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Stereo Guys: amp question

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Old 03-14-2006, 03:59 PM
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Default Re: Stereo Guys: amp question

this amp can run 2 ohm or 4 ohm, or am i misunderstanding something, cant i get a high powered 2 channel amp that will produce somewhere around 150w rms x 2 channel x 4ohm, then split them so each channel has 2 speakers, thus playing 75w rms x 2 channel x 4 ohm?
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Old 03-14-2006, 04:19 PM
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Default Re: Stereo Guys: amp question

Quote:
Originally Posted by Boomer35
this amp can run 2 ohm or 4 ohm, or am i misunderstanding something, cant i get a high powered 2 channel amp that will produce somewhere around 150w rms x 2 channel x 4ohm, then split them so each channel has 2 speakers, thus playing 75w rms x 2 channel x 4 ohm?
What the amp will produce is based on the load it "sees" at it's outputs. Your speakers, their impedance, and their efficiency dictate what you will get out of an amp, and what the effective loudness will be.

You wouldn't "split" the outputs of the two channel amp. You would combine the speaker leads using either the parallel (both hots together and both grounds together creating a 2 ohm load in the process ) or series (route from the output to one pole of a speaker, through that speaker, over to the other speaker, and then back to the other output on the amp like a loop, maintaining the 4 ohm load.)

When you parallel a pair of speakers you double the impedance, which halves your ohm load rating. (8 becomes 4, 4 becomes 2)

When you bridge, you turn the unit into a single channel "push-pull" amp and you further increase the resistance and drop the Ohm rating.

You need two bridged stereo amps for stereo, because they each become a mono amp in the process of bridging.

back to the answer to your question.

Your amp will work. It will be loud enough if your speakers have an efficiency of say... 89 dB or above.

It takes double the amp power to create 3 additional dBs of sound. So... 1 watt 1 meter 1 k= 89dB becomes 2 watts 1 meter 1 k 91dB

4 watts 94 dB
8 watts 97
16 watts 100
32 watts 103
64 watts 106
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Old 03-14-2006, 04:34 PM
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Default Re: Stereo Guys: amp question

what about a 4 channel amp, that is 100w x 4 channel @ 4 ohms but its max wattage, not rms 100w???, the rms wattage on that would be less right, say 50ish

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Old 03-14-2006, 04:39 PM
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Default Re: Stereo Guys: amp question

so with the amp i mentioned in the first post, i would take one speaker, splice it into the next speaker wire, thus creating the series, plug in the leading speaker wire into the 150 rms @ 4 ohm channel, and this would produce me 75 w rms @ 4 ohm on each speaker, then repeat this on the other side for the other 2 speakers, into the other channel, and i should have 4 speakers, recieving 75w rms @ 4 ohms
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Old 03-14-2006, 04:55 PM
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Default Re: Stereo Guys: amp question

Fund, I think you got one piece wrong in your description. Wiring 2 speakers in series that are both 4 ohms does not maintain a 4 ohm impedance. When you wire in series, you add the loads up, in this case giving you an impedance of 8 ohms.
This assumes of course, that I remember something from my days as an installer. The possibility that I do not is very real.
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Old 03-14-2006, 04:58 PM
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Default Re: Stereo Guys: amp question

Not sure. We could chase our tails for hours if we don't use the same language.

Here is a link to a pdf with a great diagram of series vs. parallel and the explanations of each.

http://www.installdr.com/TechDocs/999016.pdf
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Old 03-14-2006, 05:03 PM
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Default Re: Stereo Guys: amp question

Rainmn...

My "not sure" was for the previous question.

I spent way more years doing home than car, and more years doing pro than homes.
Inverse square law... right?

You are making me second guess myself rainmn.
I almost got up and went and found my meter.

Now I have to go read that pdf....
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Old 03-14-2006, 05:06 PM
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Default Re: Stereo Guys: amp question

Dam Rainmn.

You're right!

Tells you how often I used series.

In this case he may need a bigger amp because he will get less from the amp with an 8ohm load than a 4ohm load. (What, maybe 40% less?)

The good news is that the amp will run cooler at 8 than it would at 4.
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Old 03-14-2006, 05:10 PM
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Default Re: Stereo Guys: amp question

Ok... I was full of chit on the resistance of a series load.
That's how you know that it was off the top of my head.

The rest was legit.

Sorry Boomer.

Good catch Rainmn. One more guy a owe a beer ona long list.
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Old 03-14-2006, 05:42 PM
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Default Re: Stereo Guys: amp question

Quote:
Originally Posted by Boomer35
this amp can run 2 ohm or 4 ohm, or am i misunderstanding something, cant i get a high powered 2 channel amp that will produce somewhere around 150w rms x 2 channel x 4ohm, then split them so each channel has 2 speakers, thus playing 75w rms x 2 channel x 4 ohm?
IF this amp can run on a 2 ohm load DO NOT RUN ANYTHING IN SERIES.

Run them in parallel - run speaker wires from 2 speakers to the left side of the amp and 2 speaker wires to the right side of the amp.

Done deal - simple!
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