# 4 ohms vs. 8 ohms



## Sonically_Sound (May 26, 2011)

I am getting together a new 2-way active set up and I am wanting to go with raw Seas Prestige U18RNX/P as my mid but, they are 8 ohms. My amp produces 115 watts at 4 ohms per channel so that would be cut in half to 57.5 watts.

My question is: How much will the sound level change? I am reading that it will drop 3 decibels.

For those who have used 4 ohm and 8 ohm speakers how big of a difference in the loudness? Could it be considered a deal breaker?

If I can't go with those Seas drivers I am either going to get some CDT ES-6's or Morel Dotech 6's. The Seas seem to be on par with the CDT and Morel drivers for $100 dollars less. So, if the impedance issue isn't a big one I'm just going to go with them.

Thanks for any advice!!


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## 96jimmyslt (Jan 31, 2011)

The only reason I would ever go with 8ohm speakers is if I already had a 4ohm amp.

Since the wattage gets higher the lower the ohms, most, if not all amps are geared towards 2ohm or even 1 ohm.

8ohm is obviously OLDER technology and rarely used.

I have an 8 ohm 10" 250w rms sub and I am powering with a 4ohm amp and it sounds fine.

But I would still get 4ohm speakers if you are buying.


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## t3sn4f2 (Jan 3, 2007)

Here's a thread on the topic by the person who started this site.

http://www.diymobileaudio.com/forum/how-articles-provided-our-members/31-real-deal-8-ohm-drivers.html


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## haibane (Sep 29, 2005)

I have to clear a few things up from this post.


96jimmyslt said:


> Since the wattage gets higher the lower the ohms, most, if not all amps are geared towards 2ohm or even 1 ohm.


Its better stated that as there is less resistance less of the power is lost. Power doesn't really change its just dissipated differently based on the load it passes through. Power lost to heat etc...


96jimmyslt said:


> 8ohm is obviously OLDER technology and rarely used.


8 ohms isn't an older technology. It is a home audio standard and therefore people still make them. It makes the most sense for home amplifiers etc. Different voltage. Different current etc.

However yeah I do agree I would just go with a 4 ohm myself because its simply easier. I don't know that is as much of a loudness adjustment as it is a loss of dynamics due to the lack of less extremes.


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## MiniVanMan (Jun 28, 2005)

Uggh! I hate going back and rehashing this stuff, but what the hell.

Here's a little experiment. Something you probably all did in the 5th grade.

Here's what you need.

1 - 6, or 9 volt battery. 6 volt has better current potential.
1 - Iron Nail
1 - roll of copper wire.
1 - paper clip


Take a designated length of copper wire and roll it around the nail. Attach each end of the wire to the battery. Anybody remember from 5th grade what this does? Judge how strong the electromagnet is by testing the force exerted on the paperclip.

Now, do this again, but double the length of wire windings around the nail, thus doubling the resistance of the wire. Now, you have half the voltage, but double the windings. Is the force now stronger, or weaker than before?

This is absolutely no different than a speaker. More windings creates a stronger electromagnet to interact with the magnetic field of the speaker magnet. Less voltage, but more force being exerted. 

Less heat generated inside your amp at double the impedance, therefore more efficient power, which means, that you really can't say that a 100 watts at 4 ohms is only 50 at 8 ohms. That would require a 100% efficiency and that simply doesn't exist.

More efficient amp, more efficient speaker. Hmmmm, sounds like a win/win for higher impedance speakers.


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## unpredictableacts (Aug 16, 2006)

96jimmyslt said:


> The only reason I would ever go with 8ohm speakers is if I already had a 4ohm amp.
> 
> Since the wattage gets higher the lower the ohms, most, if not all amps are geared towards 2ohm or even 1 ohm.
> 
> ...


:laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh:
Research is your friend.


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## 96jimmyslt (Jan 31, 2011)

unpredictableacts said:


> :laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh::laugh:
> Research is your friend.


So they actively manufacture 8ohm subs now?

And they had 4, 2 and 1 ohm subs years ago?


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## jcollin76 (Oct 26, 2010)

96jimmyslt said:


> So they actively manufacture 8ohm subs now?
> 
> And they had 4, 2 and 1 ohm subs years ago?


Yeah more in home audio, but used quite a bit in car audio as well. Kinda the premise of diyma.. implementing raw drivers from home audio, or purpose built car audio, and using whatever gives you the best sound in your application and install. LOTS of guys here using 8ohm speakers, and 4, and 3, and 2, and 1...


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## haibane (Sep 29, 2005)

96jimmyslt said:


> So they actively manufacture 8ohm subs now?
> 
> And they had 4, 2 and 1 ohm subs years ago?


Depends. I mean they do, but they aren't directed toward car use. People still buy them and use them in cars though. Also it really depends on the wiring to answer your years ago thing. subs capable of wiring 4,2,1 ohms have been around for quite a while. Not so much 1 ohm, but definitely 4,2. DVC subwoofers have been around for at least 30 years if not 70.


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## jcollin76 (Oct 26, 2010)

t3sn4f2 said:


> Here's a thread on the topic by the person who started this site.
> 
> http://www.diymobileaudio.com/forum...d-our-members/31-real-deal-8-ohm-drivers.html


^^^^If you haven't read this, do. Lot of good info I think would help you out a lot.


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## MiniVanMan (Jun 28, 2005)

96jimmyslt said:


> So they actively manufacture 8ohm subs now?
> 
> And they had 4, 2 and 1 ohm subs years ago?


OH NO'S!!!! Them pro audio people don't know what they're doing. Somebody better tell them they need 1 ohm subs to make your chest implode.

Peavey 18" Low Rider Subwoofer Speaker Driver

Selenium 18SWS800 18" 800W Subwoofer

Peavey 18" Low Max Subwoofer Speaker Driver

Eminence Delta Pro-18A 18" Driver 8 Ohm

Ahhhh, hell, just about every woofer/subwoofer on this page.

18" Professional Audio Drivers


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## subwoofery (Nov 9, 2008)

Been there, done that... 

Kelvin


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