philrab Posted June 2, 2014 Report Share Posted June 2, 2014 Pretty self explanatory question, but hopefully one I won't be crucified for asking. Is it possible, or even likely, to have coil rub in a subwoofer at certain frequencies and not at others, or possible to have coil rub only during some songs and not others? I'm asking because I'm chasing my butt on an intermittent noise coming from my hatch. Certain songs, almost regardless of volume, I can hear a rattling noise almost like coil rub. I've gone back there and gently pushed on the subwoofer's cone, and it's silent. I've tapped on everything back there with my hand, and can't hear anything obviously making noise. IF this sub is shot and needs to be replaced, so be it, but it perplexes the Hell out of me that I'd have coil rub sometimes and not at others. Regardless of the noise, it's an Image Dynamics ID8d4 in a sealed fiberglass stealthbox at roughly 0.3 cu ft. (within manufacturer's recomended range) and it seams to be working fine. I'm just trying to rule out coil rub so I can concentrate on chasing loose trim panels for rattles. 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
timc31610 Posted June 2, 2014 Report Share Posted June 2, 2014 Here is my guess, at certain frequencies you sub sees higher excursion than at other frequencies most notably lower frequency notes. It could be possible that at or near max excursion your coil moves out of alignment. Possibly due to a slightly misaligned surround or spider. In your situation this may not be the case but in my mind it seems entirely possible. Of course I am not a professional and any advice or suggestions I have should be completely ignored. My Build Log 94 Civic http://www.stevemeadedesigns.com/board/topic/188644-94-civic-4-door-build-loq-suggestions-wanted-will-be-super-slow-mo/ Faceebook reluctantly Link to comment Share on other sites More sharing options...
Phaeton Posted June 2, 2014 Report Share Posted June 2, 2014 might just be your hatch or something flexing. My truck has that problem, i put my sp4 on its side rather than up/down and i thought i was getting rub but it was my roof rattling like a mofo. i wouldn't worry about it too much until something goes horribly wrong, then i would get a new sub. 1997 subaru legacy outback Four 15's in a almost wall Rockford Fosgate t2500-1bdcp Rockford Fosgate T400-4 on tweets Rockford Fosgate T400-4 on highs Rockford Fosgate T400-2 on midrange Rockford Fosgate T400-2 on midbass Optima Yellow top batteries 270A Singer alt (working on a bracket for a second) Lots of Second Skin Link to comment Share on other sites More sharing options...
bassman619 Posted June 2, 2014 Report Share Posted June 2, 2014 Maybe its bottoming out? Or maybe misaligned..dk u hear the sound with the trunk open? Could also be subsonic filter tuned too low ..if you try all of this and still have problems id take it to a sub repairman and see what he says You need trunk space to get groceries and shit...bitches love groceries Link to comment Share on other sites More sharing options...
philrab Posted June 2, 2014 Author Report Share Posted June 2, 2014 There's some food for thought, let me answer everyone Here is my guess, at certain frequencies you sub sees higher excursion than at other frequencies most notably lower frequency notes. It could be possible that at or near max excursion your coil moves out of alignment. Possibly due to a slightly misaligned surround or spider. In your situation this may not be the case but in my mind it seems entirely possible. Of course I am not a professional and any advice or suggestions I have should be completely ignored. I've heard it at higher freqs (like 60-70) and down low. Seams to be no rhyme or reason to it. Also, I'd think that pushing the subwoofer's cone through it's range of motion, that if it was coil rub I'd hear or feel something but nothing. might just be your hatch or something flexing. My truck has that problem, i put my sp4 on its side rather than up/down and i thought i was getting rub but it was my roof rattling like a mofo. i wouldn't worry about it too much until something goes horribly wrong, then i would get a new sub. I don't think flex (not with a little 8" on 500rms, if so I'm impressed) but I wouldn't put it past some of the plastic trim rattling it's way loose. Whatever it is, sometimes I hear it others it's silent. I'm just trying to rule out subwoofer before I go chasing my tail. Maybe its bottoming out? Or maybe misaligned..dk u hear the sound with the trunk open? Could also be subsonic filter tuned too low ..if you try all of this and still have problems id take it to a sub repairman and see what he says Possible it's bottoming out. I want to say it doesn't sound like it's bottoming out, but I'm not going to be that smartass that asks for advice then screams "no, that can't be the problem". I don't have a subsonic filter on my Kenwood mono amp btw. The biggest problem I have it it's intermittent nature. If I could get the damned thing to do it consistently, I could find it. Of course, if it was consistent it'd probably blow up or break something.... Thanks for the direction guys. Maybe this weekend I can get my four channel amp dropped in and do some rattle hunting in the hatch. Maybe get someone to play some test tones while I lock myself in the hatch and listen. 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
timc31610 Posted June 2, 2014 Report Share Posted June 2, 2014 I bet you almost wish it were the sub, at least then it would be easy to find...lol My Build Log 94 Civic http://www.stevemeadedesigns.com/board/topic/188644-94-civic-4-door-build-loq-suggestions-wanted-will-be-super-slow-mo/ Faceebook reluctantly Link to comment Share on other sites More sharing options...
slowfkncar Posted June 2, 2014 Report Share Posted June 2, 2014 Most likely it is something on your car rattling. If not,the woofer might have loose mechanical soft parts (you might not find the problem by pushing it with your finger,instead unmount the woofer and play it at low power and see if anything mechanical is loose. Spider,joint,surround ect. Link to comment Share on other sites More sharing options...
Guest Posted June 2, 2014 Report Share Posted June 2, 2014 Yes I had a sub that would sound like complete ass 45hz and up The lows would only sound awful at low volume and everything still flexed like normal when the noise started Turned out the former was bent causing coil rub This came from abuse and heating the coil so much that it bent at the bottom portion Pull your sub and visually inspect the coil... is it dark or half charred? While it is out you can also play it free air, to ensure that it is the sub causing the noise Goodluck! Link to comment Share on other sites More sharing options...
philrab Posted June 3, 2014 Author Report Share Posted June 3, 2014 Yes I had a sub that would sound like complete ass 45hz and up The lows would only sound awful at low volume and everything still flexed like normal when the noise started Turned out the former was bent causing coil rub This came from abuse and heating the coil so much that it bent at the bottom portion Pull your sub and visually inspect the coil... is it dark or half charred? While it is out you can also play it free air, to ensure that it is the sub causing the noise Goodluck! Stupid question, how can I inspect the coil without tearing the sub apart? Looks like next day I get to do some work I'll pull the sub and free air it. 2015 Toyota Tacoma Build Thread 2007 Mazda 3; 5000K HID's, Kenwood Excelon KDC-X997, Infinity Reference 6.5 comps in front and coaxials in the rear doors, JL 320.4 four channel, Rab Designs built ported enclosure with an SA12, Kenwood monoblock, Redline Leater shift boot/e-brake boot/center console cover, JBR short shifter/shifter bushings/rear motor mount. Build Thread 1996 Mazda Miata: Kenwood Excelon HU, Alpine speaker in the doors, Clearwater (miata specific) headrest speakers. 1994 Mazda Protege: Kenwood Excelon HU, Infinity Reference 2 ways all around, 2x RF Punch 10's in ported boxes. Link to comment Share on other sites More sharing options...
Guest Posted June 3, 2014 Report Share Posted June 3, 2014 Yes I had a sub that would sound like complete ass 45hz and up The lows would only sound awful at low volume and everything still flexed like normal when the noise started Turned out the former was bent causing coil rub This came from abuse and heating the coil so much that it bent at the bottom portion Pull your sub and visually inspect the coil... is it dark or half charred? While it is out you can also play it free air, to ensure that it is the sub causing the noise Goodluck! Stupid question, how can I inspect the coil without tearing the sub apart? Looks like next day I get to do some work I'll pull the sub and free air it. I think the coil on that sub is pretty tucked away and you might not be able to visually see it very well You can also gently, but firmly, push the woofer cone down by hand, if you hear scratching towards the bottom, sub is blown. Link to comment Share on other sites More sharing options...
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