What is Floyd Toole saying about extra amplifier power and headroom?


I've been reading Floyd Toole's "Sound Reproduction The Acoustics and Psychoacoustics of Loudspeakers and Rooms" and came across a passage that I wish he went into further detail about. It has to do with whether having amplifier headroom has any noticeable improvement in sq. He happens to be talking about getting the bass right in small rooms, but in doing so, he also touches on the use of a larger amp for extra headroom: 

Remedies for unacceptable situations typically included spending more money on a loudspeaker with a “better” woofer (without useful technical specifications, that was a lottery of another kind) and a bigger amplifier (for useless headroom ...

It's the last part ("useless headroom") that I'm curious about. I have notoriously hard-to-drive speakers (Magico Mini IIs). Although the recommended amplification is 50w - 200w, in my experience, that's a bit of an underestimation. I'm driving the Minis with a Musical Fidelity M6PRX, which is rated at 230w @ 8ohms. (The Minis are 4ohm.) The combination sounds excellent to my ears at low to moderate listening levels, but I notice a slight compression in the soundstage at higher levels. My listening room, while small, is fairly well treated with DIY panels made from Rockwool, sound-absorbent curtains, and thick carpeting. So I don't think I'm overloading the room. But I have wondered if an amp with far more power than what's suggested (more headroom) would drive the speakers with a little less effort.

Those of you familiar with Toole or with driving speakers with power to spare, what are your experiences? If I went with, say, a pair of monoblocks that drive 600w @ 4ohm, would the extra headroom address the compression I'm hearing at higher levels? Or am I wasting my time and, potentially, funds that would be better spent elsewhere? 

Thanks!  


diamonddupree

Showing 1 response by p05129

MC is very wrong again on many accounts. Headroom - this is where an amp can really shine in producing high instant peaks and crescendos. If any amp, listening amp, guitar/bass amp, pushing an amp too hard will cause distortion, clipping, or possibly shut it down. Headroom is a buffer of sorts, just like the car you drive, do you always need 300hp to go to the store? No, but when passing or trailering you might hedge that way. MC always gives his wisdom on speaker sensitivity and since he thinks his low fi speakers are 94db rated, he tells everybody to ignore speakers less than 90+db efficient. He ignores a few reviews of tekton speakers where the reviewer actually measured tekton 7db lower than the rated 94db from the manufacturer. If this is the case, which I’m guessing is fact since 1 of the trade mags does measurement tests and MC doesn’t, I would think MC would follow his own advice and start looking for a quality speaker this time around that’s 90+db efficient. IMO, it’s foolish to state a speaker needs to be greater than 90db unless you want to use a low powered SET amp, then by all means look for a high efficient speaker.