I have a 2400 watt amp with 4 ohms and I'm going to get two subwoofers I was wondering how many ohms I need in each subwoofer

Is it a dual channel or mono amp? You don't want to Ever put an impedance load on an amp lower than it's rated - so if you're getting two Separate sub boxes, each one should be 8 ohms. That way when you wire all the subs to the amp it becomes a 4 ohm load ('parallel wiring' divides the impedance). Be absolutely certain that the polarity is correct, in other words - " + to + and - to - ". Otherwise the signals will cancel each other and you'll not have very much bass at all.
Let me know if this helped or if you more info!

It's a 2 channel amp and I'm getting 2 12 in subwoofers and I'm putting them in one box

Ok, without knowing what amp you've got I'll give you a basic rule: Don't Ever have the two channels of the amp get connected to the same 'thing'. This will blow most amps up totally. So, run a separate wire (two conductors of course) from each speaker to each channel of the amp. And the heavier gauge wire the better - maybe #12 or #14 would really work well. And remember the " + to + " part... out of phase will ruin the sound.
I'm here so please ask if you have more questions.
Dave

So I still need 8 ohms or since it's a 2 channel amp I only need 4 ohms subs?

Check on the amp, if it says "4 ohms per channel" then go with 4 ohm speakers! It should sound killer! If it talks about "max 4 ohms total" then you'll use the 8 ohm speakers... since as we learned earlier... parallel wiring divides the impedance. If you start wiring guitar amp cabinets I'll tell you all about 'series' wiring...

Technically, the amp info would state 'minimum x ohms' either per channel or total - not 'max'...

2 X 600W at 4 ohms 2 X 1200W Max 4 ohms that's the watts and ohms of my amp that I got

You're doing fine, what you need to watch for is the power going into each speaker. You'll need some serious speakers to handle that kind of power. If you mean there's a switch to choose between 600w and 1200w, I'd probably choose the 600... 1200watts will blow most speakers into next week. Keep in mind that's Max Watts and is dependent upon the input signal.

You I think I'm gettting 1500 watt subs so they should handle 1200 watts of power but they need to be 8 ohms right?

I'm guessing that the info on the amp actually says 600w at Eight Ohms and 1200w at 4 ohms. That would make the most sense. Either way, it sounds like you could use 4 ohm speakers (clarify: that's 4 ohms each speaker) and run one wire from each amp output to each separate speaker and you've got it. Again, use heavy gauge wire like I said.

K thanks for your help

My pleasure! I'm here quite a bit dealing with electronics and engineering issues - check out my profile if you like. And if you could rate my answers, I think it means something here...
Good luck with your sound system!
Dave

LANZAR VIBE276 2 CHANNEL AMPLIFIER - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=6214#toppage) that's my amp with all the watts and ohms info

Thanks, I'll check it out - if there's anything unusual or different from what I've told you I'll get back to you.

K thanks

All right, so it's 600w RMS (which is basically 'regular normal watts') and 1200w Max or Peak... either way it should make some Serious noise for you. Lol
Will you be using a Sub-output from your tuner/CD/whatever source? That's often a single RCA type connector - looking at the picture I see there's two RCA inputs. You'll need a simple RCA 'Y' adapter from Radio Shack unless there's a switch on the amp which combines the input signals. I really wish there were more pictures, I could tell you more about spkr. Wire connectors...

So should I get the subs with the 8 ohms? Or the 4 ohms?

Use speakers listed as 4 ohms and wiring them individually, you've got it! Like you said, the speakers you've chosen are high power so you're good to go.

You ill have to take some pics of them in my 89 Camaro and post them up somewhere so u can see them

I got one more Question for you which subs would be better? BOSS AUDIO BLX12C Blade Exxtreme Series Dual Voice Coil Subwoofer (12") - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=8941)
OR
LANZAR 12 INCH MAX SPEAKER MAXP124D - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=6529)

Give me a few minutes to take a look - and I've got one other email to finish. Back in a bit...

OK thank you so much for your time

I'll be back in a couple minutes... lots going on. Lol
Check this out, OK?
http:// www. Crutchfield. Com/ISEO-rgbtcspd/learningcenter/car/subwoofers_faq.html

OK thanks just get back to me on the subs on which one u think is better thanks

Dual Voice Coil Subwoofers (http://www.crutchfield.com/learningcenter/car/subwoofers_dual.html)

Read the above article as well...

I am reading them at the moment

Ok, this is getting pretty technical (not a problem - I taught advanced audio engineering) so let me try to simplify this: You amp choice and speaker choice don't match as well as they should. Basically, the speakers are Dual Voice Coil (DVC) and the amp you've chosen will 'see' these spkrs as 8 ohms each... which is not getting you much power. Either get Single Voice Coil spkrs at Four Ohms each.. OR.. find a single channel/Mono amp that is rated for Two Ohms output. You're on the right track, but everything isn't quite matching up.

So what if I were to get a dual voice coil 2 ohms speakers would the amp see it as 4 ohms instead?

So what if I were to get a dual voice coil 2 ohms speakers would the amp see it as 4 ohms instead?

Yes!

Or, check out this speaker...

BOSS AUDIO BL128 Blade Series Metallic Injection Cone Subwoofer (12" Single voice coil) - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=9208)

And now I've got to sign-off for tonight - early day tomorrow. I'll check for messages in the morning and follow-up with whatever info I can provide.
Thanks for a great question tonight!
David

You I looked at that speaker the max watts are 700 though

What about these ones
LANZAR OPTI1222D DUAL MAGNET 2 OHM WOOFER - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=6709)
I believe they are dual 2 ohms voice coils

so what if i were to get a dual voice coil 2 ohms speakers would the amp see it as 4 ohms instead?

Yes!



Half true. He could wire the coils in series for 4 ohms or parallel for 1 ohm.

If you bought two, dual-coil (2ohms/coil) speakers then you could wire the entire system into several different configurations to match your amplifier(s). It is essentially like having 4x2ohm resistors to do what you like with.

If you wired all four coils in series you'd get 8ohms, for example. If you wired each speaker's two coils in series with each other, then wired the two speakers in parallel, you'd have 2 ohms overall, etc.

The trick then is to match impedences with your amp's optimum output. If you want "x" watts, choose an amp that will put out "x" watts (rms) at "y" ohms. Then wire your speakers to get "y" ohms.

Some amps will offer you multiple channels... this lets you simplify the wiring and run each sub on different channels if you so choose. Alternatively, some amps will let you "bridge" two channels together to half the impedance.

Make sure you choose a conductor based on the overall amerage that will be running through your system:

If you have a total impedance of 8ohms, for instance, and your power is 1000W (rms) then your amperage is going to be I=sqrt(P/R)=sqrt(1000/8)=11.2A. Your peak current will be 11.2*sqrt(2)=16A. A #12 AWG wire should be used.

If, however, your total impedance is 1ohm, and your power is 1000W (rms) then your amperage is going to be I=sqrt(1000/1)=31.6A. Your peak current will be 31.6A*sqrt(2)=45A. In this case a #8 AWG wire should be used. (2 sizes thicker than before!)

Okay….. lets try to take this down to the lowest common denominator:
1. Millertime has a hot Camaro.
2. He wants a killer sound system.
3. He would like to achieve maximum 'thump' for the $$ invested.
4. Item #3 above (and my answers) are in direct proportion to the initial posting, i.e. Subwoofers.
5. My responses are directed toward actually reaching the intended goal (as a practical application) and less in the context of a E.E. lesson.…

So, that's about it! And my information to Millertime came from His choice of components.
I do appreciate your input - but I believe bridging & sqrt formulae are not what he had in mind.
And as Dennis Miller always says "these are just my opinions .. I could be wrong" ……

So would these subs work LANZAR OPTI1222D DUAL MAGNET 2 OHM WOOFER - ( AUTOTOYS.COM ) (http://www.autotoys.com/x/cust/product.php?productid=6709) I just want to double check and make sure and should I use 4 gauge wire?

To any and all who were following this thread or may have wondered why it slammed to a halt in mid-stream... by mutual consent, it moved to a different location. Millertime has his system figured out and all ended quite well.

2 8 Ohm speakers wred in parrallel(plus to plus and minus to minus) does bring resistance(Impedance) down to 4 Ohms.
If you had 2 2 Ohm speakers and wire in series(Plus of one speaker to negative of other speaker)and with the plus and minus remaining, go to amp output.

You can do a series/parallel with 4 8 ohm speakers to end up with 8 ohms. Output to each individual speaker will be reduced, and Amp will not be loaded down.
Wiring these same 4 speakers in parallel would reduce to 2 ohms(Bad for 8 ohm Amp)