5-way Horn Stack  

I put this horn stack together in the corner of my parents' family room after I graduated. It's a fully active 5-way mono system, all horn-loaded. The subwoofer is my 27Hz horn spaced from the wall as outlined in my webpage showing FEA results for several horn subwoofers in corners. In this orientation, response extends to 25hz. It is powered by both channels of an Adcom amp. A straight 75hz horn with an EVM12L covers 90Hz to 400Hz. It was previously powered by a 6C45pi amp with Magnequest output iron and a Heathkit regulated lab supply, but now an inverted gain-clone amp drives it. A JBL 375 compression driver with a phenolic diaphragm mounted on a 40 degree horn covers 400Hz to 3kHz. It's driven by a SE45 amp. A JBL 2470 with an aluminum diaphragm on a 500Hz tractrix horn covers 3kHz to 12kHz and is powered by a SE46 amp with 866A rectifier tubes (totally unnecessary in this application, but they look cool). A Fostex FT17H covers 12kHz and above - up to around 50kHz if one were to believe the spec sheet. It's powered by a battery powered LM1875 chip amp.

Even though there are a lot of problems with this system (time alignment, polar response, under-powered midbass), it still sounds pretty good. I thought the higher-power midbass amp might solve some of the problems I hear with this setup, but it did not. Yes, the higher power is nice, but what has been missing from this system is the 'snap' that defines a good horn stack to me. I now think that time-alignment is the culprit here, and to that end I plan on trying a DSP crossover next.

I have also rebalanced the system a bit with the result that I now have better detail retrieval. I am still trying to strike a balance between subjectively having no bass and having boomy bass. I am hoping that the addition of the DSP crossover will make this sort of thing easier to do.

Copyright 1999-2004, John H Sheerin

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