A simulation of the St Albans Rutt organ
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  A digital simulation of the 1935 Rutt theatre organ at the St Albans organ museum  

Colin Pykett

 

Posted: 9 December 2021
Revised: 20 December 2021
Copyright C E Pykett

 

Contents
(click on the headings below to access the desired section)

 

Introduction

 

The Rutt theatre pipe organ at St Albans

The Rutt virtual pipe organ as simulated -

Stop list

Voicing

Tremulants

Unification

Playing interface

What does it sound like?

Acknowledgement

Notes and references

 

 

Introduction

 

In 1935 a three manual six rank theatre pipe organ by Robert Spurden Rutt (1880-1960) was installed in the Regal cinema at Highams Park, north-east of London [1], though in terms of its tonal resources it was really only a 2/6 instrument because the middle keyboard was a coupler manual with no voices of its own. The organ was maintained until 1963 when the cinema was repurposed, resulting in the console being boxed in among other things. After more than 20 years of subsequent neglect it was then acquired by the St Albans organ museum and theatre [2], restored and reopened in 1987.

 

Rutt was a well-regarded builder of 'straight' church and concert instruments in the UK though this theatre instrument is extremely rare, being one of only three which they made. However I have first hand knowledge of their obvious interest in pushing at the boundaries of traditional organs from my student days in London.  During that period I was organist for a time at the Methodist Central Hall at Southfields near Wimbledon. Here was a large three manual instrument spread across the entire platform, together with its 'sloping lid' detached console having a horseshoe array of stop keys which looked not unlike a cinema organ to a casual observer [3]. Besides this feature there was a significant amount of borrowing and extension together with some tonal percussions (xylophone and carillon). One wonders why Methodists, of all people, would have squandered money on such pointless liturgical extravagances. The explanation might be that the church formed the 'central hall' focus of a complex of shops and business premises of a style sponsored across Britain at that time by the philanthropic J Arthur Rank show business conglomerate, so there was perhaps little pressure on funds for any organ that might have been desired. Installed in 1928, it would have probably incorporated some then-novel features from the contemporaneous 'Rutt Electric Organestra' range of unified instruments (probably based on the earlier 'Hope-Jones Unit Orchestra' in the USA), so it would not be surprising if Rutt had jumped at the chance of expanding into the then-buoyant British theatre organ market before the second war. At the time that market was dominated by the Compton and Christie (Hill, Norman & Beard) marques as well as imported Wurlitzers.

 

Around the time that the organ arrived at St Albans in the 1980s I had become well acquainted with the late Bill Walker, who formerly chaired the board of Trustees of the theatre among his other interests and activities until his untimely death in 2003. These interests included his positions as CEO both of the Livingston Organ brand of electronic instruments and the Organ Supplies and Services company. So I was grateful to the Trustees for permission to digitally sample the Rutt with the intention of developing a sample set for use in the Prog Organ virtual pipe organ [4], and this forms the subject of this article. On the same occasion I sampled the Wurlitzer also in the care of the St Albans theatre, and a companion article describing this is available elsewhere on this website [5]. To spare the reader a lot of cross-referencing, this article includes some repetition of background material included in the earlier one.

 

 

The Rutt theatre pipe organ

 

 

 

Figure 1. The Rutt console at the St Albans organ theatre, England

 

 

The Rutt console is pictured in Figure 1 and its pipe ranks are listed in Table 1. (The Tuba Horn might not be original, consisting of similar Rutt pipework from elsewhere).

 

 

RANK  PIPES 
 
 Open Diapason  73
 Tibia Clausa 97
 Concert Flute 73
 Viol 73
 Vox Humana 61
 Tuba Horn 73
 

TOTAL

450

 

Table 1. Pipe ranks of the Rutt organ

 

It is assumed that readers are familiar with the concept of the fully unified organ as used in theatre instruments. Suffice to say that each pipe can, in theory, be played from any key on any manual of the console. Thus the Tibia, for example, is an 8-octave rank which appears on all divisions at various speaking pitches ranging from 16 foot to 2 foot (see the full specification of the organ at reference [1]).

 

The pipes, percussions and effects within the original instrument can be thought of as a stand-alone core resource of sounds which can be drawn on in any number of different ways by a console having a wide variety of possible stop lists. The console and the pipework are separated by what is called the 'relay' which maps the one into the other, this far-sighted and elegant unification architecture having been invented by Robert Hope-Jones in the 1880s. Originally the relay in theatre instruments was a colossal electromechanical affair, though nowadays it is often implemented electronically with computer control when organs are rebuilt. Consequently the specification chosen by Rutt in this case was only one option out of many feasible alternatives. This is quite different to a traditional organ built strictly along 'straight' lines, where each pipe rank corresponds to one, and only one, speaking stop at the console and there is therefore no need for a relay.

 

 

The organ as simulated

 

The simulated organ was designed in the same way as the pipe organ. It consists of a core sound engine set up in a desktop computer containing the same six ranks of sound samples as the pipe organ, together with a range of tonal percussions and traps (non-tonal percussions). Prog Organ sees to the relay function in this case since it has a level of note and stop switching sitting between the console and the sound engine itself, implemented in software. None of the Rutt effects such as bird whistles were included though, since the light music I play seldom calls for them and I did not want to tie up controls on the console with things which would not be used.

Some particular aspects of the simulation are as below:

1. The pipe ranks and percussions are distributed across two virtual 'chambers', each with its own swell pedal, whereas the original pipe organ is built within a single chamber.
2. Individual software-adjustable tremulants are available for the notes within all ranks.
3. Each note of each rank plays in stereo with software-adjustable panning.
4. Up to six independent sound channels plus three derived sub-woofer channels.
5. 10 channels of external convolution reverberation (hardware).
6. External graphic EQs (hardware).
7. Piano sustain pedal (foot switch to the right of the swell pedals).

Some of the notes above will bear amplification, as follows:

 

Stop list

The current stop list of the instrument is shown in Table 2, though any number of variations would be possible without modifying the core sound engine itself. This is one of the attractive features of simulating a unified organ - you can set up any stop list you like without having to delve into the sound engine. In effect, you would be merely modifying the 'wiring' of the relay. In the case of Prog Organ it means that you would have to write a different Configuration File, equivalent to the Organ Definition Files of some other VPOs.

 

    ACCOMPANIMENT                 SOLO

      

      PEDAL               OTHER
 Violone   16    Tibia Bass  16   Tibia Bass 16  Main Tremulants 
 Bourdon 16  Violone 16  Open Diapason    8  Solo Tremulants
 Open Diapason   8  Open Diapason   8  Tibia Clausa   8
 Viol   8  Tibia Clausa   8  Violone   8
 Concert Flute   8  Viol   8  Octave   4
 Octave   4  Tibia Clausa   4  Tibia   4
 Violin   4  Violin   4  Ophicleide 16
 Concert Flute   4  Tibia Twelfth  2 2/3    Tuba Horn   8
 Flute Piccolo   2  Tibia Piccolo   2
 Vox Humana 16  Ophicleide 16
 Vox Humana   8  Tuba Horn   8
 Vox Humana   4  Vox Humana 16
 Vox Humana   8
 Vox Humana   4
 Glockenspiel  Glockenspiel  Accpt to Pedal
 Chrysoglott  Chrysoglott  Solo to Pedal
 Chimes
 Piano

 

 

Table 2. Stop list of the simulated instrument

 

The stop names and some of the chorus work in this specification are loosely based on those of the real organ [1]. In this reduced specification the Accompaniment division is based around the less assertive Flute rank rather than the Tibias, though it can be filled out with the Diapasons to balance the fuller-sounding Tibias on the Solo if necessary. Although there are only two tremulant stop keys, they control all of the independent tremulants for each rank in their associated 'chamber' whose parameters can be adjusted within wide limits, discussed in more detail later.

 

Voicing

With all sound samplers, including Prog Organ, you are pretty much stuck with the sound of each recorded sample in the same way that you are stuck with the sound of a symphony orchestra recorded on a CD. In other words, the options for voicing individual samples are limited. They cannot be voiced in anything approaching the way that organ pipes can when a skilled voicer undertakes the tonal finishing of a real instrument. S/he can adjust the attack and decay characteristics of individual pipes, and particularly their steady-state tone colours, within wide limits. There are those who argue that this major drawback does not matter, though it is noteworthy that they tend to have vested interests in selling or promoting a particular brand of sampled sound organ. But of course it matters. Whoever heard of a real pipe organ that cannot be voiced! And why should an organ builder (me in this case) be denied, purely through technology limitations, the opportunity to voice an instrument realistically? Unfortunately though, one just has to put up with the situation by balancing it against the undoubted advantages of sampled sounds. To get round the problem one would need to move to a synthetic sound generation system such as physical modelling, additive synthesis or (a technique I invented) trendline synthesis [6]. However these also have their own pros and cons. But as in life generally, half a loaf is better than none, and the Prog Organ sound engine offers several options for adjusting the sound of each sample in lesser ways. Some of these are listed in the notes above and they include adjustable stereo pan between a pair of loudspeakers, EQ (tone control) and volume. But all current digital simulation methods are imperfect, and it reveals something about those who maintain that they are not.

 

Tremulants

The notes above also mention that Prog Organ can add an adjustable tremulant to each sample, not just to each stop or rank, and this brings us to another important topic. Few would disagree that its multiple tremulants are one of the glories of the theatre organ, yet here again we meet head-on another shortcoming of sampled sound synthesis. I have spent years trying to solve the problems of simulating tremulants successfully. To be brief, the difficulties of denoising and looping tremulated samples are writ large, since these are bad enough for untremulated sounds. But having done it, one can then accommodate in the sound engine a duplicate set of tremulated samples, even though this is grossly inefficient from several points of view. But to my mind the worst problems with the duplicated approach are twofold: the tremulants cannot be adjusted, and the relative phase of a tremulant becomes randomised across a rank when several notes are keyed, whereas it beats in phase for all the pipes in a real organ fed from the same tremulated wind line. This can make this type of simulated tremulant sound rather unrealistic and sometimes positively unsatisfactory. Instead of a clear beat or giggle, the tremulant becomes ill-defined and foggy especially when chords are played. In contrast, Prog Organ's tremulants are parametric, meaning that the sound engine applies a low frequency periodic variation to certain parameters of each sample such as its frequency and amplitude. More subtle variations are also possible, such as changing the timbre of a sample over each tremulant cycle. This is done by passing the sample through a filter whose parameters are controlled in real time by the instantaneous amplitude of the tremulant oscillator. Although I would not claim that the Prog Organ tremulants are perfect in every particular, at least they are adjustable over a wide range, and they do not suffer from the random phase problem. A lengthy article is available elsewhere on this website which discusses the tremulant issue in detail [7].

 

Another important aspect of tremulants is their intimate association with the ambience of the auditorium. This relationship is so close that the effect of an otherwise good tremulant can vanish altogether in completely anechoic conditions! This can astonish those who have not come across it before. An article elsewhere on this site discusses the effect and contains some sound clips which demonstrate it [8]. The UK cinemas in which theatre pipe organs were installed were frequently badly designed acoustically since they were often repurposed silent movie picture palaces where the acoustics were originally of little account, or former Victorian or Edwardian music halls. So their acoustics were generally not well controlled and quite often far from dry. Even if an auditorium does sound dry in the sense of having a short reverberation time, it will always be non-anechoic because its boxy shape with several pairs of long parallel boundaries still results in enough reflections to add significant colouration to the sound in the form of room modes. The upshot was that theatre pipe organ builders had to match the subjective effects of their tremulants to an often unsatisfactory building, unconsciously or otherwise, which is one reason why some of them seem inadequate (too violent or reticent) when transferred elsewhere. Even tremulants need to be 'voiced' on site!

 

As a consequence of all this, Prog Organ uses convolution reverberation to add room ambience to the sounds of this simulated Rutt instrument rather than trying slavishly to emulate the vestigial wetness of the St Albans organ theatre itself. Not only is this venue not the organ's original home, but attempting to reproduce realistically the reverb tails of wet tremulated samples is difficult in any case [9]. Up to ten channels of reverberation are available from five external hardware units. Each one handles a stereo pair, and even if presented with a mono input signal it will generate a stereo output from the convolver in the same way that a real room does. Therefore a wide range of room ambience can be simulated depending on how the reverb processors are patched between the outputs of Prog Organ and its several loudspeaker channels, together with the settings chosen for each one. But the main point to take away here is that reverberation can add dramatically to the effect of tremulants if chosen with discretion.

 

Unification

Unless instructed otherwise, Prog Organ does not allow any sound sample (simulated pipe) to speak more than once at any moment. This is because a pipe in a real theatre pipe organ can itself only speak once - obviously - regardless of how many simultaneous demands are made on it by the relay. It is a simple programming matter to incorporate this feature, so it is surprising that it apparently eludes some sampled sound organs. Of course, it means that there are missing notes when the simulated organ is played, just as there are missing notes in any pipe organ which uses extended and duplexed ranks. But that's life. Simulating unification properly also has the advantage that the polyphony demand on the sound engine of a unified digital organ is far less than that for a straight organ with the same stop list, and this can be beneficial. For instance, the relatively low polyphony figure of only 450 would be sufficient to play all the simulated pipes of this Rutt organ at once (see Table 1 above)! Since this would never be necessary, a much lower value could be used in practice - with Prog Organ I have found that a polyphony demand of 128 is not nearly approached in normal playing using this sample set. Consequently it would be possible to simulate effectively a unified organ such as this one using quite simple RPi or Arduino technology because of the relatively small memory footprint and polyphony requirement of the core sound engine owing to the small number of pipes.

 

Playing interface

As with most VPOs, the simulated organ can be played in two ways. One can simply fire pre-prepared MIDI files into it and then just sit back and listen to the results, much as a fairground organ plays from punched cardboard music books. Since the sound-producing elements of the real organ are represented within the sound engine as sampled sounds, this would produce a convincing imitation of the real thing. The second approach is to connect an actual organ console to the sound engine so that the organ can be played in real time by a human performer. Since I am one of these, I prefer this latter method.

 

 

Figure 2. The Prog Organ virtual pipe organ console used during sample set development


In theory it would be quite possible to drive the sound engine from the actual Rutt console at St Albans, given a suitable hardware playing interface (either using MIDI or the contact scanning feature of Prog Organ [4]). In practice, the Prog Organ console which I use for developing sample sets (Figure 2) is a far cry from the splendid article pictured earlier (Figure 1), being limited to two manuals with no second touch and only 46 stop keys. However the stop keys are motorised, there is a combination capture system, two swell pedals and a foot switch which currently functions as the piano sustain pedal. So by straight organ norms it is a reasonably well equipped console for a large two manual instrument, much better than the collection of plastic MIDI controller keyboards balanced on the piles of books to be found among the ranks of VPO enthusiasts! And one should not forget that the number of pipes in the Rutt is actually less than that of a miniscule straight organ with only seven speaking stops on the manuals and two on the pedals, so the complement of 46 stop keys can in fact draw out a good deal from the six ranks. Furthermore, the lack of a third manual in the Prog Organ console is not the drawback that it might appear since the middle keyboard on the Rutt is only for coupling purposes. So in practice it is not difficult to coax quite a lot from this console, and it is capable of rendering much of the staple repertoire of the theatre organ.

 

 

What does it sound like?

 

Stating the obvious, the Rutt organ at St Albans is not a Wurlitzer and therefore it cannot be expected to sound like one. It has to be judged on its own terms rather than by Wurlitzer norms. There must be few places in the world where two theatre pipe organs are installed side by side as at this venue, enabling a player to exchange one console for the other and make direct comparisons in a matter of seconds - a rare and remarkable experience.

 

Much the same applies to the two virtual pipe organs which have been created from the respective sample sets. The Rutt Tibias in particular are engaging to play though quite different to those of the Wurlitzer, having what I can only describe as an almost bell-like sound in the upper register when tremulated, and this seems to have been captured in the simulation. On the other hand I would judge the Vox Humana rank to be less successful than that on the Wurlitzer. The characteristic vocal formants of all Vox's tend to fade higher in the compass, but this seems more pronounced for the Rutt rank. However it is possible this merely reflected the state of the pipework when I recorded the samples and it might have been altered since. When developing a sample set of any organ you spend untold hours working up-close and personal to the sounds of individual pipes, and as a result I have gained the impression that there is more of a lingering flavour of the traditional church organ in the Rutt voices than in those of the Wurlitzer - who did not build church organs anyway. To some extent the same applies to Compton theatre organs in my opinion, since to me these also have a distinct and slightly 'churchy' voice of their own which could not be mistaken for a Wurlitzer.

 

The recordings below might give some idea of what the Rutt organ sounds like. Unfortunately much of the best light music in the theatre organ repertoire is still in copyright so one has to fall back on the lighter classical or Victorian/Edwardian music hall genres, which greatly restricts the options. Among other effects the recordings demonstrate the Rutt Tibias when played as single notes and in chords, and they also show that the ambience of the empty theatre at St Albans has been captured quite well.

 

  Daisy Bell (Harry Dacre) - 1.44 MB/1m 34s

 

  Evensong (Easthope Martin) - 3.95 MB/4m 18s

But it goes without saying that if you really want to hear what this venerable instrument from yesteryear is capable of, then you should visit the St Albans organ theatre itself. Those who work so hard to keep organs like this one in such fine condition deserve our support.

 

 

Acknowledgement

 

Many thanks go to the St Albans organ theatre for permission to sample this rare and interesting organ.

 

 

Notes and references

 

1. National Pipe Organ Register index number A00545

https://www.npor.org.uk/NPORView.html?RI=A00544

(accessed 7 December 2021)

2. https://stalbansorgantheatre.org.uk/

(accessed 20 November 2021)

3. National Pipe Organ Register index number N05504

https://www.npor.org.uk/NPORView.html?RI=N05504

(accessed 7 December 2021)

 

Note that the Trumpet unit at Southfields mentioned in the NPOR, playable from two manuals and the pedals, was in fact a Tromba.

4. 'Prog Organ - a virtual pipe organ', an article on this website, C E Pykett.

5. 'A digital simulation of the 1933 WurliTzer organ at the St Albans organ museum', an article on this website, C E Pykett 2021.

6. 'Trendline synthesis - a new music synthesis technique', an article on this website, C E Pykett 2016.

7. 'Tremulant simulation in digital organs', an article on this website, C E Pykett 2009.

8. 'The interaction of tremulants with room acoustics', an article on this website, C E Pykett 2009.

9. When reproducing wet samples it is necessary to match the instantaneous phases and amplitudes of both the audio signal and the tremulant at key release to those at the beginning of the reverb tail if there is to be no audible discontinuity. This is difficult enough for untremulated samples, let alone for tremulated ones. For a detailed discussion see:

'Wet or dry sampling for digital organs?', an article on this website, C E Pykett 2010.