Subs don't work right?

[psychogoateater 10+ year member]

Hi, i just bought 2 12" concept subs from someone i know but they make a rattling noise. i checked and there are no tools inside so that can't be the problem. they still put out a beat but there is deffinitely something wrong. my 2 10" subs sound better. when each one is hooked up by itself, it sounds fine. but when they are both hooked up, they sound crappy again. i am using a lightning audio 1200 watt amp so wouldn't that be enough power? any help would be nice. thanks

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[Beat_Dominator 5,000+ posts]

Are the 2 wired in parallel or series? What is the voice coil configuration on the subs? Dual, Single? 4ohm, or 2ohm?

Sounds like you might have them wired where they are being over powered and bottoming out.... or there could be some other issues at work here.

 

[DJ Kontakt 10+ year member]

what is the model number?

and i bet you have them hooked up opposite of eachother

 

[stones 10+ year member]

I have heard subs make funny rattling sounds when the polaritys of one sub was opposite of the other.

Check all your speaker wires again, in fact tear everything apart and hook it up again(not the power wires, just the speaker wires).

To be extra sure that the terminals on the speaker inputs are correctly labeled take a 9volt battery, touch the positive terminal of the battery to the positive terminal of the sub, same shit for the negative.

Now when you touch the battery to the terminal the cone should move outward slightly, this is good, it means that the terminal is properly labeled

If the cone moves in slightly, thats bad, it means the factory has mistakenly hooked the negative lead of the VC to the positive speaker terminal, the speaker will still work fine you just need to hook the positive wire the negative terminal, this should be covered under warranty though.

Give the actual model numbers of the subs and the amp, if we know exactly what amp and sub you have we can give you the best possible way to wire it.

 

[psychogoateater 10+ year member]

i don't knw if anybody is still following this, but i had to do something earlier.

Here are the model numbers:

lightning audio bolt amp B2.300.4

Concept sub CSE-124

 

[stones 10+ year member]

According to the model # you have given for the sub it has the following specs-

300 watts RMS single 4ohm coil

And the specs for the B2.300.4 amp are

50x4 @ 4ohms

75x4 @ 2ohms

150x2 @ 4ohms - 900 Watts Max Power

With these specs I would connect one sub to each of the two bridged channels, that way both subs each get 150 watts each.

Since its a four channel I would use an RCA splitter to split the sub signal to both RCA inputs. Also I would set the gain sensitivity and xover frequency identical for both A and B channels.

If you have verified that the wiring polarity is correct and the output is still not to your liking I would then consider a ported box for the subs as I have owned a pair of Concept SS12's and found their sealed box performance to be less then impressive, when put in a ported box they really came to life though.

 

[psychogoateater 10+ year member]

is there any way to tell if they are blown? or if something else is wrong with them? because i don't want to spend the extra money if they still won't work. also, the amp is the 1200 watt model...

Bolt 75x4 @ 4ohms

100x4 @ 2ohms

200x2 @ 4ohms - 1200 Watts Max Power

Variable x-over from 40-400Hz

+12db Juice Boost Bass EQ

Pass thru ouputs

would the sealed box make them rattle? i don't really know difference the ported or sealed boxes are. i know what they are but i don't know in what circumstances to use each.

 

[Savstyle 10+ year member]

is there any way to tell if they are blown? or if something else is wrong with them? because i don't want to spend the extra money if they still won't work. also, the amp is the 1200 watt model...
Bolt 75x4 @ 4ohms

100x4 @ 2ohms

200x2 @ 4ohms - 1200 Watts Max Power

Variable x-over from 40-400Hz

+12db Juice Boost Bass EQ

Pass thru ouputs

would the sealed box make them rattle? i don't really know difference the ported or sealed boxes are. i know what they are but i don't know in what circumstances to use each.

just so you know max ratings mean absolutly nothing. Rms is the important one

 

[stones 10+ year member]

To tell if they are blown-

1- If the voice coil is scorched or burned the will cut in and out or not play at all.

2- If the spider has torn loose from the neck of the cone or the basket, you can tell this by a close visual inspection on the back of the woofer, gently move the cone up and down and search for any torn areas on the spider (that ribbed cloth thing the cone is connected to). A damaged spider can cause rattles.

Another cause for rattles, if you have loosley mounted your subs and air is leaking out around the mounting diameter or any holes in the box (not ports thats different)

The subs will bottom out easily as they have no acoustic suspention due to the leaks. A sealed box must be airtight.

Ported boxes take the backwave of the sub and change it to add to the front wave of the sub, if you play a sub with no enclosure at all it will make no sound because the backwave will cancel out the frontwave, a port will change the wavelenght of the backwave so it doesnt cancel out the frontwave.

Ported boxes are generally louder then sealed due to the extra air movment from the port. the extra volume is at the expense of a larger enclosure and slightly less accurate sound. the port provides acoustic suspention to the sub by restricting airflow at certain frequencys, the most restriction happening at the ports tuning frequency, below the ports tuning frequency the port no longer provides acoustic suspention and allows the sub to play without resistance, this is why some amps have subsonic filters to cut out these ultra low frequencys below tuning.

More info-

4.4.2 Sealed Box

-----------------

* Advantages...

- Small enclosure volumes

- Shallow (12 dB/Octave) roll off on low end

- Excellent power handling at extremely low frequencies

- Excellent transient response/ group delay

characteristics

- Easy to build and design

- Forgiving of design and construction errors

* Disadvantages...

- Not particularly efficient

- Marginal power handling in upper bass frequencies

- Increased distortion in upper bass over ported design

- When using high power and small box, magnet structure

is not in an ideal cooling environment

4.4.3 Ported Box

-----------------

* Advantages...

- 3-4 dB more efficient overall than sealed design

- Handles upper bass frequencies better with less

distortion

- Magnet is in good cooling environment

- When properly designed, a ported box will slaughter a

sealed in terms of low frequency extension

* Disadvantages...

- Size (not so critical outside the mobile environment)

- Woofer unloads below Fb

- More difficult to design/ can result in boomy, nasty

sounding bass if misaligned

 

[psychogoateater 10+ year member]

so if i inspected them and they look fine and they still play and beat somewhat then they aren't blown? they sound alright until they get so loud then they just rattle, almost like they are shaking too much. would that be an air leak problem?

thanks for the info on sealed and ported boxes by the way

 

[stones 10+ year member]

Possible air leak yes.

 

[psychogoateater 10+ year member]

somebody told me that if there is multiple voice coils then one of them could be bad and it would still make sound just not the best. is that true? from what you said, it doesn't sound like these are dual coil.

are air leaks bad because they disrupt the pressure in the box? maybe that is the reason they shake so bad?

 

[stones 10+ year member]

somebody told me that if there is multiple voice coils then one of them could be bad and it would still make sound just not the best. is that true? from what you said, it doesn't sound like these are dual coil. are air leaks bad because they disrupt the pressure in the box? maybe that is the reason they shake so bad?

1- yes, one coil could go bad before the other but this usually still drives the amp into protect mode (cuts out), it could technically still work though depending on the severity of the damage to the coil.

2-If each subwoofer has only a single positive and negative terminal to connect the speaker wire to then its a single voice coil.

3-A leaky box will not give the acoustic suspention the woofer needs (air pillow) allowing the subs to "max out" at low volumes, when your Concept sub maxes out the voice coil will slam against the bottom of the magnet and cause a rattling noise (each tap being the coil hitting the magnet a single time) doing this for long periods of time will damage the subwoofer.

Making sure the box is well sealed for proper operation and setting the gain sensitivity on your your amp to a lower setting will cut back the power a bit to stop this, also lowering you xover point will help, I reccomend a setting of 80hz.

 

[psychogoateater 10+ year member]

i believe mine is single coil then

i will try making sure everything is sealed... thanks for all of the help.

if this doesn't work then i'm going to be so mad i'll beat someone up!!!!

or i'll run away crying...

 

[stones 10+ year member]

A little silicone bead around the mounting edge will help to seal things up.