# Impedance and Phase Plots

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#### GordB

Hi everybody.

I'm still working on my design here. Working in Vituixcad 2 running simulations.

Here is a 2 woofer 2 mid range bass reflex cabinet design.

I have posted the impedance and phase plots here, and would like some feedback.

Minimum impedance is 3.24 ohms at 153 Hz.

My questions are:

What would the nominal impedance of this cabinet be?

Are there any issues with phase?

My amp is a two ohm capable class D. Is this a safe load?

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#### Robh3606

I would say 4 ohms, I would think your amp should be fine rated at 2 ohms.

Rob

#### GordB

Thanks Rob.

Can you offer an opinion on phase?

#### Robh3606

Can you offer an opinion on phase?

Sorry no, I typically just don't worry as long as it doesn't go to low. We need an amp guy to chime in hear to address current demands of phase vs Imp

Rob

Roger!

#### Lojzek

Worst case current demand will be when you multiply Z by cos (phase angle). So at 153 Hz; Z=3.24; phase= about 15 deg; Real part of Z = 3.24*cos(15)=3.13

#### GordB

I'm not real sure what you mean here.

Are you saying the minimum impedance is actually 3.13 ohms?

Btw you are bang on the money at 15 degrees.

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#### Lojzek

Correct, it is called resistance.

#### GordB

OK.

Now, can we infer the nominal impedance of this loudspeaker from this information?

#### Robh3606

I am sticking with 4!

Rob

#### GordB

Thanks again Rob.

#### eriksquires

It is safe, but lots of amps would sound weak in the bass as a result. This is what commercial speakers call "discerning" of amplifiers.

#### GordB

Hmm

It is safe, but lots of amps would sound weak in the bass as a result. This is what commercial speakers call "discerning" of amplifiers.

This amp is a Mesa d800+. It's rated by the manufacturer at 400 watts into 8 ohms, 800 watts into 4 or 2 ohms.

At 10% distortion mind you. So more likely 300/600 reasonably clean.

B&O Icepower 700 S1 module equipped if I'm not mistaken.

I can say however that it will generate a ton of spl with a good cab.

But that's a topic for another thread.

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#### GordB

One more question:

Is it safe to infer that this would be a 4 ohm nominal cabinet?

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