fi q 15 w/bp power

[streetbeater07 0]

Ok i have two d1 q 15 w/bp power and when I first recieved the subs, they hit extremely hard but after a couple of weeks and a local comp, the subs just dont perform like they used to. when they hit the lows now the bass kind of fades away and sounds like a fart and they dont even put out the pressure like they used to either. I've checked the box first to make sure there were no leaks and everything is fine. I think the spiders have gotten weak cause they just dont "thunder" anymore. Time for recones right?

[johnecon2001 82]

Tell us a little more about your setup please.

[streetbeater07 0]

up front: pioneer deh p7800mp

amp: mmats dhcx 2200.1

two optima yellow tops

1/0 wiring

big three upgrade

8.18 cuft tuned to 27hz

[theabunai 3]

your box is on the larger recommended side of the chart.. nothing wrong with that but i gotta ask, with that size enclosure, power and tuning so low what's your subsonic filter set at ?

[KU40 173]

there is no way a sub should need a recone after just a few weeks. It should take years for the soft parts to become weak enough to maybe notice.

Do they make any other noise (mechanical)? I'd be so afraid for that sub in an 8 cubic foot box with 1400 watts of power on it. The mechanical limits have been reached a number of times I'm sure.

[streetbeater07 0]

the enclosure is for two subs, and the amplifier has no subsonic filter.

[theabunai 3]

the enclosure is for two subs, and the amplifier has no subsonic filter.

So you are letting it play below tuning ?? That is a bit dangerous... subs tend to unload below tuning... not saying it's the cause, just throwing caution to the wind there...

[KU40 173]

the enclosure is for two subs, and the amplifier has no subsonic filter.

oh, I skimmed over the two part. my bad.

as for no subsonic, no biggie. Mine doesn't have one and I've been using it for........3 years with no problems.

I would check the amp. play a sine wave and hook up a dmm to see the voltage coming out of it. Chances are if the subs sound like they're fading when the bass hits, it's the amplifier lowering the amount of power it's putting out. subs only play what's given to them.

[theabunai 3]

I have to disagree about the subsonic being a no biggy...

I have seen 3 subs go bad before my very eyes..

A LMS ultra Tc sounds capable of over 4K mechanically rip with half it's rated power when we played a song that dipped below it's tuning at a low volume....

BTL went south (and the video is floating around i believe it was during the 12" challenge) when Lloyd them were testing it when it hit below tuning...

2 12" T2 in a ported box off of saz-1500D both crashed into the basket when they decide to play a chopped and screwed version below the boxes tuning...

I think for ported systems with lots of power, subsonic is a pretty important thing...

Many a Fi subs have had broken tinsel leads and burnt coils and by reading some of scott's and nicks posts quite a few are due to subsonic filters not being set properly...

[streetbeater07 0]

tis teh reason why i need recones..........

[theabunai 3]

tis teh reason why i need recones..........

Merc sorry i couldn't have posted about SubSonic Filters prior to your comp...

It's okay bro i'm sure now that this has happened you've just educated yourself that much more and this will help you grow in the car audio world...

BTW REPPIN FI TILL IT MUTHA FUKCIN BREAKS

That's hard core

[KU40 173]

I have to disagree about the subsonic being a no biggy...

I have seen 3 subs go bad before my very eyes..

A LMS ultra Tc sounds capable of over 4K mechanically rip with half it's rated power when we played a song that dipped below it's tuning at a low volume....

BTL went south (and the video is floating around i believe it was during the 12" challenge) when Lloyd them were testing it when it hit below tuning...

2 12" T2 in a ported box off of saz-1500D both crashed into the basket when they decide to play a chopped and screwed version below the boxes tuning...

I think for ported systems with lots of power, subsonic is a pretty important thing...

Many a Fi subs have had broken tinsel leads and burnt coils and by reading some of scott's and nicks posts quite a few are due to subsonic filters not being set properly...

I guess I just know when the note is being played below tuning and turn it down to where it won't rip itself apart.

[KU40 173]

also, a subsonic won't help during a comp at all. You should be playing a note above tuning frequency.

[theabunai 3]

The subsonic isn't to HELP you at a comp... It's to protect the subwoofer from unloading...

A subwoofer moves the LEAST at tuning.. It moves the most (unloading) Below and above tuning... regardless of how many watts you put to a speaker unloading is dangerous to the mechanical handling of the sub not thermal... As a speaker plays throughout the day the speakers coils and moving parts heat up.. they expand... this expanding coupled with a speaker unloading is a lot of mechanical stress on the sub that usually leads to damage....

As for comps... You shouldn't be playing a note above your tuning you should be playing a note at your cars peak frequency... That could be AT tuning, most cars in peak response is around 40~42 hz. For us comp guys we would then tune the box to the cars frequency.. then we play that tone, since i stated above that the speaker moves the least at tuning in a comp we can now play it longer and a bit harder since it's less stress mechanically on the sub...

furthermore, some comps don't do sine waves or test tones... some do music... music is dynamic, it has peaks and valleys.

If you search subsonic on this forum you'll see just how important it is.

http://www.soundsolutionsaudio.com/forum/i...ghlite=subsonic

Just ruffle through a few posts and read....

[KU40 173]

I know what a subsonic is and does. My comment about not helping at a comp wasn't in terms of it would increase your score, it's that it would be pointless (and perhaps even detrimental) to have on during a comp. If have a box tuned at 40 hz and you're playing a 40 hz note at your comp and have your subsonic set at 25, what good is the subsonic doing? none. It's not attenuating any frequencies that might be harmful to the sub, because you're playing a 40 hz note. If you play a 40 hz tone and have your subsonic set at 38 (just below tuning), guess what the subsonic is doing? lowering your score. The subsonic isn't the point at which the frequency response starts to roll off, it's the -3db point. So your 40 hz note would be getting attenuated probably at least 2 db's by the subsonic filter.

You can argue your point all day if you want, but I have never used a subsonic and have never blown up a sub due to mechanical limits being reached from unloading. Go ahead and use it if you want, I wouldn't stop you at all.

[Noobtastic14 0]

sounds to me like you've just gotten used to the sound.

Time to upgrade!!

-Drew

[theabunai 3]

I know what a subsonic is and does. My comment about not helping at a comp wasn't in terms of it would increase your score, it's that it would be pointless (and perhaps even detrimental) to have on during a comp. If have a box tuned at 40 hz and you're playing a 40 hz note at your comp and have your subsonic set at 25, what good is the subsonic doing? none. It's not attenuating any frequencies that might be harmful to the sub, because you're playing a 40 hz note.

Once again NOT EVERY COMP uses tones... some have music... music is dynamic... Furthermore.. most amps subsonic are adjustable UP TO 60hz... so once again YES they could be detrimental in a comp... A competition is where you would take your equipment to the limit, this is the perfect time for having a subsonic.. The car we entered in a sanctioned comp under team sundown had 2 3000D's and 2 18" LMS ultras...

in his first run he hit a 152.8 on the TL legal sealed on the dash... he went to do a demo, didn't have his SSF set properly (by mistake) and he tore a sub to pieces... once again 6K total and a song that dipped below 26hz and he just pulled himself out of the comp... we got the sub reconed, set his SSF and played the exact same song and this time louder with a few more batteries and the speakers never missed a beat and his score improved dramatically...

If you play a 40 hz tone and have your subsonic set at 38 (just below tuning), guess what the subsonic is doing? lowering your score. The subsonic isn't the point at which the frequency response starts to roll off, it's the -3db point. So your 40 hz note would be getting attenuated probably at least 2 db's by the subsonic filter.

I can also argue the opposite... you'll want to cut off the low end with a SS filter a bit below the box's tuned frequency to prevent damping loss and over-excursion of the subs. sloppy bass = sloppy score, loss of dampening = loss of control on the sub, also it depends on the subs Fs, motor strength and a host of other things that would determine where i would adjust my SSF to, not just box tuning, you seem to be a competitor i'm sure you've figured that out right???.... not all SSF have the same attenuation roll off that you speak off... some are steeper with a more narrow "Q" making you scenario moot and incorrect.. It comes down to knowing your system... If i know my box is tuned to 40hz and that is my in car peak then i would adjust my SSF down more depending on my Q width of the SSF, if the SSF has your -3db roll off then i would set it lower then 38 but i certainly would NOT eliminate it from my system.. who am i to go against all the Engineers that put them on the amps to begin with, I know it must be because they are pointless and placing them on some of the best competition amps in the business when they have no use at all is smart practice;) ... In this business, I would rather play it smart and keep all my equipment alive then play it brave and keep buying recones/speakers..

You can argue your point all day if you want, but I have never used a subsonic and have never blown up a sub due to mechanical limits being reached from unloading. Go ahead and use it if you want, I wouldn't stop you at all.

And that works for YOUR system... Obviously it didn't work for the OP, it hasn't worked for about 50+ other people if you search Subsonic filter on this board, it hasn't worked for the 3 people i seen, it was proven detrimental in the ROE 12" challenge where the BTL would've posted a higher score had it NOT slammed into the basket because someone forgot to put the SSF up (hmmm kinda argues your point in competition doesn't it), and hasn't worked for countless others on other forums... But just because you've not blown anything doesn't mean nobody else will.

I did make one misstatement though and thank you to the competitor that PM me... There is also a place for Subsonic filters in sealed enclosures (i had stated high powered ported enclosures)... I stand corrected on that..

the point is not to prove you wrong, but rather to prove that it does have a purpose in life... It has been documented countless times here on why a sub went poof.... ported, low song, high power no SSF = broken speakers.

sounds to me like you've just gotten used to the sound.

Time to upgrade!!

-Drew

The original poster has already talked to Fi about this issue and he stated the reason why he needs recones.... Subs playing below tuned frequencies = damaged subs = recones....

[KU40 173]

I've never been exposed to comps that play music. If I was, I'd make sure and play a song that stayed above tuning.

Also, I didn't specify a rolloff rate or Q in my argument, so your saying there are amps with a steeper slope or more narrow Q than what I was talking about can't apply. Sure, I'm being nitpicky.

You mentioned "It comes down to knowing your system." Well, I agree. I know my system well enough to know what level I can play a song at that has really low notes (perhaps lower than my tuning frequency). It comes down to common sense, IMO. If you are listening to music that constantly has notes being played below your tuning frequency, you made a poor decision on box design.

I've heard from competitors and others who agree with me and say subsonic filters aren't necessary. One held a number of state records in West Virginia, might still. So I guess we're even.

Also, has it actually been confirmed that unloading and overexcursion caused his problems? I know you suggested it and he said it was the reason, but he didn't say how he knows. Not to mention that his tuning frequency is 27 hz, which is pretty low, and not much music goes below that. But if he tore apart the subs and found evidence of it, then I concede.

Edited July 9, 2008 by KU40

[theabunai 3]

KU there is nothing to concede.. my point is that SSF are useful in protecting an investment not to prove you wrong in any way.. please we are just discussing an issue...

You are right some competitors do not use SSF.. but some competitors do not use HO alternators or batteries depending on the rules. but that does not mean there is no place for these things in competition..

You've never been to a sanctioned bass race competition ?

http://www.termpro.com/dbdrag/rules/index.asp?Page=3

the official rules state music only... it is one of the biggest events for SPL...

the rules clearly state "Contestants must play music (instead of tones, sweeps, etc.)"

Bass race is very popular..

also wayne harris's (the creator of term lab) Psychlone Competition is music only..

sure there are amps with steeper slopes... RF uses a 12 DB slope, others use 18 and some of the High end ones use 24 db... of course the stepper the slope the faster the attenuation or "cutt-off"

my whole post is just basically stating that SSF are very useful as with any feature on the amp.. when applied in any given scenario may be beneficial and necessary in some cases.. to dismiss them as "useless" is in my opinion not a very good idea...

[KU40 173]

I didn't mean to make it sound like I thought they were useless. I know they are helpful in many situations, and just because I don't use mine doesn't mean others shouldn't. To go along with the slopes you mentioned, I'm pretty sure I've seen a 36 db/octave slope on an amp somewhere........

I have never been to a bassrace. I really only competed a little bit for about two years, and that was 3+ years ago. I think that was before the bass race idea caught on. When they kept raising the price of admission I just decided it wasn't worth it, and I haven't been to a competition since. Nor have I kept up on all of the rules of the various organizations. I try to stay out of competition discussions because of this, and unfortunately the ones I do get into (like this one) make me revert back to the rules I knew way back when.

I'm still curious as to what evidence 07merc has for the diagnosis of unloading causing damage. I'm not saying it wasn't the cause, I just want to make sure that it did happen so he's not wasting money on recones if that's not really the case. I just say this because a couple years ago when my sub amp was starting to go it just began by putting out less power so my sub didn't hit as hard. If he would like to test this, hook up another woofer to it and see if the fading of sound happens again. And likewise, see if you can hook up your sub to somebody else's amp to see if the fading sound happens. These two tests can determine if it's the sub or amp. You may also want to check the voice coils with a DMM to see if their resistance has changed, which would lead you to a woofer problem as well.