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Author Topic: Quick power amp ohms question  (Read 760 times)

Sam Saponaro Jr

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Quick power amp ohms question
« on: October 16, 2019, 11:50:38 pm »

I should probably know this,but am not sure. ??? I've allways either run amps bridged or 8,4 or 2 ohms a side in stereo mode. Is it safe to run say 8 ohm on one channel and 4 ohm on the other channel.
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duane massey

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Re: Quick power amp ohms question
« Reply #1 on: October 16, 2019, 11:56:53 pm »

Yes.
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Duane Massey
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Sam Saponaro Jr

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Re: Quick power amp ohms question
« Reply #2 on: October 17, 2019, 12:30:28 am »

Thanks I figured as much,but figured I'd ask before I made problems for myself.
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Bob Stone

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Re: Quick power amp ohms question
« Reply #3 on: October 17, 2019, 07:22:07 am »

For most amps this is perfectly fine. I believe there's a few out there that don't like unbalanced loads, but quite unlikely from the typical big names (qsc, crown, lab gruppen, etc.)
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Ivan Beaver

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Re: Quick power amp ohms question
« Reply #4 on: October 17, 2019, 08:30:19 am »

For most amps this is perfectly fine. I believe there's a few out there that don't like unbalanced loads, but quite unlikely from the typical big names (qsc, crown, lab gruppen, etc.)
I have never heard of "amps that don't like unbalanced loads".

Once you start to think about it a bit more, unless you are running the same model speaker on each channel, it is very likely that the loads will be "unbalanced".

impedance is NOT a single number (although many would like to think it is).  It varies QUITE A BIT, based on freq.

it is not uncommon to be 4 ohms at one freq, and 30 ohms at another.

So how would you "balance" the loads playing music?  Unless it is single sine waves.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
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Mike Caldwell

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Re: Quick power amp ohms question
« Reply #5 on: October 17, 2019, 10:13:35 am »

What model amp or amp do you have?

In bridged mode what load do you run the amps at, generally 4 ohms is the lowest to go.

In addition to unbalanced loads per channel a lot of systems run different audio band passes per channel.

Bob Stone

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Re: Quick power amp ohms question
« Reply #6 on: October 17, 2019, 04:58:47 pm »

I have never heard of "amps that don't like unbalanced loads".

Once you start to think about it a bit more, unless you are running the same model speaker on each channel, it is very likely that the loads will be "unbalanced".

impedance is NOT a single number (although many would like to think it is).  It varies QUITE A BIT, based on freq.

it is not uncommon to be 4 ohms at one freq, and 30 ohms at another.

So how would you "balance" the loads playing music?  Unless it is single sine waves.

I forget where I read it but it's unlikely to apply to anything in the pro space these days. If I remember right (don't quote me on this) but it was something to do with increased current on certain parts of the circuit. Sort of similar to how if you draw current from only one leg of a dual pole single phase line, the neutral sees more power than if you draw from both legs evenly.
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Ivan Beaver

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Re: Quick power amp ohms question
« Reply #7 on: October 17, 2019, 07:43:37 pm »

I forget where I read it but it's unlikely to apply to anything in the pro space these days. If I remember right (don't quote me on this) but it was something to do with increased current on certain parts of the circuit. Sort of similar to how if you draw current from only one leg of a dual pole single phase line, the neutral sees more power than if you draw from both legs evenly.
That ONLY applies because of the PHASE of the current.

Since the 2 legs are out of phase, the total current through the neutral is zeroed out.

But in an amplifier, each channel has its own circuit, and the only that might be shared is the power supply.

Some amps have separate power supplies, other have a common one.
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Ivan Beaver
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Sam Saponaro Jr

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Re: Quick power amp ohms question
« Reply #8 on: October 19, 2019, 01:15:42 am »

What model amp or amp do you have?

In bridged mode what load do you run the amps at, generally 4 ohms is the lowest to go.

In addition to unbalanced loads per channel a lot of systems run different audio band passes per channel.
Crest 7001
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ProSoundWeb Community

Re: Quick power amp ohms question
« Reply #8 on: October 19, 2019, 01:15:42 am »


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