Let's talk amplifiers and box rise

[SCATHED]

What's up fellas?

Let's discuss amplifiers and box rise. If impedance is raised two times (or more) due to box rise, does that mean you should use an amplifier that is double the subs rated power?

For example say you have a sub that is 1500 watts rms and wire it down to 1 ohm, is it wise to purchase an amp that is rated for 3000 watts rms at 1 ohm? And then set your gain as you normally would (dmm, dd-1, etc)?

[boom50cal]

no

different frequencies will give you different impedance curves.

wicks has graphs of his results in his build.

[Wicks]

no

different frequencies will give you different impedance curves.

wicks has graphs of his results in his build.

LOL

I saw "box rise" and had to jump in on this one.

There is SOOOO much more to "box rise" then just the box.

Its really "impedance rise" and its what speakers inside a box inside a cabin do.

There is no easy fix like just doubling amp power.

Different frequencies are going to have different effects on the system as a whole.

Then you have to factor in whether a window is open or a door or how many people are in the car.

Where the port is, whether you're playing a song or a tone.

You can see by my plot, my impedance ranges from 1.78 up to 12ohms.

If I upgraded my amp to handle 12ohms then when I played a 32Hz song(1.78ohms) or tone then as Doc Brown famously said...."You're going to see some serious shit!"

[ChevyBoy95]

no

different frequencies will give you different impedance curves.

wicks has graphs of his results in his build.

LOL

I saw "box rise" and had to jump in on this one.

There is SOOOO much more to "box rise" then just the box.

Its really "impedance rise" and its what speakers inside a box inside a cabin do.

There is no easy fix like just doubling amp power.

Different frequencies are going to have different effects on the system as a whole.

Then you have to factor in whether a window is open or a door or how many people are in the car.

Where the port is, whether you're playing a song or a tone.

You can see by my plot, my impedance ranges from 1.78 up to 12ohms.

If I upgraded my amp to handle 12ohms then when I played a 32Hz song(1.78ohms) or tone then as Doc Brown famously said...."You're going to see some serious shit!"

I had a whole set of paragraphs typed out, but I feel this is easier to understand due to actual implementation and graphical representation.

OP, look up AC impedance (what your amplifier is really "seeing") and compare it to DC resistance.

[ALPINE408]

well wicks just ended this thread thank you

[ShadeTreeMechanic]

Hey Wicks,

Is the red line voltage or current? Because of the inductive load the voltage and current will be out of phase with each other correct? Thanks, I'm learning a lot.

[Wicks]

Hey Wicks,

Is the red line voltage or current? Because of the inductive load the voltage and current will be out of phase with each other correct? Thanks, I'm learning a lot.

Indeed they are and that leads into a clamping discussion which is also greatly misunderstood.

The plot is color coded. Look at the vertical labels on the sides and the Legend at the bottom.

Blue is impedance. Red is phase angle.

The green circles are where the phase angle is zero which means that the voltage and current are in phase.

Also note that that's where the impedance changes direction.

Where the red line changes direction is where the phase angle is +180 or -180 degrees out of phase.

Pretty interesting how all these factors are interlinked and how the react with each other.

[_paralyzed_]

I only came here to say it's "impedance rise" not "box rise" as Wick's already pointed out. I understand none of it.

[ShadeTreeMechanic]

So when you clamp your amp, it looks like you are doing better than you are because you are not measuring phase angle. Does the SMD dyno measure phase angle?

[Wicks]

So when you clamp your amp, it looks like you are doing better than you are because you are not measuring phase angle. Does the SMD dyno measure phase angle?

The Amp Dyno AD-1 uses tones on a resistive load so phase angle is irrelevant. The AD-1 is mainly just to BRUTALLY test an amplifier to see what its capable of and debunk false manufacturer claims of power output.

The AMM-1 measures phase angle and real power on a live system so you can actually see what your system is doing.

Yes, because of phase angle clamping can be extremely misleading, yet some people will angrily yell at you that the ol' interwebs told them that Power = Voltage * Current..... SMH