Can I add another sub to my mono amp?

[DubStyle311 10+ year member]

Hey,

Right now, I am running a JL 12w3v2 with a Crossfire VR600 600watt monoblock amp.

I love the setup but I find that I cannot get the sub to play at a loud enough level unless I crank up the volume on the HU. If i want to listen at a talking level, the sub is barly audible.

I am considering adding another 12w3 and I would like to know if you guys think that my 1 channel amp can handle it.

Right now i belive its running at 600rms @ 1ohm. I am looking at the instruction manuel and it says that it runs at 300rms @ 2ohm.

My questions:

A) Would it be possibly to simply buy the speaker and a single box, and wire it into my current amp?

B) Would I get a similar sound level as my friend who runs a JL 500/1 amp and 2 10w3v2s in 1 box?

Click to read more...

 

[JimJ 5,000+ posts]

As long as the impedance is equal to or above the amp's minimum safe rating, you'll be fine.

 

[bimma85 5,000+ posts]

As long as the impedance is equal to or above the amp's minimum safe rating, you'll be fine.

Also might wanna make sure that to stay above that load, that you dont have to go too high.

As for your buddy, depends on the install car etc. His amp will give his subs 500 watts with pretty much any load it sees. However if you wire your subs up at 2 ohms, they may only get 300 watts total.

have you tried a different box? Is it sealed or ported?

 

[DubStyle311 10+ year member]

the amp manuel says its input impudence is 20Kohms

how would i go about figuring out what 2 12's would be?

 

[JimJ 5,000+ posts]

Ignore the input impedance, it's the load impedance you're concerned about.

 

[DubStyle311 10+ year member]

thanks for the advice guys

i wont be doing the install so it sounds like this job will need a really good install on it so i might go hit up these real professional install guys, even tho theyre gonna charge me out the ***...

 

[bimma85 5,000+ posts]

thanks for the advice guys
i wont be doing the install so it sounds like this job will need a really good install on it so i might go hit up these real professional install guys, even tho theyre gonna charge me out the ***...

More than half the shops here wouldnt touch my car if they paid me, just make sure they actually know what they are doing //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. Hope ya enjoy it....what box is it in?

 

[DubStyle311 10+ year member]

Also might wanna make sure that to stay above that load, that you dont have to go too high. As for your buddy, depends on the install car etc. His amp will give his subs 500 watts with pretty much any load it sees. However if you wire your subs up at 2 ohms, they may only get 300 watts total.

have you tried a different box? Is it sealed or ported?

Just out of curiosity, how difficult would it be to wire two indivual sealed boxes to the monoblock amp at 1ohm?

Like does wiring it at 1 ohm make the wireing job a lot more difficult?

 

[jujumantb 10+ year member]

Just out of curiosity, how difficult would it be to wire two indivual sealed boxes to the monoblock amp at 1ohm?
Like does wiring it at 1 ohm make the wireing job a lot more difficult?

not hard.

the problem with adding a second sub to an amp is that, generally, adding a second sub will double the impedance, making your amp put out half the power it did with the single sub. So you double your cone area, but halve the power.

That may have been confusing, look at it like this.

Say your amp puts out 600watts @ 1 ohm and is only stable donw to 1 ohm, nothing less (as most monoblocks are). Now say your sub is a dual 2 ohm, so wiring the sub's coils in parallel gives your amp the 1 ohm load, allowing it to put out all of its 600watts.

Now, say you want to add a second sub. You have to get an identical sub, so in this case, another dual 2 ohm sub which you wire down to 1 ohm like the first sub. So now you have, in effect, two 1-ohm subs you are trying to hook up to your amp.

If you wired them to the amp in parallel (both +'s together, both -'s together, it presents the amp with a .5ohm load, less than the 1 ohm load it is stable at, meaning it will likely go into protection, not work, or fry. So your only option is to wire them in series to the amp, presenting it with a 2 ohm load. Usually, a 600watt @ 1 ohm amp will put out only ~300watts @ 2 ohms. So instead of your single sub getting 600watts, your two subs are splitting only 300watts, meaning only 150watts per sub.

You can see how this is less than ideal.

 

[DubStyle311 10+ year member]

thanks a lot man, great answer

so basically unless my amp can handle a .5 ohm load then i really shouldnt add another sub,

yeah, just checked the manual and its a 1ohm min, guess im shit out of luck

thanks again

 

[jujumantb 10+ year member]

so basically unless my amp can handle a .5 ohm load then i really shouldnt add another sub,

Basically that is how I would look at it. I mean, its kind of hard to say how loud it would be in comparison, but I highly doubt it will be worth your while. Maybe somebody who has done this can chime in on an SPL difference. Cone area is always very important, especially if you're ported, but halving the power is a pretty big deal too. And plus, for me, just knowing that my amp is not being used to its full potential is kind of a bummer //content.invisioncic.com/y282845/emoticons/crying.gif.ec0ebefe590df0251476573bc49e46d8.gif

 

[DubStyle311 10+ year member]

lol, now i gotta see if i can convince my friend to trade me my crossfire amp for his 500/1