A sound came from heaven like the rush of a mighty wind. Acts 2:2
Wind stability is a hot topic in the current world of the pipe organ. Instant arguments arise when anyone mentions the subject, and few of those on the cutting edge of organ thinking would be called neutral about this subject.
Over the centuries, builders have applied ever-increasing engineering competence to the problem of supplying wind to the pipes of the organ. The bellows were enlarged, weighted, sprung, ribbed, leveled and made complex with a wide variety of air valves, feeders, wind conductors and shock absorbers. All of these changes were made in a conscious effort to gain steadier wind for the organ, and there is evidence that, as time went on, winding systems became steadier as each technological improvement was added. It seems doubtful that any pre-20th century organbuilder set out to achieve a greater unsteadiness of wind than the engineering abilities of his time would allow. The problem even received the attention, of J.S. Bach, who made a list of recommendations for the rebuilding of the organ at Mühlhausen In 1708. His first three recommendations concern the bellows and chests, and he wanted the unsteady wind problem solved so that all three manuals and pedal (with 32') would have a steady sound even when large groups of stops were drawn. Even though Bach did not like the unsteady sound of the Mühlhausen organ, it is not possible to know what sort of steadiness he wanted or would accept. It is clear that Bach wanted less of the unsteadiness which the organ had, and he placed this priority at the top of his list.
The goal of absolute steadiness of wind and sound was finally achieved in the late 19th century. The electric blower and sophisticated wind regulating devices provided wind so steady and free of vibration that any size chord, playing technique or registration could be used without fear.
It was not long, however, before the long sought goal of steadiness of wind would be called into question, and by the 1960s some organbuilders worn viewing steady wind as unhistoric and dull. Bellows and winding systems which had been discarded centuries ago were revived and installed in new organs for the express purpose of achieving unsteady wind. What Bach had discarded, we now embraced, and every organbuilder was forced to rethink the problems of winding in a new light. Not having the benefit of years of trial and error development which prototype winding systems had at the hands of former builders, the revived systems were applied as copies or experiments. Some of these were notably unsuccessful, but the work continued as each organbuilder struggled to achieve just the right kind of unsteadiness.
With the revival of old-style winding systems, it is possible for the first time to "program" the wind character which is desired. Where an early builder could only achieve the sort of winding which he had learned or developed within the limits of the technology and engineering of his time, a modern organbuilder may now pick from a wide variety of historic and nationalistic styles.
Is there such a thing as a perfect winding system? From one viewpoint, a perfect winding system is steady and without detectable flaw. Another view is that a winding system should give and flex and contribute to a change in the sound of the organ, and a corollary of this second idea would say that the organ's winding system should reflect the historic period which a particular instrument is attempting to replicate. We will never agree on which is the proper approach, and it seems that we will have organs built with steady wind and organs built with unsteady wind for some time to come.
A subtopic of this discussion is related to hearing and interpretation. When unsteady wind was first adopted as a purposeful and intentioned part of new organs, the underlying distraction was that it called attention to itself. One was forced to hear this unsteadiness and acknowledge that the organ was preaching its technology, or lack of it, to us. Now, after some years, we are accustomed to "listening" to winding systems to hear if the wind is steady or unsteady so that we can classify the builder and the organ, and place them in our ideology. It remains an open question as to whether we are distracted or enlightened by being able to hear both steadiness and unsteadiness in the organ. The question may even be moot since some fine new instruments have controls that make it possible to change from steady to unsteady wind, and the question of what these controls actually contribute has yet to be decided. Do they fall Into the category of chiff controls found on some electronics which also allow for some sort of conversion from Classic to Romantic sounds, or are they a valid new device for the pipe organ?
There can be no doubt that an organ with unsteady wind creates sounds which are more like prototype instruments than does an organ with absolutely steady wind. Unfortunately, we have no record of what Bach thought about the vast majority of organs he heard, saw and played in his lifetime, nor whether the rebuild at Mühlhausen produced the steadiness he sought. I think it certain that what might have been called steady In the 18th century is not what we might call steady today. I think it also true that how an organ sounded several hundred years ago and how it was "heard" by organist and listener is now irretrievably lost to us. Neither the sound which was produced nor the sound which was heard can be recreated in our time.
The value of having organs with a wide variety of winding systems, and for which it is easy for us to hear steady and unsteady characteristics, is that they enrich our knowledge, as long as we understand that authenticity in historic matters is not possible, and that we can only allude to the situations of the past rather than reproduce them. No other musical instrument is so varied in its history and design, and the incredible variety of styles and sounds available from the pipe organ will certainly keep It alive as the King of Instruments.