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© 2013 Trinity United Reformed Church - Milton Grove, Wigan, WN1 2PG  

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© 2013 Trinity United Reformed Church - Milton Grove, Wigan, WN1 2PG  

Pipe Organ - Upgrade Work Carried out in 2014

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Trinity URC Organ Upgrade Works (Autumn 2014)

As I advised in the September 2014 magazine, a hugely generous donation from an anonymous donor has enabled the organ scheme at Trinity to be enlarged to its maximum extent. The donor was most insistent that "organ hardware" was installed with his donation rather than my suggestion of putting the money into a maintenance fund. There is precious little space in the case sitting on the beam in the church, but the current organ builder, Principal Pipe Organs of York, advised that there were two tonal additions that would virtually complete the tonal scheme of a high quality instrument which we are fortune to have at Trinity.

The "Technical Bit"

Organ pipes are made of various mixtures of tin and lead - tin very much more expensive than lead! The pipes made for the organ this time are largely made of various % of tin:lead with higher tin compositions known as "spotted metal". The higher the tin % the brighter the tone (and the higher the cost!) and gets its name from the mottled spotted surface you get from the alloy caused by mixing the two metals together. Some parts of the pedal pipes are made of zinc for added strength and cost reasons.

One of the new spotted metal pipes constructed for the organ at Trinity - note the mottled surface

On the Great Manual of the organ (this is bottom keyboard and operates pipes at the front and top of the case) a new mixture stop has been added. A mixture stop is a stop that gives depth and new tones to an organ by playing multiple notes that are not the notes you play with the keyboard! Confusing? Perhaps... Odd? No! When any musical instrument is played, it is largely the strength of the harmonics of the note that give it its quality - which is why, to a significant extent, why the same note played on an oboe sounds so different to a clarinet or flute despite all being wind instruments

When you play a C, you also hear the following notes sounded to differing degrees

Harmonic Series showing first 8 harmonics heard when Bass C (fundamental) is played

Mid C; Octave C (2nd harmonic, 8th note); Octave G (3rd harmonic, 12th note);              

Double Octave C (4th harmonic, 15th note); Double Octave E (5th harmonic, 17th note);

Double Octave G (6th harmonic, 19th note); Double Octave Bflat, 7th harmonic, 21st note)

Double Octave C (8th harmonic, 22nd note) and so on....

More on the development of harmonics and how pipes are constructed is available:

For example, a clarinet is very strong in the odd harmonics (fundamental, 3rd, 5th) with the even harmonics almost completed absent which is very similar to a reed pipe on an organ.

A flute has all the harmonics present - which gives a flute its complex, warm and sometimes "throaty" tone with full harmonic structure. This is very similar to the warm flute stops on a pipe organ.

A violin sets up sounds waves via a string, but it too has a complex harmonics structure. You can actually isolate the harmonics of the string by a technique of lightly touching the string with your finger which generates only that harmonic and not the notes fundamental - this is often written into music by composers and can also enable the playing of very high notes without having to move the left hand a long way up the violin fingerboard.

In a pipe organ, its depth, tone colours and brilliance are enhanced on good organs by having stops that enhance these different harmonics when you draw the appropriate stop.

The really highly skilled work of an organ builder is making sure that each stop is regulated for volume and tone so that the whole sound is balanced and doesn't strain the ear, or lose the fundamental note that's being played. This process is known as "voicing" and "regulating" the stop and had to be completed on every one of the ca.1200 installed pipes in the organ we have at Trinity taking many days. If you play a middle C on one of the keyboards with all the stops drawn you actually sound:

Mid C pitch (8ft stop),

Octave C pitch (2nd harmonic or 4 foot stop);

Octave G pitch (3rd harmonic or 22/3' foot)

Double Octave C pitch (15th note; 4th harmonic or 2 foot stops) ;

Double Octave E (17th note, 5th harmonic, 13/5' stop)

Mixture 19.22.26 (playing Double Octave G [19th], Triple Octave C [22nd] and Triple Octave G [26th] when you play the note Middle C).

So playing one note sounds 8 different notes....but your ear still hears it as a middle C!

The New Great Organ Stop

The name for the new stop that has been installed is a "Sesquialtera 12.17" so named because it plays the 12th and 17th (3rd and 5th harmonic) notes above the fundamental note when you play a middle C.

These notes are a SIXTH apart [Ses = sixth] when you play a middle C on the keyboard - this stop plays a G (one and half octaves higher - the 12th) and an E (two and bit octaves higher - the 17th) - this stop is particularly useful for giving added "bite" and edge to the organ sound rather than raw decibels - rather like complex spices adds bite to a meat dish you might prepare in the kitchen...

The stop has been installed alongside the existing Great soundboard at the front of the case and when all the stops are drawn and one note is played the, organ actually plays eight different notes, but the human ear hears it as the note that's been played if the organ is voiced correctly!

Sesquialtera 12.17 pipework and soundboard before installation into the organ at Trinity

The Pedal Organ Stop

The second stop installed is a Pedal department 16 foot Trombone stop - which plays at 16ft pitch - that is an octave below the note you play. This is a stop that supports the organ tutti (or full sound) in both voluntaries and singing - it needs to be used sparingly, but will certainly enhance the bass section of the organ. The new pipes, made from spotted metal and zinc can be seen at the back of the organ case reaching up into the beams of the roof. The Trombone is a reed stop, which means the sound is generated by vibrating a metal tongue in a complex device known as a boot rather than simply blowing air throw a simple pipe.

Trombone Boot showing the metal tongue, weight, block and shallot that generates the air vibration in the long resonators - the wire is used to tune the pipe in situ by changing the length of the tongue.

In addition to the above, the organ has been fitted with an EPOC memory capture system which is a solid state device that allows the player to select up to 96 different combinations of stops at the touch of one of 25 selector buttons which enables the resources to be controlled.

The full specification of the organ in November 2014 is as follows:

Great Organ (bottom keyboard) 10 stops, 580 pipes

Pipe Length1

Stop Name

Tone Played


Open Diapason

Principal organ tone


Stopped Diapason

Flute Tone (solo/accompanying)



2nd harmonic (tonal build up)


Fifteenth 2'

4th harmonic (tonal build up)

22/3' + 13/5'

Sesquialtera 12.17

3rd and 5th harmonics (bite/piquancy)

Mixture 19.22.26

6th, 8th,10th harmonic (brilliance)



Quiet solo reed stop



Powerful solo reed stop

Swell Organ (top keyboard) 13 stops 480 pipes

Pipe Length1

Stop Name

Tone Played


Salicional 8'

Quietest stop on organ, "string tone"


Rohr Flute 8'



Voix Celeste 8'

String stop tuned slightly sharp


Gemshorn 4'

2nd harmonic build up


Flageolet 2'

4th harmonic build up




Mixture 19.22

6th/8th harmonic adding brilliance


Cornopean 8'

Chorus reed adds lot of power


Trumpet 8' (from Great)

see above Tremulant

Pedal Organ 8 stops 138 pipes

Pipe Length1

Stop Name

Tone Played


Sub Bass 16'

Underpinning bass on organ


Bass Flute 8'

Harmonic progression from Sub Bass


Principal 8'

Basic organ tone


Choral Flue 4'

Harmonic progression from Sub Bass


Fifteenth 4'

Harmonic progression from Principal


Trumpet 8' (from Great)

see above


Bassoon 16'

Reed for use in Baroque music


Trombone 16'

Powerful pedal reed for full organ tutti

The new trombone pipework prior to installation - note zinc resonators with spotted metal top


ORGAN UPGRADE WORK - A Big Thank You for a Very Generous Donation -

You may have noticed some changes to the organ, particularly the addition of new large pipes at the top of the case viewed from the rear.

It was back in December 2013 that I received an email via my address on the church website from someone who, with his wife, had attended a service at Trinity back in September 2013 on his way from holiday in Scotland to their home in Somerset.  The person concerned had strong links to one of our previous churches and said that he and his wife had found the service thoroughly uplifting and was delighted to see a choir and a fine pipe organ in use.  They had introduced themselves to both Chris Parker and myself, but neither of us could remember the specific conversations we had.

It became clear that he was extremely knowledgeable about the pipe organ and he asked whether he could make a donation to "add to the resources" of the instrument. I suggested that he could make a contribution to the maintenance budget, but he was adamant he wished to contribute to "significant hardware".

The organ at Trinity, was pretty complete after the work in 2007 and the organ case was also pretty full, so it was unclear if anything could be added. In the end, our organ maintainer, Principal Pipe Organs of York, suggested the addition of two stops which would fill the case completely, but complete the tonal scheme to the maximum possible extent along with associated upgrades and electrical changes. The donor agreed to fund the changes and the work was completed in August and September 2014. The majority of the gift aid element of the donation was added to church general funds.

We are greatly indebted to his generous offer while respecting his request for anonymity. The organ in its completed form has been in full voice since October/November 2014.  Thank you.


Trinity Players