choosing the right 15" sub

[Dangerous10k 0]

So right now i have 2 15" Fi Q's but im starting to get annoyed with them, They are in a 9 cubic feet box tuned to 33 hz (thats probally 7.5 cubes after port and displacement) Anyway they hit the low notes very hard but the high's suck, I heard the can somehow be reconed into a bl or changed into a bl is this true?

Edited October 10, 2009 by Dangerous10k

[slim2fattycake 85]

I am guessing by highs you mean more SPL? Redo your box with a higher tuning is the cheapest thing to do. And I really haven't heard anything about having the Qs be able to recone to BLs. That doesn't even sound right.

[shizzzon 461]

I would tune to around 35-37hz..

I'm surprised u say they are diggin the lows hard because most things i've read about the Qs tuned in the lower 30s say the low end is terrible.. apparently they didnt know what they were doing.

[jcarter1885 995]

I would tune to around 35-37hz..

I'm surprised u say they are diggin the lows hard because most things i've read about the Qs tuned in the lower 30s say the low end is terrible.. apparently they didnt know what they were doing.

To me that just doesnt sound right (had to be doing something wrong or thought box was tuned low and wasnt), they are low end monsters so I wouldnt see how they cant dig the lows. Thats like someone saying their BL doesnt get loud, has to be install issues.

I have heard of Q's lacking the high end, so Im with Shizzzon here, tune a little higher before abandoning the subs could save you some money by just making another enclosure for them.

What is your LPF set at on headunit or amp, whichever your using as the crossover?

[Dangerous10k 0]

I would tune to around 35-37hz..

I'm surprised u say they are diggin the lows hard because most things i've read about the Qs tuned in the lower 30s say the low end is terrible.. apparently they didnt know what they were doing.

To me that just doesnt sound right (had to be doing something wrong or thought box was tuned low and wasnt), they are low end monsters so I wouldnt see how they cant dig the lows. Thats like someone saying their BL doesnt get loud, has to be install issues.

I have heard of Q's lacking the high end, so Im with Shizzzon here, tune a little higher before abandoning the subs could save you some money by just making another enclosure for them.

What is your LPF set at on headunit or amp, whichever your using as the crossover?

[Dangerous10k 0]

lowpass is set to around 70 hz im just saying when you got rap songs that have multiple bass notes , the q's hit the low's hard but the highs aren't loud at all with my old kickers same amp it was the other way around, but the other notes used to have alot more spl it seems with my old kicker 12's in a 3.0 cubic feet box with a aero port, tuning was probally something like 36 hz. The box is a half wall so changing subs is probally cheaper than changin the box,in order to change box i have to take my center console out front seats out, and it is heavy as hell so i dont want to change the box. I hit 142.1db at 50hz with the Q's but to me it seemed like the kickers were louder in a much smaller box.

Now someone was telling me that I could use the same basket and motor and have it changed into a bl somehow

[shizzzon 461]

well.. of course the kickers would be louder when tuned higher and in a smaller box... you are stating the obvious.

You need a higher tuning...

[kjones 2]

you would want to switch to the bl. because kickers play up higher than the q. the q is built for sq, blending in not taking over like kickers do. my ssd is the same way softer up top. the bl is more suited for you it hits up there.

[Dangerous10k 0]

yea but 2 12's in a prefab box with a tiny little aero port vs 2 15's in a 7.5cubic feet box after displacment and port that has a port that is like 39" x 3",maybe ill take the subs out and see if i can make the port shorter to raise the tuning freq, anyway the question is can fi do some machine work to the q's and raise the FS?and lower the qts?

[kjones 2]

Im not sure, but i think they can change the spiders for you. Have you thought about midbass speakers?

[RE XXXv3 31]

What vehicle? You should be able to hit 142 @ 40hz with a 12" in a trunk.

[Dangerous10k 0]

yea i though about it i could lower the highpass on my 6x9's but i dont want to end up blowing them i got infinity kappa 6x9s in the back and 6x8 infinity componets in the front, off a soundstream that pushes 120rms x 4 treble sounds really good just which i had some more powerful 50-70 hz, I need more sound deadning i got the whole car dynamated with one layer of xtreme but my trunk still shakes like its about to pop off and fly away at anything under 40 hz lol, this is in a mustang so space is limited i was thinking about maybe putting in a 8" sub somewhere and have it in some kind of bandpass from 50-80 hz but wouldnt that throw off the phase?

[BigCProductions99 21]

What vehicle? You should be able to hit 142 @ 40hz with a 12" in a trunk.

...God Help Us.

[mccleery3 166]

^^^^^^what bigC said!!

[lithium 358]

yea i though about it i could lower the highpass on my 6x9's but i dont want to end up blowing them i got infinity kappa 6x9s in the back and 6x8 infinity componets in the front, off a soundstream that pushes 120rms x 4 treble sounds really good just which i had some more powerful 50-70 hz, I need more sound deadning i got the whole car dynamated with one layer of xtreme but my trunk still shakes like its about to pop off and fly away at anything under 40 hz lol, this is in a mustang so space is limited i was thinking about maybe putting in a 8" sub somewhere and have it in some kind of bandpass from 50-80 hz but wouldnt that throw off the phase?

dont thro an 8 back there, bad idea.

try cutting some port off your box and raise the tuning.

next idea, would be a new front stage with big midbass upfront to pick up where sub drops off.

[Aaron Clinton 2,372]

What vehicle? You should be able to hit 142 @ 40hz with a 12" in a trunk.

There are so many unknowns there is no way you can know this.

[Lucky 76 5]

The problem is not the subs it is the box . The q is a sound quality sub and if u look at the response curve it is pretty flat. Adjust your tuning and you will be fine. You need to find the sweet spot for your listening pleasure. In most cases the lower u tune it the more high end you will loose and vice versa.

[audiophyle_247 2]

Reducing the airspace inside the enclosure is a great way to raise port frequency, throw some phone books or large blocks of wood in there.

Quick, easy, and quite effective.

[Lucky 76 5]

i would recommend the wood blocks. The phone books could create port noise due to the pages. Plus you could measure how much volume you are actually decreasing the box by

[Dangerous10k 0]

I think what the problem is is, that the box is flexing like crazy cause looking inside the enclosure the only bracing is the port, but im starting to think the reason the kickers wer louder is that they were woofers/port fired at the trunk, where as this half wall is subs/port towards front seat,i was thinking about just changing to a sealed box,or gettin 12's or 10's firing towards the trunk. My friend has two Kove Auido 15's in a sealed box (3/4" mdf probally around the neighborhood of 5.5-6 cubic feet, and his sounds really good) {hits all notes equally loud} amp is really low powered like somewhere around 200rms each sub off a a rockford amp i really like the way his sounds, I just want to be able to hit all the notes louder without crazyloud trunk rattling. I mean i know its gonna rattle outside but when it rattles so much all you can here is rattling inside the car then its just annoying

Also I found out that this box is tuned at the lowest 35hz (kinda hard to determine the volume of the enclosure because it is a trapeziod half wall with another trapezoid going into the trunk

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shaped like that with small section into the trunk and big section where the back seat used to be subs/port forward volume is hard to determine because i really cant measure the part that seperates the trunk and cabin so volume is somewhere around 8 cubic feet and the tuning is somehwere around 35-38hz

maybe all this rattling is caused by the box not being braced worth a crap?

Edited October 25, 2009 by Dangerous10k

[Dangerous10k 0]

let me post a pic

[ChristianMcKay 1]

I think what the problem is is, that the box is flexing like crazy cause looking inside the enclosure the only bracing is the port, but im starting to think the reason the kickers wer louder is that they were woofers/port fired at the trunk, where as this half wall is subs/port towards front seat,i was thinking about just changing to a sealed box,or gettin 12's or 10's firing towards the trunk. My friend has two Kove Auido 15's in a sealed box (3/4" mdf probally around the neighborhood of 5.5-6 cubic feet, and his sounds really good) {hits all notes equally loud} amp is really low powered like somewhere around 200rms each sub off a a rockford amp i really like the way his sounds, I just want to be able to hit all the notes louder without crazyloud trunk rattling. I mean i know its gonna rattle outside but when it rattles so much all you can here is rattling inside the car then its just annoying

Also I found out that this box is tuned at the lowest 35hz (kinda hard to determine the volume of the enclosure because it is a trapeziod half wall with another trapezoid going into the trunk

___

/ /__

/___/__/

shaped like that with small section into the trunk and big section where the back seat used to be subs/port forward volume is hard to determine because i really cant measure the part that seperates the trunk and cabin so volume is somewhere around 8 cubic feet and the tuning is somehwere around 35-38hz

maybe all this rattling is caused by the box not being braced worth a crap?

Just brace the box, I don't think it'll be completely necessary to seal it though. Sealing it will just make it bottom out like crazy unless you do a good bit of bracing to make up for the excess cubic feet. Most people I've talked to who had sealed Fi Q's said they didn't like the sound as much.

Edited October 25, 2009 by Christian McKay

[Lucky 76 5]

Those subs are recommended to be ported. The problem is your enclosure. You might have leakage as well as a bracing problem. Do those first. It will save you the hassle of building a new box not to mention it would be cheaper. Those subs should be pounding hard and sounding good while doing it. Perhaps it is that you have them tuned so high? Try fixing these things. Also rattles are fixed with sound deadening =)

[ChristianMcKay 1]

Perhaps it is that you have them tuned so high?

You mean low?

[Lucky 76 5]

If you want the q to sound good. It is recommended on the fi website that it be tuned between 28 and 33 hertz. What a ported box does is it makes something similar to a peak in the frequency. So if you tuned a box to 33 hz (if the sub's response was completely flat) the peak would be at 33 hz and any frequency higher or lower is not as loud.

Here is an example of a ported box tuned to 26.3 hz. If you look the biggest peak is at that frequency and then it dips.

So if you tune the qs' box between the recommended guidelines (28-33 hz), your output will be more balanced through the frequency spectrum.