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Peter Munro

modern bellows types

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As an alternative to traditional bellows types, one often meets with what I call the 'floating pan' reservoir. I understand that there are several names for this type of reservoir and some even call it Schwimmer type, I believe. We all know that the use of adequate electric blowers has tended to relegate the reservoir to more the role of a regulator. In this connection, I'd be interested to know if, and how, the size of such reservoirs can be equated to the 'stop value' of an organ. Also, what part the choice of wind valves plays in any such calculations; that is, whether an inboard valve (inside the reservoir) or external slide or roller valve. All views and comments are most welcome. Thanks.

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As an alternative to traditional bellows types, one often meets with what I call the 'floating pan' reservoir. I understand that there are several names for this type of reservoir and some even call it Schwimmer type, I believe. We all know that the use of adequate electric blowers has tended to relegate the reservoir to more the role of a regulator. In this connection, I'd be interested to know if, and how, the size of such reservoirs can be equated to the 'stop value' of an organ. Also, what part the choice of wind valves plays in any such calculations; that is, whether an inboard valve (inside the reservoir) or external slide or roller valve. All views and comments are most welcome. Thanks.

 

 

Schwimmers: [iMHO of course]

The Schwimmer-type to which you refer used to be extremely common in neo-classical organs, they have the great advantage that they take up little room and avoid filling the job up with bulky trunking. As has been realised by most builders in Europe, but not by some of our native builders (I am purposefully not naming the UK firm which almost always uses these in all types of organ) the sort of wind rock-steadiness that results can be extreme, so extreme that the organ no longer appears to breathe like a normal instrument. Many enlightened firms over here have gone back to conventional double-rise bellows, enlightened firms over there often use wedge bellows, sometimes in pairs. Both of these methods generally give a very musical wind system: they do not starve, they do not go into spasm, but the tone is more natural, more 'singing'. Sorry if this paragraph sounds like a contender for Private Eye's Pseuds column.

 

 

Wind Controls:

The normal Schwimmer or sprung pan below a soundboard is more-or-less invariably controlled by an inbuilt linked valve. There are a variety of designs. The pressure was set by tightening a spring assembly outside (and beneath) the floating board. In the hands of some firms, a certain sort of playing (fast, rhythmic, chordal) could on rare occasions set the whole thing into spasm. The two organs upon which I have heard this personally (Ellesmere College Chapel and Gloucester Cathedral) were both by HN&B (who sometimes used an aluminium circular disc directly linked with wire and moving within a tube to cut the air off when the schwimmer was full). I have never seen this type of 'reservoir' controlled by an external valve, not least of the problems with using a guillotine or roller valve would be that they are usually fitted to a horizontal feed and rely on gravity to work.

 

Size:

Because of their position below a soundboard, Schwimmers can be built in proportion to the needs of the department, I suppose this is part of their charm to an engineer. In organ building, from the earliest days, the mantra was: make the bellows as large as you have room for. With the advent of electric blowing this is not as necessary as it was perhaps, but it is a discipline none the less.

 

At R.H.Walker when we were building some of the first new tracker jobs in the UK our boss (Peter R.J.Walker) used to go into laborious calculation about the foot-hole diameters of each pipe in a division, and then times the result by 7 to give an optimum pallet size. Rule of thumb is quicker: a long narrow pallet is the most efficient (a good flush of wind combined with lightness of touch at the key), and feed the pallet box with plenty of air - as much as you have room for! Put it this way, if you allow plenty, the notes will never starve. Bear in mind, on modern tracker jobs, the action is probably working 2 to 1, that is to say, if the key goes down 3/8", the pallets are only opening 3/16" - that is what makes a modern tracker job so much lighter than the old Victorian jobs where most actions are set at a leverage of 1 to 1. All sort of tricks go on, however. It is common to find other devices in play even in nominally 'all-mechanical' jobs. Balanciers, for example. These are an essentially pneumatic device intended to keep the bass notes (and therefore the larger pallets) light enough. They effectively knock out some of the wind resistance.

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In the hands of some firms, a certain sort of playing (fast, rhythmic, chordal) could on rare occasions set the whole thing into spasm. The two organs upon which I have heard this personally (Ellesmere College Chapel and Gloucester Cathedral) were both by HN&B (who sometimes used an aluminium circular disc directly linked with wire and moving within a tube to cut the air off when the schwimmer was full).

 

As I have mentioned before, I worked for HNB in the early 70s. At the time they used a butterfly valve (similar to that in a car's carburetor) to control the wind, linked to the pan by a lever arrangement. This was always unstable, I suspect because the wind flowing around the valve became turbulent and shook the valve plate, and caused a great deal of heartache. The problem was that the slightest 'play' in the lever pivots made the whole thing vibrate violently, followed usually by a complete collapse of the system, the regulator pan blowing out, and raw wind being fed to the pipes. Not a good idea.

They overcame the problem by attaching the valve to a bracket near the centre of the pan, and therefore inside the soundboard, feeding it with raw wind via a flexible trunk, and coupling it to the pan with a short length of phosphor bronze wire. This was stable, and solved the problem. Older members of the company didn't like the idea much, as it meant that there was raw wind (ie, straight from the blower) inside the soundboard. In practice, though, it didn't seem to cause any trouble. Mike Smith, who was an HNB man at the time, and who worked for Manders for some years after HNB went out of business, (I believe he was the on site foreman for the St. Paul's rebuild) would be able to give more information.

 

Incidentally, on the HNB regulators, the springs (a battery of coil springs about six inches long) were always inside the soundboard, and were originally not adjustable. The pressure was adjusted in the factory by adding and removing springs. I believe John Norman had a fear that they might be tampered with by maintenance staff, which would interfere with the voicing of course. The problem was that they all had to have the same tension, which is not easy to achieve, as apparently similar springs do not necessarily stretch the same amount. We had to measure the extension of the springs with weights attached to ensure none stretched more than others. Later designs could be adjusted by a threaded rod with a suitable nut on the end, which was far easier and quicker to do, but they were still inside the soundboard. I had earlier worked for Walkers, and on their Positive extension Organs the springs were substantial curved strips of metal, a bit like springs on a railway wagon but smaller, outside the soundboard, and the control valve was a cone inside the supply trunk and close to the soundboard. I don't recall the details very clearly now -- it's a long time ago, but it seemed to work without any trouble.

 

Regards to all

 

John

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There does seem to be something to be said for Schwimmers IF they are fairly inexpensive and maintenance free, given that large and failing reservoirs can spell a death sentence in old organs, especially where they are literally built into the frame. Rock steady wind presumably is not inevitable given that you can still have a tremulant. So why are they not more widely used in rebuilds?

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There does seem to be something to be said for Schwimmers IF they are fairly inexpensive and maintenance free, given that large and failing reservoirs can spell a death sentence in old organs, especially where they are literally built into the frame. Rock steady wind presumably is not inevitable given that you can still have a tremulant. So why are they not more widely used in rebuilds?

 

 

Because proper organ builders have more respect for old organs than that. Sorry!

You might as well say, why not rip out all existing actions, regardless of whether they work or not and replace with electro-pneumatic? EP is efficient and when well-made goes on without much attention for years. I'm quite happy with EP, BTW if the organ requires higher pressures than in the earlier eras.

 

If all one was ever after was rock-steady wind, there is no need to look further than this 'sprung-pan' method.

Rock-steady wind to some ears (including mine) is just that bit unnatural - it's a 'can you tell the difference between marge or butter' question, I suppose.

I hasten to say, I am not advocating 'unsteady wind' that blatantly wobbles at the first sign of a running bass, or sags so the trebles go out of tune with a big chord in the bass, merely wind that has a natural give-and-take to it.

 

For one thing, the more unyielding the wind supply, the more insistent is the coarseness of ET tuning.

Regarding your tremulant question, that's a moot point with these devices too. A schwimmer tends to smooth out the effect of any normal tremulant, so many builders have been forced to turn to such things as fan tremulants placed over the pipes.

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Rock-steady wind to some ears (including mine) is just that bit unnatural...I am not advocating 'unsteady wind'..merely wind that has a natural give-and-take to it.

I'm sure that capable and knowledgeable organ builders and players are familiar with Stravinsky's description of the organ as 'the monster that never breathes'.

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As an alternative to traditional bellows types, one often meets with what I call the 'floating pan' reservoir. I understand that there are several names for this type of reservoir and some even call it Schwimmer type, I believe. We all know that the use of adequate electric blowers has tended to relegate the reservoir to more the role of a regulator. In this connection, I'd be interested to know if, and how, the size of such reservoirs can be equated to the 'stop value' of an organ. Also, what part the choice of wind valves plays in any such calculations; that is, whether an inboard valve (inside the reservoir) or external slide or roller valve. All views and comments are most welcome. Thanks.

There is an article in the IBO's Organ Building Journal, Vol.7 "A method for calculating wind reservoir size" by Andrew Moyes, which you may find to be of interest. In this article Andrew explains the process and calculations he uses to size regulators.

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There is an article in the IBO's Organ Building Journal, Vol.7 "A method for calculating wind reservoir size" by Andrew Moyes, which you may find to be of interest. In this article Andrew explains the process and calculations he uses to size regulators.

 

 

Say no more, squire, say no more!

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There is an article in the IBO's Organ Building Journal, Vol.7 "A method for calculating wind reservoir size" by Andrew Moyes, which you may find to be of interest. In this article Andrew explains the process and calculations he uses to size regulators.

 

Thanks for this. I'll try to get a copy.

PM

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Because proper organ builders have more respect for old organs than that. Sorry!

You might as well say, why not rip out all existing actions, regardless of whether they work or not and replace with electro-pneumatic? EP is efficient and when well-made goes on without much attention for years. I'm quite happy with EP, BTW if the organ requires higher pressures than in the earlier eras.

 

If all one was ever after was rock-steady wind, there is no need to look further than this 'sprung-pan' method.

Rock-steady wind to some ears (including mine) is just that bit unnatural - it's a 'can you tell the difference between marge or butter' question, I suppose.

I hasten to say, I am not advocating 'unsteady wind' that blatantly wobbles at the first sign of a running bass, or sags so the trebles go out of tune with a big chord in the bass, merely wind that has a natural give-and-take to it.

 

For one thing, the more unyielding the wind supply, the more insistent is the coarseness of ET tuning.

Regarding your tremulant question, that's a moot point with these devices too. A schwimmer tends to smooth out the effect of any normal tremulant, so many builders have been forced to turn to such things as fan tremulants placed over the pipes.

 

Or you can use a device which imparts a rhythmic 'nudge' the the pan. These are easily regulated for both depth and speed and work well.

 

John

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Or you can use a device which imparts a rhythmic 'nudge' the the pan. These are easily regulated for both depth and speed and work well.

 

John

 

As J.W.Walker used to supply on their Positif extension organs? Yes, I agree these are good.

Thanks for your contributions John, you clearly know a great deal more than I do.

 

 

P/C

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As J.W.Walker used to supply on their Positif extension organs? Yes, I agree these are good.

Thanks for your contributions John, you clearly know a great deal more than I do.

 

 

P/C

Funny thing is, while I saw a fair few 'Positives' while a key holder for Walkers, I don't remember any tremulants at all. In all probability that is my faulty memory, though. I have a vague recollection of the tuner I worked with moaning that the only way to get a tremulant on these instruments was to use a fan type, which he regarded as worse than second rate! The 'nudging' device was on an instrument we built at HNB for, if I recall correctly, St. Mary's (?) Horsell, near Woking.

 

Regards top all

 

John

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