Doctor B.
Coping with SPOD
I picked up a pair of Infinity Reference E-L speakers in a thrift recently for $8. The cabinets and grills are perfect and at first glance the foam surrounds on the woofers looked perfect as well. After a couple days of use, they started to disintegrate. There is a stamp inside the speaker showing the manufacture date as 1991. 17 years and a couple days of use and the surrounds were in pieces. I picked up a pair of new foam surrounds at Audio Atlanta, just three blocks from my office, and put them in. I didn’t remove the dust caps and insert shims around the voice coil, but used a tone generator program on my laptop run through my receiver to center the cones. This method worked well.
I decided to see if I could get a little better sound by upgrading from the original electrolytic crossover caps to polypropylenes. There is a significant difference in size between electrolytics and polypros. The polypros couldn’t fit on the crossover circuit board or fit through the hole in the back of the speaker even if they were attached sideways. I used 22 gauge wire to connect the new caps to the circuit board and hot-glued the new caps to the back of the inside of the cabinet.
I wanted to try Dayton Metalized Polypropylenes. The original caps are 6.8uF and 2.5uF. Dayton doesn’t make a 2.5uF cap, so I used a 2.0uF in parallel with a 0.47uF. Cost for the six caps from Parts Express was $10.14 plus shipping. The old caps had drifted higher in value. The values of the new caps are much closer to spec.
I am using these speakers in my A/V system as surrounds connected to a Realistic 12” passive subwoofer (catalog #40-4050) and driven by a 100 watt Optimus STAV-3150. The sub has a crossover that sends the low frequencies to the dual coil sub and the high frequencies to the surround speakers. I replaced the electrolytic caps in the sub’s crossover. Even low end polypros would be expensive since the values are pretty high: 2 each 150uF and 100uF. Daytons would run $106.66. I decided to go with electrolytics, which cost only $6.90.
I replaced the caps in the sub first and this made a tremendous difference in the sound of the Infinitys. They are much, much brighter and higher in volume. Apparently, the old electrolytics had developed some resistance. Since replacing the caps in the Infinitys, I haven’t noticed as much difference in their sound as I got when I replaced the caps in the sub, but they do sound very good now.
My TV room and living room are different in size and shape so it is hard to compare my A/V system with the Infinitys and the Realistic sub with my main system with full size Sansui SP-3000s (recently recapped with Dayton Precision 1%). I can say that I am just as pleased with the sound of my A/V system as I am with my main system.
Pictures below show Infinity Reference E-L crossover with original caps compared with Dayton Polypropylene caps, crossovers with polypros connected, polypros glued to inside back of cabinet, and the completed speakers.
I decided to see if I could get a little better sound by upgrading from the original electrolytic crossover caps to polypropylenes. There is a significant difference in size between electrolytics and polypros. The polypros couldn’t fit on the crossover circuit board or fit through the hole in the back of the speaker even if they were attached sideways. I used 22 gauge wire to connect the new caps to the circuit board and hot-glued the new caps to the back of the inside of the cabinet.
I wanted to try Dayton Metalized Polypropylenes. The original caps are 6.8uF and 2.5uF. Dayton doesn’t make a 2.5uF cap, so I used a 2.0uF in parallel with a 0.47uF. Cost for the six caps from Parts Express was $10.14 plus shipping. The old caps had drifted higher in value. The values of the new caps are much closer to spec.
I am using these speakers in my A/V system as surrounds connected to a Realistic 12” passive subwoofer (catalog #40-4050) and driven by a 100 watt Optimus STAV-3150. The sub has a crossover that sends the low frequencies to the dual coil sub and the high frequencies to the surround speakers. I replaced the electrolytic caps in the sub’s crossover. Even low end polypros would be expensive since the values are pretty high: 2 each 150uF and 100uF. Daytons would run $106.66. I decided to go with electrolytics, which cost only $6.90.
I replaced the caps in the sub first and this made a tremendous difference in the sound of the Infinitys. They are much, much brighter and higher in volume. Apparently, the old electrolytics had developed some resistance. Since replacing the caps in the Infinitys, I haven’t noticed as much difference in their sound as I got when I replaced the caps in the sub, but they do sound very good now.
My TV room and living room are different in size and shape so it is hard to compare my A/V system with the Infinitys and the Realistic sub with my main system with full size Sansui SP-3000s (recently recapped with Dayton Precision 1%). I can say that I am just as pleased with the sound of my A/V system as I am with my main system.
Pictures below show Infinity Reference E-L crossover with original caps compared with Dayton Polypropylene caps, crossovers with polypros connected, polypros glued to inside back of cabinet, and the completed speakers.
