More than new boards

Since summer 2018, the Gewandhaus concert hall in Leipzig has been undergoing essential conversion work in breaks between seasons. In future, it will have an extended, but exquisitely elaborate, stage topography of 56 individual lifting platforms and 12 compensating platforms, to fulfil all the orchestra’s needs and bring it up to the highest technological standards. The finishing touches are due to be completed in September 2020.

The refurbishment of Leipzig’s premier concert hall, the Gewandhaus, started in summer 2018 – almost unnoticed by audiences.

Structural engineering improvements were made in the 2018 summer break, which involved stabilizing the front stage area in the main hall. To do this, the foyer ceiling underneath was opened from below and reinforced with a 7 cm-thick layer of ferroconcrete. Though slight in relation to the total thickness of over 0.5 m, structural calculations showed the crucial difference it will make for the new technology. The walls around the orchestra platform in the main hall previously absorbed too little sound. Consequently, when the brass instruments and timpani were played in front of the smooth back wall, the effect was like an explosion. The musicians seated at the back, most exposed to these decibels, had to rely on visual orientation. They could see the concertmaster but not really hear him.

For ten years, the previous platform equipment was kept in use thanks to careful maintenance. But the system, which rendered some 85 m² of the platform surface variable, was no longer state-of-the-art and had started showing major signs of wear and tear, both technical and visual. It was operated by a procedure almost as outdated as reconfiguring the stage by hand, and its maintenance was becoming increasingly costly.

High standards and some compromises

The planners were tasked with creating a maximum of mobile stage surface without changing the outer shell of the stage. The existing foundation strip in the platform system’s machine pit, the ventilation ducts and the three-side, full-surface wooden veneers on the lifting platforms made the planning task a major challenge.

The lifting platforms are now raised – up to 1.30 m over the stage floor – via compact, controlled chain drives. The platforms are driven by four-sided double- and triple-scissor lifts. Ensuring platforms that are ‘virtually’ vibration-free when raised, considering the very small surfaces (of between 1.2 m² and 3.7 m²) and limited installation spaces, required a special technical solution focusing on the stability of the lifting platforms (dynamic working load 1.5 KN/m² at a max. speed of 0.02 m/s).

The stage surface with the new platforms meets the geometric standards required. The gap dimensions between the platforms and the adjacent side walls and adjoining rear stage wall are of equal size and max. 10 mm. The position of the platforms in relation to one another and the fixed edges must remain constant, whether lowered or raised. This qualitative specification needed to be observed equally by the machine builders and the carpenters.

There is a limit to how delicate the lifting platforms can be, due to considerations of both stability and expense. The smallest of the 39 new platforms installed in summer 2019 at the rear of the stage is only 1.2 m². As the lifting platform for the grand piano is to be kept, with is unique construction and function, the hitherto fixed-surface front of the stage cannot be entirely fitted with lifting platforms. Bearable compromises have been found.

Still no sound sails

In terms of acoustics, some things have changed: The rear parts of the side walls were given a jagged design and the rear wall of the stage has been texturized. The Gewandhaus’ own acoustics expert Hans-Peter Tennhardt came up with some initial ideas. Eventually, acoustic engineers Karlheinz Müller and Winfried Lachenmayr of Müller-BBM developed the solution of redesigning the wall surfaces surrounding the orchestra platform so that there is still no need for sound sails, which would obstruct visitors’ view of the organ. Efforts were also made to ensure the general appearance remained unchanged as far as possible, despite the incorporation of new forms and materials. There is, then, the same dark-toned wood and the same design parquet pieces on the platform, as required by the preservation order.

Less work for everyone

Schöneich welcomes the reduction in workload for the technicians, who need to reconfigure the stage daily. “We might have, for example, orchestra rehearsals on two successive mornings and a rental event on the evening in between that needs a different stage set-up. That means rebuilding twice. As well as the reduction in the legwork, which the lifting system now takes over, assembly and disassembly times are considerably shortened. That is a boon when it comes to near-capacity use of the main hall.” Yet the automatization will not cause any job losses, stresses Schöneich: “There is no threat of redundancies. Hours won’t even be cut, as the number of events is increasing. A lot more is presented as an event today, creating more work for our staff.”

The extended, state-of-the-art platform system will allow the Gewandhaus to meet the standards of a modern music orchestra. With the new stage controls, countless orchestra arrangements can be programmed and saved. “The instruments can now be optimally spread across the new stage surface. And there are hardly any danger zones that might appear due to additional overbuilding,” says Seipel, summing up the benefits and results of the refurbishment.

The third and last stage is due to take place in the 2020 summer break, from early June to mid-September. The building phases were planned so that they can be completed separately, and the concert hall stay open in between. Whether the refurbishment project can be continued and completed on schedule under the extraordinary circumstances of the Corona crisis remains to be seen in the coming weeks and months.