instrument is unsatisfactory in terms of the way its registers blend with each other, its mixtures might scream in the treble or its mutations might be bass-heavy.  Some recent organs are widely regarded as total failures because of such problems, which is scandalous in view of their cost.  

This article suggests ways in which digital techniques might be used to guide the voicing and regulating processes so that the probability of getting it right first time with pipes is increased.  It combines the use of modern digital music technology with the regulation procedure used by the well-known voicer Anton Gottfried, adopted by Ralph Downes for the organs for which he was the consultant in the mid-twentieth century.  The most famous of these instruments was that at the Royal Festival Hall in London.

This paper first appeared in Organists' Review, November 1996.  In addressing the physical basis underlying the musical effects which can be obtained from a sensitive mechanical action, it showed that certain phenomena which occur at the beginning and end of pipe speech can be modulated by the rate at which the note is keyed and released.  It therefore confirmed the reality of such articulation effects, which are of course only realisable with a properly designed mechanical action.  In particular, the behaviour of flue pipes as they come onto speech was illustrated by means of a series of frequency spectra closely spaced in time, showing how the amplitudes of the fundamental frequency and its harmonics are sensitive to the wind pressure excursions occurring as the pipe valve opens.  Such behaviour differs in detail depending on how quickly the valve opens, and thus it offers the player some control over the starting transient if the action is sensitive enough.  Comparable phenomena which occur as the valve closes were also discussed.

The reality of such phenomena makes it difficult to argue, as some do, that touch sensitivity on the organ does not exist.  However the musical importance of the phenomena, and whether players actually exploit them, are another matter.

This article surveys the advantages and disadvantages of electronic (solid state or multiplex) transmission used in organs with electric action to communicate between the console and pipes.  Such transmissions are mandatory in the relatively few cases where the console must be often moved or disconnected.  But in this and other cases it is shown that the other potential advantages of relative cheapness and increased reliability (though not always realised) may be offset by a number of disadvantages peculiar to electronics.  These include some examples of spectacular failures, obsolescence and difficulties caused by scanning delays.  Also, musically speaking, the use of electronic transmission puts pipe organs into the same category as electronic organs as far as control by the performer is concerned.  The article suggests that the traditional, non-electronic, approach to electric actions might be looked at more carefully particularly if an old action is being renovated, and some suggestions for refurbishing old electric actions are given.

Two articles elsewhere on this website describe the tonal structures of flute and principal stops in terms of certain characteristics of their sounds such as their frequency spectra.  Because the dimensions of open metal flute pipes and principal pipes are so similar, it is remarkable that our aural perception mechanisms assign a quite distinct perceptual character to the two classes of tone.  This article examines how these mechanisms might be operating on the information contained in the sound waves impinging on the ear using techniques borrowed from computer pattern recognition and artificial intelligence, and it is shown that a computer is also capable of discriminating between these types of tone.

These results might not be of mere academic interest.  On the contrary, their implications could be profound.  Because of the rate of advance in artificial intelligence research, the article goes on to suggest that machines will progressively encroach on many currently sacrosanct aspects of professional life over the next few decades. For example, in the musical field, the results here can be extrapolated to show that a machine would have little difficulty recognising not only various organ stops but other types of instrument as well.  Such abilities would be necessary for a machine which would demonstrate greater powers, such as a critical musical analysis based on a live performance.  Once such capabilities have been demonstrated, it would then be legitimate to ask questions such as whether machines could replace teaching staff in universities and music colleges as they already have done in banks etc.  Because machines do not require salaries or pensions, it would be surprising if these institutions did not begin to ask such questions themselves in the relatively near future.  At present artificial intelligence is a largely invisible and under-discussed topic, pushed beyond the public's event horizon by other media issues such as climate change, yet its implications will be profound in decades to come.

An earlier article on this website looked at the tonal structure of organ flutes.  It is quite a long article, mainly because of the diversity of flute stops and their different characters.  This article takes the analysis further to examine in a similar manner the variety of sounds obtained when the dimensions of open metal flute pipes are varied by relatively small amounts so that they become Principals.  In fact, it is remarkable in itself that our ears and brain assign a quite different perceptual character to the two classes of tone when the pipes which give rise to them are not so very different in construction.  As with flutes, the range of different principal tones which exist is explored by relating it to the harmonic structures of the pipes.  Other factors are also investigated, including some of the fads and fashions which have come and gone in principal stops.

Swell boxes in pipe organs vary widely in their effectiveness but the best are seldom simulated properly in electronic organs.  When a real swell box moves from an open to a closed state, the volume of sound is not merely attenuated as it is when you manipulate the volume control on your hi-fi system.  The tone quality varies as well in that high frequencies are attenuated more rapidly than the lower ones.  This effect is infrequently simulated, but even when it is it can still be identified as artificial if the tonal characteristics are incorrect.  Many electronic organs also attenuate the sound far too much when the "box is closed", nor do they incorporate means to prevent the sound varying too quickly.  In a pipe organ it is impossible to close or open a swell box arbitrarily quickly if the linkage is mechanical, simply because of the inertia of the heavy mechanism.  If the linkage is electric, the shutters (shades) will still respond with their own time constant regardless of how quickly the pedal itself might be operated.  Getting all these factors right in an electronic organ is difficult, and its pedigree as a mere simulation is often revealed when they are wrong.

This article discusses the problem in detail, including circuits and techniques suitable for electronic organs that I have developed over some twenty years.

All organ enthusiasts know about Robert Hope-Jones.  All clock enthusiasts know about Frank, his brother. But that seems to be that - there seems to be little knowledge of the one beyond the horizon of the other, and little historical cross-referencing between the two of them seems to exist.  This article does not purport to be anything other than an introduction to Frank and his work for those organ devotees who might be unaware of him, but hopefully it will be of some interest.  It draws some fascinating parallels between the technologies invented by the two brothers and between their personalities, and it ponders on the remarkable fact that both were ground-breaking innovators within their respective spheres of activity.  Both also seemed to have had an entrepreneurial appetite beyond the average.  The names of both men continue to reverberate today and it is this which makes it worthwhile looking at them in this article.

Despite what some might claim, digital electronic organs are little different to the synthesisers used by pop musicians.  All of these, together with other sound devices such as computer sound cards, use the same basic principles to generate sound.  They are decidedly complex pieces of hardware and software, and they have attracted much attention in the professional literature dealing with digital signal processing and computer music.  Unfortunately the majority of this is intended for the specialist who is familiar with topics such as digital filtering, interpolation and software synthesis.  If you do not know what these terms mean, that merely proves the point.  Even if you have met these terms, you might have been put off by the mathematical framework which so often accompanies them.  Because so little information is available describing how a synthesiser works at a relatively simple level, this article attempts to fill the gap by explaining in simplified terms how synthesisers have evolved from their "Moog" ancestry in the 1960's to the present day.  It comes with a promise that homomorphisms, finite difference calculus, z-transforms and cubic splines will not be mentioned!  However the important but rather complicated subject of frequency shifting by interpolation and decimation is discussed, but as simply as possible.

The subject of tuning and temperament continues to provide a never ending source of interest and income for a constant stream of academics.  Because it requires just that little extra effort to comprehend the necessary simple arithmetic (it is wrong to dignify it as mathematics), it is easy for those with the inclination to wrap up their work in a cloak of mystery and authority which is actually largely spurious.  It disguises the fact that many of the claims made about the temperaments favoured by Bach, say, are completely unproveable.  In reality, they fall into the same category as the story that he once found some coins in fish heads thrown out of the window of an inn, and they are about as useless.

This article  shows that much recent work on temperament is unscholarly in that it projects today's understanding, values and culture several centuries backwards as though these things have never changed.  Thus the authors of such material are merely wallowing, apparently unconsciously, in a sea of reverse anachronism.  They are literally out of time.  Some are also apparently unconscious of the errors in their work.  By looking at the realities of musical life in the 17th and 18th centuries it is suggested that some if not many contemporary temperaments can be traced to the fact that stringed keyboard instruments had wood frames, with the consequential tuning instability this implies.  Also the role possibly played by impure octaves in these temperaments is examined.

This article originally appeared in Organists' Review in 1993, and it is reprinted here because this historic and interesting instrument is one of those which has now been simulated digitally as one of the "vanished organs" which is described in the article Re-creating Vanished Organs.  The organ at Pilton was one of a number of small two manual church organs built by Robert Hope-Jones in the 1890's, and although much of its original pipework still exists its identity has changed virtually beyond recognition by the interventions which have taken place since.  Nowadays there is only one other comparable organ (at Llanrhaeadr, Clwyd) but this is even smaller than the Pilton instrument, though no less idiosyncratic.  Therefore there might be some historical value attached to an attempt to re-create an approximate aural impression of the organ as it might have sounded originally.  Even Hope-Jones's famous Stop Switch has been included in the digital reconstruction, one of several features which have long since vanished at Pilton.

The story of electric actions for pipe organs during the twentieth century is not one of unalloyed progress.  Some still regard an electric action as one of the most unreliable types, and it is not uncommon to find players who insist on the presence of an organ builder when they are to give a recital on an electric instrument.  This article examines how electric actions have evolved, and shows that there seemed to be a lofty disregard for the principles of good electrical engineering by some organ builders during the twentieth century.  It then goes on to examine whether this resulted in real or perceived unreliability, and whether the situation changed when electronic (as opposed to electromechanical) control systems started to appear around 1960.  It also shows that some electrical equipment, marketed in the 1970's and possibly still in use, was potentially lethal.

Digital electronic organs first appeared about 35 years ago, around the same time as the first microprocessors.  However they needed specialised hardware as well; this reflected chiefly the large number of independent sound generating circuits required.  The hardware could only be manufactured sensibly by using custom LSI:  large scale integrated circuit techniques.  At the time this was ground-breaking, though expensive, musical instrument technology and far in advance of what was available elsewhere.  Although simple synthesisers had started to appear also, they used analogue circuit techniques and were limited to monophonic (one note at a time) operation.

Today the situation has reversed.  The commercial electronic music industry - which services the pop music scene - has made tremendous technical strides.  This is because the digital sound and multimedia business is now growing as fast as the computer business itself, whereas traditional electronic organs only supply a tiny and declining niche market.  The upshot is that, for example, an average computer sound card retailing for well under £100 has technical capabilities at least equivalent to the obsolete and much more expensive systems which continue to be used by some digital organ manufacturers.  If one pays a little more and buys the hardware and software used by commercial music professionals, the capabilities are even more stunning.

This article develops this theme by examining in detail what can be accomplished through the use of modern off-the-shelf computer technology instead of yesterday's specialised components.  It illustrates what can be done at trivial expense using today's personal computers, and it is no surprise to find that some digital organs are now using this approach.

The organ in St Mary's church, Bradford Abbas in Dorset, was dedicated recently after a major rebuild for which I was the consultant.  Originally it completely occluded the West door, it was covered in bat droppings, and it contained some of the worst examples of organ building most will have seen.  Today it stands at the east end of the north aisle, and it has been completely overhauled.  This article describes the challenges facing the church, emphasising how remarkable it is that the task was completed in less than three years.

The majority of electronic organs are sadly deficient in the way they reproduce extreme bass notes because the provision of the necessary loudspeaker system would add substantially to their cost.  This annoys many owners of such instruments which often boast 32 foot pedal stops, but whose effects progressively vanish towards the bottom of the compass!  This article explains why extreme measures have to be taken to reproduce extreme bass, regardless of the claims often seen in advertising material and elsewhere.  However it suggests some relatively simple and inexpensive ways in which the bass response of an electronic organ can be improved.

In 1891 Robert Hope-Jones gave a lecture to the College of Organists in London (they were not "Royal" then) about electric actions for organs.  The transcript reveals a great deal about him.  If it was verbatim, his delivery must have been uncomfortably unctuous.  He was also secretive and he seems to have blinded his audience with dubious science. Moreover, some of what he said is difficult to reconcile with the facts. Yet he also demonstrated undoubted competence, and a piercing and accurate technical vision that is impressive even by today's standards.  Thus the paper reflects in fascinating microcosm the excesses and contradictions of his future work and his personality.

The way the lecture was received at the time and since is just as interesting.  Frequently, commentators ranging from engineers to musicologists and historians seem to have been mesmerised by what he said.   These and other matters are the subject of a detailed critique of the Hope-Jones lecture in this article.  It examines why there persists to the present day a desire in some quarters to deify the man and his works when the realities of the situation point elsewhere, notwithstanding the positive aspects of his legacy.

Any commercial electronic keyboard today will provide a MIDI output, which is useful for connecting it to other instruments including some pipe organs.  However MIDI pedalboards are much rarer, which among other things makes it difficult to put together a simple home practice facility.  Therefore this article shows how the appropriate MIDI signals can be generated from the closure or opening of a simple key contact.  Full details are included for a MIDI encoder suitable for a standard 30 or 32 note pedalboard; the encoder uses only a handful of standard integrated circuits, thus removing the need to program microprocessors or read-only memories for which few have the knowledge or facilities.  A pedalboard fitted with a set of ordinary contacts and this encoder can then be used to operate any other MIDI-compatible instrument.  Some suggestions are given showing how the pedalboard can be used in several configurations, to provide simple and inexpensive organ practice facilities in conjunction with commercial MIDI keyboards.  The material may prove useful to schools and colleges, as well as to individuals who possess basic electronic skills.

There is a widely held belief that Robert Hope-Jones's organs were designed to use so little current that they would run on a few dry cells, or even a single one, for months at a time.  Even eminent organ historians have continued to repeat the story to the present day without apparently questioning it.  Yet a little elementary analysis causes one to stop and think about the issues involved, and more detailed engineering  investigations show the belief to be completely untrue.  It is untrue because it would have been impossible, and this article proves it by examining some circuits and components Hope-Jones would likely have used.  Not only his key actions, but his stop and combination actions are considered, and their energy requirements are shown to far exceed the capabilities of dry cells. 

A consequential and intriguing question, therefore, is why Hope-Jones himself apparently encouraged the propagation of the dry cell myth.  This also is addressed in the article which, besides addressing  the engineering issues, will look at some commercial realities of the late Victorian era and the approaches used by some other contemporary organ builders to power their electric actions.

The article demonstrates the phenomenal success of a misinformation campaign which has led scholars and other Hope-Jones pundits up the garden path for over a century.

This provincial and very active organ builder completely transformed the organ landscape of Nottinghamshire and its environs during the first half of the twentieth century, such that by 1950 it was becoming unusual to find a church which did not have an organ by Wragg!  They were also entrusted with the care of the city's most important organs.  These facts alone make it curious that there seems to be no definitive account of the firm's work. If there is a budding historiographer out there who is looking for a project, perhaps this is a suggestion that might fill the gap while there is still sufficient of its work remaining to flesh it out.  This short note outlines the origins of the firm and mentions some of its work.

The subject of how today's digital electronic organs are voiced is many-facetted.  At one level it intrigues people because some manufacturers seem to find a veil of secrecy serves their interests, just as some pipe organ voicers do.  Another factor relates to the argument as to whether electronic organ makers are merely copyists of pipe organ tone, or whether they can create their own sounds.  To the technically-minded the subject has intrinsic interest also.

This article describes the types of digital organ available and how they work.  It then covers matters such as how recordings of organ pipes can be made, how these may require pre-processing before being incorporated into an instrument and how sounds can be created without the need to first make recordings.

The variety of flute-toned stops on the organ is immense, judging by their names alone.  Most authors seem satisfied having addressed the matter in descriptive terms (e.g. the shapes of the associated pipes), and it is therefore more difficult to go further to discover a physical basis for the range of tones and why our ears perceive them as they do.  For example, what is it about the sound of a Stopped Diapason that makes it blend better with other fluework than a Harmonic Flute?  Or why must the Tibias of a theatre organ sound as they do to satisfy aficionadi of that style of instrument?   Or why is a Claribel Flute usually regarded as quieter than an Open Diapason when its measured sound level can be higher?

This article summarises the outcome of some 25 years research into these matters, and it covers aspects of the subject ranging from the physics of sound generation in organ pipes to the perceptual mechanisms involved in hearing.

This is a review paper which draws together work published in the public domain on the design and performance of mechanical and electric actions for pipe organs, including relevant data from elsewhere on this website.  The subject is approached by considering the fundamental physical principles which govern the performance of such actions.  In the case of mechanical actions the subject of repetition rate is discussed in some detail in view of the paucity of the literature on this aspect. Other matters include pluck and hence pallet design.  Among many other aspects, the apparently widely-held view that the key always dominates the inertia of an action because it is the most massive component is shown to be flawed.  This is most eloquently demonstrated by examining the behaviour of a suspended tracker action in which the keys are usually long and massive.  In the case of electric actions another widely-held view, that direct electric actions are invariably slower than electro-pneumatic ones, is also shown to be unsupported by experimental data.

This work began because of the commonly held belief that direct electric actions are relatively slow due to the electrical and mechanical inertia of heavy-duty electromagnets.  Some figures are put into the argument, derived from both theory and experimental measurements, and the results compared with those for electro-pneumatic actions.

Detailed measurements of the dynamic response of a direct electric action were made as a function of wind pressure and other parameters.  The principal measurements reported are the attack and release times relative to the instant at which the key contact closes or opens, and the maximum repetition frequency that can be sustained.  Similar data are presented for representative electro-pneumatic actions for comparison.

This paper summarises a recent experimental and theoretical study which looked at pluck compensation and inertial effects in large mechanical action organs using high wind pressures.  A novel yet simple form of compensator was devised which (as an example) reduced the pluck of a large pallet from 335 gm to 90 gm at a wind pressure of 115 mm w.g. while allowing the player to retain direct mechanical control over pallet movement.  Theoretical studies are also reported which estimate the maximum allowable length of tracker runs for a given repetition performance (e.g. 6 notes per second).

MIDI (Musical Instrument Digital Interface) is a system developed by the commercial electronic music industry to enable the products of various manufacturers, such as synthesisers, to be connected together.  It also appears  in some electric action pipe organs which use electronic transmission to connect the console to the pipes.  Organists need to be aware of the implications for their art of playing an organ which employs MIDI, and this paper outlines some of the possible consequences.

Calculating the windway area necessary to supply a given set of pipes without robbing is not straightforward.  It is important to use the smallest value possible if pluck is to be minimised, rather than to rely on conservative design rules which may result in excessive values.  Once the necessary value has been arrived at, the pallet can then be designed using standard long/thin valve theory.  This paper summarises the results of some experimental work in this area.

Even today there is sometimes confusion over how the flue pipe works.  This paper reviews the most recent theories, and presents some original results not previously published.

The famous (some would say infamous) Hope-Jones organ at Worcester, built at the end of the 19th century, was intimately linked with Elgar and his music, partly because of some myths which still persist.  The most common one is the belief that he wrote the Sonata for the inauguration of this instrument.  While the true story can be found by looking into the published literature, not all of this is immediately accessible.  Thus this essay draws together the various threads linking the organ, the composer and the music.

This article first appeared in Organists' Review in August 1998 and it  now is reproduced here because of the number of requests received for copies.

The controversies created by electronic organs cannot be resolved by those who are content with the sour reactions which merely conceal ignorance.  Written at a non-technical level by an author with no vested interests, this recent paper updated an earlier one (see below) and it has been widely used and quoted by those seeking objective information on the complex issues involved in today's digital electronic organs.  It was also received positively by some of the leading manufacturers.

This article first appeared in The Musical Times  in January 1987 and it  now is reproduced here because of the number of requests received for copies.

The article was written at a non-technical level by an author with no commercial interests at the time when some electronic instruments were moving from analogue to digital technology.  From today's perspective it therefore has some historical content.  Now that all organs are digital, it was superseded by a more recent article (see above) introducing the reader to the updated technology in more detail.