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Author Topic: What are your thoughts or experience running at 2 ohms?  (Read 1853 times)

Brad Gibson

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What are your thoughts or experience running at 2 ohms?
« on: August 18, 2021, 06:28:31 PM »

I have several QSC PLX2 3602 amps and I am considering a new speaker system that will require me to run them at 2 ohms per channel.  What are your thoughts or experience running at 2 ohms?
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John Roberts {JR}

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #1 on: August 18, 2021, 06:42:11 PM »

My general advice is not to do this for normal operation, but it is OK to do this in case of emergency when say an amp fails and the show must go on.

JR
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Nathan Riddle

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #2 on: August 18, 2021, 07:07:56 PM »

I have several QSC PLX2 3602 amps and I am considering a new speaker system that will require me to run them at 2 ohms per channel.  What are your thoughts or experience running at 2 ohms?

PLX sucks at 2ohms.

I'd say "2 ohms" is relative. My subs (TH118) are 4ohms 'nominal' they have a dip at 3ohms.
I run 2 in parallel on a DNA20K4 or PLD4.5 Technically the amp should see 1.5ohms or 2ohms...

I rarely see less than 4 ohms (at any freq) even with both paralleled. Why? Power compression/voice coil heating.

---

You said 'speakers' nominal impedance means very little. It's just so that the MFG don't have to answer questions like "what amp do I use" (Ivan speaks lots about this issue when DSL used more granular impedance).
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John Schalk

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #3 on: August 19, 2021, 10:40:54 AM »

I have several QSC PLX2 3602 amps and I am considering a new speaker system that will require me to run them at 2 ohms per channel.  What are your thoughts or experience running at 2 ohms?
Used PLX amps, and for that matter, pretty much any class H amp design, are pretty cheap these days.  Why not just get more amps? 
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Steve-White

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #4 on: August 19, 2021, 11:02:10 AM »

Brad - refer to post's #2, #3 & #4.  Never setup the baseline in any part of any system to the extreme limits of performance.

There are probably amps out there that can survive driving 2 ohm loads - there are more amps out there that will not.

Experience says don't do it.
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Caleb Dueck

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #5 on: August 19, 2021, 01:14:13 PM »

I have several QSC PLX2 3602 amps and I am considering a new speaker system that will require me to run them at 2 ohms per channel.  What are your thoughts or experience running at 2 ohms?

Require 2 ohms?  That is a red flag.

As others have said -
Don't do it. 
Doubly don't do it with subwoofers.   
Triply don't do it with PLX or any other lower tier amps.

10AWG cable that's really short, as a temp band-aid, depending on the amp, is OK.  Linea amps, as long as you look closely at the crest factor and de-rate the power, and account for line losses through the speaker cable, are OK (but not great). 
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Scott Holtzman

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #6 on: August 19, 2021, 03:24:12 PM »

Require 2 ohms?  That is a red flag.

As others have said -
Don't do it. 
Doubly don't do it with subwoofers.   
Triply don't do it with PLX or any other lower tier amps.

10AWG cable that's really short, as a temp band-aid, depending on the amp, is OK.  Linea amps, as long as you look closely at the crest factor and de-rate the power, and account for line losses through the speaker cable, are OK (but not great).


Does 4 Ohm Bridge count the same as 2 Ohm dual channel in your opinion Caleb?  I have one rig with six PL236's running 4 ohms briged.



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John Roberts {JR}

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #7 on: August 19, 2021, 04:14:23 PM »


Does 4 Ohm Bridge count the same as 2 Ohm dual channel in your opinion Caleb?  I have one rig with six PL236's running 4 ohms briged.
4 ohms bridged IS 2 ohms per channel

JR
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Bradley Gibson

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #8 on: August 19, 2021, 05:33:53 PM »

4 ohms bridged IS 2 ohms per channel

JR


I have been running JBL SRX 728 bridged at 4 ohms for years and not 1 failure of amps or drivers.  That is why I wanted to start this discussion.  Why can I run the bridged at 4 ohms but others are saying stereo at 2 ohms is a no, no? 
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Doug Fowler

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Re: What are your thoughts or experience running at 2 ohms?
« Reply #9 on: August 19, 2021, 06:04:36 PM »


I have been running JBL SRX 728 bridged at 4 ohms for years and not 1 failure of amps or drivers.  That is why I wanted to start this discussion.  Why can I run the bridged at 4 ohms but others are saying stereo at 2 ohms is a no, no?

Because you have no fallback.  Two is one, one is none.
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Re: What are your thoughts or experience running at 2 ohms?
« Reply #9 on: August 19, 2021, 06:04:36 PM »


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