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

@mapman very interesting. So what would I do to increase current delivery? I've done a fair amount to treat the room and I feel like my sub is already pretty well integrated. Here's my room:

https://systems.audiogon.com/systems/9016
 

@onhwy61 sorry, I don't have an SPL meter. And I'm not sure I understand the distinction between dynamic compression and soundstage alterations. I'll have to dig around and pay more close attention. Thanks!

@mapman thank you! Very helpful! 

@erik_squires the day I try to install that is the last day my amp would ever work. 
MiniDSP comes tomorrow. I have no idea what to expect. Should be interesting. 

@millercarbon, I never said I felt stuck with or married to my speakers. The Magico Minis sound incredible to my ears. And I paid a fraction of what they cost new. So I have zero regrets. I'm here exploring tweaks to my system. If I wanted to read about your Tekton Moabs, there are 10,000 other posts on this forum where I can find that information. Give it a rest. 

@mapman I've never been able to find anything showing the MF power output @ 4ohms but regarding current, the manual says, "current peak-to-peak: 140 Amps."

FWIW, it's a stereo amp (dual mono) and not an integrated one. Knowing that, would that point to the speakers being a limitation? And would an active crossover be the fix for that, something like this:

https://www.jlaudio.com/products/cr-1-home-audio-subwoofer-crossovers-96020

???

BTW, I already have a powered sub (JL Audio Fathom 110). And it seems to integrate with the Minis nicely. 

And the Bel Canto monoblocks are on my list of amps I want to try out. My local hi-fi store is a Bel Canto dealer so I think I can take them for a spin. 

Thanks @erik_squires, IMO, all speakers, even floorstanders, could use a subwoofer and I have one in my system, a JL Audio Fathom 110. It has a 900w class D amp and auto room correction. I have the LP freq. on the subwoofer set to 38hz; the Minis go down to 37hz. With the room correction and the LP freq where it is, I feel like I have the sub and satellites integrated pretty well, at least to my ears. I’m using a single sub because I don’t think the room can handle a second one, and after reading Toole, it seems like I have the recommended placement just about right.

Edit: Here's my room:
https://systems.audiogon.com/systems/9016

What do you think the effect would be of adding extra headroom? Or should I be looking more at low noise and low distortion?

Thanks for the links. I’ll read them now.

@noble100 thank you for that. Makes a ton of sense. I've been very pleased with the tightness of the bass coming from the JL sub and I was considering a second one a while back. I think, based on your comments and a few others', that my first order of business is an active crossover to stop the Minis from going below 80hz and letting the JL sub handle those frequencies. I really appreciate your response. 

@erik_squires I've considered an active crossover to accomplish what you suggest. My local shop didn't think it would have much of an impact but I'm still curious. I feel like there should be as little overlap of frequencies produced by both the sub and the mains as possible. It sounds like this is what you're saying too. I was considering this device:

https://www.jlaudio.com/products/cr-1-home-audio-subwoofer-crossovers-96020

Other commenters who know the Minis well have suggested getting all the bass out of them as they can produce, which is why I have the LP freq set to 38hz. I've played around with it in a few different places and it sounds good the way it is now. I listen to the Wood album by Brian Bromberg and can hear right down to the texture of the strings on his 300-year-old double bass. It sounds incredible. 

@noble100 good stuff and much appreciated. I just ordered a MiniDSP HD and should have it in a few days. I'll see how that works out and go from there. Thanks! 

@atmasphere , I just finished the section in the book on bass arrays and my room dimensions don't fit the use case that Toole recommends it for. My room is very irregularly shaped and small, so I wouldn't be able to arrange the subs the way he suggests. In addition, the frequency response he shows for my current sub configuration shows very flat response for the limited frequency range I'm using it for, which is basically 27hz (the lower limit of the sub) to 38hz (where I have the LP frequency set). It's a narrow range but it really fills out the bottom octave. 

I'm not encouraged by your observation about the low efficiency of my speakers since I have no desire to change that part of the system so I have no choice but to deal with it. Perhaps what @mapman was saying about increasing current flow could help this situation. I'll have to look into it. Thanks for your thoughts! 

@gregm I'm going to look at hi passing the Minis with an active crossover, perhaps the Loki that @tketcham is recommending or a Mini DSP. Both look like inexpensive ways to figure out what's happening. And to answer your question, yes, this is only at very high listening levels. My neighbors love me. 

@onhwy61 I'll try an app to test SPL. Wasn't aware of one so thanks! 

@tketcham that looks great. This is definitely the way. I was also just looking at a MiniDSP unit. Is that the same as the Loki? It looks like an active crossover that controls roll off frequencies for anything connected to it. It's also super inexpensive. Thanks! 

@onhwy61 I downloaded a free SPL app, Decibel Meter, and holy cow, I guess I should be deaf by now! I'm averaging 100 db and occasionally hitting 105. And I'm still BELOW the level where I hear the soundstage issue I posted about. Maybe I should just listen at lower levels?!?!

@erik_squires thanks for the links. I read both articles and they have me thinking of the one area in my room I haven't treated, the ceiling. The sounds I'm trying to correct is at admittedly very loud levels, so it's possible that it's creating reflections off the ceiling that don't exist at lower levels. After that, I think I need to look at active crossover to control the LP freq. The JL unit I linked above is fairly pricey. I looked at the Schitt unit in your article but it looks like that's more of an EQ than an active crossover. BTW, the reason I have the JL sub's LP freq at 38hz is that I wanted to minimize the overlap between where the mains drop out and the sub picks up as much as possible. The Minis go down to 37hz. Sounds like the active crossover will give me more precise control of the LP freq so maybe it's worth the price, and actually a deal compared to new monoblocks with extra headroom. Am I on the right track? Really appreciate your responses! 

@mapman I'm going to try rolling off the Minis closer to 80hz or thereabouts with an active crossover and see what that does before I get a second JL sub, which I may do at some point down the road. I also want to demo the Bel Cantos from my local dealer and possibly some Simaudio monoblocks. I'm still not sold on Class D for mains but willing to give them a shot. Thanks for your responses! 

@mapman according to Valin, "the MAGICO Mini is a textbook-perfect load (never dipping below 4 ohms and staying about 6 ohms for most of its frequency range)."

@barts thanks, lots of customization with that unit. Are you familiar with the MiniDSP? Any thoughts on how they compare? Much appreciated. 

@yyzsantabarbara very interesting and now I have a lot more reading to do! I just ordered a MiniDSP and I think next will be a mic that I can use to measure the speakers and room response. I think I'll probably still wind up with a new amp down the road but I'll have a much better idea of what to look for when I do. Thanks! 

@mapman guilty as charged! I'll let you know how the DSP works out. Thanks again! 

@mapman based on what you were saying before about current delivery, with the BC's Peak Output Current @ 45A, wouldn't that be a little too low for the Minis? And much lower than the MF @ 140A? 

@yyzsantabarbara I plan on doing exactly that. I already use Roon but haven't done anything with the filters yet so this should be fun. 

One thing about the MiniDSP that I wonder about (if @yyzsantabarbara @erik_squires @tketcham or anyone else knows) is whether it will limit the upsampling available in Roon. I typically upsample to DSD 256, but from what I've been reading on the MiniDSP, it has a sample rate up to 192kHz, at least the USB input does. (Not sure if Toslink would be higher.) Anyone know if the MiniDSP limits upsampling and if there's a way to bypass it? 

@yyzsantabarbara In advance of the MiniDSP arrival, I now have Roon upsampling set to 176kHz/192kHz, the maximum power of 2 upsampling the MiniDSP will handle. Whether the Roon upsampling or the active crossover results in greater sonic improvement, time will tell. That's some Holiday Inn, BTW! I guess those commercials were right. 

@tketcham according to the MiniDSP manual:  "Asynchronous XMOS USB input for streaming audio (up to 192 kHz)."

And for Toslink, it says, "Connect a single digital source to the optical (TOSLINK) connector. Thanks to its asynchronous sample rate converter (ASRC), all sample rates between 44.1 and 192 kHz are accepted."

What I'm wondering now is whether the sample rate limit is irrelevant if you're feeding the MiniDSP an analog signal. IOW, if I have the MiniDSP after my DAC in the signal chain, the DAC has already converted the digital file to analog, so wouldn't the DSP just pass along the analog signal to the amp that the DAC fed it? Or will it still downsample the file before passing it down to the amp?

@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! 

@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. 

@cakyol hahaha! condoms! who needs those? ;)

@erik_squires no, the JL only has a low pass filter. They make an active crossover that does high and low but it's not cheap. I have a feeling I'm going to try the MiniDSP just to see what rolling off the mains at around 80hz sounds like and I'll probably take it right out. I like my DAC and I'm not crazy about the DSP ding its own conversion after the Brooklyn. 

@atmasphere the JL sub that I have makes it very easy to set up with auto room correction. It comes with a mic that you place at the listening position, run a test sequence and the sub's internal DSP corrects for the room modes. I've never had a problem setting up the sub anywhere I've placed it. In corners, against wall, midwall. Once I run the room correction software, from the listening the position, there are no nulls, peaks or modes as far as I can tell. 

@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! 

Thanks @https://forum.audiogon.com/users/audiorusty. My DAC is my preamp. The Brooklyn DAC+ is both a DAC and a preamp. But most everything else you said applies. I'll take the analog outputs from the Brooklyn and connect them to the analog inputs on the MiniDSP, then the analog outputs from the DSP to the MF amp. Only thing is, I run XLR cables to my sub because when I've run RCA, there's a low-level hum from the sub that completely goes away when I use XLR cables. And the MiniDSP doesn't have XLR outputs. So I'll have to stick with the XLRs going from the Brooklyn to the sub (L & R). 

@erik_squires another cheap option?

https://www.hlabs.com/products/crossovers/

Inline RCA active crossover? They make high pass filters for 70hz and 100hz. Any reason why these wouldn’t work?

Actually @audiorusty, I think the DBX would work. I could run XLRs from the DAC to the XLR inputs and run all XLRs out to my amp and sub. Thanks, this may be a better analog option instead of the DSP. 

Thanks @audiorusty, there seems to be no shortage of RCA crossovers and XLR crossovers but not many that have both. The only ones I've found are by JL Audio and SPL and both are fairly pricey. The DBX seems to be XLR only unless there's one I'm missing. 

I'm so glad I posted this thread because I've learned a ton. (You're not the only one @larry5729! Thank you @erik_squires @mapman @onhwy61 @mrdecibel @noble100 @yyzsantabarbara and everyone else!)

I have about an hour of listening with the MiniDSP. The setup was straightforward enough. I set the high pass filter for the mains at 90hz and the sub low pass at the same. The sub has its own LPF. The HPF I had to set using the MiniDSP software installed on my Mac. Once I had the software synced with the unit, which took about five seconds, I was able to set the high pass. Couldn't have been easier. I'll have to play around with the crossover point but a few observations so far. 

The amp is obviously not working as hard as before. I can reach the same SPL at a lower volume on the DAC (which doubles as my preamp). With the JL sub going up to 90hz, the bass is tighter and more finely detailed. I've been listening to an album called Wood by Brian Bromberg. He plays a 300-year old double bass with a lot of slapping, sliding and plucking techniques, which gives you a good taste of transient detail and the excellent character of the 18th century bass. There's a lot of it with the JL going up to 90hz and with the Magico Minis rolling off earlier. And there was a lot of detail already there before. But now, it's even more three-dimensional. It's the same thing with a Charlie Haden/Jim Hall album that's been on heavy rotation, where the bass articulation just jumps out of the soundstage.

I'm not sure if it's the mains not having to extend down to 40hz or the extra headroom from the amp not having to drive the mains that low, or maybe a combination of the two, but the DSP makes both the sub and the mains sound better, and the whole system more resolving. Brad Mehldau's piano from a 1990 Art of the Trio live recording sounds slightly smaller than another Art of the Trio recording from 1997, and both pianos sound smaller than Chick Corea's on Trilogy 2. I've listened to all three albums many times and never noticed the difference in the apparent size of the piano. Quite an upgrade for just a $200 piece of gear.

I guess I should just be happy at that but of course, I have reservations about the conversion going on inside the MiniDSP, which seems to make my DAC an afterthought. I'm really curious how an analog crossover would work but for now, I'm going to enjoy the improvements this inexpensive little upgrade has given me. Thanks again to everyone who took the time to respond and share their expertise. 

@yyzsantabarbara this goes back to my original question which is why does Floyd Toole, who obviously knows a few things, discount the value of headroom? It seems to help in so many scenarios but unfortunately, he doesn’t elaborate on it. LMK how the amp works out. I’m curious to know. 

Thanks for all the crossover recommendations. I've bookmarked all of them. And thanks @noble100 for the Toole link. One thing I've noticed in reading his book and even in his posts is that his observations are for multi-seat listening. In the book, almost everything he has to say about low frequencies and subwoofer placement has to do with optimizing for multiple seating positions. I think this explains a lot about his own choices in home audio. I'm mainly concerned with single-seat listening. My home theater system is good enough for my purposes. 

Next move for me is a mic to measure the response at my listening position. Then I can tinker with PEQ and see what that's all about before deciding if an analog crossover is worth a look. And then there's Butterworth vs. Bessel vs. Linkwitz-Riley filters. The force of the rabbit hole is strong. 

@yyzsantabarbara a second AHB might not even do it. There's a pair of Belo Canto Ref 1000s available right here on Agon I think for less than $2k. 

@yyzsantabarbara Thiel says those speakers, though rated at 4ohm, will go down to 2.8. With recommended power at 100w - 600w, I bet they spend a fair amount of time at or near 2.8. The AHB puts out 190 @ 4ohm, 240 @ 3ohm. I'm still learning here but I would say that's way underpowered for the Thiels. Have you considered a high output Class D? I believe @mapman is running Bel Canto Ref 1000 monoblocks after switching from a lower-powered Musical Fidelity and says the difference was night and day. I bet those would do wonders for your Thiels as well.