Spectra 6600, Interfaces, wiring information needed

Read more on the Acoustat Spectra 6600 in our home audio section

Kevin Ferry2004-02-23 22:21

Andy, First of all, I\'d like to say you\'ve done an excellent job helping Acoustat owners share information! Your comments have been most helpful, and have guided my most recent electrostatic aquisition. I just picked up a pair of Spectra 6600 speakers. So far, I must say they are awesome. They image as well as my 1+1s, but they have fast, articulate bass as well.

My question is this. Regarding the schematic that you posted for the 6600/4400 speakers, there are four wires coming from the bass transformer. White, Blue, Green and Yellow. The White and Blue wires are ran in the same plastic tube, with the Blue wire stopping a couple of inches short of the circuit board. The white wire is hooked up, which is consistent with the schematic for the 6600. The Green and Yellow wires are then ran through a tube together and wrapped up under the transformers. The Green wire is apparently for the spectra 4400. Since I don\'t have an owner\'s manual, I was wondering what the Blue and Yellow wires are for.

I am very familiar with the older interfaces, and have messed around with different positions on the bass transformer tap. Is this what all four of these wires do? If my assumption in regards to the schematic is correct, the four wires give different levels of bass ”step up.” Following this idea, it looks as though the order from least to most ”step up” would be White, Blue, Green and Yellow. Changing these wouldn\'t be as easy as the old interfaces, though, and would require a soldering iron. The bass is perfect in my room, and I certainly don\'t need more. I was just curious what the other wires were intended to do. Thanks in advance, Kevin Ferry


Andy Szabo2004-02-23 22:21

Congratulations on your acquisition of Acoustat\'s finest. I\'m jealous: if I had the space, I would certainly seek out a pair of 4400\'s or 6600\'s.

Isn\'t it great that these speakers, despite their size, image as well as the ”line source” Model 1+1\'s? That\'s the magic of Spectra\'s electrically controlled dispersion. Believe me, the Model 6\'s of the pre-Spectra era most certainly did not image as well as the Model 1+1\'s. There was always that trade-off between imaging and dynamic capability. Finally, you now have the best of both worlds!

You are correct regarding the purpose of the transformer taps. The green tap is for the 4400, and the white tap is for the 6600. The other ”unused” taps are for modifying the bass boost if so desired (and I don\'t remember anyone ever wanting to do so). The 6600 could have more bass boost by using the blue, green, or yellow tap (there is no provision for less bass boost). The 4400 could have more bass boost by using the yellow tap, or less bass boost by using the blue or white tap.

It was never intended for these taps to be changed by the consumer: considerable disassembly is required to gain access to the connections. Even though the electrical components are the same for the two models of speakers, the interfaces were custom wired for each model, and therefore were supplied with a specific model of speaker.

The older (pre-Spectra) MK-121 interface was done differently. Because this interface was used for so many different models (1+1, 2, 3, 2+2, 4) it was impractical for Acoustat to stock interfaces wired for each model. So, all MK-121\'s were shipped as ”universal” interfaces, set on the red tap. It was left to the consumer to change the tap, if needed, for the specific model of speaker.

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