2 plus 2, Bypassing crossover

Read more on the Acoustat 2 plus 2 in our home audio section

Dave Thorngren2008-02-19 06:23

Hey Andy,As a proud owner of a variety of planar-type speakers I must admit that curiosity has been known to get the best of me. Armned with a passive crossover and suitable amplification, I have mixed and matched numerous Magnepans, Janzens and Acoustats with interesting results. Here\'s my current dilema: I have recently acquired a set of 2+2\'s which suffer from poor high frequency reproduction. I took your advice of applying contact cleaner and sand paper to the minor corrosion on the HF pot I did indeed find, yet the problem remained. My uneducated guess is a bad cap in the crossover. In the interim, I used a set of my modified and seperated Tympani 1D tweeter panels to replace the missing frequencies. The result: a wide open soundstage, larger sweetspot and less beamy presentation. What do you imagine the result would be if I removed the 2+2 crossover completely and dedicated all 4 esl panels to mid and low-end reproduction similar to the 1D configuration and used an external crossover? My current passive XO (which I find works well with many differant speakers and would most likely be using in this application)has its\' low pass set at 1KHz. Thanks for all your inforative work. Dave


Andy Szabo2008-02-20 19:41

I don\'t have any experience with trying to make the MK-121 operate at lows and mids only, so I can only guess at the results if you disconnect the high frequency portion of the interface. The simplest way to try this would be to disconnect the RC-network that feeds the high frequency transformer\'s primary, and see how you like the results. Since there is considerable overlap between the low and high frequency transformers, I\'m not sure what the effective crossover point should be for your tweeter system. Different results might be had if you take it a step further and also disconnect both phases of the high frequency transformer\'s secondary. If only the high frequency transformer\'s primary is disconnected (as above)leaving the secondary components in-circuit may have some interaction, so you might want to try it both ways. At best, this will require some experimentation to get the transition correct between the ESL panels and the tweeters. Ultimately, you may find it best to allow the ESL\'s to play full range, and just roll-in the tweeters at the frequency where you find the Acoustats lacking.

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