Strange noise on BTL N2 at higher frequency bass

[djanice1980 0]

The Fi BTL subs are amazing! I don't know if it is the new head-unit I have or the new amplifiers but WOW. It is amazing how tight the sound is compared to my old setup. My old equipment had a hard time keeping up with fast bass tone - changes and sounded a little mushy. I don't know if it is because I am running a higher ohm rating and therefore the subwoofers have a little more control, or if because I am pushing with 1 amplifier and pulling (180 switch) with the other, or if it is because my source unit is just THAT much better with the signal or what but - I am truly impressed with how good musically the subwoofers are. How clean and tight the sound is. Fast or slow - the subwoofers keep in rhythm. Very clean! It seems that they need a LOT of power to make them move though. I noticed it even before I installed them - the cones were VERY tight compared to the Fosgates I had just installed. I'm sure it is to help maintain very tight control under extreme movements of the cone. They are very impressive!

I did a lot of research when purchasing Fi BTL N2's and am overall satisfied with my purchase so far....but.......

I have a 2005 Nissan Altima and recently have gone through a major audio overhaul. I took out my old pioneer head-unit and replaced my Rockford Fosgate T1's and T1500 amplifier. My original idea was to get 2 - T2500bd1-CP amplifiers and link them then use 2 12 T2's. Upon install of my T2's - I guess they couldn't handle the power (or because of my inexperience) I blew them literally within 30 seconds of installation. I sent the T2's in for warranty replacement and researched better subwoofers.

I may have gone a little crazy with the upgrades - 3 new Kinetik 2600 batteries, 1/0 wire everywhere, 800 watt RF 4 channel for mids and highs, and the bass amplifiers, and new springs in the rear to support all the weight. After all that - I was NOT about to give up when my subs blew. After watching Steve Meade try to destroy a Fi 18 by plugging it in to a wall socket - I was SOLD!

I placed my order about 3 weeks ago and about a week ago - my new subs came in! After installation and some tweaking. I noticed that one of the subwoofers made an almost mechanical noise - almost like something was hitting the cone when certain bass frequencies were being played. I thought - well...maybe I don't have a good enough seal around the basket...maybe the sub is vibrating against the box or something at certain frequencies. So I took out both subwoofers and made sure they were sealed up tight with a bit of rope caulk and very tight in the box. The next day I tested them and they sounded quite nice! Problem SOLVED!....or so I thought.

It seems that whenever I play the subs for an extended period. Just enough so they kind of warm up. One of the subs makes the noise still! Even more strange is that it seems to only happen when I am playing higher frequencies - read... north of 38hz or so. I did some testing with a friend tonight.... We played a resonance test over and over and listened to both subwoofers and only the one makes the sound and only after warmed up and again only higher frequencies. It is really noticeable when playing rock when the drum beat hits - makes a nice POP noise.

What the heck could be going on (gone wrong)???? What should I do? Leave it for a while and see if it gets any betteer/worse? Send it in? Am I just hearing things??? Do I have something set wrong? Believe me - I'm trying to be ever so careful with gain and distortion. It seems that with this much power - distortion is VERY unforgiving.

Someone is probably going to ask so... Box is 2.00 cu/feet per sub. About 1.9 after displacement. BTL N2 12 / 2 ohm DVC / cooling option / high XMAX coils. Wired in Series (4 ohm) then parallel (2 ohm). When the amplifiers are linked they only support a 2 ohm load. Slot port - tuned to about 33hz. Crossover set to 25 hz and 80hz both high and low pass filters set at -24 db slope I think / subsonic filter is ON - I think RF has subsonic set to 27hz???

Anyway - thanks for any help.

Oh and BTW - have 2 RF T2's for sale if anyone us interested LOL brand new in the sealed box.

Edited September 28, 2011 by djanice1980

[lamontp1 0]

The Fi BTL subs are amazing! I don't know if it is the new head-unit I have or the new amplifiers but WOW. It is amazing how tight the sound is compared to my old setup. My old equipment had a hard time keeping up with fast bass tone - changes and sounded a little mushy. I don't know if it is because I am running a higher ohm rating and therefore the subwoofers have a little more control, or if because I am pushing with 1 amplifier and pulling (180 switch) with the other, or if it is because my source unit is just THAT much better with the signal or what but - I am truly impressed with how good musically the subwoofers are. How clean and tight the sound is. Fast or slow - the subwoofers keep in rhythm. Very clean! It seems that they need a LOT of power to make them move though. I noticed it even before I installed them - the cones were VERY tight compared to the Fosgates I had just installed. I'm sure it is to help maintain very tight control under extreme movements of the cone. They are very impressive!

I did a lot of research when purchasing Fi BTL N2's and am overall satisfied with my purchase so far....but.......

I have a 2005 Nissan Altima and recently have gone through a major audio overhaul. I took out my old pioneer head-unit and replaced my Rockford Fosgate T1's and T1500 amplifier. My original idea was to get 2 - T2500bd1-CP amplifiers and link them then use 2 12 T2's. Upon install of my T2's - I guess they couldn't handle the power (or because of my inexperience) I blew them literally within 30 seconds of installation. I sent the T2's in for warranty replacement and researched better subwoofers.

I may have gone a little crazy with the upgrades - 3 new Kinetik 2600 batteries, 1/0 wire everywhere, 800 watt RF 4 channel for mids and highs, and the bass amplifiers, and new springs in the rear to support all the weight. After all that - I was NOT about to give up when my subs blew. After watching Steve Meade try to destroy a Fi 18 by plugging it in to a wall socket - I was SOLD!

I placed my order about 3 weeks ago and about a week ago - my new subs came in! After installation and some tweaking. I noticed that one of the subwoofers made an almost mechanical noise - almost like something was hitting the cone when certain bass frequencies were being played. I thought - well...maybe I don't have a good enough seal around the basket...maybe the sub is vibrating against the box or something at certain frequencies. So I took out both subwoofers and made sure they were sealed up tight with a bit of rope caulk and very tight in the box. The next day I tested them and they sounded quite nice! Problem SOLVED!....or so I thought.

It seems that whenever I play the subs for an extended period. Just enough so they kind of warm up. One of the subs makes the noise still! Even more strange is that it seems to only happen when I am playing higher frequencies - read... north of 38hz or so. I did some testing with a friend tonight.... We played a resonance test over and over and listened to both subwoofers and only the one makes the sound and only after warmed up and again only higher frequencies. It is really noticeable when playing rock when the drum beat hits - makes a nice POP noise.

What the heck could be going on (gone wrong)???? What should I do? Leave it for a while and see if it gets any betteer/worse? Send it in? Am I just hearing things??? Do I have something set wrong? Believe me - I'm trying to be ever so careful with gain and distortion. It seems that with this much power - distortion is VERY unforgiving.

Someone is probably going to ask so... Box is 2.00 cu/feet per sub. About 1.9 after displacement. BTL N2 12 / 2 ohm DVC / cooling option / high XMAX coils. Wired in Series (4 ohm) then parallel (2 ohm). When the amplifiers are linked they only support a 2 ohm load. Slot port - tuned to about 33hz. Crossover set to 25 hz and 80hz both high and low pass filters set at -24 db slope I think / subsonic filter is ON - I think RF has subsonic set to 27hz???

Anyway - thanks for any help.

Oh and BTW - have 2 RF T2's for sale if anyone us interested LOL brand new in the sealed box.

you might want to check your dust cap

[Julian 641]

Pop it out of the box and lay it vertically cone up and push gently and listen for any scraping. It could be the dust cap flopping about, if i remember correctly the BTL's have sewn in leads so that should eliminate any tinsel lead slap.

[orlando144 20]

If you say its only noticable on the higher frequencies im thinking its not the dustcap. But chack anyways. If it were the dustcap it would probably make the noise even at 30hz,40hz, which would be anoying to hear not just a pop im guessing. I had the same problem on a diferent sub and came out to be coil rub because of bad spiders.

[djanice1980 0]

I checked the dust caps this morning and they look fine.

Ran a resonance sweep first thing and it was ok until higher frequencies again. I swear it sounds like a rock is hanging by a string in from of the cone and the cone is hitting it.

[djanice1980 0]

From reading around on the Internet, I'm starting to think that the coils are rubbing against the magnet and scraping it. I wonder if it is a bad spider also. I'm going to take the woofer out tonight and check it out.

[orlando144 20]

I was listenin to my btl in my room a hile ago and i heard a scratching/popping type of sound. I thought clipping so i unhooked the wires and the sub still made the sound as i pushed down on it... Wires on the box were wrong. If your sub isnt wired correctly it may also be the problem.

[NDMstang65 403]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

[djanice1980 0]

The cap looks fine. The spider looks fine. The terminals look fine. I dunno what it could be.

Edited September 29, 2011 by djanice1980

[djanice1980 0]

I was listenin to my btl in my room a hile ago and i heard a scratching/popping type of sound. I thought clipping so i unhooked the wires and the sub still made the sound as i pushed down on it... Wires on the box were wrong. If your sub isnt wired correctly it may also be the problem.

I believe I have it hooked up correctly. 1 side + to other side -. Then positive on one side to amp and negative on other side to amp. Series - then both subs connected together at amp (parallel). 2 ohm load. No crunching or anything when I push down on the woofer. Cone moves freely.

[djanice1980 0]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

What is properly? I have tried 100hz, 80hz, and 63hz cutoff with -24db slope. On the other end - 25hz, 31.5hz, and with -24db and -32db slopes. Same noise. The other sub does not make the sound - the subs are wired parallel. I'm using the subsonic filter on the amp. Pioneer p99-reference series headunit for the crossover.

[djanice1980 0]

If the gap is too big and it doesn't feel like the coil is blown and touching the side - is there a possibility that something is under the cap? Like a piece of cone or rubber or plastic or something? Maybe it starts flying around and smacking against the cone. You would think that I would hear it though when I move the sub around. I wish I could record how it sounds.

[jesseadkins187 5]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

i have a quick question nick not even about this topic (sorry) but why is it that the recones that we get from Fi are not the same as the original soft parts that come on your guys sub's? "cone" "surround" etc.. ??

[NDMstang65 403]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

i have a quick question nick not even about this topic (sorry) but why is it that the recones that we get from Fi are not the same as the original soft parts that come on your guys sub's? "cone" "surround" etc.. ??

We constantly change things up soft parts wise, the recones you have now are the latest rendition of changes and are totally sourced from here.

[NDMstang65 403]

If the gap is too big and it doesn't feel like the coil is blown and touching the side - is there a possibility that something is under the cap? Like a piece of cone or rubber or plastic or something? Maybe it starts flying around and smacking against the cone. You would think that I would hear it though when I move the sub around. I wish I could record how it sounds.

Doubt that very seriously...

Send the sub in and we'll check it out, it's extremely odd though..i've never ran across anything like that.

That coil looks really dark though from the one picture that you posted...D2 coils are not that dark out of the box fyi.

[jesseadkins187 5]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

i have a quick question nick not even about this topic (sorry) but why is it that the recones that we get from Fi are not the same as the original soft parts that come on your guys sub's? "cone" "surround" etc.. ??

We constantly change things up soft parts wise, the recones you have now are the latest rendition of changes and are totally sourced from here.

Oh alright was just kinda curious cause the originals seemed more heavy duty like cone stiffer and foam is thicker... and about the dual 2 coil comment being really dark i noticed mine are extremely dark when i got them today like a dark purple.. was kinda wondering if it was the glue or some type of thermal stuff cause my original dual 1 coils are like shinny copper lookin even posted a vid on my youtube channel

[orlando144 20]

That coil looks black.!

[NDMstang65 403]

Doubt very seriously if it is anything of the above, the gap is way too big for the coil to scrub and it would do it at low frequencies, not at high frequencies...

You are positive you have your crossover set up properly?

i have a quick question nick not even about this topic (sorry) but why is it that the recones that we get from Fi are not the same as the original soft parts that come on your guys sub's? "cone" "surround" etc.. ??

We constantly change things up soft parts wise, the recones you have now are the latest rendition of changes and are totally sourced from here.

Oh alright was just kinda curious cause the originals seemed more heavy duty like cone stiffer and foam is thicker... and about the dual 2 coil comment being really dark i noticed mine are extremely dark when i got them today like a dark purple.. was kinda wondering if it was the glue or some type of thermal stuff cause my original dual 1 coils are like shinny copper lookin even posted a vid on my youtube channel

Dual 1's are lighter then dual 2's..and those cones/surrounds are in an extreme vehicle on the 180dB mark so i don't think you'll have a problem with them.

That dual 2 coil in that sub has been hot...it's nearly black. The D2s we have now in the last batch have been a darker brown color, but not black

[Shogen 325]

The cap looks fine. The spider looks fine. The terminals look fine. I dunno what it could be.

Just a FYI, it really looks like you took that photo in black/white on your camera... Did you ??? Cuz it the basket doesn't even look the right color, let alone the coils...

[Dictator 39]

Holy shiz that coil is BLACK!

[Jd377 6]

B&W setting on camera I assume. I did the same once to help the camera focus easier in low light since it's dark in there.

[djanice1980 0]

Lol - it's not black. I tried to adjust the photo. It's kind of a orange copper color. Its really hard to take a picture in the hole. Dark in there! I'll try and photo it in the sun.

[Shogen 325]

just put a desk lamp or flashlight point from a side angle into the coil area...

[djanice1980 0]

Here's a better...well...here's another pic.

Sorry - my iPhone sucks. It keeps trying to focus on the outside.

It's looking through one hole and out the other. Even in the sun there wasn't enough light. Had to adjust exposure and saturation.

The coils look to be a deep orange color with a slightly red tinge.

Edited September 29, 2011 by djanice1980

[djanice1980 0]