Powerplant amp vs 12 DVC

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bryzaa

Member - Posts: 22

Joined: March 29, 2006

Location: New Zealand

Posted: April 23, 2006 at 7:36 PM / IP Logged

I have just bought a FP-1000D Fusion D-Class powerplant amp and I am planning to run it on my Boshmann ZD-12XAL Competition dvc 12" sub and I am just wondering about the power that my sub will be able to handle. I have tested my power output from my Battery wire to my amp and have 14.2v when the car is running, The factory specs sheet says my amp will do @ 12.6v 450w at 4 Ohm and 725w at 2 Ohm it also gives me specs which don't add up it Says @14.4v 575w at 4 Ohm and 1000w at 2Ohm. Now when I work this out watts per volt at 14.4 volts I should get @ 14.4v, 514w at 4 Ohm and 828w at 2Ohm. My sub is rated at 750 rms and I don't want to blow it to smithereens just yet so have considered using the 8 Ohm circuit, but just to be fancy I am installing the relay switch to change between 2 and 8 Ohms, I just want to know that would the spec sheet be right in assuming 1000w at 2 Ohm as this would be overpowering my sub quite a bit as apposed to 828w, with the gain turned right down shouldn't be too much of a problem, right? Any comments would be appreciated

I have included a link to the online spec sheet for my amp - http://www.fusioncaraudio.com/products.php?action=view&product_id=89

Bryzaaa

bryzaa

Member - Posts: 22

Joined: March 29, 2006

Location: New Zealand

Posted: April 23, 2006 at 7:42 PM / IP Logged

Could I even put some form of resister in the amp power wire to bring it down to 12.6v that would be a safer level to run my sub

Bryzaaa

sprawl85

Copper - Posts: 204

Joined: March 15, 2006

Location: United States

Posted: April 23, 2006 at 8:12 PM / IP Logged

check it with a multimeter and see how much it is really putting out. The subs should have came with a spec sheet. It should have a dcr listed there. Most of the time on dvc subs it is listed with both coils in parralel anyways, but check and make sure. What you'll do is wire it to the amp 2 ohms. Then make sure you have the gain turned down and play a 60hz test tone. Turn the gain up a lil bit at a time and take measurments of ac voltage with the multimeter. then use

P=E^2/R

P is the power rating in watts you will get

E is the ac voltage

and R is the dcr number you got from the subs spec sheet

So say you test it at 50 volts ac and the dcr in the manual was 2.6ohms

50*50 is 2500

2500/2.6 is 961 and change and that's how many watts it would be puttin out.

This is a good estimation. No need to choke the amps power off when you can just turn the gain down and set it this way.

fiberglass reminds me of peanut brittle... but fiberglass tastes better!

stevdart

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Joined: January 24, 2004

Location: Pennsylvania, United States

Posted: April 23, 2006 at 8:29 PM / IP Logged

sprawl85, why wouldn't you use nominal impedance for R?

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

bryzaa

Member - Posts: 22

Joined: March 29, 2006

Location: New Zealand

Posted: April 23, 2006 at 8:31 PM / IP Logged

The actual resistence of my subs read with dmm are 2 x 3.7 Ohm so I could wire It up at 1.85 Ohms or 7.4 Ohms. I am just a little worried that at less than 2 Ohms I will be drawing even more power and It is already near its rated limit

Bryzaaa

stevdart

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Joined: January 24, 2004

Location: Pennsylvania, United States

Posted: April 23, 2006 at 8:37 PM / IP Logged

bryzaa wrote:

It also gives me specs which don't add up it Says @14.4v 575w at 4 Ohm and 1000w at 2Ohm.

It shouldn't necessarily add up. Those are supposed to be real test figures. More often than not, an amplifier will not double the power output with half the load because of limitations in it's engineering.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

bryzaa

Member - Posts: 22

Joined: March 29, 2006

Location: New Zealand

Posted: April 23, 2006 at 8:46 PM / IP Logged

Im not refering to lack of power when halving the resistance, believe me I have more than enough power here. I am refering to the power (watt) per volt. Shouldn't it have the same power per volt at 14.4v as it does at 12.6v as the resistance remains the same??

Bryzaaa

stevdart

Platinum - Posts: 5,816

Joined: January 24, 2004

Location: Pennsylvania, United States

Posted: April 23, 2006 at 8:53 PM / IP Logged

You would think so. But you might as well be looking at only the 12.6 numbers because the load on the power supply isn't going to allow a voltage as high as 14.4 while running your system anyway.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

bryzaa

Member - Posts: 22

Joined: March 29, 2006

Location: New Zealand

Posted: April 23, 2006 at 8:56 PM / IP Logged

Sweet so the load on my system should drop the power a little but the slightly lower resistance of my sub should make up for some of that by drawing a more powerful load from the amp right? So if I am getting at 12.6v 725w rms at 2 Ohm would I get around 800w - 820w at 1.85 Ohm?

Bryzaaa

stevdart

Platinum - Posts: 5,816

Joined: January 24, 2004

Location: Pennsylvania, United States

Posted: April 23, 2006 at 9:30 PM / IP Logged

You need only be concerned with nominal impedance. The typical DCR of a 4 ohm woofer is about 3.4 ohms. Use impedance, not DCR, so just look at it from the standpoint that you are putting a 2 ohm load onto the amp.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

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