Situation: Part of a play is set in a theatre, backstage, in the 1970s. This backstage area features an oldschool loudspeaker which has to play announcements by the show caller. This loudspeaker only accepts +/- wires as inputs, not the standard XLR signal, and is passive. Simply mapping the plus and minus / mass of the XLR cable to two cables would not work because the signal would be too weak to be heard.
Mac OS with audio files >> A&H SQ5 >> dSnake >> Stagebox >> XLR out >> XLR cable >> XLR to 3.5 mm jack adapter >> CD player AUX in >> loudspeaker + / - cables out >> oldschool loudspeaker
While setups like this should normally be simplified, since every additional element in a signal chain increases the risk of signal failure, it worked just fine for an entire theatre season. Without my solution, a costly second best option, or a setup less true to the director's wishes, would have been needed.
The stagebox was staying at a fixed position, the XLR cable and adapter were stowed away at FOH. The CD player was hidden in a corner of the stage. However, the CD player and the loudspeaker cables had to be removed between plays, because some other productions were taking place in the same theatre season. Thanks to two screws attached to the back of a prop wall by stage technician Martin N. and a shelf-like hidden space, the loudspeaker cables, permanently attached to the oldschool loudspeaker on one and to the CD player on the other end, plus the CD player itself, could easily be stored with the prop wall, which could be wheeled away. Before each performance, the CD player volume settings (always at the same level) were checked, and the system was line checked before each show. This way, we had a quick "plug and play" solution ready at hand. It was of utmost importance to connect the CD player to a non-dimmed socket, called "Ewiger Strom" in German. During rehearsals, when the CD player was attached to dimmed AC, it would make weird buzzing noises and turn silent.
If you would like to take this design a step further, see below:
This design is a draft which I did not put in practice, but may be useful for theatre purposes. It turns two balanced signals into two unbalanced signals.
You need:
- a stagebox
- two XLR cables
- a special adapter (which you need to solder yourself)
- a 3.5 mm jack cable
- an old household stereo player (which is the „amp“ for the two unbal signals) with a 3.5 mm jack aux input and two oldschool loudspeaker outs
- four loudspeaker cables (2x signals, 2x minus/sleeve)
- two oldschool loudspeakers
- one socket for the stereo player, ideally completely separate from lighting apparatus sockets to avoid hum or issues related to dimming
- stage camouflage to hide the stereo player
Here‘s how it works:
You are sending two signals (double mono, or stereo) to two stagebox XLR outs. Every parameter, including SPL and EQ, can be adjusted for each channel individually, which is very useful if e. g. you want to pre-program a panoramic fade in QLab, or one speaker is in a very different acoustic position from the other.
Next comes the cool adapter you need to solder together as shown in the draft. It uses the classic headphones TRS configuration. One signal to T, the other signal to R, everything else to S.
The two signals now travel to the 3.5 mm jack output which is fed to an old stereo player with a 3.5 mm jack input. Adjust stereo player settings as needed.
The stereo player is the amp for our signals. Next, the signals are fed to two oldschool loudspeaker cables, which feed the two loudspeakers.
For easier use, the stereo player can be hidden in a prop that can be moved around, and only fed with electricity when the play where it is needed actually takes place. Proper cable management (e. g. figure of eight wiring) and formatting cables to the length required (no excess metres of speaker cable) make life easier.
Enjoy!
If you use this design, please credit me (Gwen Korinek) and Festspiele Reichenau.
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