# my sub is not working or is missing something.



## mecsound (May 3, 2014)

hello everyone, this is sort of my first post..and i apologize if its in the wrong place.

so straight to the issue..my sub woofer seems to be broken or missing something to make it function properly. 
starting from a low volume level, i only hear vocals and barely any bass coming out of the sub...that is until i turn the volume up to about half way, which is when i start to hear some a horrible type of rattling bass or something to that effect. like a completely ruined speaker. thing is, the sub is brand new. so i thought that i might be needing a passive crossover, which seems to be incorrect too because all that the crossover did was reduce the vocals that i was hearing in the first half of my volume gauge/knob.

i think i sould have started with these details but here they are:

im using the Lepai LP2020+ with a 5A power supp.
i have two 3" mid speakers connected to the lepai..and is working perfectly
then there's the sub which is my new addition: it is a 10" sony speaker...im not sure what the model number is but i could upload a picture as needed...its said to be 220W and i checked that its 8ohms with a multimeter:
http://item.taobao.com/item.htm?_u=4vcnm1vedc9&id=21622716270
and the crossover i have is:
http://item.taobao.com/item.htm?spm=2013.1.0.0.VFHHTS&id=16420127679
these pages can be translated with bing if u really want to.

thing is i DONT have any proper knowledge about sound.
i was just trying to add a sub that isnt too overly priced and wanted a big boom at first, now i just want the sub to be working like a decent sub would.

i read a little about active crossovers, and im thinking that the sub might need one of those to be working properly, is that the case? and if so, please recommend some tips to making this system work without spending much money. i dont mind buying any individual components and am actually ready to do anything to make it work, even if it means making a diy active crossover from scratch..i just need tons of guidance, plus im a student with a tiny bit of circuit knowledge..hopefully this will help add to that.


i hope this is enough info..if theres anything else that u need, please ask...but most of all..please tell me that there is a way to make this work and my sub isnt dead/blown.

*oh also the sub has two magnets directly behind each other..what exactly does this mean? is it a different type of sub? there is only one positive n negative terminal on the speaker, so i dont think has dual coils? 
anyways thats just another mystery for me now.

main question is how do i make this sub sound like normal?

any decent help will be very appreciated.
:T


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## lcaillo (May 2, 2006)

Is this a car audio application?

How is everything wired up?

Sounds like you are driving the amp to clipping.


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## mecsound (May 3, 2014)

oh no this is an indoor application and ok yeah i think the amp is clipping.

The wiring is pretty simple, the left mid is connected to the left channel and right mid to the right channel.
As for the sub, i tried connecting it in either channel and then i tried bridging it, and they all have almost the same effect.


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## lcaillo (May 2, 2006)

What kind of cabinet do you have the woofer in?

Your amp is not very powerful and is not going to be able to handle a low impedance very well. You are almost certainly running it beyond its ability.


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## mecsound (May 3, 2014)

after doing a little more research, i know i need to get another amp or something for the sub. plate amps look nice and easy to install etc, but the box that i have wont manage to fit a plate on it without me buying tools just to fit it in. So im thinking there must be way for me to get everything that a plate amp basically has without too many extra features like adjustable phase,gain,crossover points etc...and then ill install it inside the box, leaving just a switch to power it on or off. 

i know i need atleast 250-300W output at 8Ω to match my speaker but i need some recommended plate amp that i can strip and put inside my enclosure or i need a tutorial on what exactly active crossovers consist of and how to go about making you own (all parts need to fit though the 10" speaker hole).

im pretty sure that most people are thinking i should just go ahead and get a quality plate amp and maybe even keep it outside the enclosure, but i actually want to and need to learn a bit more about circuitry and probably will end up modding this system with a better amp or replacing amp components at a later stage once i understand everthing better, but for now i just need the sub to operate well enough im my small room.

does anyone know of a simple circuit board that will power up my sub and then i can run a cable straight into the lepai?

again any help will be appreciated.


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## mecsound (May 3, 2014)

the cabinet is 50x30x40cm i think..or somewhere pretty close to that, and i think its ported, has a whole in the back for air.


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## lcaillo (May 2, 2006)

Does it do the same noise if you just connect the sub?


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## mecsound (May 3, 2014)

yep same noise.


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