OHM issues and impedence matching transfoermers

[herbykw 10+ year member]

I have some issues. I thought i had a good understanding of OHM loads and everything, but i dont know now.

Heres the scoop, i bought a MA Audio EHO sub a while back. It is quad voice coil at 1.5 ohm each and 5500w rms. I just bought a MA Audio HK802SX. the amp is 2 channels and

2200w rms per channel at 0.5om

1400w rms per channel at 1 ohm

I wired the subs in parrallel at 0.75 ohm as per the12volt.com

about a minute after install a bad smell started comming from the sub and was kinda crackly. I kept the amp turned down. From my understanding the smaller the ohm number the less impedance. From my logic(not saying that means anything) if the sub is wired to handle more impedance then its recieving, then to me that would be like pushing less power then the sub can handle, right?

A friend explained the math may not add up for that to be right. He said i should get a impedance matching transformer to adjust the ohms to match exactly from the amp to the sub.

CAN ANYONE HELP??? Is there anychance the sub is still salvagable, or toast?

Click to read more...

 

[audioarsonal 10+ year member]

Did you parrallel all the coils together?Or just 2 coils to each channel?As for the "Ohm matching transformer" is this because your running .75 not .5 or 1?

 

[audioatg 10+ year member]

Well If you have it wired two coils per channel it be 1 ohm per channel. That be 2700watts give or take what your electrical system is.. Whats the lowest ohm load the amp can handle mono mode.

 

[Livin' Loud]

You probably blew it,.

 

[audioarsonal 10+ year member]

Well If you have it wired two coils per channel it be 1 ohm per channel. That be 2700watts give or take what your electrical system is.. Whats the lowest ohm load the amp can handle mono mode.

It would actually be slightly less then 1 ohm as it is a quad 1.5 ohm.So 2 coils parralleled woud be .75 ohms.

 

[SPL KID 10+ year member]

you had it wired at .375 mono which is lower then any amp is meant to handle. even though you put 2 coils on seperate channels it still mono's the total sum together. the amplifier may be damaged not just the subwoofer.

 

[ultimate157 5,000+ posts]

you had it wired at .375 mono which is lower then any amp is meant to handle. even though you put 2 coils on seperate channels it still mono's the total sum together. the amplifier may be damaged not just the subwoofer.

No, its a 2 channel amp.

What is the model number of your sub?

 

[audioatg 10+ year member]

It would actually be slightly less then 1 ohm as it is a quad 1.5 ohm.So 2 coils parralleled woud be .75 ohms.

Im reading it as he had it wired stereo mode. Using one channel to a set of coils. So that be around 1 ohm if he did that. Like two coils 1.5 1.5 parralleled to one channel and the other set to the other channel.

 

[ultimate157 5,000+ posts]

Im reading it as he had it wired stereo mode. Using one channel to a set of coils. So that be around 1 ohm if he did that. Like two coils 1.5 1.5 parralleled to one channel and the other set to the other channel.

1/1.5 + 1/1.5 = 2/1.5

1.5/2 = .75 ohms

 

[Haunz 10+ year member]

^ 1.5ohms is more then likely the cold DCR of the voice coils... meaning it is essentially a quad 2ohm sub.... Not ideal for maximum power out of that amp.. but if you are running 1ohm per channel it shouldn't hurt anything...

It is normal for a new sub to smell when you first give it alot of power... but there shouldn't be any 'crackling' noise...

If the cone still moves freely without any rubbing you are OK.. try it again..

As far as impedance matching autoformers... one for subbass frequencies with the kind of power you are running would be huge, weight a ton, and cost a fortune.... forget that option...

 

[ultimate157 5,000+ posts]

^ 1.5ohms is more then likely the cold DCR of the voice coils... meaning it is essentially a quad 2ohm sub.... Not ideal for maximum power out of that amp.. but if you are running 1ohm per channel it shouldn't hurt anything...

That is what I assumed.

 

[audioatg 10+ year member]

1/1.5 + 1/1.5 = 2/1.5
1.5/2 = .75 ohms

1.5/1.5= around 1.

1.5/1.5/1.5/1.5= below .5

 

[ultimate157 5,000+ posts]

1.5/1.5= around 1.
1.5/1.5/1.5/1.5= below .5

Your approximation of 1.5 being around 1 is quite a big difference, especially being that DCR is almost always below nominal impedance. In your case a 2 ohm nominal sub is quite different than a 1 ohm nominal.

Either way I fail to see where he is paralleling all coils to a single channel?

 

[DidUHearThat? 10+ year member]

Quad 1.5 ohm coils? Why?

 

[audioarsonal 10+ year member]

I dont' think the amp has a problem with the ohm load.IIRC it can run as low as .5 per channel.I think its the sub.You may have warped the coil due to overheating or clipping.Was it set with a DMM.What kind of electrical do you have to back the amp?You may be sending a dirty signal from low voltage?