Impedance

Posted: Mon Jun 16, 2008 4:37 pm

>_<

Posted: Wed Jun 18, 2008 2:32 pm

Impedence is when that german scientist started researching metals and found that some conducted electricity better than others. His name was (insert german first name) Ohm. That's all ohms is. A basic measurement of how much electricity will pass through a wire. How thick a wire is determines how much eletricity will pass through it, and also what type of metal.

Posted: Wed Jun 18, 2008 3:26 pm

Hi, I certainly agree with you. Your advice is really very helpful for us.
Thanks a lot!

Posted: Wed Jun 18, 2008 7:32 pm

It's a spammer, ban him!
Man, 265 posts all spam, how slow are the mods Rolling Eyes

Posted: Wed Jun 18, 2008 7:35 pm

I do keep wondering...

Posted: Wed Jun 18, 2008 7:44 pm

Um... I have a job...

Posted: Thu Jul 03, 2008 7:55 pm

Sidhu wrote:

Amps need to drive a speaker the same as or less than their output impedance

no, No, NO! First of all, you will never find a speaker with impedance levels that of amplifiers (way, way under 1 ohm). If you did this the overwhelming majority of the power would be dissipated in the AMP, not the speaker.

Amplifiers are VOLTAGE SOURCES - they need to have as low an output impedance as possible, and they are RATED to drive a certain amount of power into specific loads (e.g. 4 ohms, 8 ohms).

A stout power amplifier will continue to double its output power each time the speaker load is cut in half:

100 W into 8 ohms
200 W into 4 ohms
400 W into 2 ohms

Most amps can't do this for a number of reasons - insufficient power supply, insufficient current-sourcing capacity of the output devices are chief among them.

But amplifiers are NOT impedance-matched devices.

Posted: Thu Jul 03, 2008 9:07 pm

The one we have goes 90W into 8 ohms. 120W into 4 ohms Surprised

.
Terrible.

Posted: Thu Jul 03, 2008 10:20 pm

Here's an example of how impedance relates to output power.
From L-Acoustics' LA48A owner's manual:

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