Spectra 11, Malfunction

Read more on the Acoustat Spectra 11 in our home audio section

Marc De Bourcy2006-01-21 14:40

Hi Andy: I recently emailed you regarding my original set of Spectra 11 ESL. I have realized that, after hooking them to my NAD 7400 Monitor amplifier, the two subwoofers do not respond at all. After having plugged in the two adapters at the back of the ESL, there seems to be no effect at all; I simply hear the two top panels at a very poor and unclear sound quality; could it be that my two ac adaptors are defect??? Please advise, since I am a bit lost here. Again, I think I would need someone here in NYC to look at them; could you recommend somebody for Manhattan... thx

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Andy Szabo2006-08-02 21:19

You haven’t really provided me with any new information since your last letter. Furthermore, in reading some of your previous letters, it seems the problem has changed. If the problem is in one channel only, it should be easy to isolate the trouble by swapping interfaces, amplifier channels, etc. The woofers in the Spectra 11 will operate without the wall transformers connected. The wall transformers only provide bias power for the ESL panels. The audio input signal travels from the input cup through the white plug on top of the woofer cabinet, and then into the interface. At this point, the signal is split into two. One signal goes through the woofer low-pass crossover, and then back through the white plug to the woofer itself. The other signal goes through the ESL high-pass crossover, and then into the audio step-up transformer. The audio transformer is connected to the ESL panel via the five colored pins on the edge of the printed circuit board. The power from the wall transformer, likewise, travels from the input cup through the white plug, and into the interface for the high-voltage bias power supply. My point in describing the signal flow is to try and help you isolate the problem. As you can see, the white plug is vital to all signals: audio input, power input, and woofer feed. This plug is polarized, meaning that it can be plugged in only one way. (The plug is polarized, or keyed, by making two of the plastic guides a D-shape, rather than round.) However, if the polarizing feature of the plug has been defeated or mangled somehow, then the various connections could be crossed, yielding who-knows-what weird results. Take a look at this plug: make sure it is oriented correctly, fully seated onto its mating connector, and that all the metal pins inside the plug and jack and straight and gripping tightly. That’s about all the advice I can offer without more information from you. If I was in your listening room, I’m sure I could identify (if not fix) the problem in less than an hour. (That’s not bragging – there’s just not that much that can go wrong!) But since we must attempt repair by writing, I need more help from you. Since you are the original owner of these speakers, I am assuming they were working at one time. Under what circumstances did they suddenly stop working? Is the problem the same in both speakers? Did you change another system component and the problem started? Were the speakers disassembled for some reason, and then put back together? Did some unauthorized person have access to your system and damage it by overdriving it? (i.e. do you have a teenage son?) Give me more help, and I will try to help you as best I can…

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