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boltdbz

Choosing a speaker amp

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So I'm getting an amp for my 6.5 Infinity Reference speakers, here are the specs:

Peak Power: 180 watts

Power Handling, RMS: 60 watts
Nominal Impedance: 3 ohms
Frequency Response: 53Hz-21kHz
Sensitivity (2.83V/1m): 93dB
"Nominal Impedance: 3 ohms"
What does this rating mean, and why isn't it at an even number of ohms?
Main question, when choosing an amplifier how do I match this rating to what output I will have?

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If they are 3 ohm speakers...then I would NOT get the RF pbr 300x4 as that is only meant for 4 ohm loads. You can look at the average of 2 and 4 ohms on an amp and figure about thats how much your speakers would be seeing.

Such as, the Rockford Fosgate p400x4 is rated at 50 watts rms x4 @ 4 ohms & 100 watts rms x4 @ 2 ohms. So if you were to use this amp, you can supply about 75 watts rms to 4 of these speakers. (Which is about what I would recommend, as long as you don't bring it into clipping)


'98 Chrysler Concorde LXi
Pioneer DEH-80PRS (HU/processing)
Rockford Fosgate T1652-S (components) for front
Rockford Fosgate T1693 (6x9s) for rear
Rockford Fosgate T600-4 running those
Rockford Fosgate T1500-1bdCP running a

Rockford Fosgate T1D215 15"
in a 3.1 cu ft. net tuned to 34 hz (firing in cabin)
Kicker PKD1 (0 & 4 AWG)
stock 130 amp alt for now; One yellow top Optima
Installed everything myself & built box (brother helped)

Used a DD-1 to set gains.

Build Log: http://www.stevemeadedesigns.com/board/topic/165894-first-build-accumulated-since-i-was-14/

Just Pics: http://www.stevemeadedesigns.com/board/garage/vehicle/1463-chrysler-concorde-lxi/?tab=images

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Closer yet, the R300x4 would supply roughly 63 watts rms to 4 speakers @ 3 ohms. (Cheaper amp too!)


'98 Chrysler Concorde LXi
Pioneer DEH-80PRS (HU/processing)
Rockford Fosgate T1652-S (components) for front
Rockford Fosgate T1693 (6x9s) for rear
Rockford Fosgate T600-4 running those
Rockford Fosgate T1500-1bdCP running a

Rockford Fosgate T1D215 15"
in a 3.1 cu ft. net tuned to 34 hz (firing in cabin)
Kicker PKD1 (0 & 4 AWG)
stock 130 amp alt for now; One yellow top Optima
Installed everything myself & built box (brother helped)

Used a DD-1 to set gains.

Build Log: http://www.stevemeadedesigns.com/board/topic/165894-first-build-accumulated-since-i-was-14/

Just Pics: http://www.stevemeadedesigns.com/board/garage/vehicle/1463-chrysler-concorde-lxi/?tab=images

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i heard that infinity does low ohm loads like that to make up for the resistance in the speaker wire (stock, i assume), so that the amp will see more towards 4 ohms. no idea if thats true or not, but it makes sense i guess...

Edited by Kranny

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i heard that infinity does low ohm loads like that to make up for the resistance in the speaker wire (stock, i assume), so that the amp will see more towards 4 ohms. no idea if thats true or not, but it makes sense i guess...

Well if I'm going to amp my speakers I'm going to upgrade to like 12 ga so do you think it would see closer to 2?

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i heard that infinity does low ohm loads like that to make up for the resistance in the speaker wire (stock, i assume), so that the amp will see more towards 4 ohms. no idea if thats true or not, but it makes sense i guess...

Well if I'm going to amp my speakers I'm going to upgrade to like 12 ga so do you think it would see closer to 2?

you can't lower ohm loads like that with bigger speaker wire. its impossible to do so. the absolute lowest ohm load you can get with a single Reference speaker is 3 ohms. 12 gauge is a bit excessive for 60 watts. you'd be fine with 14 gauge. it'll be easier to run and to get through the door jamb grommet.

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If they are 3 ohm speakers...then I would NOT get the RF pbr 300x4 as that is only meant for 4 ohm loads. You can look at the average of 2 and 4 ohms on an amp and figure about thats how much your speakers would be seeing.

Such as, the Rockford Fosgate p400x4 is rated at 50 watts rms x4 @ 4 ohms & 100 watts rms x4 @ 2 ohms. So if you were to use this amp, you can supply about 75 watts rms to 4 of these speakers. (Which is about what I would recommend, as long as you don't bring it into clipping)

even though the PBR says 4ohm, it will run a 3ohm load speaker, I have it runinng on my wife with a 3ohm load, please dont talk if you dont know what your talking about.

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These 3 ohm speakers are usually used for cars that has a stock amplifier which most of the time is 4ohm, so if you replace the speaker with this 3 ohm load speakers you will hear a big difference in sound since you are putting more wattage on them. These 3 ohms speakers will run on a regualr 4 ohm amp. for the price The PBR is about $140 for 75watts and a lot smaller. than the other rockford amp.

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