In Reply to: Impedance question, please help me Mr. Wayne posted by Gabriel on July 23, 2003 at 09:37:17:
I'm not Wayne, but I can help you out with this... Assuming you are using all passive crossovers, your final system impedance will vary from frequency to frequency. It always does, but it will moreso in this case. Generally speaking, the amp will see a 2 ohm load from 400 Hz and up, and a 4 ohm load below that. If your amp is designed to, it will deliver twice as much power into the 2 ohm load as it will the 4 ohm load. At reference, this will effectively cause the midrange to play at 99db and the high range to play at 98 db, with the woofer stuck at 94 db. However, this is not necessarily a bad thing. If you are building passive circuits, you can pad both the tweeter and midrange to match output with the woofer. If you are running an active, triamped system, you can simply adjust the gains on each amp to match.Adding a second woofer in parallel will increase system sensitivity to 97 db, but with the addition of a second amplifier (thus doubling power) it'll bring it to 100.
Adam
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