8, Interfaces, taps on audio transformer

Read more on the Acoustat 8 in our home audio section

Kevin Ferry2004-02-23 22:21

Andy, Thanks again for taking the time to answer so many questions regarding  Acoustat products. Your articles and responses have helped me a great deal as I  continue to aquire old Acoustat stuff. My most recent find is a nice set of Model 8 speakers. I have a question regarding the taps on the bass transformers. On most Acoustat models, there is a red, orange, and yellow wire for 2, 3, and 4 panel speakers, respectively.

On the models 6 and 8, however, the taps are green, blue, and gray. The instruction manual states that the blue tap is for 6 panel speakers, and the gray tap is for 8 panel speakers.

Do you know what the green wire is for? I am assuming, because of the order of the wires as they leave the transformer, that the green wire is for more bass.

Do you know how many panels can be ran with this tap? Are they then appropriate for 4 panel speakers?

Also, I would like to know if you have the turns ratio for the bass transformers, both the red/orange/yellow and the green/blue/gray units. I am
assuming that the turns ratio is different for each tap?

Finally, is the high frequency transformer the same in both interface models? Do you know the turns ratio for that transformer? My interfaces are the latest, red label medallion units. Thanks again in advance for


Andy Szabo2004-02-23 22:21

The Acoustat low frequency transformer taps follow the standard resistor color code, as shown below. Each successive tap provides less bass boost: the red tap provides the most, and the gray tap the least.

Models 1+1, 2, 2+2, 3 and 4

red 2
orange 3
yellow 4

Models 6 and 8

green 5
blue 6
gray 8

For the low frequency transformer used in the Model 6\'s and Model 8\'s, the blue tap is intended for the Model 6, and the gray tap is intended for the Model 8. The green tap is extra, and is available to provide more bass boost, if desired, than the ”standard” setting.

Note that the gray tap on the Model 8 actually drives only four panels, since there are two interfaces per speaker. But do not confuse that ”4 panel” tap with the yellow ”4 panel” tap used on speakers with four total panels. The yellow tap provides considerably more boost than the gray tap.

If you want more bass than is provided by the Model 8\'s gray tap, try the blue tap. Using the green tap on the Model 8 would probably provide too much boost, but there is absolutely no harm in trying it. Similarly, if you want more bass on a Model 6, try the green tap.

The high frequency transformer is the same for all models. Only the low frequency transformer is different for the Models 6 and 8, due to the much lower bass boost required.

Sorry, but I do not have any turns-ratio or any other technical data on the audio transformers. Wish I did! Good Luck with your Model 8\'s. They represent one of the largest commercial esl\'s ever made, if not the largest. They are rare, too. I don\'t know how many were ever made, but I\'d be surprised if Acoustat made as many as 50 pairs. That number could be considerably less.

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