Spectra 22, Wiring question

Read more on the Acoustat Spectra 22 in our home audio section

Tom Montgomery2009-03-13 02:22

I took delivery on a pair of Acoustat 22s and trying to assemble them ran into this problem: the transformers each have seven inputs (labeled and color coded in descending order WHITE-YELLOW-BLACK-RED-BLACK-YELLOW-BLUE). Each speaker has only five connectors (BLUE_YELLOW, RED and BLUE/BLACK for one, for the other BLUE_YELLOW, RED and YELLOW BLACK).

So, what goes where ...and why?

Thanks for any input in advance, Tom


Andy Szabo2009-03-26 19:41

The seven outputs from the transformer interface are as follows:

blue-black: rear stator, lows only
blue-yellow: rear stator, mids and lows only
blue: rear stator, full range
red: diaphragm, +5000 volts
white: front stator, full range
white-yellow: front stator, mids and lows only
white-black: front stator, lows only

As to why your Spectra 22s have less than seven groups of wires per panel, I am stumped. My guess is that someone has modified the speaker, although from the remaining colors on your speaker, I am not sure what they were trying to accomplish.

Unless you can contact whoever modified these speakers, (to find out what they did), you will probably need to remove the grille cloth and (hopefully) find the missing wires. For each Spectra 22, you should find these wires (10 total):

blue-black: 1 wire
blue-yellow: 2 wires
blue: 1 wire
red: 2 wires
white: 1 wire
white-yellow: 2 wires
white-black: 1 wire

Unless the missing wires have been cutoff flush with the internal panels, you should be able to reconstruct the speaker. If you can\'t fix it, you should ask for your money back. If you can find all ten wires, but you\'re not sure how to reconnect them, I can help with that.

I know this is not the definitive answer you were looking for. Do write again if you need more help. I\'ll do everything I can to help you get your speakers working properly. Good Luck!

Tom Montgomery2009-05-21 19:32

Thanks for the info Andy; this has clarified what I need to do. I can see now that all ten leads from the panel array are present and that the previous owner seems to have pulled the leads off the \"bass only, black\" connectors on the board and combined them with the \"full-range, white\" connectors ...in effect, making two full-range sectors ( at least I can see through the sock that there\'s ten leads going into the panels). I haven\'t yet removed the sock and followed all the leads to the panels but I have bought twenty new plugs and jacks from Mauser (using your valuable info here on TAC). My next task is to rewire the speakers, planning to use 16ga vampire wire. I should mention that I have very little experience in attempting this work and have questions:

It looks like from your factory tour photos here at TAC that the bias wires are taped onto the frame and otherwise attached how? I could\'nt see the how the other, stator wires are attached to the panels, but I assume when I get the sock off that I\'ll see how they\'re attached and merely follow your instructions here as to which wire (front and back) goes to which sector. I\'m somewhat confused by your reference to the original color coding, since my transformer jacks are only one color each(white, yellow etc.), as are the pins from the arrays. As I could buy only red pin connectors, the color coding is irrelevant to me now and I\'ll find another way to ID the leads for future hookup. Although the connectors have been obviously resoldered and rearranged, the board itself, resistors underneath and so on I remeber as having been untouched ...so I\'m hoping the board itself is untouched. Any advise for me on attachment at the array end or other considerations for which I should be looking out?
Thanks, Tom

Andy Szabo2009-05-21 22:41

I recommend against replacing the internal panel wires with anything different than original. The original wire is custom-made, with a special oxygen-free copper conductor, and a 10,000-volt rating on the insulation. The gauge of the wire is small, but the current flow is very low. Almost any \'audiophile\' wire will not have sufficient voltage rating and may arc-through.

Furthermore, the wires are not connected to the panel with any sort of detachable terminal. The wires continue uninteruppted inside the panel and form the stators. The bias wire is also permanently connected to the diaphragm.

The bundled wires are secured to the wooden frame by nylon cable-clamps, not tape.

When referring to the different colors on the interface board, the single red bias jack is in the middle. The \'blue group\' is on one side, and the \'white group\' is on the opposite side.

It looks like the previous owner tried to \'un-Spectra\' the speaker. That doesn\'t really work, since the transformers and RC networks were designed to drive a split-sector system. If you don\'t have the owners manual, I recommend you get the Acoustat Manual CD available from this website. It shows the schematic and a diagram of the interface board, which should help you understand the connections. Keep writing with your questions until we get these speakers back to factory-original configuration. It\'ll be worth the effort!

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