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Subwoofer question

3K views 33 replies 2 participants last post by  ranger91 
#1 ·
I have a 1991 Ford Ranger Super Cab.

I Have a 800 watt amp with built in crossover that is user tunable.

My 2 sub options that i have tried so far are a Rockford Fosgate P1 P1S410 10" in a sealed 20 cubic inch box..and a JBL GT120 12" in a sealed box.


The 12 obviously hits harder than the 10...but as far as quality which sub is better of the 2?


The reason im asking is because i want to go to 2 subs,and didnt know if i should get another P1 10" RF..or another JBL GT120 12"


ive been wanting to go with a single 15"..but with my budget it just isnt feasable...


Here is what my system is as of this moment:


Kenwood KDC-205 CD Player 50w x 4

Performance Teknique ICBM-891 4 channel 800 watt amp

Stock Ford Ranger front door speakers

Kenwood 280W 6x8 rear panel speakers


the small speakers are hooked up to the 50 x 4 cd player,then RCA goes to amp and the amp uses +ch1 and -ch2 and says "MONO" going to the sub


im just not happy with the bass..or lack of.


a friend of mine has a single 12" W3 in his subaru powered by a T500 Fosgate and it just kills my setup.
 
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#2 ·
The enclosure will make more difference in the end sound than which model of sub you buy. That said, I am a bigger fan of JBL subs than fosgate. I have owned both brands (my favorite set of fosgates were the Audiophile line. Had 2 12's... Loved them!)


If you can do it, build a ported enclosure. A correctly designed and built ported enclosure will destroy a sealed enclosure in output, sound quality and less distortion for a given output.


Another issue in your comparison is amplifiers. Your friend has a much better sub amp than you do. That 800 watt rating is max and possibly when it gets hit by lightning. It's not a bad amp it is just listed as supplying more power than it really can. Especially in the subwoofer frequency area which can be tough on an amplifier.


Any other questions, I will try to chime in.
 
#3 ·
i was thinking about that,i have the material and skill to build a new box,but how do i know what to build? also i am limited on box space,all i have is the area being the seat..which is about 16" from back of seat to edge of cab under back window.


the 12" box everyone told me to port it..so i did,and it sounded like crap after that..so i patched my 3.5" port hole.
 
#4 ·
Well odds are that the "port" you installed was incorrectly done.


There are lots of places you can look for a definition of a port and how it works so I will say that is your homework.



You can have a port that has to little area, this causes port induced distortion and chuffing and if it is way to little you get a form of air lock where it just buggers up the sound terribly.


You can tune to high. This in conjunction with my first problem really screws up the sound. a lot of boxes are this way. tuned in the upper 40's or higher, you end up with a "fart box". A one note wonder.


If you can take the max available space you have/are willing to give up, I can try to give you a design. I need height width and depth for the design.
 
#7 ·
LOL. Bet is sounded bad. That was tuned aqbove 100 hertz. And rolls off the bottom end at 18db per octave. Bet there was no bass and you popped the woofer a lot!!



I am in Des Moines Ia for work tonight. Will attempt to get you something at least by tomorrow night.
 
#8 ·
Your max dimensions gives 2.34 cubic feet using 3/4 material.


Skip buying a second JBL 12. They are discontinued. Here is the manual for it though.

http://magnitola.ru/manuals/JBL_GT120_f.pdf


Actually the space you have available will give you just about the perfect space. Will get loud on very little power!! They model it with 300 watts. Shame your sub amp does not have a SSF to keep the woofer from unloading below tuning. Before I bought anymore equipment, I would build that box (JBL Vented) and give it a listen.
 
#10 ·
They mention 2.25 cubic feet after woofer and port displacement. That is internal volume. Build a box to the dimensions you gave. install woofer and 4" ID pvc pipe that is 13.31 (13.25 will be fine) and call it a day. Give it a listen. See if it gives you what you are looking for sound-wise.


My guess is that it will. If you want more, then decide your path. You should be able to sell the box and woofer for a decent price. Especially if it jams as well as I think it will.
 
#12 ·
I am a fan of 3/4. It tends to flex less. Odds are you could get away with 5/8 material.
 
#13 ·
i just picked up a non carpeted box,it is made for 2 12" subs,but i can cut a new face and re-cut the hole for my single sub..the dimensions are 15.50" deep...13.25" tall..and 30.25" long....all INSIDE the box dimensions...what would the footage be on this and would it be close to what i need since the price was right ($15)?
 
#17 ·

Quote:
Originally Posted by ranger91 /forum/post/21321721


ok..so made a single 12" front panel and put the box all together,didnt port it yet...hopefully porting it is the same as a miracle,because it sounds like CRAP right now.

Strange. Because a sealed enclosure is usually the easiest to implement in a vehicle. It's just the most forgiving. And you are saying it sounds like crap.


Well a port is far from a miracle.


Can you describe the sound? What is it lacking?
 
#18 ·
I tried to look up your amplifier. Closest I could find was an ICBM 893


Max Output Power :

1000W @ 2 Ohm


Power Output :

65W x 4Ch @ 4 Ohm

80W x 4Ch @ 2 Ohm

160W x 2Ch Bridged


24dB Crossover
Variable Low Pass Filter (30Hz ~ 500Hz)

Variable High Pass Filter (50Hz ~1KHz)

Variable Bass Boost (0 ~ 18dB)

Variable Subsonic Filter (10Hz ~100Hz)


Wired Bass Remote Control

RCA Line Output

Double Sided PCB

High & Low Level Input

Two Way Protection

Tri-Mode Speaker Connection Stable

2 Ohm Stable Stereo

Soft Delayed Power On

0.05% THD


The bolded items have me concerned.


First, let's look at bass boost.


DO NOT USE IT except in tiny amounts. There is bass boost on most head units, there is also the loudness button, and the amp boost.


Make sure they are all at zero.


Bass boost causes your amp to work exponentially harder. A 3db bump is asking your amp to work twice as hard. A 10 db bump is 10 times as hard. Now compound that by multiple boosts and you end up with crappy sound.


An amp puts out a finite amount of power. once you hit that amount, cranking the boost only makes you hit it faster. This causes the amp to clip and sounds bad.


Setting your gain is important as well. This may also be causing sound quality issues.


Low pass high pass and SSF settings.


A low pass cross over let's the low frequencies pass while filtering out the higher frequencies.


A high pass crossover filters out the low frequencies and lets the high frequencies pass


So if you have the settings wrong, you end up with bad sound.


In the case of your subs, 60-120 hertz LOW PASS should be used.


Now the SSF is a HIGH PASS crossover as well. It is used to keep the ultra low frequencies from robbing power from your amp and protecting your subwoofer. Your amp has a variable SSF that can be set 10-100 hertz. If you have it set to high, it will not let your sub play any lows. Having the SSF is great because if you port, you want to attenuate the lows below the tuning frequency to keep your sub from unloading. This causes massive woofer movement and tends to destroy a sub after a while. Sometimes that "while" can be measured in seconds.



I would look at your head unit and amplifier settings. Turn off all bass boost and loudness contours. Any eq settings to 0. Then look at the amp. Turn the gain to the minimum setting. Make sure bass boost is at zero.


On the outputs with the low pass and SSF, set the low pass to around 80-100 hertz.

Set the SSF to 20-30 hertz.


Not sure if your head unit has sub level control but set that to zero if it does or at the minimum setting.


Turn the gain up a 1/4.


Give it a listen. I am hoping that except for output/loudness it sounds better. Good even.


Looking at those amplifiers, there is much better to be had and cheaply. I can recommend a few if you would like. I would keep the current amp and use it to power the non subwoofer speakers.
 
#19 ·
let me explain..i left the box sized as it was (3.69CF) 15.50 deep, 13.50 tall, and 30.50 wide...and left it sealed.


Today i am leaving the box the same,except instead of 15.50 deep i am going to 9.5 deep which gives me 2.26CF.


and then i will port it with 4" PVC at 13.25 long


it sounded good with the volume down kinda low (10 of 35)..and then start increasing the volume and the bass kinda went away and got more loud/rattle sounding.


i like to keep the volume at 20 of 35...and with my smaller sealed box it sounded OK..just didnt have the THUMP i feel like i should be getting.


not sure if this description helps at all...but here goes...


with my other box(small sealed) i could have the volume at 20 and it was loud and sounded OK in the truck...you could feel decent vibes from bass...now get out of the truck and close the door and walk 10 feet away,and you couldnt even here ANY bass.


im not looking for bass that can be heard 6 blocks away..but it would be nice to achieve the maximum with the equipment i have..and i feel the answer lies within the box.
 
#20 ·
So you are cutting the box down in size? Sorry a little confused. I maybe am misunderstanding.


Adding the port should be fairly easy. Rememer to set the SSF to ~20hertz if you can. Will help keep the woofer from bottoming out.
 
#22 ·

Quote:
Originally Posted by ranger91 /forum/post/21324489


let me explain..i left the box sized as it was (3.69CF) 15.50 deep, 13.50 tall, and 30.50 wide...and left it sealed.


Today i am leaving the box the same,except instead of 15.50 deep i am going to 9.5 deep which gives me 2.26CF.


and then i will port it with 4" PVC at 13.25 long


it sounded good with the volume down kinda low (10 of 35)..and then start increasing the volume and the bass kinda went away and got more loud/rattle sounding. This confuses me a bit. Not sure why this is happening

i like to keep the volume at 20 of 35...and with my smaller sealed box it sounded OK..just didnt have the THUMP i feel like i should be getting. Porting should give you quite a bit more low end. it should pressurize your cabin quite well.not sure if this description helps at all...but here goes...


with my other box(small sealed) i could have the volume at 20 and it was loud and sounded OK in the truck...you could feel decent vibes from bass...now get out of the truck and close the door and walk 10 feet away,and you couldnt even here ANY bass. Windows are up? That may not be as bad as you think. Now if the windows are down, I would definitely check the SSF setting and make sure its not set to high cutting the lows out.

im not looking for bass that can be heard 6 blocks away..but it would be nice to achieve the maximum with the equipment i have..and i feel the answer lies within the box.

As long as the amp setting are correct, I agree. To the point of trying a bandpass enclosure.


I am a "the enclosure dictates the response more than anything" kind of person.
 
#23 ·
SSF= Subsonic filter


Are you sure the model number is ICBM891?


NVM- I found it on Amazon.
 
#24 ·
yes,it is ICBM-891 800W


Here are some basic specs i found:


Product Specification:

General Product Type Amplifier

Recommended Use Car

Audio System Crossover Slope 24 dB/octave

Low Pass Frequencies 30 - 500 Hz

High Pass Frequencies 50 - 1000 Hz

Additional Features Subsonic filter, bass level remote control

Continuous Power / Channel Qty 50 Watts x 4

High Level Inputs Yes

Output Power / Total 800 Watt

Distortion Factor 0.05%

Amplifier Output Details 50 Watt - 4 Ohm - 4 channel(s) ¦ 65 Watt - 2 Ohm - 4 channel(s) ¦ 130 Watt - 2 channel(s)

Amplifier Output 4-channel

Crossover Active crossover

Bass Boost Gain 0 to +18dB

Connections Connector Type 1 x audio line-out ( RCA phono x 2 ) ¦ 2 x audio line-in ( RCA phono x 2 )
 
#26 ·
Where is the subsonic filter adjustment set at? Make sure it is set on the lowest setting to start. Then turn it up until around 20hertz. This may not be marked so will have to be done sort of by feel/what you hear.


The remote bass level is just a remote gain adjustment. (I hate them as kids tend to kill amps using them but thats just my opinion)


I called performance Teknique and they do not have electronic copies of their manuals....
 
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