Ohms

[Scott]

<font color='#000000'>Can someone give me &quot;non-techie&quot; explanation of speaker ohms (8,6,4) and their performance relationship to amplifier power....?</font>

 

[Guest]

<font color='#000000'>As I understand it . . .

An ohm is the unit of opposition to current flow. &nbsp;It is a unit of resistance. &nbsp;RESIST. &nbsp;RESIST. &nbsp;The lower the number, the greater the resistance (4 ohms is twice as resistant as 8). &nbsp;The greater the resistance, the more your amp is asked to work. &nbsp;Believe it or not, a speaker works by resisting current.

Most receivers are content to do enough work to &quot;push&quot; current through an 8 ohm load. &nbsp;When a speaker with more resistance (6/4/2 ohms) is connected, the receiver's amp has to work much harder to push that current into the speaker's innards. &nbsp;When the amp isn't up to the task, it goes into thermal overload (overheats), sends a distorted signal, even blows a speaker.

Why 8 ohms as the accepted mass standard? &nbsp;Dunno. &nbsp;Possibly because 8 ohms is mathmatically enough resistance to make drivers reproduce sound from 20Hz-20kHz. &nbsp;

Basically, if the speaker is too resistant, the amp can't get the signal through; if it's too &quot;loose&quot; (16/32/64 ohms) then the drivers may not work hard enough to produce acceptable sound.

For your sake, and mine, I invite any technophiles to correct or improve upon my offering.</font>

 

[RDL]

<font color='#000000'>Speaker impedance directly affects an amplifier.   A lower impedance results in the amplifier having to supply more current.  This is because the relationship between power and current is:

                              I^2( R ) = P
I = current
R = impedance
P = power

With this in mind, a speakers impedance only limits your amplifiers maximum volume level.  The lower the impedance, the lower the over all SPL level your amplifier will be able to produce before it clips.  You should also know that a speakers impedance rating is usually rated in &quot;nominial&quot;, which means when the speaker is standing still.  All speaker impedances change throughout thier frequence response.

An example:
Say a speaker is rated at 6 ohms nominial,  it is possible that it could drop to 4 ohms or even 3 ohms at lower frequences like 90Hz. 

Not really a big deal,  but if your amp can't handle such a low impedance then odds are the amp will clip. If you buy speakers with a low impedance, make sure you buy an amplifier that can handle them.  This well result in the best performance from your system.

I hope this helps.</font>

 

[Guest]

<font color='#000000'>Puzzled about the Orvis statement... &quot;The lower the number, the greater the resistance (4 ohms is twice as resistant as 8)&quot;. That ain't the way the truth. The higher the number, the higher the resistance. A pure short (0 ohm), has no resistance. Actually a speaker is rated by impedance. Impedance is the restriction of AC current flow. Resistance is usually the restiction of electrons in DC. Music is AC.</font>