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AR4x woofer coils - Alnico vs ceramic woofer changes


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Don't know about foam surround AR4x woofers--have only seen cloth myself (but have only worked on 3 pair of 4x's). But I CAN tell you the earliest 4x's used the #4 coil, later ones used #5.


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Was there any change in the coil when AR changed from the fabric surround woofers to the foam surround ones? The schematic in the library shows a 2.3 mH #5 coil.

Hi Carl,

The #5 coil is 1.20mh, and was used from around 1970 until the end of the line. Earlier 4x's had the #4 (.88mh) coil. The change did not occur as the result of the introduction of the foam surround woofer. 4x's are pretty equally divided between the #4 and #5 versions, with the edge going to #5. The vast majority of 4x's were equipped with cloth surround/alnico magnet woofers. A small number were manufactured with foam surround/ceramic magnet woofers at the very end in the mid 70's, but the #5 coil appears to have remained in use. The #5 coil was introduced around the same time as the stuffing was reduced to 11oz from 18oz. It is uncertain if changes were made to the cloth surround woofer at that time.

The 2.3mh coil is #11, and is found in the AR-5.


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