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Ohm vs Ohm

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buddrousa

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It all depends on the impedance and output power of the amp. A PA designed for a 4 ohm load works best with a 4 ohm speaker. A PA designed for a 8 ohm load works best with a 8 ohm speaker. Using the correct speaker with the correct PA makes the speaker sound better and the PA last longer.
 

gonefishn1

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They will be the same. The watt listed is the amount of input the speaker can handle and the Ohm is the impedance you should try to match to the amplifier output.
 

cmdrwill

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4 Ohm 5 Watt Speaker

Why?, the same voltage across 4 ohms is more power which is louder. E squared divided by the resistance equals power..
 

AZ_chris

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It's going to a CDM1550.
I have both so I didn't know which would be louder. I don't know what the CDM1550's rating is for Ohms on the speaker output either (I believe it's 4 ohms)...

If cmdwill says 4 Ohm, i'll go with that.
 

jonwienke

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Louder is not "better".

At a given input voltage, a 4-ohm speaker will be louder than an 8-ohm speaker.

BUT (and it's a big hairy one)

If you use a speaker with a higher impedance than the amp is designed for, you will have quiet output.

If you use a speaker with lower impedance than the amp is designed for, you will blow the amplifier.

DO NOT use a speaker with a lower impedance than what the amp is rated for. Look it up, the spec should be easy to find online.
 

SteveSimpkin

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According to the specifications for a CDM1550, the external speaker amplifier output is rated at 13W maximum into a 4 Ohm speaker. Therefore your 4 Ohm 5W speaker is underrated and could be damaged at high volumes. While not an ideal match, the 8 Ohm 8W speaker would be a safer choice if you could not find a 4 Ohm speaker rated at 13W or higher.
http://www.staleycom.com/documents/specifications/CDM1550_Specifications.pdf
 

Rred

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You don't present any criteria for "louder". If the speaker that is rated at a higher maximum amperage, is really 1/2 as efficient as the lower rated speaker, then the "more powerful" speaker will actually be WEAKER. Regardless of how you match impedances and systems.

And "loudness" should always come back to a reference in decibels (db) at a given power input level, and a given specific frequency, as in "95db for a 20W input at 5,000 KHz" as well as a specific THD (total harmonic distortion) rating. Which might be 0.005% THD for a really good audiophile system, or 2.0% THD for a cheap car stereo.

Without any reference to sound levels (in db, with or without other data) there's no reason to even guess which speaker might be "louder". If I had to roll the dice, I'd say "whichever one is bigger" or has a bigger magnet on the back, might be the louder one.
 

AZ_chris

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Rred, I think you're overthinking it a little for a simple two-way radio speaker...
Doesn't matter as the question got answered.
 

Rred

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That could be, Chris. Just plug in anything, and it usually works. If "works" is the only concern.
"Works really well" is a whole other ballpark, in pretty much everything.(G)
 

buddrousa

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And you are taught in electronics school to match speakers to amps. Other wise you risk killing the amp speaker or both. Things are designed and built for a reason and those specs should be followed for reasons. Your way of thinking is that SWR means nothing as long as it works. You are guessing those of us that are educated know.
 
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