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Discussion Starter #1
say u have a 500 watt sub and 500 watt amp

do two of those subs on the same amp yield more output? how about 4?

i know it's a very broad but doesn't everyone pretty much face that type of decision once you have a capable amp?
 

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say u have a 500 watt sub and 500 watt amp

do two of those subs on the same amp yield more output? how about 4?

i know it's a very broad but doesn't everyone pretty much face that type of decision once you have a capable amp?
It depends on what your impedance amp is stable to, and how beefy a power supply it has.

Example: Let's say you add a 4 Ohm sub rated to 500 watts to that single-channel 500 watt amp.

You get 500 watts.

Now, let's say you add TWO 4 Ohm subs, in parallel (positives hooked together and negatives hooked together) you are now presenting the amp with a 2 Ohm load.

If the amp is really well built, the amp will give you 1,000 watts - so each sub will get 500 watts, and your overall sub volume will be 3 dB louder.

Most amps will not "double down" like that...so you can expect, assuming the amp is 2 Ohm capable, power in the neighborhood of 700-800 watts with most brands.
 

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Discussion Starter #3
what about same power?

let's say like one of those regulated JL Amps?
 

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say u have a 500 watt sub and 500 watt amp

do two of those subs on the same amp yield more output? how about 4?

i know it's a very broad but doesn't everyone pretty much face that type of decision once you have a capable amp?
Let's for the sake of argument take a specific amplifier. In my example we will use the Sundown Audio SAZ1500D
manufacturer ratings at specific ohm loads
We will take them as 100% accurate. We will not figure for impedance fluctuations or efficiency differences at differing loads or different input voltage increases or decreases etc.
4 ohms 400 watts
2 ohms 800 watts
1 ohm 1500 watts

1 4 ohm sub wired will get 400 watts max
1 2 ohm sub will get 800 watts max
1 1 ohm sub will get 1500 watts max

2 8 ohm subs wired parallel for a 4 ohm load will share 400 watts (200 watts each)

2 4 ohm subs wired parallel for a 2 ohm load will share 800 watts (400 watts each)

2 2ohm subs wired parallel for a 1 ohm load will share 1500 watts (750 watts each)


4 8 ohm subs wired parallel for a 2 ohm load will share 800 watts (200 watts per sub)

4 4 ohm subs wired parallel for a 1 ohm load will share 1500 watts (375 watts per sub)

The power output is dependent on the impedance of each subs coil configuration and how it/they are wired. You can have 4 16 ohm speakers wired parallel for a 4 ohm load or a series wiring configuration for 2 2 ohm subs for a 4 ohm load and still only get 400 watts out of the amp.
Does this answer your question?
 

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You're forgetting the increase in cone surface area. Doubling the cone area and keeping the same 500W will in theory increase the output by 3 dB.
 

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So it only works that way if the power is increased at the same time as adding a second sub?
 

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When you add a sub in parallel the amplifier will attempt to double power, thus the second driver sees approximately the same amount as the original. In series the current (P=VI) at each sub will be cut in half=1/2 the excursion, so even adding 2X Sd you limit excursion by 1/2 and it comes out a wash.
 

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Discussion Starter #9
again, an amp like a jl slash 500?

one 500 watt sub or two of them? what's the output difference in that scenario, final ohm load should not matter correct?
 

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You are supposed to get +3dB from doubling the cone area (off the same power) or doubling the power, in theory, and +6dB if you do both. You can go ported and raise the dB as well, or tune higher for more dB up there, etc. But that is the math not reality, so you might see more or less hard to say, even doubling the box space in the car might change what you end up with. I've never added another sub to a car system and not heard an increase in output. You also need 10X the power to be twice as loud (+10dB) with no other changes, by the math. That is why doubling the power is not a huge change, neither is halving the power.
 

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Discussion Starter #11
cool, so same power from my example on 2 subs = 3db output, got it
thanks
 

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say u have a 500 watt sub and 500 watt amp

do two of those subs on the same amp yield more output? how about 4?

i know it's a very broad but doesn't everyone pretty much face that type of decision once you have a capable amp?

The rule of thumb is that doubling cone area keeping power constant increases SPL by 3dB.
 

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It depends on what your impedance amp is stable to, and how beefy a power supply it has.

Example: Let's say you add a 4 Ohm sub rated to 500 watts to that single-channel 500 watt amp.

You get 500 watts.

Now, let's say you add TWO 4 Ohm subs, in parallel (positives hooked together and negatives hooked together) you are now presenting the amp with a 2 Ohm load.

If the amp is really well built, the amp will give you 1,000 watts - so each sub will get 500 watts, and your overall sub volume will be 3 dB louder.
3dB louder is doubling cone are on the same mount of power. Another +3dB comes from doubling power.
 

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You're forgetting the increase in cone surface area. Doubling the cone area and keeping the same 500W will in theory increase the output by 3 dB.
No, because you are cutting the power in half. Each sub is getting 250 watts now.

Remember:

double power = 3 dB gain.
Double speakers = 3 dB gain ( if each speaker gets the same amount of power).

So your scenario plays out like this:

Cut power from 500 to 250 on one speaker = 3 dB loss
Add second speaker with 250 watts to second speaker = 3 dB gain.

So...your scenario cancels out. Same volume.

Unless you wire subs in parallel and amp power doubles...then each sub gets 500...so you get your 3dB gain.
 
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