Exile XM20.1

[slavoise]

I purchased all my amps and am starting to re-think my under helm sub setup I plan to do. I purchased the XM20.1 in hopes of getting the new big 12 when it goes back into production, but I am not re-thinking the idea.

 

My question would be this: with that amp, is it possible to correctly run 2 subs? I'm thinking if I don't go with the big 12, that I may want to do 2 L7's or something like that under the helm. 

 

 

[Wylietunes]

You would want to go with two 4 ohm DVC woofers to yield the amps 1 ohm or 4 ohm rms. 

 

Or two 2 ohm DVC woofers to yield its 2 ohm rms

 

Two 12's woofers would be 2x the surface area of a single 12, obviously, but with no additional amp power. Thats WAY more moving air with the amp working no harder than with a single 12 woofer. Surface area is a more efficient way to produce output than woofer excursion.   

[slavoise]

When doing 2 subs on that amp, do you just half the rms and peak of the amp to figure out how much each sub is getting?

[Wylietunes]

The woofers will divide the amps output, what ever it is based on the woofers combined impedance.

[David Analog]

I completely agree with Wylie. There are two ways to make more bass within the context of a sub driver and before you consider the enclosure loading factor. Surface area and excursion. And surface area is the far more efficient way versus excursion. However, the bad news is that with double the surface area you need to also double the enclosure displacement. The good news is that a space 15.125" cubed is twice the displacement of a space 12.0" cubed. So much of this depends on the size and shape of space you have to work with.  

Subwoofer power handling really doesn't equate to subwoofer output. It's by no means a 1 to 1 ratio. Past a point, you won't get close to twice the acoustic output (+ 3dB) with twice the amplifier power. Things begin to compress rather quickly as those power levels continue to rise.

When it comes to subwoofer power handling, you won't see much correlation from brand to brand since this is essentially an unqualified spec. You should expect all 12" subs with a 3" voice coil to honestly handle 1000+ watts.   

[slavoise]

Appreciate the help and knowledge that you guys bring to the table! 

 

I was talking to my installer on the phone today and he was pushing me away from JL (saying he keeps having to replace surrounds) and that I should look at only marine grade subs. These 2 subs will be going under the helm, I don't expect them to see a lot of water at all. What is your thought on non-marine grade subs in a boat?

 

Thanks!

[Jake (((O)))]

I've never run a marine sub in 20 years of owning an inboard. Never lost a sub.

[David Analog]

The surround is not a factor on the newest JL Audio W6 subs as they are no longer foam. They are now rubber.

Foam is a better performing surround material for woofers with extreme X-max. But it will usually fatigue in a marine application within 7 to 8 years. I have seen evidence of foam failing earlier but it had to do with the flaws in system design and installation execution. Poor box building. Poor box design. Poor system tuning. Just like running your tires at high speeds when low on air pressure, you can accelerate the failure time.

The JL Audio 12W6 is a really, really excellent subwoofer! Works in a sealed enclosure of 1.0 cu.ft. net. That's small.  

[slavoise]

What is your thought on using the amp with 2 12W&-AE-3? They are 4 ohms...

 

Can they be wired correctly to that amp?

 

Will that amp be too much or not enough power? 

 

Will that amp work with 2 W7's? Or do I need 2 amps for that?

[Ship Faced]

When doing 2 subs on that amp, do you just half the rms and peak of the amp to figure out how much each sub is getting?

 

Not quite.  As stated, Impedance is where your answer lies. 

 

Abbreviated cliff notes notes on electrical theory as it relates to speakers: (gosh I hope these rambling analogies make sense) Remember, I said abbreviated.

 

Watts = Work.  Horsepower is another unit of work. I like work.

 

Ohms = Resistance  Exactly, that resistance to the flow of electrons. "Impedance" is more complex, but its basically the teenage sister of resistance - more complicated and changing but basically serving the same function in the convoluted electrical household - resistance to electron flow.  

 

Circuit = The path that connects opposing charges.  In order to move these electrons, we have to give em a road that connects + to - .

 

 

 

In order to do any work in a circuit we need to resist the flow of electrons, we sometimes refer to this in the audio world as 'load' (see light bulb above) - for today, think of this load like a toll booth: slow down and then keep going.

 

Loads come in two basic flavors:

 

Resistive loads generate heat - think toaster wire.  With this flavor, the resistance pretty much stays the same.

 

Inductive loads generate magnetic fields - think electric motor or speaker.  Inductive loads actually change their resistance as they're used (This is where "impedance" is used instead of "resistance"), ignore this complicated nuance for purposes of this discussion.

 

How we wire speakers plays shenanigans on resistance and therefore work as expressed in watts. 

 

Take the following examples:

 

 

Series:

I've got a one lane road (circuit), I have to slow down for 3 toll booths.  My dump trucks of music have to slow down 3 times - that's going to reduce the amount of work "watts" that happens at my music fun factory. 

 

Make Sense?

 

Wiring in series as shown below, the restriction (Impedance) adds up.  Every electron in the circuit has to fight its way through successive restrictions as it travels.

 

 

 

Now lets confuse things a little.

 

Parallel.

 

 

With this configuration, I effectively added two lanes to my road (circuit) and every dump truck full of music only needs to slow for one toll booth.  Wahoo!  Now my music fun factory has more dump trucks of music pulling in because they only pass one toll, not 3 like above.   Wiring in parallel the resistance is cut by the number of paths we give current to move through.  (if each path has the same impedance)     

 

When we add more load to a circuit with everything else staying the same (voltage), we can do less work.  That's why you see amplifiers rate their watts differently at different ohm loads. 

 

It all comes down to how you wire the speakers and what ohm speakers you're using. 

 

 

If the above analogies are carried to far, the caveats will make me an internet liar.  At face value, it should present as simple truth.

[slavoise]

Not quite.  As stated, Impedance is where your answer lies. 

 

Abbreviated cliff notes notes on electrical theory as it relates to speakers: (gosh I hope these rambling analogies make sense) Remember, I said abbreviated.

 

Watts = Work.  Horsepower is another unit of work. I like work.

 

Ohms = Resistance  Exactly, that resistance to the flow of electrons. "Impedance" is more complex, but its basically the teenage sister of resistance - more complicated and changing but basically serving the same function in the convoluted electrical household - resistance to electron flow.  

 

Circuit = The path that connects opposing charges.  In order to move these electrons, we have to give em a road that connects + to - .

 

simple circuit.gif

 

 

In order to do any work in a circuit we need to resist the flow of electrons, we sometimes refer to this in the audio world as 'load' (see light bulb above) - for today, think of this load like a toll booth: slow down and then keep going.

 

Loads come in two basic flavors:

 

Resistive loads generate heat - think toaster wire.  With this flavor, the resistance pretty much stays the same.

 

Inductive loads generate magnetic fields - think electric motor or speaker.  Inductive loads actually change their resistance as they're used (This is where "impedance" is used instead of "resistance"), ignore this complicated nuance for purposes of this discussion.

 

How we wire speakers plays shenanigans on resistance and therefore work as expressed in watts. 

 

Take the following examples:

 

 

Series:

I've got a one lane road (circuit), I have to slow down for 3 toll booths.  My dump trucks of music have to slow down 3 times - that's going to reduce the amount of work "watts" that happens at my music fun factory. 

 

Make Sense?

 

Wiring in series as shown below, the restriction (Impedance) adds up.  Every electron in the circuit has to fight its way through successive restrictions as it travels.

 

 3.jpg

 

Now lets confuse things a little.

 

Parallel.

 

4.jpg

 

With this configuration, I effectively added two lanes to my road (circuit) and every dump truck full of music only needs to slow for one toll booth.  Wahoo!  Now my music fun factory has more dump trucks of music pulling in because they only pass one toll, not 3 like above.   Wiring in parallel the resistance is cut by the number of paths we give current to move through.  (if each path has the same impedance)     

 

When we add more load to a circuit with everything else staying the same (voltage), we can do less work.  That's why you see amplifiers rate their watts differently at different ohm loads. 

 

It all comes down to how you wire the speakers and what ohm speakers you're using. 

 

 

If the above analogies are carried to far, the caveats will make me an internet liar.  At face value, it should present as simple truth.

Damn son... Great way to explain it! That totally makes sense now. 

[slavoise]

So based on a wizard I found and assuming I go with 2 W6's below is the ohm load on the amp. I'm assuming based on what I see the amp will work fine with it.

 

 

[David Analog]

Before we get carried away with basic Ohm's Law, let's consider we are not talking about a simple DC light bulb or resistor with an infinite supply. An amplifier is a far more complex animal. The amplifier power supply is a fixed resource that will facilitate only so much current. Once you reach the wall...that is all you get. For example, you will notice that the amplifier produces 25% more power at half the impedance load instead of 100% more power as Ohm's Law would suggest. Cut the output load impedance in half again and you get little to no additional power (you hit the wall), efficiency continues to drop like a rock, and you have runaway thermals issues.  

[David Analog]

Yes, two JL Audio 12W6s with both VCs in parallel and with both subwoofers in parallel would produce a 1-ohm load for 1000 watts per each subwoofer. Given the conservative way that JL Audio subs are rated, the fact that the 2000 watts is with a 14.4V supply which you won't achieve, the actual power would hit the sweet spot for those subwoofers.

One big amplifier is definitely enough. Too much current draw and the voltage supply begins to radically sag and the amplifier(s) produce less and less real power. There is an optimum efficiency with everything. You may have found it.  

[slavoise]

Winner winner chicken dinner! Thanks!!! Now for the build and pics to follow!

[bagger103]

I put my big 12 in a ported box under the helm with the same amp and holy crap!!!! It hits so hard!! I love it

[David Analog]

slavoise,

Reach out about whether you're running sealed or ported.

Sealed is pretty straight forward. For ported there are techniques to cut down the enclosure size a bit but without compromising the port surface area.

[Ship Faced]

Before we get carried away with basic Ohm's Law, let's consider we are not talking about a simple DC light bulb or resistor with an infinite supply. An amplifier is a far more complex animal. The amplifier power supply is a fixed resource that will facilitate only so much current. Once you reach the wall...that is all you get. For example, you will notice that the amplifier produces 25% more power at half the impedance load instead of 100% more power as Ohm's Law would suggest. Cut the output load impedance in half again and you get little to no additional power (you hit the wall), efficiency continues to drop like a rock, and you have runaway thermals issues.  

 

I figured you'd come back with some rebuke of this simple analogy once I saw you post above.  I was just trying to convey the basic concept of output to load and how the speakers are wired can change that.  I don't think I got "carried away"

 

Did you hear me say "This applies to everything all the time."

 

Hell, I even stated "If the above analogies are carried to far, the caveats will make me an internet liar."    

 

Dude, I'm not trying to compare electrical knowledge dicks with you, but by all means continue to wave yours about for the benefit of ego instead of helping the OP.   I'm sure its a big one, but that doesn't mean average folks want to see it all the time.  That post was about you pontificating.  

 

I cede.  You win. 

 

You made a liar out of me on technical nuances that don't really help anyone and I openly admitted existed to the fault of my explanation.

 

Congrats. You are the Ron Jeremy of electrical dicks.  Though distinctive, you're still kind of a dick.

 

Slavoise, the above technical posturing courtesy of Analog can be boiled down to:  "Amplifiers can only send so many dump trucks of music through a circuit to the fun factory.  If you create a road that has less impedance "restriction" than what they're designed for, you're not going to get more work out of them as linear math above would suggest, in fact they'll get pissed off at you and burn up."    

 

 

I don't sound as smart as Analog, probably aren't... I'm okay with that; But I'm no simpleton.   

[adam4x4]

4-12's one 2500 amp

[David Analog]

Ship Faced,

My comment about not getting carried away was directed at slavoise because I wanted him to know that there is no free ride when it comes to more and more power at lower and lower impedance loads. I think that is in fact very relevant to his project. I meant to supplement your message....not rip it apart. I agree with all that you stated within the context that it was delivered. Have a great day.   

[Ship Faced]

Ship Faced,

My comment about not getting carried away was directed at slavoise because I wanted him to know that there is no free ride when it comes to more and more power at lower and lower impedance loads. I think that is in fact very relevant to his project. I meant to supplement your message....not rip it apart. I agree with all that you stated within the context that it was delivered. Have a great day.

 

My bad. Guess I assumed the "carried away" was directed at the holes in my simple explanation. Read the wrong tone of your words, I guess. Apologies.

[Wylietunes]

Appreciate the help and knowledge that you guys bring to the table! 

 

I was talking to my installer on the phone today and he was pushing me away from JL (saying he keeps having to replace surrounds) and that I should look at only marine grade subs. These 2 subs will be going under the helm, I don't expect them to see a lot of water at all. What is your thought on non-marine grade subs in a boat?

 

Thanks!

Ill be the first to say, a 100% marine built woofer is not always needed in every application. However, there are some advantages of a marine built woofer, and some of these features can be found on non marine woofers. First and foremost, is the cone material. I suggest steering clear of any woofer that has a paper based cone. These can be described with such words as laminated, overlay, cellulose, pulp, etc. This means the cone is paper and likely has a layer over top. Some may tout a carbon fiber dust cap, but thats not the cone. Its by no means ideal for the humid environment of a boat. Look for a cone thats 100% synthetic material. Look for a woofer with a synthetic spider over cotton as well. 

 

The Kicker woofers all have rubber surrounds and synthetic cones. I think all now have enclosure magnets. Many have aluminum baskets over steel, if not all of them now.  As an added bonus, Kicker now offers a marine grill for the L7 series that are loaded with RGB LEDs. They come in gray, white and chrome. 

[slavoise]

Bringing this back from the dead...

 

Exile still says 6-8 weeks on expected time for the new big 12... I don't want to wait that long.

 

Here is what I'm planning (if I can fit them) 2 JL 12W6 in a sealed box at the drivers foot.

 

Here is my question for those who have removed the plastic there... is there enough room? Do you know roughly how wide this area is? My boat is currently 5 hours away from me. I want to get my subs ordered so when I pickup the boat in a few weeks I can have everything ready to bring to my installer.

 

My second question is: how easy is it to get the black plastic footwell off?

[brucepalombo]

Remember though, you drop the amp load on the amp and you drive the workload on the amp. Havasu running 115 in the summer, you amp will be able to cook eggs at 1 ohm.