Is this 2 OHMS or 4 OHMS

[paintballer 10+ year member]

hey guys. I set my gains on my Mono class D amplifier for my subwoofers with a DMM, and i followed the voltage formula, V=Squareroot(RMS Wattage X Resistence).

http://www.circuitcity.com/ssm/Specifications-of-MTX-Dual-12-1350W-Subwoofers-Enclosure-TCE4512X2D/sem/rpsm/oid/147568/rpem/ccd/productDetailSpecification.do#tabs

Those are my subs and my amp is here

http://www.alpine-usa.com/en/products/product.php?model=MRP-M450&lang=en&tab=F

The lowest RMS wattage was of the amp, so i plugged the numbers in. I just figured the sub box was running at 2 ohms. i got

V=sqrt(400RMS X 2Ohms) = 28.3 volts, which then i got with the DMM in AC current while turning up the gain with the subwoofer volume on the deck at max (15). i actually put the gaina t about 27, just to be safe.

But here is the problem. Should I have plugged in 4 OHms into the equation instead of 2 Ohms. I dont know what my subs are runing at. There is only 1 input terminal on the prebuilt sub box, but there are two subs. So i dont know if combined they are running at 4 ohms, or was putting 2 ohms into the equation correct?

If the sub prebuilt box is running at the 4 Ohms, then the volts would 40, right? Then i would have to raise the gain again. When i did the test i used a 80 hz test tone and the sub volume was at a max of 15 on my alpine deck. Is that alright. The LPF is on like 90 or 100 HZ

Thanks for the help guys

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[paintballer 10+ year member]

BUMp^ anybody have any suggestions

 

[jeepintn 10+ year member]

you set your gains based on the ohms you will be running the amp at, and if your subs are the ones in the link, dvc 2 ohms, you need to wire in series-parallel to end up with a 2 ohms load

 

[creyc 10+ year member]

Single 2-ohm connection

According to a google search on that box.
So yes, you set it up right. The box is getting 400W @ 2 ohms.

 

[paintballer 10+ year member]

Cool. Thanks guys. Yeah i set it at a voltage AC reading of 28.3 volts with DMM and gain dial, and then i lowered it a tiny bit to be safe, and also because i dont know if the DMM is totally accurate( its a 20$ radio shack brand one). I had the sub volume on the deck at `15 (max) and and i was using a 50 hz test tone. I had the LPF turned all the way up to 200 hz so that i wouldnt get any interferrence. I then finally set the LPF at 100 hz.

When im playing my music, it should be totally safe to have sub volume at 15(max) then correct, since i set the gains with that setting, and at a volume of 25. (alpine deck). I did witha lamb of god cd (Sacrament, which is recorded pretty **** loud), and it sounded good at the max. Im just hoping its not clipping.

I guess my question or paranoid thinking stems from the fact that i dont know if the DMM is totally accurate. The dial is turned up to like 1/3 of the way(gain dial), so im guessing its pretty accurate.

Thanks again guys:veryhapp:

 

[creyc 10+ year member]

Remember, you can always HEAR clipping, and that test is free.

Turn it up, pop the trunk and have a listen near the driver. For the sake of experimentation you can even bump the gain dial into the clipping territory just to know what it sounds like, but turn it down once you hear it because it's not good for the sub for any extended period of time.

If you tested the way you described then yes you're safe running your system even on max volume.

 

[spacegear 10+ year member]

you can always check the resistance. using 1k so you'll know how many ohms ur sub is.