noob question - ohms?

[Wfs0801 10+ year member]

I see on all the subs I'm looking at that it says "2 ohms" "4 ohms" etc. I did a quick search and everyone was explaining ohms as the way that you wire the speakers, if so then how does a speaker have an ohm rating from the start? It just kind of confused me, I'm obviously new to this stuff but I'm trying to learn. Could anyone offer a better explanation of what ohms are and how they affect the speakers and their output?

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[ckunke002 10+ year member]

Ohms is the measurement of impedance in an AC electrical circuit. Speakers will be measured in ohms per voice coil, but if you are hooking up several speakers to a single channel, or a speaker with 2 voice coils (DVC or dual voice coil) to a single channel, then the final impedance that your amp will see will be different than the individual voice coils ohm ratings. The lower a voice coils ohm rating, the less resistance it puts up against your amplifier powering it. So in theory, the lowest ohm speakers are the most efficient, because they are easiest to power. Well, amplifiers can only power such low impedance loads, hooking up a speaker/sub with too low of an ohm rating to a amp that isn't built for it can damage the amp. (For example, hooking up a 1 ohm load to an amp that is only capable of powering 2 ohm loads at the lowest)

 

---------- Post added at 06:57 AM ---------- Previous post was at 06:57 AM ----------

 

Subwoofer Wiring Diagrams this will teach you ALOT

 

[Wfs0801 10+ year member]

So, because of a lack of total knowledge, it'd probably be best for me to look for amps/speakers/subs that match each others ohm ratings? At least until I get a better understanding, which I will work on.

Another question, what if I have multiple speakers going to the amp? For example, my sub amp will be powering 2 subs. Then I will also have an amp powering the 4 speakers inside the cabin of the car. All of these will be running on separate channels (from my knowledge that is best, but I'll still look into more before deciding), Does having multiple speakers and/or channels affect the ohm rating of either the amp or speakers?

 

[ckunke002 10+ year member]

No, amps channels are all individual, you cannot affect other channels by how many you hook up or whatever. If an amp is rated to deliver 4 channels of 75 watts RMS @ 4 ohms, then each of those channels can do that, and you can use 1 or all of the channels or anything in between.

For your first question, yes. But say you run into a dual voice coil sub that you want to buy, you will need to know how different ways of wiring it up will affect the impedance your amp will see. Here's a good example...

http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/1-DVC-2-ohm-mono-low-imp.jpg

This is called a dual voice coil (DVC) 2 ohm sub. It is called 2 ohm because both of it's voice coils are 2 ohms, not because the load your amp will see is 2 ohms. When you have 2 voice coils, depending on how you wire the sub the final impedance will be different. For the example above, the impedance the amp sees drops to 1 ohm. But the link below shows that with the same dvc 2 ohm sub, you can wire it up to be powered at 4 ohms

http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/1DVC_2-ohm_mono.jpg

But in the meantime, try to determine how much power you want/need, then match subs and amps. Example, say you want a 300 watt RMS sub, and you find one you like that is a single 2 ohm voice coil, or maybe a DVC 4 ohm (which can be wired to be 2 ohms, refer to the links again), then you need to find an amp that can put out that much power at that impedance. Amps will list their power outputs at a couple different impedances, and the lower the impedance of the voice coil(s) wired to the sub, the higher the power it can deliver to them.

 

[Lowflyin 10+ year member]

[quote name='Wfs0801']So, because of a lack of total knowledge, it'd probably be best for me to look for amps/speakers/subs that match each others ohm ratings? At least until I get a better understanding, which I will work on.

Another question, what if I have multiple speakers going to the amp? For example, my sub amp will be powering 2 subs. Then I will also have an amp powering the 4 speakers inside the cabin of the car. All of these will be running on separate channels (from my knowledge that is best, but I'll still look into more before deciding), Does having multiple speakers and/or channels affect the ohm rating of either the amp or speakers?[/QUOTE]


The link @ckunke002 ; posted will tell you that. I suggest read A LOT more before you buy anything at all.

 

[s3th 10+ year member]

Does having multiple speakers and/or channels affect the ohm rating of either the amp or speakers?

Not necessarily, it just depends on how you wire the subs series/parallel/or sometime series-parallel, that will then determine what the final impedence/ohm load will be going into the amplifier.
Heres a good website to get a good idea of what combinations look like what impedances.

Subwoofer Wiring Diagrams

Select quantity of subs then the ohm of each sub, weather it be two 2 ohm dvc subs or two 4 ohms dvc subs.

 

[Wfs0801 10+ year member]

Thanks a lot for the information and having the patience to answer all my questions. It's starting to make sense to me but I will visit the links you guys have suggested to read more about it, I really appreciate the help.

 

[Wfs0801 10+ year member]

Ok, I've read the links on subwoofer wiring, and I think I'm getting a better hold on it. But just to be sure. The subs that I'm currently looking at are 550 Watt RMS DVC 4 ohm. So I'd need to look for a 2 channel amp that can handle 4 ohm loads of at least or more than 550 Watt RMS, correct? I'm still a little fuzzy but it seems to be coming together in my head a little lol.

 

[Vincer77 10+ year member]

You can wire two single voice coil subs as either 2 or 8 ohms. Many amps can run 2 ohms and will put more power to subs. You will need to check your amp specs. If it will handle 2 ohms, you can run them both of single channel.

 

[Wfs0801 10+ year member]

So my options, with these subs are to either get a 2 channel amp and run 4 ohms to the subs or get a single channel amp that can handle 2 ohms and run them both on 1 channel? I think it'd be easier to simply find the 2 channel amp and run the 4 ohms.

 

[ckunke002 10+ year member]

So my options, with these subs are to either get a 2 channel amp and run 4 ohms to the subs or get a single channel amp that can handle 2 ohms and run them both on 1 channel? I think it'd be easier to simply find the 2 channel amp and run the 4 ohms.

You said "subs", making me assume you mean 2 of them but I'm not positive that's what you mean lol. So for each one of these subs, you're options are to either wire them in parallel for 2 ohms, or wired in series for 8 ohms. Now finding the amp to drive 8 ohms at those levels will be a very unnecessary task, that is a lot of resistance. What you will want to do is drive them at 2 ohms.

You also mentioned powering the voice coils separately, by using a 2 channel 550w per channel @ 4 ohm amp. Again, this is asking a lot out of an amp in comparison to a mono channel amp that would simply have to put out 550w @ 2 ohms on it's one channel and you would end up spending a lot more. Essentially every amp made for subs is stable at 2 ohms, so you might as well take advantage of that and wire up as efficiently as you possibly can.

If you want 1 of these subs, I would buy a monoblock amplifier that can do around 600-700 watts RMS (for wiggle room) on it's only channel at 2 ohms. If you want 2 of these subs, I would get a 1 ohm stable mono amp that can do around 1300-1400 watts RMS and wire up both DVC 4 ohm subs to the channel in parallel creating a final 1 ohm load to your amplifier. You will simply have to shop for an amp can do 1 ohm loads, because many are not made to.

Keep reading around and learning, I remember when i was first learning about this stuff I always wanted somebody to take their time and really properly explain this stuff because it's definitely confusing at first.. so I hope it helps for you!

 

[ckunke002 10+ year member]

here's a diagram of wiring 2 dvc 4 ohm speakers to be a 1 ohm load

http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/2-DVC-4-ohm-mono-low-imp.jpg

 

[Wfs0801 10+ year member]

I had a post in a different section asking about wiring up my subs (yes, it will be 2 of them) and everyone over there told me to wire them up parallel to be a 1 ohm load and that it'd be cheaper to get a mono channel amp that is stable at 1 ohm. I've found one that outputs about 1,300W RMS at 1 ohm and I it's a brand that I've heard a lot of good reviews on so I think I'll be getting that. Basically everything you just posted has tied in with what others just told me, making me more confident that the mono amp at 1ohm is the cheaper and more efficient route to go.

I think with this knowledge I'm officially done with everything regarding my HU, as well as my subs/amp (just need to take measurements for the box). Now all that's left is to get speaker sized for my interior speakers and find those and an amp to run them, which this information should help me on.

Here's a question though, with these 2 subs, being powered by a 1300W RMS amp, along with the 4 interior subs/amp, would I need an extra battery? Or would I just need a high output alternator and to do the big 3 upgrade?

 

[ckunke002 10+ year member]

I would figure that if you did the alternator/big 3 that would be just fine, but I wouldn't spend much time pounding away with your car off running off the battery. Doing the alternator is the best you can do though, because it's the source.

 

[Wfs0801 10+ year member]

I figure at this point, whether I need the extra battery or not, upgrading the alternator will only help. So I'll probably upgrade it, install the system, and if I see that I need an extra battery, I'll go through the lengths of installing it. I guess that'll be a 'wait and see' type thing.