Contour Enthusiasts Group Archives Forums Modifications Audio Ohms, Watts, and conversions

Hey guys... hopefully some of you are more up on your electronics engineering than myself, as it's been a while since I've done this stuff. Anyway... Question;

I have an 200W 8 ohm impedence, 3.6 ohms DC resistance speaker. I have a 280W Amp. The power rating on the amp is at 4 ohms. Someone who recalls calculations involving impedence and all that jazz help me out, what kind of power would the amp be feeding that speaker? Do I need to worry about blowing the speaker, or can I crank it fearlessly?
I'm pretty confident the amp will remain stable, as it's designed to be stable at 2 or 4ohms, and it's a high current amp. Any help?

The impedance and resistance of the speaker throw me off in this case. Typically an 8ohm impedance will have a resistance somewhere around 5.5-8 ohms. I have never come across anything this low before.

About the amp...at worst, the amp will be providing 140 watts to the speakers. At the Fs or resonant frequency of the driver, the amp will see something closer to the 3.6 ohm figure and will be pushing closer to the 280 watt figure.

Did that help?

Are you going to be bridging the amp or running it in stero mode?

Also who is the maker of the amp?

"I have an 200W 8 ohm impedence, 3.6 ohms DC resistance speaker"

dnewma04 is right your speaker should be 5-7 ohm dcr. What you have is a 4ohm speaker in front of you. If you have a 2 channel amp you can bridge it to that speaker with out a problem. AS for blowing you speaker, unless you pump strait distortion (turn your bass all the way up on the radio and loudness on is a pime example) you should be fine.



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Commonsense may not be as common as I thought

Ooops, you guys were right... don't I feel like a dumbass? The DCR is 7.3 ohms. I got my papers mixed up... Does this affect your calc's at all Dave?

Keyser, none of that matters, but if you really want to know, it's a Sony, model XM1002HX. It's 100W x2, bridged to 280 x1. The sub is a Rockford Fosgate 1810, to break that down simply, rockford puts their specs in their model no.'s, it's a single voice coil (1810), 8 ohm (1810), 10" sub (1810). And since it is SVC, I can't run it stereo anyway. I can run it off the left channel of the amp and feed it 100W, but I'd rather feed it off the bridge, as long as I'm not going to blow it, as this is what happened to the Kenwood I had (even though the kenwood was rated at like 230RMS and 500 max, yeah right).

[This message has been edited by Goody (edited March 30, 2001).]

The speaker should see 200 watts from the amp because it'll be bridged into an 8 ohm load. Should work perfectly.

Sweet, that's what I was hoping for. Thanks much, I just needed someone to double check my un-scientifically backed theories. I went to school for electronics engineering for a couple semesters, but have forgotten most of that stuff except the very basics, and math never was my friend...

It would have mattered if it was a Radio Shack amp and had .3 thd and wasn't bridgable. Just didn't know the facts to give an analysis. With what you have you should be fine.