Ohms question

[bigtexashonk]

1 - 8 ohm cab run with 1 - 4 ohm cab + a 6 ohm load. Correct or not?

[Chef]

Not.

2.67

[Chazinroch]

That's right 2.67 ohms. The lower the ohm number the less resistance. Less resistance draws more power. That why amps rated at 4 ohms start to over heat and/or burn up when paired with a 2 ohm speaker load.

[bassmeknik]

yep, 2.67 ohms (or 2 2/3 ohms if you prefer)

[ThisBass]

Originally Posted by bigtexashonk

1 - 8 ohm cab run with 1 - 4 ohm cab + a 6 ohm load. Correct or not?

1 - 8 = -7
1 - 4 = -3

- 10 + 6 = -4

Correct or not?

[Chef]

In terms of ohms, that^^^^^^is totally wrong.

[ThisBass]

Originally Posted by Chazinroch

That's right 2.67 ohms. The lower the ohm number the less resistance. Less resistance draws more power. That why amps rated at 4 ohms start to over heat and/or burn up when paired with a 2 ohm speaker load.

Appro 3 Ohm

Unlikely the "average" amount runs below 3 Ohm

[two fingers]

2.67 Ohms. Reciprocal formula. More here.

http://www.tpub.com/neets/book1/chapter3/1-26.htm

[B-string]

No Parallel: RT = (R1R2)/(R1 + R2)
4X8 / 4+8= 2.6666.......... Rounded to 2.67

[Kmonk]

As already mentioned 2.67 ohms.

[ThisBass]

Originally Posted by Chef

In terms of ohms, that^^^^^^is totally wrong.

but

SQRT(-1) = j [ohm]

[B-string]

If you would like to rewrite the books be my guest, won't make it correct. Formula and links have been offered.

[ThisBass]

Originally Posted by two fingers

2.67 Ohms. Reciprocal formula. More here.

http://www.tpub.com/neets/book1/chapter3/1-26.htm

I'm not at school but thinking about the real physics of speakers.

You can't predict the impedance unless you measure the impedance with a proper frequency band measuring voltage and current.

Most of the time the impedance calculates a bit above the nominal.
Depending on EQ settings the impedance varies upwards to higher values (most of the time).

But, ..so what.

[ThisBass]

Originally Posted by B-string

If you would like to rewrite the books be my guest, won't make it correct. Formula and links have been offered.

That's right, but understanding Formulas is a very different animal

edit:
Sorry I was wrong, I tried to tell:

Adaptation of Formulas

[Chazinroch]

The OP stated this:

1 - 8 ohm cab run with 1 - 4 ohm cab + a 6 ohm load. Correct or not?

But I think they meant this:

1 - 8 ohm cab run with 1 - 4 ohm cab = a 6 ohm load. Correct or not?

2.67 is correct.

[ThisBass]

Originally Posted by B-string

No Parallel: RT = (R1R2)/(R1 + R2)
4X8 / 4+8= 2.6666.......... Rounded to 2.67

That's not wrong (theoretical) but does not reflect the behavior of a real terms 8 Ohm and 4 Ohm speaker.

[Chef]

No.
one 8ohm cab with one 4 ohm cab = 2.67 ohms, as has been said many times in this thread already.

Originally Posted by Chazinroch

The OP stated this:

1 - 8 ohm cab run with 1 - 4 ohm cab + a 6 ohm load. Correct or not?

But I think they meant this:

1 - 8 ohm cab run with 1 - 4 ohm cab = a 6 ohm load. Correct or not?

2.67 is correct.

[B-string]

Speaker are rated for nominal impedance, the point in the pass-band they present the maximum load on the "amp". This is the figure of concern and a simple resistance formula can apply. In reality speakers have inductive and capacitive reactance (to a much smaller degree) as well.

IF you limit the "speakers" to a frequency much higher than lowest part of the impedance curve then you will need to calculate that new impedance. From there you can use the same resistance formula to obtain the new load presented.

[ThisBass]

Originally Posted by ThisBass

1 - 8 = -7
1 - 4 = -3

- 10 + 6 = -4

Correct or not?

That was meant to be a joke

[B-string]

You forgot the