Help on Mono Block Class-D Amp

[Phatmat 10+ year member]

I am a bit lost in choosing an amp, but have a few in idea. The sub I am mostlikely going to run with is the Kicker CompVR. However, the frequency response of the CompVR (12") is 25 - 500Hz (http://www.kicker.com/compvr). The amp I would like to buy says: "Variable low-pass filter (50-200 Hz at -24 dB per octave)". Does this mean the sub can only perform frequencies up to 200Hz (sub: Kenwood KAC-8104D, http://www.kenwoodusa.com/Car_Entertainment/Amplifiers/KAC-8104D).

I was firstly curious about the question above, wondering whether the amp can deliver the full frequency range of the sub. Secondly, what amp would you recommend I use to power the Kicker CompVR 12"?

1) Pioneer GM-D7400M Mono

2) Pioneer GM-5300T Car Amplifier 2 Channel (Bridged)

3) Kenwood KAC-8104D Mono

Also, the amps can only deliver half their power when at 4 Ohms compared to 2 Ohms. Would it be best if I buy the 2 Ohm CompVR then, would this give me more power?

Any help will be great, thanks.

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[dman4486 5,000+ posts]

I am a bit lost in choosing an amp, but have a few in idea. The sub I am mostlikely going to run with is the Kicker CompVR. However, the frequency response of the CompVR (12") is 25 - 500Hz (http://www.kicker.com/compvr). The amp I would like to buy says: "Variable low-pass filter (50-200 Hz at -24 dB per octave)". Does this mean the sub can only perform frequencies up to 200Hz (sub: Kenwood KAC-8104D, http://www.kenwoodusa.com/Car_Entertainment/Amplifiers/KAC-8104D).
I was firstly curious about the question above, wondering whether the amp can deliver the full frequency range of the sub. Secondly, what amp would you recommend I use to power the Kicker CompVR 12"?

1) Pioneer GM-D7400M Mono

2) Pioneer GM-5300T Car Amplifier 2 Channel (Bridged)

3) Kenwood KAC-8104D Mono

Also, the amps can only deliver half their power when at 4 Ohms compared to 2 Ohms. Would it be best if I buy the 2 Ohm CompVR then, would this give me more power?

Any help will be great, thanks.

A subwoofer is intended to hit sub-bass frequencies. most of the time people cross a sub over at around 80hz. You do not want your sub trying to play above that frequency. the mids in the front of your car should pick up from ~80hz and go up from there.

Now for power, Kicker recommends 500wrms. So choose how many drivers you want, then figure out what resistance you will run and then figure out what amp will supply the power you need.

That being said, yes an amp will put out more power at lower resistance. It however will most likely not be double what it is a 4ohm. The ratings on amplifiers are typically 4ohm ratings and the 2ohm is calculated and fudged a little to make them look better.

 

[Phatmat 10+ year member]

Sorry, with that Kicker CompVR link I gave you need to click the 12" (Max Rec Amplifier Power (WATTS PEAK/RMS)* 800/400).

I am wondering, Kicker says:

Max Rec Amplifier Power (WATTS PEAK/RMS)* 800/400

How do I know whether this is at 4 Ohms or at 2 Ohms? Or would the 2 Ohm model be 400w RMS and the 4 Ohm model be 400w RMS also?

Though, will 4 Ohms run with more bass, as it required more power? Because what is the advantage of running at 4 Ohms, compared to 2 Ohms where double the wRMS can be achieved?

 

[brynm 10+ year member]

2/4 ohms just gives you more wiring options, and yes the power rating of a sub is not dependent on the impedance of the sub.

 

[dman4486 5,000+ posts]

Sorry, with that Kicker CompVR link I gave you need to click the 12" (Max Rec Amplifier Power (WATTS PEAK/RMS)* 800/400).
I am wondering, Kicker says:

Max Rec Amplifier Power (WATTS PEAK/RMS)* 800/400

How do I know whether this is at 4 Ohms or at 2 Ohms? Or would the 2 Ohm model be 400w RMS and the 4 Ohm model be 400w RMS also?

Though, will 4 Ohms run with more bass, as it required more power? Because what is the advantage of running at 4 Ohms, compared to 2 Ohms where double the wRMS can be achieved?

4 ohm would be more efficient, but the amp could not put out as much power.

The vr comes in a dual voice coil 2ohm or 4ohm configuration. with the d2 you would be able to run at either 4ohm or 1ohm. with the d4 you would be able to run 2ohm or 8ohm. With the amps you posted, you would have to get the d4 and wire it to 2ohm.

 

[Phatmat 10+ year member]

Why do you say 4 Ohm is more efficient? By efficient what do you mean, does it use less power?

Also, I'm not sure if this was answered and I just missed it, though is the only benefit of running 4 Ohm compared to 2 Ohm the power efficiency? I would then technically get more bass running at 400wRMS 2Ohm than I would running at 200wRMS 4Ohm?

edit: Also, if my amp is 500wRMS and I need it to be 400wRMS, nearly all amps have the ability to be turned down right, is it just a switch or something?

 

[brynm 10+ year member]

Why do you say 4 Ohm is more efficient? By efficient what do you mean, does it use less power?
Also, I'm not sure if this was answered and I just missed it, though is the only benefit of running 4 Ohm compared to 2 Ohm the power efficiency? I would then technically get more bass running at 400wRMS 2Ohm than I would running at 200wRMS 4Ohm?

edit: Also, if my amp is 500wRMS and I need it to be 400wRMS, nearly all amps have the ability to be turned down right, is it just a switch or something?

The efficiency is the ratio of actual power produced versus the power used. A more efficient amp should run cooler and be easier on your car's electrical system. Yes your subs will be louder with 400 watts than they will be with 200.

You use the gain, or on the kenwood the input sensitivity to set the output of the amp. You set it to match the output voltage of your cd player