Trying to figure out proper ohms to hook up 2 subs

Spyro

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I ordered two JL Audio 12" w3v3 4 ohm single voice coil subwoofers rated at 500w RMS. The box I got has two separate terminals, one for each sub, so I can't wire them together. I have a hard time understanding the RMS wattage that comes out from the amplifier when the two subs are hooked up to it. So I could buy a JL Audio Monoblock XD 600/1 which has 600 W x 1 @ 2 ohms, 500 W x 1 @ 3 ohms, and 400 W x 1 @ 4 ohms. Which in this case, since both speakers are the same, @ 4 ohms, it would be pushing 200W to each sub correct? Or would it become 2 ohms giving 300w each? Any wattage below 500 each speaker would be safe to prevent overload basically. But I also have an extra amp laying around which is an Autotek SM1-1500 Monoblock which is rated a lot higher but @ 4 ohms 375 W x 1 and @2 ohms 750 W x 1. and if i could save a few bucks I might use the this one.
 
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Esotericimage

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Well you would need to get either 2 mono amps or a dualchannel amp.

Id get matching amps. Since its a 4ohm svc its pretty simple. But having 2 different amps with 2 different outputs isnt the way to go..

How much bass you trying to do? I have a single 10 in a sealed custom box and my kicker 300.1 is only at 1/3rd on the gain and its quite loud. But for me, i like my music and movies loud and clear. Just not full of bass.

But maybe you want to be heard from down the street.. idk
 


Spyro

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Well I'm going to use just one mono amplifier, and generally speaking, th subs become parallel once they get wired to the amplifier. I'm trying to split the voltage between both subs. I want loud bass but not where its gonna blow up my glass. I have one 12 inch kicker solo baric L5 4 ohm wired to 2 ohms pushing 300 watts rms on a jl audio 300/1 xd series amp and the subwoofer alone is rated at 600 watts rms 1200 peak. I was going to put it in my camaro, but I dont want the glass to shatter on the hatch because the speakers have to be face up, thats why I'm putting the jl audio subs instead
 

Esotericimage

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Ahh no.. your doing it wrong.

Dont wire up 2 speakers to 1 amp.
 


lethal6

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You aren't breaking that back window with a single kicker 12. Even if you had enough power and equipment to push the 175db needed to break a back car window, you aren't going to be in the car when it happens. Your ears can't handle that.

Neither of your set ups are powerful enough to shatter tempered glass.
 

Spyro

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Okay sounds good to me, but I bought the subs already, so would the two subs together make the amp put out 2 ohms to power the subs?
 

lethal6

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If you wire 2 single coil 4ohm subs in parallel, the resulting impedance will be 2ohms.

The wiring manual for the amp will show how to achieve this safely based on its abilities. Either that or Google wiring how tos. There are hundreds of them, even videos.
 

HeX

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You had a Kicker solobaric sub tuned down, now want more bass, then purchased two stronger subs to also tune down? That logic doesnt make much sense. Unless you run an amp that cranks much higher RMS wattage than the sub(s), you wouldnt come close to blowing it out. You definitely dont have to worry about that with JL subs as theyre purposely underrated by a little over 20% for such reasons. But whats done it done.

Hook the subs up the proper way and get either a bridgeable monoblock amp in proper RMS range to the subs or get a 2-channel amp. Otherwise, you're defeating the purpose of buying quality JL subs. Sell your current amp & sub to recoop the funds.
 
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HeX

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Whatever happened to this set-up?
 

Spyro

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Sorry, life came by and took over lol. I ended up using the SM1-1500 autotek monoblock to push 375 watts @ 4 ohms with the custom box set up. The subs are knocking really hard and not killing anything. Power is constant and no distortion at all. Everything worked out great, I'll try to post some pics soon

20150604_141035.jpg
 
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HeX

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The box looks pretty good from that angle. Why did you use a non-bridgeable monoblock (one-channel) amp on two subs? Its rated 375 watts @ 4 ohms for one channel. It doesnt retain the same rating when you ghetto wire two subs into it, which isn't good for the amp. Did you even bother to calculate the box measurements to be within the subs' optimal range?

Once again, youre not utilizing the range of the quality 500watt RMS subwoofers you purchased. That one amp isn't even enough for one of those subs. You could've only used one sub and likely sound better than you do now. I hope you only plan to keep that set up momentarily until you get a proper amp for the set-up.
 

Spyro

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The box was custom built to spec by a JL audio dealer with the proper dimensions to fit the car and proper air space. And what your telling me is that I should be pushing 750 watts to ONE 500 watt sub @ 2 ohms so I can void the warranty? These are the specs from the amp: 1 x 375 W at 4 Ohms, 1 x 750 W at 2 Ohms, 1 x 1500 W at 1 Ohm Maxx Power
 

supaman

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HeX: you need to learn a little about car audio before you start giving out information.

Spyro: When wiring your subs, you could have gone 2 ways, parallel or series. Parallel would give you a 2 ohm load when you wire your 2 4ohm speakers (number of ohms divided by number of connections). Wiring in parallel would be the + of your amp to both positives of the speakers and - to both negatives of your speaker (think of it like a "Y" connection). A series would give you an 8 ohm load (number of ohms multiplied by the number of connections). This would be wired differently and you don't an 8 ohm load so don't worry about it. And wiring 2 subs to a monoblock amp is not ghetto rigging anything. The amp does not know if you have 1 or 100 speakers connected to it, your ohm load is what matters. My guess is you have it wired into a 2 ohm load. And as far as power, my guess is that autotek amp is not putting out anywhere near the power that it is stated. You are not going to blow out the glass in your hatch with your set-up even if you were to properly supply power to those subs (which is the 500w rms). I typically try to over power the sub around 10%, that RMS wattage is what it can continuously handle, so you will not blow the sub by giving it that power. Ignore peak power, that crap is for marketing. Your set-up looks good though, JL subs are really nice, i'd upgrade to the jl amp in the future if you can, would probably sound a lot cleaner.
 

HeX

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Please read my previous response again as I answered this exact question. Perhaps you misunderstand what an amplifier channel is.

A channel on am amp mean one line per sub or voice coil. In your case, youbs are single voice coil, so each sub should have its own channel.

Your JL sub's are 4ohms each. They each handle 500watts RMS max. Your amp is rated at 375 watts RMS @ 4 ohms for ONE CHANNEL, not two. Therefore, the amp is still underrated to power one single JL sub, but its just fine to power just one.

Have that one-channel amp rigged to split its max 4ohm 375watt RMS wattage to power two 4ohm subs. The amp can't split power evenly through each individual wire strand splitting between each sub so each sub will get waving uneven power at around half of those 375 watts, which is roughly 162 watts per sub. Thus, each 500watt capable sub is only receiving about 160watts of power. With that amp, you're only using roughly one-third of each subs capacity. Hence, two-thirds of your sub cost is not being utilized. I simply cannot break down the explanation any further that this.
 

HeX

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I get what you mean, Supaman. Except that his amp isn't bridgeable so those SVC sub's can't be wired in series or in parallel. Hence, they must be "ghetto rigged" by having 2 sets of wires running out its one channel instead the one set of wires and the individual line(s) in between each sub. A lot of shop rig setups as I described, and just because it works doesn't mean it should be done. Besides, that's just a shame when he spent that money on awesome subs and a nice box.
 

supaman

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HeX: An amp does not care about voice coils, it cares about resistance. That one channel only means it is supplying a certain amount of power at that one channel at certain ohm resistance. His amp has 1 channel, capable of supplying power at 2ohms, stated at 750w for that channel. So as long as you end up with 2ohms on that channel is is supplying that power, it can be 1 or a billion subs. He has 2 subs, both with a single 4 ohm coil, so when he wires those in parallel fashion, he has a 2 ohm resistance on that single channel, and is being fed 750 watts. I think you are just confused, nice car by the way.
 

supaman

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HeX: you posted in the midst of my post. 1. I agree, it is a shame that he has spent the money on the quality JL sub and not amp, but that happens a whole lot. 2. It is not "rigging" this is how it is suppose to be wired. Parallel and series are not dependent on that amplifier, they are wiring methods to achieve ohm loads. Bridging an amp just means that you are combining that power from separate channels into 1 signal, which typically results in a higher power rating and lower ohm stability. His amp isn't bridgeable because he does not have separate signals to be bridged. I have been doing this stuff for about 15 years now, and although this is my 4th post on this forum, you can see I have been here for a long time.
 

HeX

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Supaman, it definitely doesn't help that we're basically replying while the other is responding but at least we're slowly getting on the same page ;-)

So please correct me if I'm wrong. I've understood in my experience that it is incorrect to hook up 2 separate pairs of wires to a monoblock amp. It can be done but it shouldn't for the reason I previously stated. I personally won't for the reasons I said regardless of what others may do. I simply refuse to set up a system to perform less than optimally. Its just not logical to underutilize quality equipment. (This is where I'd post a picture of Spock)
 


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