enhancing sound system - Page 2

scott_fx · 05-11-2008, 03:41 PM

those are some good reads!

rijndael · 05-16-2008, 02:52 PM

thanks Scott for jumping in and explaining it better than i could....but what i was trying to say (and im pretty sure i said it but dopey got it switched around) was that he shouldnt run a 4ohm speaker at 2ohms...however...if he has an amplifier that is running 2ohms he can lengthen the wire to create the resistance level he needs (I may have worded it wrong and led you to believe you get 2 from 4...not the other way around...you create resistance...not lose it)...either way...hes not running it at 2 ohms, but it was a suggestion because he may want/need more power.

ill find that site sometime tonight and ill post it here...i found it by accident the first time...

AWehmeyer · 05-16-2008, 02:57 PM

It doesn't work that way. You can change the amount of power that the amplifier makes by adding resistance either in series or in parallel. If you put a resistor in parallel with the speaker, the amplifier will make more power. The speaker will see the same amount as before and the rest of the pwoer will be turned into heat in the resistor. If you put the resistor in series, or add more wire, the amplifier will make less power and the power that it makes will be divided between the speaker and the resistor in inverse proportion to the resistance of the two components. In either case, the speaker doesn't get any more power.

rijndael · 05-16-2008, 03:01 PM

but doesnt the resistance change so that it doesnt damage the speaker?

rijndael · 05-16-2008, 03:16 PM

here...this isnt the exact place where i found it the first time...but this should answer your question..

http://www.newton.dep.anl.gov/askasc...0/phy00028.htm

EDIT: Here is another one better explaining what i mean. If i am wrong and resistance itself does not hurt the speaker...please let me know...cause that was one thing i thought hurt speakers...im a computer guy...i have my local audio shop handle my audio and i try to learn as much as i can...

http://www.wavetechnology.org/FREEBI...gauge_dave.pdf <<<yes...its a PDF

also, since the current flowing from the amplifier stays the same (100W is 100W)...doesnt he end up with 100W at 4ohm by doubling the length of wire but with less stress on the amp itself creating less heat and thus longer life of the amp?

scott_fx · 05-16-2008, 05:27 PM

the resistance of the wire is doubled, not the total resistance of the speaker

rijndael · 05-16-2008, 07:05 PM

alright...now i think you guys are just messin with me...when did i honestly say that the resistance of the speaker changes?

resistance has to do with energy...not a speaker...use your heads people...lol

lbridges · 05-16-2008, 09:21 PM

Quote: Originally Posted by rijndael

1) If i am wrong and resistance itself does not hurt the speaker...please let me know...cause that was one thing i thought hurt speakers...
2) since the current flowing from the amplifier stays the same (100W is 100W)...doesnt he end up with 100W at 4ohm by doubling the length of wire but with less stress on the amp itself creating less heat and thus longer life of the amp?

1) Resistance doesn't hurt the speaker. What hurts speakers is overdriving the amplifier. When overdriven an amplifier begins to turn a musical sine wave into a square wave. This causes overheating as well as putting out a lot of power at frequencies not intended (a pure square wave would have an infinite frequency spectrum and a 100% duty cycle on the speaker - it could never cool down).

2) Assume a speaker with 2-Ohms Resistance. The wire leading to it will likely have less than 0.1-Ohm Resistance, resulting in the amp 'seeing' 2.1-Ohms. Doubling the length of the wire then results in the amp seeing 2.2-Ohms (the speaker didn't change). A potentially nasty side effect would probably be induced by too much wire - coiling a wire would cause unwanted inductance - resulting in a low-pass filter effect.