Mixing ohm loads

[Surfwagon]

I have 3 ohm coaxial Infinity’s in the dash and knee panels and the new Alpine SPV 65’s in the soundbar, which are 4 ohm. Everything is running off of an Alpine KTP-445u mini amp. Is mixing amp loads bad for the whole system?

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[calemasters]

You may get by with this. But I don't think it is a good practice to change the output impedance by 25%, thus increasing the load on the amp.

 

[Jebiruph]

There's something called maximum power transfer that is acheived when the input impedance (resistance) of the speakers matches the output impedance of the amp. That's what impedance matching is, matching inputs and outputs. If you always have your system cranked all the way up, the extra amps used by lower impedance spekers might make a difference, otherwise I wouldn't worry. I've been running the 3 ohm Infinities with my factory 5" radio for over 2 years with no issues.

What does Alpine recommend for your amp?

 

[Dagwood]

If your running the dash and lower dash speakers paralleled you have the Amp in a 1.5ohm load on two of the four outputs. It's rated only down to a 2ohm load.

 

[SG19JLUR]

I have 3 ohm coaxial Infinity’s in the dash and knee panels and the new Alpine SPV 65’s in the soundbar, which are 4 ohm. Everything is running off of an Alpine KTP-445u mini amp. Is mixing amp loads bad for the whole system?

Your setup is fine. As long as you don't exceed (meaning go lower than) the rated impedance of the amplifier you will be fine. That amp is rated down to 2 ohms, so your 3 ohm speakers are fine. And having different impedance loads on each amplifier channel is not a problem at all.

 

[Dagwood]

Your setup is fine. As long as you don't exceed (meaning go lower than) the rated impedance of the amplifier you will be fine. That amp is rated down to 2 ohms, so your 3 ohm speakers are fine. And having different impedance loads on each amplifier channel is not a problem at all.

That's six speakers on a four channel Amp. Parallel wired upper and lower fronts results in a 1.5 ohm load.

 

[SG19JLUR]

That's six speakers on a four channel Amp. Parallel wired upper and lower fronts results in a 1.5 ohm load.

I just re-read the original post and it sounds like you're right, he's running the dash speakers AND the knee speakers plus the sound bar. I thought he was just running a pair of 3 ohm speakers and a pair of 4 ohm speakers. Exceeding the rated impedance of the amplifier is not a good idea. Even if it's working now it could cause the amp to fail prematurely. You could run the 3ohm speakers in series rather than parallel, which would present a 6ohm load to the amplifier. It might make a little bit less power, but it's safer to do it this way.

 

[Surfwagon]

I just re-read the original post and it sounds like you're right, he's running the dash speakers AND the knee speakers plus the sound bar. I thought he was just running a pair of 3 ohm speakers and a pair of 4 ohm speakers. Exceeding the rated impedance of the amplifier is not a good idea. Even if it's working now it could cause the amp to fail prematurely. You could run the 3ohm speakers in series rather than parallel, which would present a 6ohm load to the amplifier. It might make a little bit less power, but it's safer to do it this way.

How would I go about running them in series?

 

[huntb]

How would I go about running them in series?

Amp+ -> Knee speaker + , Knee Speaker - -> Dash speaker +, Dash speaker - -> Amp-

 

[SG19JLUR]

How would I go about running them in series?

 

[Dagwood]

I wouldn't run in series, ohm load would be 6ohm. Leaving it alone while only slightly below what's recommended might reduce the life of the amp but I personally would prefer. Although the best answer would be another amp just like it, one 4ch amp feeding the four front and one 4ch feeding rear and bridged to one very efficient 4ohm sub. A sub that will be decently loud on 90 watts

 

[AusJeepNoob]

Shouldn't make much of a difference. Get a multimeter and set it to measuring resistance. Connect to the speaker terminals and you should see the nominal impedence of the speaker. Now push down on the cone slightly. The impedence will be different. Impedence in speakers is dynamic so even if the nominal impedence is less than what the amplifier is rated for it will rarely see that load.

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