Loads on components?

[Trendkill 10+ year member]

Ok so lets say I have a 2 way component set (woofer and tweeter) and they are 4 ohm speakers. Is there any difference in resistance between these two setups:

a.) 2 channel amp, woofer and tweeter on the same channel, run through supplied crossover

b.) 4 channel amp, each speaker run off it's own channel, only the crossover in the amp is used

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[Keeshwah 10+ year member]

The load is identical in both scenarios. You're just describing the difference between an active and a passive setup.

 

[Trendkill 10+ year member]

In setup "a" there are two speakers on one channel, so you would have to run them in series or parallel, which would be 8 or 2 ohms respectively, right?

In setup "b" there is one channel for each speaker so the speakers would remain at 4 ohms?

I'm confused.

 

[headless 10+ year member]

Crossovers are whack. Drivers aren't hooked up in parallel or series when through a passive x-over - the x-over causes the amp to see a 4 ohm load.

 

[Trendkill 10+ year member]

that seems to clear things up. So crossovers for a 2 way setup have a pos/neg for input, woofer and tweeter for a total of 6 connections?

EDIT: Also, in setup "a", do both speakers see 100w if the amp is putting out 100w per channel? Or would it be split 50w to each?

 

[helotaxi 5,000+ posts]

The speakers in a passive setup are in fact wired in parallel. The corssover acts like a resistor whose value changes with frequency. For a low pass filter, the impedance of the crossover itself increases as the frequency increases past the filter frequency. A high pass filter works exactly the opposite. Wire the two in parallel and the result is that the impedance of one half of the circuit approaches infinity as the other approaches the nominal impedance of the driver on that half of the circuit. The total result is that the nominal load "seen" by the amp is the same as the driver that is playing that given freq. If the mid was a 4 ohm and the tweet was an 8 ohm, the amp would see 4 ohms below the crossover freq and 8 ohms above and somewhere between the two right around the crossover freq.

 

[DejaWiz 5,000+ posts]

that seems to clear things up. So crossovers for a 2 way setup have a pos/neg for input, woofer and tweeter for a total of 6 connections?
EDIT: Also, in setup "a", do both speakers see 100w if the amp is putting out 100w per channel? Or would it be split 50w to each?

Short answer - both speakers get 100W since the mid and tweet are receiving that power at different frequencies from the amp.

 

[Trendkill 10+ year member]

Thanks guys. Great answers //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif