McIntosh dipole surrounds are not dipolar


Hi all. I need help with McIntosh HT-3’s. I have two pairs separately purchased and decided to try one pair of them as fronts (knowing that this is not ideal) but with the idea of seeing how “poor” they would sound. What I found was the opposite. There seems to be too much presence for a dipole which is meant to be an invisible speaker offering a very diffuse sound field. Then I tried the other pair at the rear with the null adjacent to the seating position. Again the surrounds were very present and not as diffuse as I expected. So I took a single AA battery to the binding posts and found that both drivers push when polarity is observed correctly. This seems wrong to me. I would expect one to push and one to pull. When reversing polarity both drivers pull. This tells me I have a bipolar configuration. (I am very familiar with bipolar speakers since my stereo setup are Mirage M3si and I also have used Mirage MBS in a HT setups) I don’t expect there to be an oscillator of sorts in the crossover but haven’t opened everything up yet. This could mean that I could “fix” them by reversing polarity on one side of the speaker. I have tried getting help from McIntosh but I get directed to a service tech and that’s all. Does anyone have a schematic for the crossover?
bcwoody

Showing 1 response by imhififan

Your battery test only tell half the story
•Special Crossover
At frequencies below 350Hz both Low Frequency Drivers operate in-phase; above 350Hz both the Low Frequency Drivers and Tweeters operate out-of-phase thus providing the desired diffused surround effect. Both the Low and High Frequency Drivers are crossed over at a 12dB per octave rate.

http://www.mcintoshlabs.com.ua/files/products_documents/135.pdf