Subwoofer not playing right

[gknudsen22]

Hello, I recently installed a set of used JL audio shallow depth 12W 1v3-4 inside an enclosed under seat box in my truck. It’s being powered by a JL audio XD700/ 5v2 (XDv2 series) amplifier


So basically my concern is that the subs are not hitting hard at all once the volume is raised. They also sound like garbage at higher volume. They sound pretty good and hit decent when turned down. I think I was expecting more when I got 2 12’s consider my single full size 12 in a ported box hit 5x harder than these. Is it the shallow depth sub? Is it the non ported box? I have no clue. I attached a video which you can hear the subs at normal playing volume vs higher volume.

Here is the example video:

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Click to read more...

 

[1aespinoza 10+ year member]

I have no clue

Definitely something wrong in the install. My nephew had those same subs in a similar box with a JX500/1. They were also in a 21' Ram Crew Cab with the OEM radio and the sound was tight.
What line output converter did you use? That box looks like the one he currently has, which is one cubic foot per sealed chamber. Those subs require 1.25 cu.ft. sealed and 1.75 cu.ft. ported per sub. An incorrect box can make the best sub sound bad and vice versa.
Do you have the box specifications?

 

[Doxquzme Premium Member]

Definitely something wrong in the install. My nephew had those same subs in a similar box with a JX500/1. They were also in a 21' Ram Crew Cab with the OEM radio and the sound was tight.
What line output converter did you use? That box looks like the one he currently has, which is one cubic foot per sealed chamber. Those subs require 1.25 cu.ft. sealed and 1.75 cu.ft. ported per sub. An incorrect box can make the best sub sound bad and vice versa.
Do you have the box specifications?

Agree. I felt like the sound was getting dirty way too soon. I would also stuff 1lb of acoustic stuff in each chamber or 2 pounds if it is shared. That stuff (no pun intended) really cleans up sealed enclosures. That amp is a tad bit meek for dual 12s too. Sell the JL, pick up something like this:

NVX VAD11005 5-Channel 2200W Class D Car Amplifier 818060019616 | eBay

Marine Certified Full Range Class D 5-Channel Amplifier with Bass Remote. 3-way protection circuitry (thermal, overload, and speaker short protection). • 5/4/2 Channel Operation. 5/4/2 channel operation.

www.ebay.com

I mean it's not JL but is considered decent among some of the better mid/budget lines, but they are nice amps for the money. It puts out double the 300 your JL is giving the 2 woofers. You're really underpowering those 12s in my opinion.

4 ohms: 80 watts x 4 chan. + 350 x 1 chan.
• 2 ohms: 125 watts x 4 chan. + 600 x 1 chan.
• Bridged, 4 ohms: 250 watts x 2 chan. + 600 x 1 chan.
• 5/4/2 Channel Operation

The amp is being sold by Sonic Electronics' eBay liquidator, Their Username is CARAUDIO of all things! They always take offers, I would offer the guy $200.00. he may take it or if not will almost always counteroffer. It's already a good deal and works well in your situation.

You could also keep the JL, ignore the 5th channel and add one of these:

Taramps MD 1200.1 1 Ohm Car Audio Amplifier 1200 Watts RMS + Bass Control Knob | eBay

This amplifier covers thewhole frequency range, that is, it is aFULL RANGE module. It is classified asmono and has a channel with a maximum power of1200-Watts RMS. f connection. With RCA audio inputs and outputs, it can be used with all models of head units and amplifiers with this type of...

www.ebay.com

Its output at 2 ohms matches well with the subs you have - it's good quality power that will run great, around 800 watts at 2 ohms.

- just a couple of suggestions.

 

[gknudsen22]

Definitely something wrong in the install. My nephew had those same subs in a similar box with a JX500/1. They were also in a 21' Ram Crew Cab with the OEM radio and the sound was tight.
What line output converter did you use? That box looks like the one he currently has, which is one cubic foot per sealed chamber. Those subs require 1.25 cu.ft. sealed and 1.75 cu.ft. ported per sub. An incorrect box can make the best sub sound bad and vice versa.
Do you have the box specifications?

I don’t know because I put the same exact sub In a single 12 ported enclosure I had, and the sub kicked super hard.

 

[1aespinoza 10+ year member]

I don’t know because I put the same exact sub In a single 12 ported enclosure I had, and the sub kicked super hard.

When you did this test, was it with the current setup in the truck? If yes, then the underseat box is the issue. If the box is too big, you can modify it by putting a partition according to sub specifications.

 

[gknudsen22]

When you did this test, was it with the current setup in the truck? If yes, then the underseat box is the issue. If the box is too big, you can modify it by putting a partition according to sub specifications.

Thank you I was assuming it was the box. So I basically just have to block off one sub from another.

 

[spokey9]

Are the subs wired out of phase? That can kill response

 

[Buck 5,000+ posts]

What size is the box? Sounds like it could possibly be too small of a box, where increased voltage in the coil isn’t able to actually move the cone more, so you get an air-restriction-distortion and not much sound past a certain amount of energy in the coil, restricted xmax. Just a thought.

And ported boxes are generally much louder than sealed, like you tune it to sound like you want.

Make sure your sealed box isn’t leaking, like some of the panels may have become not adhered together.

 

[Buck 5,000+ posts]

You need to read your voice coils before you do anything and make sure they read the correct ohms. OP, you’ve gotta just go through the process of elimination. If you can post up the box or net cubic feet and provide a link to the sub webpage, that’ll help too.

 

[1aespinoza 10+ year member]

Thank you I was assuming it was the box. So I basically just have to block off one sub from another.

As Buck stated, knowing box specs is important to advise on how to proceed.

 

[Doxquzme Premium Member]

Thank you I was assuming it was the box. So I basically just have to block off one sub from another.

No, not correct.

The internal volume for these woofers, as listed on JL's site is 1.10 cubic feet. Whether that is 1.1 each in a segregated cabinet or one cabinet that is 2.2, it's the same. It is very likely that the box isn't either. Once this is established, I also advise that you put a pound of Acousta stuff per woofer (so 1 per segregated or 2 in a combined volume box. Is the box a rectangle? What are the dimensions and what is the thickness of the material used to build it?

 

[Buck 5,000+ posts]

No, not correct.

The internal volume for these woofers, as listed on JL's site is 1.10 cubic feet. Whether that is 1.1 each in a segregated cabinet or one cabinet that is 2.2, it's the same. It is very likely that the box isn't either. Once this is established, I also advise that you put a pound of Acousta stuff per woofer (so 1 per segregated or 2 in a combined volume box. Is the box a rectangle? What are the dimensions and what is the thickness of the material used to build it?

Technically not correct, but the difference here would be minimal. Air itself has a resonance to sound based on density, so when you split chambers up, it splits the air into smaller groups, which causes higher resonance sections because of more dense air per chamber and some 1/4 wave stuff; one side of the box is a wood wall instead of an air wall, like a cushion. So, with 2 subs, splitting the chamber in half will make both chambers resonate slightly higher. You can look at Fc or Fsc of a sealed box to see that. Doesn’t mean it’s incorrect to do it that way either; sometimes you gotta divide chambers up to raise resonance, for structural integrity reasons related to the box or woofer moving parts.

It’s a similar thing with ported boxes, where if you have a ported box with multiple chambers, you’ll need slightly larger ports to maintain the same port velocity with the more individual chambers you add, vs a single large chamber, which can use a smaller port if you have 2,4,8 subs, whatever, all in a single shared chamber. This stuff makes a difference when you have a wall with 16 subs in it and 30,000w.

 

[Doxquzme Premium Member]

Technically not correct, but the difference here would be minimal. Air itself has a resonance to sound based on density, so when you split chambers up, it splits the air into smaller groups, which causes higher resonance sections because of more dense air per chamber and some 1/4 wave stuff; one side of the box is a wood wall instead of an air wall, like a cushion. So, with 2 subs, splitting the chamber in half will make both chambers resonate slightly higher. You can look at Fc or Fsc of a sealed box to see that. Doesn’t mean it’s incorrect to do it that way either; sometimes you gotta divide chambers up to raise resonance, for structural integrity reasons related to the box or woofer moving parts.

Okay, I'm calling semantics here.
While "technically correct" it's not very relevant, I could have made the argument that the enclosure doesn't meet the 0.62: 1: 1.62 golden mean ratio either. Does that help the situation, I think not. In a box that is this size and shape, no need to take up room with a divider or suggest that someone try or that they need to reinvent the wheel trying to get a divider in place or worse, build a new box. which may be needed anyway. If it is, a simple dowel or brace that would add stiffness would be a good thing to reinforce the cabinet's rigidity.

The statement the OP made was, ah, okay, need a divider - like that was going to make a difference or fix his issue, and honestly, it won't. I just clarified that what he was thinking would make a difference or address the issue, wouldn't.

I'm sure you realize that the pressure changes for a single driver in a volume of X will be exactly the same as for two identical drivers in a volume of 2X, right?

The wavelengths in subwoofers are long and having dual drivers share a common chamber isn't an issue at these (100 Hz or so) frequencies. Once you get to a few hundred Hz or higher, the story may be a little different due to standing waves and out-of-phase internal cancellation. Not an issue here.

 

[Buck 5,000+ posts]

Okay, I'm calling semantics here.
While "technically correct" it's not very relevant, I could have made the argument that the enclosure doesn't meet the 0.62: 1: 1.62 golden mean ratio either. Does that help the situation, I think not. In a box that is this size and shape, no need to take up room with a divider or suggest that someone try or that they need to reinvent the wheel trying to get a divider in place or worse, build a new box. which may be needed anyway. If it is, a simple dowel or brace that would add stiffness would be a good thing to reinforce the cabinet's rigidity.

The statement the OP made was, ah, okay, need a divider - like that was going to make a difference or fix his issue, and honestly, it won't. I just clarified that what he was thinking would make a difference or address the issue, wouldn't.

I assume you realize that the pressure changes for a single driver in a volume of X will be exactly the same as for two identical drivers in a volume of 2X, right?
The wavelengths in subwoofers are long and having dual drivers share a common chamber isn't an issue at these (100 Hz or so) frequencies. Once you get to a few hundred Hz or higher, the story may be a little different due to standing waves and out-of-phase internal cancellation. Not an issue here.

It’s not semantics; it’s how sound works. I didn’t make sound work that way. A larger volume of air will have a lower resonance than a smaller volume of air no matter what, because it’s the properties of the air, not the properties of the woofer(s).

I don’t know enough about the box or woofers quite to come to a conclusion yet, need more info. I said the difference would be minimal, so I’m not saying or implying anything other than that, that’s why I said it was a technicality, lol.

 

[Doxquzme Premium Member]

Okay then, wrong word. Should have said quibbling, my bad.