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I need to replace 8" woofers in my Infinity RS7b

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  • I need to replace 8" woofers in my Infinity RS7b

    There is a bad distortion coming through the woofer on one of the RS7bs I just recently picked up. I have been advised that if there is resistance/rubbing when pressing in on the driver, I probably need to replace it. Could someone either tell me a good place to get an exact match to my current woofer, or point me to a 8" replacement that would sound good in this configuration ?
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  • #2
    Can you find an exact replacement on eBay (may require patience).


    • #3
      That was my first thought too.

      What does the surround look like? If it isn't intact that will certainly make the voice coil rub. These speakers are pretty old so maybe also the woofers have sagged a bit causing the rub.

      If that's the case replacing the surrounds may make them work. Remember though if you replace the surrounds you will need to cut out the dust cap and shim the voice coil to ensure it stays centered!

      Good Luck! Mark


      • #4
        Almost any replacement will require some crossover tweaking to sound its best. An exact replacement or repairing your old woofers is the path of least resistance.


        • #5
          The foam surrounds on both woofers are completely gone; one of them sounds great, the other sounds very distorted at low volumes


          • #7
            Your best bet is to try a re-foam (if you're nervous about the dust cap part, skip it - MAYbe you'll be lucky). I never took the dust caps off my ADVE\TS, but I think they had pretty "roomy" v.c. gaps.
            BEfore you do that, just take a resistance measurement (DMM) through the coils, to see if they're "nominal" 4ohm or 8ohm woofers (just in case). 4ohm'll read closer to 3, while 8ohm'll be closer to 6 ohms.


            • #8
              I realize I've gotten this far, and have no idea how to 'line up' the woofer. Theres videos online telling you how to listen for if its wrong, but what can you actually do to adjust it ?

              So I have a 50hz sine going straight to my offending speaker, it makes a minor buzzing noise every half second or so, how do I adjust the speaker to stop that ?


              • #9
                These won't work the way you want them to until you've replaced the rotted surrounds. That's how you fix your problem.
                Have you already replaced the rotten surrounds?


                • #10
                  I thought you have to make sure its centered before you glue everything down ? I have the surrounds and glue, im just not gluing anything until im sure I know what im doing lol.

                  - Its throwing me off that the other woofer sounds great, and is in the same exact condition visibly as this one.


                  • #11
                    The v.c. (voice coil) needs to be pretty much centered in the gap. Since it's attached to the cone, if the cone gets centered, then the v.c. should be centered.

                    One way (the "recommended" way) is to cut off the dust cap (which lets you VIEW the v.c.) and THEN use thin paper "shims" (just paper really) to physically center the v.c. in the gap. That has a high probability of working well (NOthing is foolproof, though). When you're done gluing the outer edge (the "surround"), you remove the paper shims and glue a new dustcap (usually a bit larger) over the old one you cut - mostly to hide the hatchet-job !

                    SOME drivers (where the gap/v.c. fit isn't TOO critical) work fine by not cutting the dustcap. The theory is that the "spider" (the fairly rigid corrugated cloth thingy) SHOULD still be holding the v.c. centered in the gap (it's RIGHT THERE next to the v.c.) UNLESS the drivers have been ABUSED ("CRANKED") with the surrounds basically GONE. Playing them this way lets the cone rock about (back and forth) and CAN drag the v.c. cocked in the gap, possibly deforming the coil wire and also maybe scraping the insulation ("varnish") off of it. That would be bad.

                    (it's been a while since I re-foamed my Advents) I THINK I glued the surround to the edge of the cone first (after getting all the old gunk off of it), THEN (with the driver facing upright - so gravity wasn't flopping the cone over) just kinda let the surround center itself on the frame (just checked visually - really). If the spider still had a good grip on the v.c., and you get the cone centered in the frame (using the new surround) - all should be well - theoretically.

                    If you've got everything cleaned off, I'd glue the cone to the surround - then point the woofer up and use a pretty quiet test tone (you might want to use a small (temp.) piece of tape in maybe 6 or 8 places around the cone to keep it from flopping about while testing. If you still have trouble, THEN I'd cut through the dustcaps and do the shim thing before attaching the surround to the frame.

                    You should be able to Google up some YouTube vids showing you how all this is done (maybe the place you got the surrounds from has one)?


                    • #12
                      Thanks for the responses and help


                      • #13
                        Ok. So I refoamed them... Somehow magically now nothing seems to be rubbing! I am waiting till I get back from work to test them to give the glue time. I have another question; how essential is the foam gasket thing that used to go on top of the edge of the woofer.. It seems like it would be constricting the edges of it a bit and Id like to leave it off if it doesnt contribute anything (cant really see how itd do much)


                        • #14
                          I’m a proponent of using shims to center the voice coil! It really isn’t that hard. Whoever sold you the new surrounds should have provided instructions.

                          As Chris said, it isn’t going to sound right until you glue the surround!

                          You CAN do this! It will be the best way to repair the speakers, and you will be very proud of yourself when finished!

                          Good Luck, Mark


                          • #15
                            It sounds like you may have gotten the new foam installed OK, that is good news!

                            I re-foamed a pair of woofers using the test tone method and one woofer was making rubbing sounds the whole time. I almost gave up on it. I ended up having to peel the new foam off of the frame after the glue was dry and reattaching it. I adjusted the foam inwards one one side until the noise stopped. It seems that sometimes a woofer is just skewed to one side or has tighter tolerances for some reason.