, Panels, exchanging panels

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Brian Goodman2004-02-23 22:21

Andy, are the panels from the Spectra series interchangeable with older panels from the Model 1+1, 2+2 etc series? Thanks, Brian Goodman


Andy Szabo2004-02-23 22:21

The stators on all Acoustat panels are formed by a wire grid on either side of the diaphragm. On pre-Spectra panels, each grid is continuous, with a wire lead connected to each end of the grid. Therefore, each panel has five wires: one for the bias, two white wires for the front grid, and two blue wires for the rear grid. The front pair and rear pair of wires are tied together and connected to their respective ”front” and ”rear” audio drive signals. (Note: very early Acoustat panels had only three wires: one bias wire, one front stator wire, and one rear stator wire. The connections were the same)

Spectra panels are exactly the same construction, except that the stator grid is split down the middle, allowing each half of the panel to be driven by different signals. The panel still has only five wires, but the connections are different. One wire is for the bias, one for the front right stator, one for the front left stator, one for the rear right stator, and one for the rear left stator. The color-coding on the stator wires will vary, depending on where in the speaker that panel is used.

A pre-Spectra speaker (1+1, 2+2, 3, etc.) can use either the original panel type or a Spectra panel. To use a Spectra panel in a pre-Spectra speaker, merely tie together the front pair of wires and the rear pair of wires. The front pair is connected to the ”white” drive terminal, and the rear pair is connected to the ”blue” drive terminal. The fact that the stator is split will make no difference.

A Spectra speaker, however, must use a Spectra panel due to the requirement for split stators.

Keep in mind that there is no inherent advantage (except as noted below) in replacing your pre-Spectra panels with Spectra panels. This should be done only if you have a damaged panel, and the only replacement you can find is a Spectra panel. Even then, it is necessary to replace only the damaged panel. The two types of panels are compatible and should work fine together.

Depending on vintage, a Spectra panel could have a small advantage over a non-Spectra panel. In the mid-eighties, Acoustat began using a new conductive coating. The result was a speaker that could play louder without making crackling noises, especially on bass notes. Panels with improved coating can be identified by a yellow bias wire with a red stripe. All previous bias wires were either solid red or white with a red stripe. This improvement was introduced before Spectra, so some pre-Spectra models were also built with the improved coating.

The practical difference between the old and new coating is most noticeable on the smaller models like the 1+1, where the smaller total area demands more work from each individual panel. Even with this potential advantage, I would hardly recommend that anyone change panels for only that reason. I mention this only to give you a more complete picture of the evolution of Acoustat\'s panels.

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