Spectra 1100, Interface

Read more on the Acoustat Spectra 1100 in our home audio section

Karlis Dunens2004-02-23 22:21

Hi, I recently decided to build an ESL. I have already built a panel for the ESL. I was going to start work on building the interface and crossover etc.,. when a buddy of mine came across the interface and input cup for a Spectra 11. The input cup and interface each have their own 6-pin connector which I believe are meant for each other. However, i am stumped on how to connect the interface to the panel.

I just realized that the input cup is meant for the Spectra 1100 and the interface is for the Spectra 11. Does this change anything that I would have to do with the panels? I also read somewhere that they should be ok with the different input cup and that it would allow me to bi-wire the esl. Is this true?

I hope you can help because i really would love to get these things going. I am excited to be using these Acoustat parts because everything i\'ve read about them has been great. Any information is appreciated. Thanks, Karlis

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Andy Szabo2004-02-23 22:21

The schematics for the both the Spectra 11 and Spectra 1100 are shown on this site. Both models have essentially the same electrical schematic; the only differences being the high-frequency balance switch and the bi-amp switch on the 1100. These are minor differences, and amount to ”luxuries” on the 1100.

The big difference between these two models\' interfaces is the physical layout. On the 11, both the high voltage audio and the woofer crossover are located in the interface chassis. On the 1100, the woofer crossover is mounted on the input cup (necessitated by the bi-amp feature).

In your case, having the input cup for the 1100 and interface for the 11, you have the complete high voltage audio section, and two sets of woofer crossovers. The woofer crossover component values are different for the 11 and 1100, owing to the different woofer used in each model.

The 11 or 1100 interface is not a full range interface. It is intended for a hybrid ESL/woofer system only. Do not attempt to bypass the high-pass crossover into the transformer: doing so will greatly increase saturation distortion and/or cause damage. These interfaces are also designed for the sectored Spectra ESL panel. That is, there is an output for the midrange-only sector, and an output for the highs and midrange sector.

If your ESL panel is not sectored like a Spectra panel, it can still be used with these interfaces (albeit without the advantages of Spectra). Connect the diaphragm to the red connector, the rear stator to the blue connector, and the front stator to the white connector. The yellow and black connectors are for sectored panels only. The connectors are located at the edge of the main printed circuit board.

If you want to preserve the bi-amp feature, then use the crossover located on the 1100 input cup. Remove the extra crossover components on the Spectra 11 main pc board (coil, 150 uF capacitor, and 4-ohm resistor). You can also remove the yellow and brown wires leading from the interface to its plug. The wiring on the six-pin plugs will now be compatible. It is also possible (likely?) that you\'ll need to modify the crossover component values on the input cup to suit whatever woofer you use. No, I don\'t have any suggestions on what woofer to use.

Keep in mind that you may have less than the desired results using this interface with your panels. ESL panels and their interfaces should be designed as a system. Considerations such as diaphragm bias voltage and equalization may be different. On the other hand, it may work great! Give it a try!

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