[toeycrack]

im doing some research on speakers/sound system, and i wanted to get all the know it all knowledge.


what are Ohm's and what is a good range?

2 ohm
4 ohm
8 ohm



thanks

 

[mrfatride]

http://www.the12volt.com/ohm/ohmslaw.asp

 

[jmanpc]

Ohms are in a nutshell the measure of resistance that speakers show to your amplifier. In most instances, the lower the ohm load, the more current the speaker will draw from the amplifier.

Understanding ohms is critical to proper system design. If you want to get the most out of your system, you have to match your speakers to your amplifier, or vice versa. If you've got an amplifier that's 1 ohm stable, you want a sub thats dual 2 ohms, or a pair that are dual 4 ohms, etc. If you've got an amplifier thats 2 ohm stable, you should look for a dual 4 ohm sub or a pair of single 4 ohm or dual 2 ohm subs.

I know it's confusing, but it all boils down to two types of circuits- parallel and series.

Parallel wiring involves pairing the positive and negative leads of speakers, thus halving the resistance. For example: a dual 4 ohm wired in parallel comes out to 2 ohms. A pair of single 4 ohm subs wired in parallel comes out to 2 ohms. A dual 2 ohm sub wired in parallel presents a 1 ohm load.

Series wiring, on the other hand, means connecting the positive from the amp to the positive on the first speaker or voice coil, the negative from the first speaker or voice coil to the positive on the second speaker, and the negative from the second speaker to the amp. I know it sounds confusing, but it's actually pretty simple. In effect, it doubles the ohm load. A dual 4 ohm speaker wired in series equals 8 ohms, and a dual 2 ohm sub wired in series will present a 4 ohm load.

These two types of wiring can be combined to reach the proper ohm load for your amplifier. For example, if you want to wire a pair of dual 2 ohm subwoofers to a 2 ohm stable amplifier, you can wire each sub in series to 4 ohms, and then wire them together in parallel to reach a final load of 2 ohms.

I know its confusing at first but after you do it a few times, you'll find it's simple.

 

[dj elite]

ohms are a measure of resistance. one analogy i use to explain it to people just on a conceptual level (wont help you calculate it much) is a pipe- the resistance in ohms is the diameter of your pipe. 8 ohms, it's a 2 inch pipe. you can get a good amount of water through at a good pressure without working too hard. 4 ohms, 4 inch pipe- you can get more water through but its gonna take more effort from your amp to get it through. 2ohms, its even bigger... it has to work even harder (more current, more heat, more inefficiency, more noise).

those numbers are more pro-audio though... 8 is usually normal, 4 is ok, 2 is not recommended. for cars, it's a bit lower... 4 is normal, 2 is usually OK, and 1 is tricky.

 

[jmanpc]

1 ohm isn't tricky, provided you have the right equipment [goofydrunk]

 

[mrfatride]

no but he is correct...running a higher ohm load will yeild you better sound quality....good analogy though i never thought of explaining it that way

 

[jmanpc]

no but he is correct...running a higher ohm load will yeild you better sound quality....good analogy though i never thought of explaining it that way

Myth.

100w @ 4 ohms with .01% THD won't sound a bit better than 100w @ 2 ohms with .01% THD.

 

[arrestmespi]

I=v/R
amperage = Voltage divide by resistance(measured in ohms)

 

[dj elite]

Myth.

100w @ 4 ohms with .01% THD won't sound a bit better than 100w @ 2 ohms with .01% THD.

of course that is true, but often (not always) as the amp's resistance goes down and thus it works harder and produces more heat, the THD will increase. i'm not too experienced with car amps, but in a lot of pro amps, THD at 8 or 4 ohms will be .01 or .1% and it'll be markedly higher at a 2ohm load, if it can even handle it.

 

[jmanpc]

Provided the gains are set correctly, there will be no rise in the total harmonic distortion at lower ohm loads. This is accounted for by testing the amp at each load and finding the amount of power it produces below the acceptable amount of distortion. Yes, the amp certainly does do more work at lower ohm loads, as evidenced by a drop in efficiency and an increase in the amount of heat produced, but again, provided the gains are set correctly, you will lose no sound quality.