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How many ohms are my speakers?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=43729
Printed Date: June 11, 2024 at 11:35 AM


Topic: How many ohms are my speakers?

Posted By: Kobaltic
Subject: How many ohms are my speakers?
Date Posted: November 24, 2004 at 6:38 PM

I am trying to figure out how many ohms my speakers are. I got 2 10 inch dvc jl audio 10w3s and 2 12 inch dvc jl audio 12w3s. I am running them off of a jl audio 500/1 mono block. I never got paper work when I got the speakers as they were pre boxed in the HO wedges. I made a new box to house all 4 speakers but I don't know the ohm load. Is there a way I can figure it out with a dmm? Any ideas. Thanks.



Replies:

Posted By: swamprat323
Date Posted: November 24, 2004 at 7:18 PM
Are you looking for ohm for each speaker or total when all wired up. Yes you can use your DMM. depends on how acurat it is, but you can get a close idea of it. Just set the meter to OHMS.




Posted By: Kobaltic
Date Posted: November 24, 2004 at 8:30 PM
I would prefer to know the ohms for each coil, then I can figure out the load. Would I put the meter across the terminal or in series with the wire?




Posted By: swamprat323
Date Posted: November 24, 2004 at 9:20 PM
They should be written on the speaker how many ohom they are, usally on sticker or something. Unhook the speaker wire if any from the speaker, probe the speaker terminals. If you dont know can go JL website they have a thing on wire speakers, also this sight has a calculator for wire speakers in parallel and series.






Posted By: interkooler
Date Posted: November 24, 2004 at 9:42 PM

newby question,  how many ohm's are better and why?, for speakers and sub's?





Posted By: Kobaltic
Date Posted: November 24, 2004 at 10:39 PM

There is no sticker or any kind of marking on the speakers. I searched and searched but no luck. I will try to figure it out.

Interkooler- There is no right or wrong answer. It is what you want to do. Typically (but not always) subs are lower ohms usually 8 or less. Speakers range differently depending on the set up. House speakers are usally higher, 16 ohms or higher.  Ohms represent resistence in a complete circuit. The lower the ohms the more power there is. By adding speakers (or voice coils) in parallel they reduce the ohm load (by half) ithus ncreasing the power. Keep in mind that enery has to transform into other forms. In this case it transforms into sound (in the speakers) and heat (coming off the amp). The increase in power will shut down the amp faster and will draw more power draining it from your electrical system. Around 1 ohm load at 500 watts will cause your head lights to dim. If you wire your speakers in series they will double the resistence, thus reducing the power. You won't have electrical problems but you won't have any bump either. There are many charts and designs all over the net. Check rockford or jl auido for more info. It all comes down to how much  power you want and how much you are willing to spend to keep your battery at maxium power. Typically a 4 ohm load is used because it doesn't generate a lot of heat and will still pound. Also keep in mind your amp has to support the ohm load. An amp to be 1/2 ohm stable will cost you over $1000.00. There is alot more to know about ohms this is just touching the surface. All these figures are only average and/or  typical.





Posted By: interkooler
Date Posted: November 24, 2004 at 10:49 PM

thanx





Posted By: stevdart
Date Posted: November 24, 2004 at 10:49 PM

Kobaltic|:  read ohms across the speaker terminals on the voice coil.  Also check your DMM internal resistance by connecting probes and subtract that resistance from your reading.  (My DMM has .8 ohm resistance internally, so I would subtract that from whatever I read).  You will get a reading that is somewhat less than the coil's nominal impedance, so multiply the number by 1.3 to get the impedance.  For example, if the 12's are D6 and you read the resistance across one coil, the reading might be approx. 4.6 ohms.

On another issue, I hope the box you built will completely separate the different sizes of subs, and that you use one amp for the 10's and another amp for the 12's.  You'll see this issue discussed frequently here if you do a search on the topic of mixing sub sizes.

interkooler:  Main speakers should be run at 4 ohms or higher, and subs can be run at lower than 4 ohms depending on the amplifier's capabilities.  The difference is in the frequencies that the different types of speakers produce;  higher freqs will tell you if an amplifier is straining, where lows will not.  SQ systems will typically run subs at 4 ohms, too...and oftern run components at 6 ohms or higher.  The higher the ohm load on the amplifier, the less current it produces and cleaner the output.....but lower wattage.  A lower ohm load on an amp will cause it to produce more current and higher watts....with a trade-off in sound quality.  At the sub level of frequencies you would likely not be able to hear the difference.





Posted By: interkooler
Date Posted: November 24, 2004 at 10:54 PM

another question, i have read that if i invert the poles on the speakers the ohms will get lower and give a better sound quality, is that true?





Posted By: stevdart
Date Posted: November 24, 2004 at 11:09 PM

posted_image

From a wiring guide.  This is an example of how two woofers with dual voice coils can be wired in two different ways to achieve different resistance loads on the amplifier.  https://www.jlaudio.com/tutorials/index.html 

Start a new thread with your questions, interkooler, so that this poster's thread doesn't get too highjacked. 






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