i've learned alot about sound systems from here and playing around with my own but i havnt learned anything about ohms. i feel kinda dumb for asking but i dont know the details of it and how it effects certain things. any and as much info is greatly appreciated! thanks alot

 

Ohms, in electronic terms, is resistance. It's basically how much the device in question resists current flow as it travels through a circuit.

In this instance, audio equipment, it is referred to as impedance.

A speaker with 4 ohms impedance should be mated to a head unit of 4 ohms impedance. If the speaker is of a higher impedance, it will resist too much and will not perform as well as it should. If the head unit is of higher impedance than the speaker, damage can result from the speaker not resisting enough.

Connecting speakers in different ways can also affect the value of the impedance. For example, connecting 2 4ohm speakers to one channel in parallel will halve the impedance to 2 ohms. Connecting them in series will double it to 8 ohms.

Hope this helps,

Si

 

that explained some... it might help if i relate it to my system. right now i have 2 8 ohm Fosgate 10"s (i didnt buy them... christmas gift) i guess the guy said that these will be safe with any amp. from what i got from you i'de have to match the subs with an 8 ohm amp which i've never seen... what would you do in this situation?

 

Here, this might help you out.
http://www.maaudio.com/techsupport/b...ubwoofers.html

Brian

 

in this pic it shows that I would have to splice from my pos. and neg. wires...is that safe? I circled the parts I am talkin bout.

 

If you use a 4ohm amp with the 8ohm subs, you can bridge a 2 channel amp, or use a single channel amp, and wire the 2 subs in parallel. Put simply, wire both subs to the same 2 terminals on the amp using 4 wires. go from pos to pos and neg to neg in each case.

 

It's quite safe, so long as you use the right gauge cable to handle the current. Personally, I would use the method I described in the post above.

Si

 

right now i dont really have an amp that i can run my subs with. so what would you guys recommend me getting? a single channel 4 ohm amp? gah its going to suck having to run my subs in parallel in my box...
what other options would i have?
a 2 channel 2 ohm amp and run them in bridged and in parallel? crap this gets complicated. what could i get so that i wouldnt have to run them in parallel? i'm really trying to get away from that because the box is split into 2 separate compartments

i could also take the subs back and exchange them for 4 ohm ones? would that be a good idea?

 

You don't have to run the subs in parallel inside the box, just run them both to the same outputs on the amp, externally, with their own seperate wires.

Check the diagram below....you can see that the 2 subs are wired to the same 2 connectors, the positive from one channel and the negative from the other. This is called bridging, which will put out the maximum power through a single sub in mono. Connecting the second sub will bring the power back down (so a 500 watt amp would power 2 subs at 250 watts each, etc) but it will also halve the total impedance running through the circuit, hence you will theoretically have a 4 ohm load on a 4 ohm amp.

My advice would be to do this...because if your plans ever did change, you have the most versatile amp there is for your money.

Si

 

so i could do everything just fine with a 4 ohm amp? even runing 2 8 ohm subs? thanks a bunch for your help

 

You certainly can, my friend. As long as you run them like the diagram. Get yourself a 4 channel 4ohm amp with a wattage close to the wattage of both subs added together. A little less is ok, but DO NOT get an amp with a higher wattage than the subs...you will kill them.

Happy listening buddy!

Si

 

wow you've been alot of help, i've got one more question (as of now...) the amp i currently have is a clairion, 2 ohm, 380 watt with 4 channels. the RMS of my subs is 150 a piece and max is 400 so the wattage of this amp would work right? i just might need a cap? what about the ohms of the amp? i'm still confused how ohms of a sub relate to ohms of an amp and how they are affected by certain things so...
anyway thanks a bunch again!!!

 

The wattage of the amp is fine, however if you wire your subs as illustrated they will collectively have an impedance of 4 ohms, whereas your amp has an impedance of 2 ohms. To get the subs down to 2 ohms you would need to wire 4 of them in this way. And if you did that, the power would drop right down to 95 watts per sub...which wouldn't exactly shake the car to bits.

You could in theory run your 2 subs off this 2 ohm amp, but be warned that the impedance is too high on the subs, and they will not perform very well. You could really do with a 4 ohm amp in there.

I'll try and explain the ohms in a different way. Imagine if you will, that the sun is shining. If you don't wear shades, you are blinded by the rays. If you put on 2 pairs of shades, it is too dark and you cannot see. So you wear 1 pair, right?
Now, if the sun shines twice as bright, you'll need 2 pairs of shades to get perfect vision. The analogy here is that your amp is the sun, and the subs are your shades, and your sound output is your vision. Power from the sun (amp) must be matched by the power of your shades (sub). Too much shades = can't see very well. Too little shades = too much light from the sun, which can damage your eyes. You see?

 

heh that also helped alot! looks like i'll be looking for a new amplifier sometime soon. any recomendations for my setup?

 

i've decided that i'm taking these subs back tomorrow to exchange them for 4 ohm subs. everything else will be the same... it shouldnt be such a PITA to take care of now... still, can you recommend any amps around 500-650W?

 

Unfortunately no. I could recommend a lot, but they may not be available in your country. I have no idea what brands you can get over there.

Si

 

JBL 600.1 puts out about 700RMS at either 2 or 1 ohm. And you can get it for $195 from ikesound.

Brian

 

so basically, if you buy a 2 500 watt subs with 4 ohms each, then you should buy a 1000 2 channel 4ohms and just bridge,

 

Pretty much, yes.

Sub bass does not benefit from stereo sound, so they may as well be mono. And if you have 2 running mono, they will both be putting out the same sound at the same time, which is beneficial when you have them both mounted in the same enclosure.

Si