Amplifier for 2.5kw Subwoofer

[Antoni Čović]

How big amplifier to get to beat impedence rise for 2.5kw subwoofer? 

[Joshdashef]

If you wire at 1 ohms look for amplifier ratings that get near 1.5k at 4 ohms and 2k at 2 ohms atleast 

If you wire below 1 ohms then look for ratings that get near 1.5k at 2 ohms and 2k at 1 ohms

However you could probably go higher than that, add another 500 to 1k rms to each of these values and that sub would definitely be moving

[Dragonsyph]

I would get something like a 4k, or a 3k or 3.5k that does rated at 12.6. 

I was asking the same question awhile back and everyone told me to go with a 5k amp for my 3000 watt sub. 

[Antoni Čović]

It's alphard db315. Well I have 4k right now.. But I think I need something bigger.. it's wired to 0.7ohm and I clamped 1800rms out of it.

[Dragonsyph]

19 hours ago, Antoni Čović said:

It's alphard db315. Well I have 4k right now.. But I think I need something bigger.. it's wired to 0.7ohm and I clamped 1800rms out of it.

What’s the amp you have?  Might be that ur amp can’t even do rated to start if it’s onky doing 1800 at .7.  In that case a real 4K might clamp 3 to 4K and 4K+ for dyno. 

Or it could be your electrical is not up to snuff .  What does ur electrical look like?  Bats, alternator, wire size and amounts?

[k58.cross]

Impedance changes greatly by frequency, and so does power draw. Low power draw doesn't always mean low SPL, because the system draws less power when it's operating efficiently and/or resonating. 

When you clamped, did you do it at the frequency where power draw is highest? If not, go back to low-medium power and sweep frequency while watching power draw. The highest power draw will probably be at a frequency that doesn't sound very loud, like 65 Hz or something. Clamp there.

[DiBo]

On 3/18/2019 at 4:12 AM, Antoni Čović said:

It's alphard db315. Well I have 4k right now.. But I think I need something bigger.. it's wired to 0.7ohm and I clamped 1800rms out of it.

What amp are you using? That sub takes a ton of power. An Apocalypse AAK-5500.1 @.5 Easily on that sub. I want some of those woofers haha. 

[Antoni Čović]

Amplifier is DB4000.1D with 180A alternator and 250ah batteries.. Voltage drops to 12.4-12.5v. When I clamped I tried few songs and then saw wattage.. tried both low and high bass songs.

Edit: Thinking about getting one more 100ah battery and  2x 15" 1.5kw rms subwoofers wired to 0.35ohm. I talked with alphard importer for my country and he said that its okay to wire that amp on 0.35ohm  if voltage don't drop under 12v.. but idk.. 

[k58.cross]

13 hours ago, Antoni Čović said:

Amplifier is DB4000.1D with 180A alternator and 250ah batteries.. Voltage drops to 12.4-12.5v. When I clamped I tried few songs and then saw wattage.. tried both low and high bass songs.

Edit: Thinking about getting one more 100ah battery and  2x 15" 1.5kw rms subwoofers wired to 0.35ohm. I talked with alphard importer for my country and he said that its okay to wire that amp on 0.35ohm  if voltage don't drop under 12v.. but idk.. 

There will be specific frequency band in the bass spectrum where power draw is highest. You can download an app on your phone that's a signal or tone generator and just go through the frequencies until you see highest power draw. That's actually your worst case. The loudest bass notes are typically at port resonance and power draw will be low there (which is a good thing).

Your voltage dropping to 12.5 just means you used your alternator's current up and now you're drawing from the batteries as well. Adding another battery won't bring you back up to 14+ just FYI. 

Three batteries for 4kW...I don't know if that's excessive, but extra juice is always good. Each battery has a limit to how much instant current it can let out, so more batteries will let you handle those bursts better. It's up to you how much money you wanna spend and what you have room for.

[Antoni Čović]

4 hours ago, k58.cross said:

There will be specific frequency band in the bass spectrum where power draw is highest. You can download an app on your phone that's a signal or tone generator and just go through the frequencies until you see highest power draw. That's actually your worst case. The loudest bass notes are typically at port resonance and power draw will be low there (which is a good thing).

Your voltage dropping to 12.5 just means you used your alternator's current up and now you're drawing from the batteries as well. Adding another battery won't bring you back up to 14+ just FYI. 

Three batteries for 4kW...I don't know if that's excessive, but extra juice is always good. Each battery has a limit to how much instant current it can let out, so more batteries will let you handle those bursts better. It's up to you how much money you wanna spend and what you have room for.

I put biggest alternator it could fit.. probably one of few puntos mk1 in europe with  bmw 180a alternator  thats why batteries are my only option.. and with 350ah batteries I think i will be safe to not drop under 12v..