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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!  


128x128diamonddupree
diamonddupree's avatar
diamonddupree OP
75 posts
 
@noble100 thanks, I'm curious about much the same thing and will report back with results. According to @yyzsantabarbara the MiniDSP does have a robust parametric EQ capability that integrates with REW software. I won't be able to try that out until I pick up a mic, which I will most likely do after playing around with the unit for a bit.

My greater concern is the digital/analog processing of the MiniDSP. It ultimately may not be worth it for me if the unit bypasses the DAC functions of my Mytek Brooklyn DAC+. I'm hoping, by placing the MiniDSP after the DAC in the signal chain and using its analog inputs and outputs, it will preserve the analog signal coming from the Brooklyn DAC. Otherwise, it seems my nice DAC is being rendered useless by the MiniDSP. I'd rather have the Brooklyn converting digital streams to analog and not the MiniDSP. All I want the DSP to do is control the HP filter to my mains. I don't want to use it as a DAC. So we'll see.

As far as a higher-powered amp, it's still on my radar. And my sub is already self-amplified. My solution may wind up being the much more expensive JL Audio active crossover and a pair of monoblocks but I'm starting with the MiniDSP since it's relatively cheap. 
mapman's avatar
mapman
22,366 posts
 
Sounds like you are going plenty loud off a pair of stand monitors so more power may be moot but more current may still be a ticket to better sound.

Two potential issues with trying to go louder:

1) the old heat/compression factor that could make it a moot point
2) the damage 100db + will cause to the ears over time if used regularly

In my case, I wanted my system to not be a limit to how loud I go practically and achieved that. But now as with any dangerous weapon (to your ears) one must be careful how they use it.


Also if phase/impedance curves for teh minis are available and show dips/issues at lower frequencies, setting up teh crossover to have teh powered sub address those and not the main amp should help alleviate any current bottlenecks. Remember that power requirements increase exponentially at lower frequency so as frequency goes lower the drain on teh amp increases not linearly but logarithmically ie a lot! AMps do most of their work producing bass. WHich is why getting bass under control in the gear first is so important. You always want your amp to not have to work any harder than it is designed to do and manufacturers will exaggerate that ability often for fear of limiting sales. No amount of room treatments can fix that issue if present.

diamonddupree's avatar
diamonddupree OP
75 posts
 
@mapman thanks. Learning a ton. So I ordered a MiniDSP active crossover and should have it tomorrow and I'm going to try what you suggested. It's relatively inexpensive so I figured why not? The software also offers a bunch of parametric EQ customization, which I may play around with once I eventually get a mic to measure the room response. But my first concern with the MiniDSP (I don't know if you read my post from above) is that it seems to act as a DAC when I don't really want it to. I'm currently using a Mytek Brooklyn DAC+. The MiniDSP would come after it in the signal chain. What I'm wondering is, since the MiniDSP is a DAC, will it take over for the Brooklyn DAC? I really don't want it to. If the Brooklyn is already converting digital to analog, would the MiniDSP need to convert it again? Would it convert it back to digital and then back to analog again? If I run the Brooklyn into the analog input on the MiniDSP, would that bypass the DAC conversion in the DSP since it's already receiving an analog signal? I'd much rather have the Brooklyn handle the conversion and just use the MiniDSP to handle the high pass filter to the mains. I know, lots of questions. Thanks again for your responses! 
diamonddupree's avatar
diamonddupree OP
75 posts
 
@mapman oh, and yes, I've been listening way too loud! I shouldn't be doing that but sometimes I just can't stop myself! 
yyzsantabarbara
4,917 posts
 
@diamonddupree I was referring to the MiniDSP UMIK-1 microphone and not any DAC. This mic is tightly integrated with the REW software.

@diamonddupree Get the miniDSP UMIK-1 microphone for $100. Then download on a Windows 10 computer REW software. I am not sure if it works on a MAC.

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