Question regarding final impedance to 4 channel amp

[XJCJ]

For some reason I haven't seen this mentioned at all here unless Im missing a thread, but with the non-alpine system, if you have 4 ohm speakers in the dash and knees, that would be a final impedance of ~2ohms to the amp, yes? I have read that the front channels are wired in parallel so that would make it so. Trying to set gains on my amp with multimeter and just want to make sure I have the numbers right to calculate the voltage

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[CO2Wrangler]

In theory, that's correct. 4 and 4 in parallel would be 2ohms to the amp. I have the Alpine so can't confirm your particular case.

It's tough to find a 2ohm stable 4 channel amp but hopefully you've done your homework.

 

[XJCJ]

Im running the kicker 660.5, have been for a few months. Im just finally getting around to properly setting the gain, previously I just did the ear method but i had some spare time today

 

[Jebiruph]

I think it's a 4 in parallel with an 8, so 2.67 ohms.

 

[XJCJ]

I think it's a 4 in parallel with an 8, so 2.67 ohms.

I have replaced all stock speakers with 4ohm kickers. Also wouldn’t a 4 and an 8 be 6ohms?

 

[CO2Wrangler]

I have replaced all stock speakers with 4ohm kickers. Also wouldn’t a 4 and an 8 be 6ohms?

Nope. Ohms law is weird. It's the product of the impedances / sum of the impedances.

In your 8 and 4 scenario: 32/12 = 2.67

In your 4 and 4 scenario: 16/8 = 2

** This simplified math only works for 2 speakers. The real equation is 1/x = 1/Ra + 1/Rb + 1/Rc.... **

 

[Jebiruph]

Nope. Ohms law is weird. It's the product of the impedances / sum of the impedances.

In your 8 and 4 scenario: 32/12 = 2.67

In your 4 and 4 scenario: 16/8 = 2

** This simplified math only works for 2 speakers. The real equation is 1/x = 1/Ra + 1/Rb + 1/Rc.... **

That's seems easier than calculating the inverse of the sum of the inverses like I was taught.
1/(1/n1 +1/n2 +1/n...)

 

[Jebiruph]

I have replaced all stock speakers with 4ohm kickers. Also wouldn’t a 4 and an 8 be 6ohms?

Keep in mind that any parallel resistance will always be less than the lowest resistance involved. A 4 and 8 in parallel has to be less than 4 ohms.

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