Restoration of the Tyn organ

Organbuilding company of Johannes Klais from Bonn, Germany restored the Mundt organ in the church of Our Lady before Týn in Prague (Czech Republic) during the years 1998-2000. The aim of the restoration was preserving the early Baroque instrument in its shape from the year 1823 as much as possible respecting Gartner’s influence. The variant of restoring the 1673 design was abandoned as this would involve relocation of the main organ body again forwards, placing the bellows system behind it and accepting the negative influence of the sun rays through the west window. Today’s pitch of 444Hz at 22 deg. C is two halftones lower than before. It is impossible to find with certainty what the original pitch and temperament was, as the original ones were changed by Gartner’s intervention by pipe prolongation and movements of pipes around. A dependable design of the original Mundt’s console is also missing.

The instrument was taken apart in February 1998 and transported to the workshop in Bonn. The organ casework stayed in place and underwent cleaning and restoration by the Prague restorer Václav Stádník in the meantime. The wooden parts underwent a complete sanation with missing parts replaced by replicas, pigmented beeswax used for filling and with gold plating renewal.  A double-headed eagle with a crown as the imperial symbol was returned to the top of the organ after languishing for years in the depository. Logically, it completes other shields - the city one at the bottom of the positive and the provincial one at the top of the positive. The empore (organ gallery) and the bellows room were restored and a new electric installation performed.

The main part of the restoration process was cleaning of the pipework, The instrument in general withstood the ages very well, the original parts by Mundt much better than the parts supplied by Gartner. The latter ones have a lower quality material and some linden wood parts were already destroyed. Mundt’s pipework is of the highest quality both by the execution and processing of the tin alloy. According to the analysis of the Institute for inorganic chemistry (University of Bonn), Mundt used an alloy of 80,9% - 83,5% tin, 15,88% - 18,62% lead and approximately1% copper. The younger pipes supplied by Gartner are of worse material and execution, however Gartner possibly used some Mundt’s pipes available to him (this is apparent in the low octave of the Salicional 8’ register). The pipes added in 1823-1846 are of thinner material, the solder joints are very uneven and the labial shape featureless. For the renovation, a doped alloy with 82% tin content was used in the manner of the 1671 processing.

All airchests made by Mundt are well preserved and have not been touched since 1823. An interesting feature is the side-wide vents on the airchests for the main organ, pedal and bass portion of the positive. The restoration of the console was again guided by the situation of the instrument in 1823. Replicas replaced the worn down keyboards. The pedalboard was replicated taking design cues from the preserved organ in Velvary.  The bench was modeled according to the one of the Stolmir organ. Parts of the console damaged by wood worm were replaced. The mechanical key and register “tracker” action has been preserved in its 1823 shape: Gartner essentially used original Mundt’s work but had to extend the part leading to the positive. The bellows system had to be completely redone, currently consisting of 6 bellows made using the design found on other Mundt’s organs. The air pressure is set at 67mm water column pressure, the same as before the restoration. There were no other intonation changes found to the 1671 original pipework beside cutouts of the wooden registers Bourdon Flauta 16’ and both of Copula major 8’. The pipes have an extreme open foot and wide space between the bottom labium and the pipe core resulting in an optimal set-up with a relatively low pressure. The intonation is achieved by several tiny punctures into the pipe core. The restoration has not changed anything on this arrangement and the only acoustic changes were the result of completing the mixtures and removing the dust from horizontal surfaces of the organ.

The choice of the temperament scheme was guided by the desire not to cut any material from the original pipes. At the end, the modified Kirnberger III system was chosen: the C-E third the purest, with gradual increase of the number of resonances (beats) with thirds G-B, F-A, D- F sharp. This temperament scheme corresponds to Gartner’s description of the uneven temperament scheme as described in his work “A short advice on organ…” which accepts certain dissonance of accords built on F sharp and C sharp for the purpose of “purer” sounds elsewhere. [However, we have some objections to this temperament as you may read on the screenshot web page.]

(compiled by Dr. Jan Skvaril using the text supplied by Dr. Hans-Wolfgang Theobald)