A POINT OF VIEW: So … how much headroom does a system really need?

Paul McGowan writes: I suppose the term “headroom” must have come about in response to tall people trying to make sure there’s enough room for their heads to go through a doorway or fit into a carriage.  Makes sense anyway. In audio, headroom means that there’s enough space to amplify music without running into the limits of an amplifier – either by clipping the amp or running out of its linear region – neither of which is a good thing.

How much headroom does a system need?  Certainly the answer to that depends on a number of factors including: the efficiency of your loudspeakers, the size of your room, the type of material you listen to, how loud you play music etc.

I would like to suggest to you that in all likelihood your amplifier does not have enough power to do the job properly.  I write this after a lot of study on what it really takes to properly power a loudspeaker and the results were surprising to even me.

This whole subject came about as we are getting ready to finalize a new power amplifier that we’d like to ship out this coming summer.  We have a great new front end, all kinds of cool innovative stuff that’ll delight your system to no end but – and this is a big but – we had to decide how much power this amp should have.

Typically a big power amp is perhaps 200 watts per channel into 8 Ohms and 400 watts into 4, perhaps 700 into 2.  That’s no small amplifier and the general wisdom I have always ascribed to is that this is plenty of power for all but the most inefficient of speakers.  The assumption turns out to be wrong and in the coming days I will explain why that’s wrong, how headroom works and what the differences are from the way a loudspeaker is specified in efficiency and what it really takes to drive it.

I trust you’ll find this illuminating.

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