Amplifier Headroom, or dynamic headroom

[snouk dogg 10+ year member]

Hi,

I was reading over the net about "headroom".

I understand the concept but not the explanation //content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif

What I mean is that some people state that:

"you will have more headroom for transient and dynamic peaks with an amp running at 4 ohm than at 2 ohm due to less strain and having the amp working less hard"

Where others state:

"you will have more headroom with more power since you are diminishing the gain to match the RMS of the speaker(s)"

Can someone revert about the above statements?

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[jblayz1 10+ year member]

lets say you have a speaker with a frequency range of 80Hz to 4khz with an peak power of 180 watts. you don't know what frequency the speaker peaks at with 180 watts to it. it could be 100Hz it could be 500Hz, 1.5k...... what i've been told is with the speaker crossed over you want to fill that frequency cone(80Hz to 4khz) with all 180 watts or more. since you're not wasting power to unwanted frequencies it runs more efficiently.

i could be wrong...//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[squeak9798 5,000+ posts]

"you will have more headroom for transient and dynamic peaks with an amp running at 4 ohm than at 2 ohm due to less strain and having the amp working less hard"

I don't agree with that statement at all.

An amplifier is only capable of a certain amount of unclipped power no matter what impedance load it's driving.

Where others state:"you will have more headroom with more power since you are diminishing the gain to match the RMS of the speaker(s)"

This statement is a little closer to accurate, however I would say it's only indirectly related to the gain setting (at best) and the gain setting isn't a defining factor of "headroom".

As many people typically refer to the term, "headroom" is essentially how much "extra" power output capability the amplifier has as compared to how much power you need from the amplifier to fully power your speakers.

Take this example:

You're listening to music at an average power output level of 30w and the music has dynamic peaks of 6db (which means the peaks will increase the power output by a factor of 4 to 120w). You are comparing two 2-channel amplifiers; one has a maximum unclipped power output of 75w per channel the other a maximum unclipped power output of 250w per channel. As you can see, the 75w amplifier will probably clip during those dynamic peaks causing distortion during those peaks, whereas the 250w amplifier will still be well within it's linear operating limits keeping distortion to a minimum.

This is the concept behind "headroom".

It just so happens that the gain on the 250w amplifier would probably be set to a "lower" level than that of the 75w amplifier since it would probably take less input voltage to obtain an average output level of 30w from the larger amplifier. But that doesn't really "define" what amplifier has more "headroom".

Clear as mud ??

 

[snouk dogg 10+ year member]

Mud is clearer... heh just kiddiiiiiiiiiiiiiiiiing

I kind of understand now. Therefore, it is safer to operate an amp at 2ohms (1200watts and send 800watts) i.o. 4ohms (800watts) when the subwoofer needs 800watts. Correct?

 

[squeak9798 5,000+ posts]

I think it's best to sum it up as this;

Purchase the amplifier with the most power you can afford that also has the features, build quality and aesthetics you desire.

 

[snouk dogg 10+ year member]

Cheers... Will do...

Have a nice week end