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Hey guys I have recently bought a JL 10" W0 sub ported jl box with the JL jx250 mono block amp.
My issue is that the sub is missing strange ranges of bass for example the song "Boss Mode" by "knife Party" or "Beautiful Pain" by "Eminem" bump hard but songs like "Still Dre" by "Dr. Dre" or "Dont Tweet This" by "Tech N9ne" definitely are missing the proper bass hit.

I have my rca cables connected to the passthrough ports on my jensen power 750.4 amp that was installed by best buy along with my alpine type S speakers

My I have 4g power cable connected to my battery and then splits to two 8g cables via power block all of my grounds are sanded and touching bare metal.

I have messed with the dials on the JL amp but nothing changed that much.

Do you think my Jensen amp is messing with the signial?
 

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Demon Spawn
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missing range is usually a bad adjustment on your x over point, check your headunit (if aftermarket) and see if it has built in crossovers, if it does find the sub setting and turn it off or to through and set the crossover on your amp to around 150hz (almost all the way up on the jl amp) then tune from there to find your range again. if this fails to bring the range back and it still sounds flat on some songs, you could have a bad amp or sub, or an air leak in the box causing the sound to change pitch. you need to mess with the crossover and tuning on your headunit as usually missing range is a crossover issue or something on the headunit not set right.
 

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Thanks for the reply I'm going to give it a look at later tonight.
My head unit is the stock one and i dont know how bestbuy spliced in my amp, but I'll give it a look and let you know how it went!
 

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Demon Spawn
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Thanks for the reply I'm going to give it a look at later tonight.
My head unit is the stock one and i dont know how bestbuy spliced in my amp, but I'll give it a look and let you know how it went!
ok, looking into this further for you, the amp you have is a 250 watt amp. The sub is a 300 watt rms sub, is it missing on the hard hitting low notes, that should make a sub go onto a big excursion movement) but the mid bass that is easier to produce just fine? If so that is exactly where your issues lie. The amp you have is 175 watts rms(root mean square, for our sake just know rms is the power to match amp to sub) at 4 ohms the sub you have is a 300 watt rms single voice coil sub with a 4 ohm voice coil, so you have it wired to an amp that even at its best at 2 ohm (lowest it will go) is still not really adequate power to move that sub well. your only giving it around 175 watts and it wants 200-300 to really beat. the sub lists a range for rms of 100w-300w when a range is listed you want to hit the higher end of the spectrum. dont worry about max power you only care about matching rms on amp to rms on sub or speakers. so you need a more powerful amp one like: Kicker CX Series CXA6001 1200W Class D Mono Amplifier with Adjustable KickEQ Bass Boost Black 43CXA6001 - Best Buy this one is 300 watts rms at 4 ohms so it matches your sub perfect.

this site:Car Alarm, Car Stereo, Mobile Video, and Cruise Control Info for Installers has a ton of info for car stereo installs and what not. you need to remember how you will be wiring it up,
Here is a quick crash course in how this all works
Ohm-The unit of electric resistance and impedance. One ohm is the resistance value through which one volt will maintain a current of one ampere.
Ohm's Law-Current in a circuit is directly proportional to the voltage, and inversely proportional to resistance.It also includes the relationships of watts to amps, volts and ohms
Ampere-A unit that defines the rate of flow of electricity (current) in a circuit, otherwise known as an amp (not your car amp, a unit of measurement)
Volt-The unit of measure for electrical potential.
Voltage-the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit.

so think of your wiring as a river, the voltage is like water just sitting still in the river, amps would be like the flow of the water as it moves. ohms is like the size of the river, so how it resists movement or flow, wider the river lower the resistance, thinner the river higher the resistance, wattage is basically just a measure of what all this does. so if you add ohms or resistance to the flow of the circuit the more amps are needed to get the voltage across the wires. just with electricity ohms or resistance dont necessarily have anything to do with wire size though they do, just because you use a fatter wire does not mean you have lower resistance, you have to match the wire to the need.

this is a basic explanation as to why you need a more powerful amp for that sub to make it sound right and get the full range it is made to produce. I would suggest starting there and see if that helps. return the jl amp and get a more powerful version, or a more powerful one from another brand, but if you intend on using the single voice coil sub you have at 4 ohms you need an amp that will put out 250-300 watts rms at 4 ohms. you may also need/wamt to use a sealed box for better sound, when at lower power like 300 watts sealed boxes tend to sound better, will let you use a smaller box and can let you get away with using less power.

to set your gain correctly without an expensive oscilloscope or just tuning by ear you need a voltmeter and some basic math. lets say 100 watts rms is what you need at 2 ohms so you do square root of watts x ohms so it would be 100x2 which is 200 and square root of 200 is right about 14.14 volts at the speaker terminals of the amp.

this is the 12 volts sub wiring tool : Subwoofer Wiring Diagrams

this will go further into detail on setting your gain: How to Adjust Amplifier Gains Using a Digital Multi-Meter | Learning Center | Sonic Electronix

sorry i got technical, and long winded. But it was kinda needed to help explain your issue and why it is your issue, and then how to fix it correctly.
 

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Discussion Starter #5
Thank you for giving such an in-depth reply I appreciate that!
I'm going in today and I'm going to return my amp and upgrade it to the jx500 - D1.
I had a feeling that the RMS had something to do with it but I wasn't sure.
Hopefully that fixes my problem.

I'm missing some midbass and most "upper" bass notes.
When I'm listening to dubstep at the drop hits then it hits real hard

Ill keep you posted and once again i appreciate the in-depth replies
 

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Demon Spawn
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Thank you for giving such an in-depth reply I appreciate that!
I'm going in today and I'm going to return my amp and upgrade it to the jx500 - D1.
I had a feeling that the RMS had something to do with it but I wasn't sure.
Hopefully that fixes my problem.

I'm missing some midbass and most "upper" bass notes.
When I'm listening to dubstep at the drop hits then it hits real hard

Ill keep you posted and once again i appreciate the in-depth replies
that amp will fit your sub perfect, remember as well new subs take a week or so of moderate usage to "break in" and then they will sound much better, Rockford fosgate is the only ones I have ever used/seen where it has like a one day break in, supposedly Rockford does the break in at the factory so that maybe why. jl makes great stuff too, in fact my favorite audio brands are in order JBL/Harmann (same company) Rockford fosgate, Alpine, JL. and it really always comes down to price and availability for me between these brands when I need a component. They all make great stuff, so you really cant go wrong with any of them

Question, did the box come with the sub already in it? like is it a JL branded box/sub combo? or did you buy a sub and a non JL branded box ? if its the latter, take a look at the specs of your box and the spec sheet on your sub and make sure the box you have falls into the range of sizes on the sub, as well as its port tuning frequency. this makes a huge difference. If I is the first then your box is matched to the subs specs perfect and a new amp should solve all your issues, just set your gains right and set your low pass on the amp to around 150hz and tune it down from there to dial in the bass and cut out the mids. and be careful with bass boost, set your gain first then the low pass then if you want a little more bump slowly turn up the bass boost, but remember if you turn it much you will need to turn down the gain a little to match.
 

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Discussion Starter #7
Yeah it ame with the JL Audio embroidered box so i believe that its to spec. Im here at car toys right now waiting for them to open
 

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Demon Spawn
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Yeah it ame with the JL Audio embroidered box so i believe that its to spec. Im here at car toys right now waiting for them to open
yeah that's the JL prebuilt box/sub combo, that box is great for that sub, I would just get the more powerful amp and set it up, then just let us know. shouldn't require much since its already wired just hook it up and set it to the right settings.
 

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So i got the new amp it definitely hits harder but I still feel like something's missing maybe it's because the ported box or maybe it's the range on the amp also I haven't fully tuned it yet
 

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Do you have factory bose or no? If you do, depending on where they tapped in your amp may not be getting the full signal and thus not sending to the sub.

The Bose front door speakers have a roll-off in the low frequencies and if that's there they tapped in for your amp that's probably your issue.

If you don't have Bose the tuning likely needs played with
 

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Demon Spawn
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Do you have factory bose or no? If you do, depending on where they tapped in your amp may not be getting the full signal and thus not sending to the sub.

The Bose front door speakers have a roll-off in the low frequencies and if that's there they tapped in for your amp that's probably your issue.

If you don't have Bose the tuning likely needs played with
^^^^ This ^^^^ if they tapped into the wrong spot and you have bose no matter how good of a tune you give it then there will be missing range, because the sub plays a different range then the factory bose speaker would have and the bose is so integrated in with this car its kind of crazy. also check your Jensen amp, where they passed through your rca's make sure white is plugged into white and red into red I know this sounds trivial but it actually does matter for the polarity of the speaker.

on your Jensen amp it should have 6 turn knobs for adjustments and a few switches might be worth a look to see if they are set right, set the channels 1-4 in hpf to let the non bass get through and that's it, you want this slightly higher then your sub crossover.
it could also be you got a 3rd shift made sub setup and they reversed the polarity inside the box to the sub, take the sub out of the hole and make sure + runs to + on the speaker and - runs to - on the speaker, reversed polarity can definitely hinder the sound response, and bad. you must also remember 300w sub will not pound the block, it takes 1000w or more to really kick the bass. if you are used to the way setups of over 1000w sound try not to compare this to them, as it will never hit as hard.

this is out of your Jensen amp manual and maybe worth trying as well:
Crossover (X-OVER)
The Jensen Power series of amplifiers have built-in low-pass and high-pass
crossover filters for bi-amplifying the system. Adjust the crossover to
accommodate your chosen installation method. Select LPF (low pass filter)
when the amplifier will be driving woofers or subwoofers. Choose FULL when
crossover mode is not active and the amplifier is in “full range” mode. Select
HPF (high pass filter) when the amplifier will be driving full-range or separate
speakers, and you want to limit the “bass” being transferred to these speakers

Ill go a bit deeper in this too, the crossover you want around 140hz or so for door speakers (usually, I had alpine type s in my last set up and 140hz was perfect) set that and use hpf on the Jensen amp, then on your jl amp if it has one select lpf and set it just lower then what you set your Jensen to, then listen to some music you know well and listen for anything missing, is the mid bass weak, is the low end weak, is the high pitched too weak, then adjust accordingly and it maybe the Jensen has no crossover set and is on "full" (their setting for through) and it may not be passing the low signals correctly to your JL amp, try setting both 1-2 and 3-4 to high pass on the Jensen and see if that gets you more response from the sub, as the Jensen may not be passing the correct signals to the jl if set to full, as it would be trying to produce all of the range, if you tell it I only want high notes by selecting hpf and setting the crossover to around 140ish hz to start and then check again,that may solve your issues as well, because this may tell the Jensen amp to pass the low frequencies onto the output line and send them to the sub, each amp is different and I have no real world installation experience with Jensen, jl, jbl, Rockford, planet audio and alpine are the main ones I have experience with.

jl lists no spec for their box's port tuning frequency

Studum, where would you recommend he tap into for signal to his amp? he has a 4 channel for the door speakers that has a pass through rca for the sub amp, he has the sub amp on the 4 channel rca pass through for signal, I think you are correct if he has bose, the original installers may have tapped the wrong channels to get signal to the Jensen, so the Jensen may not actually be seeing bass signal to pass to the jl amp, I have bose but have yet to play with changing anything in it, as I just don't want to spend $200 to change my radio and find special speakers and what not, the stock bose sounds good for the prices to get more out of it or around it. I would suggest he follow the signal wires on the Jensen back and find where/how they got it signal and see if it is the front channels, if so would changing to the rear channels help, or would he need to tap into the sub or get an LOC and just make it go from line level to RCA, if this has not already been done
 

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If you have factory bose speakers/headunit and just added an amp with sub, then it's the factory bose not liking the added amp and sub. I had the factory bose headunit with speakers etc and just tried adding a sub and amp. It was decent but something was off no matter how much I turned bass/gain up.
The bose def didn't like the added amp and sub. They just didnt play right together.
I ended up tearing out all the factory bose stuff and installing my own system. Night and day difference. The factory bose doesn't like it when an amp an sub is added. It tweaks things on its own to subpar performance
 

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Demon Spawn
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If you have factory bose speakers/headunit and just added an amp with sub, then it's the factory bose not liking the added amp and sub. I had the factory bose headunit with speakers etc and just tried adding a sub and amp. It was decent but something was off no matter how much I turned bass/gain up.
The bose def didn't like the added amp and sub. They just didnt play right together.
I ended up tearing out all the factory bose stuff and installing my own system. Night and day difference. The factory bose doesn't like it when an amp an sub is added. It tweaks things on its own to subpar performance
That's what he did, he has a 4 channel Jensen powering his alpine door speakers, and a mono JL powering his sub, he has the sub signal wire on a pass through channel from the 4 channel amp, I think his problems either lie in the tuning on either amp or on the place the Jensen gets it signal from, if he has bose, if not then the tuning is likely the culprit
 

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Im going to mess with all of this on my day off and really give it time and effort.
If i remember correctly i gave the installer a Schosch LOC for the back of my stock (none Bose ) reciver

https://www.sonicelectronix.com/item_4993_Scosche-SLC-4.html

Now that you ask me to check my rca polarity there's a good chance that i plugged them in backwards because the Jensen 4chan amp is under my passenger seat and i from what o could see the female rca on the amp were just gray

Like i said this weekend ill just pull out my seat and really tune it ill post pics as well
 

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Demon Spawn
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Im going to mess with all of this on my day off and really give it time and effort.
If i remember correctly i gave the installer a Schosch LOC for the back of my stock (none Bose ) reciver

https://www.sonicelectronix.com/item_4993_Scosche-SLC-4.html

Now that you ask me to check my rca polarity there's a good chance that i plugged them in backwards because the Jensen 4chan amp is under my passenger seat and i from what o could see the female rca on the amp were just gray

Like i said this weekend ill just pull out my seat and really tune it ill post pics as well
good idea, you would think being a sub having it backwards would not make a difference as its just one channel, but it gets signal from both lines and if it is getting them backwards then it will sound off. quickest thing would be to swap them on your sub amp and see if it helps, that way you know right away if they where backwards or not, now it does not actually matter which colored end is plugged in where, just that they match so if you did plug red into white and vice versa then you need to do so on the other end as well. this prevents the signal from crossing and changing the way the amp processes the input. you did not have bose so that should make it easier, I would also double check what the installer did on both amps, as he may have something set wrong or plugged in wrong.
 

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So i got it sounding clean and it sounds like it's hitting correctly now.
My amp was on full with all the dials turned down to 40 also i think my rca were backwards but im not to assumed because there both black and not labeled left or right
 

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Demon Spawn
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nice little setup there man, glad we helped get your setting right. that sub doesn't eat up a whole ton of space either, you got me thinking now, though I do carry tools and a tool bag full of misc computer components (for work, im in IT) and also must regularly carry monitors and tower PCs for work so I need most of the hatch space I have a good chuck of the time. plus the bose system streaming via Bluetooth through a decent music app like google play gone mad or a few others gets the system to come alive, since those apps alow more adjustability in their EQs and send the EQed music through, so it allows for greater adjustability then just bass or treble, the google play has 5 bands bass boost and surround I have a nice curve with bass and treble up and mids up but not as much as the bass or treble (the bose system has enough mid punch) it needs extra low end so upping the bass and using a small bit of bass boost helps a ton and gets the bose system kicking, especially with it having under 300w total power (bose in our gen is rated a 265w total system power) and it sounds fantastic, and this is from a guy that used to put competition grade audio systems in every car no lower then 2000w total power, premium audio tweaked just right can sound great, no it cant be heard a mile away but I don't care about being heard before im seen anymore, just having good sound and decently loud music levels, this the bose system delivers to me just right
 
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