As I said, passive crossovers lead to all the pain and anguish you see these guys expressing. You get to leapfrog over that. They fret over careful driver selection because they don't have direct control over the drivers. Worse, as Floyd Toole explained, drivers can run into frequency response and sensitivity differences on the manufacturing line.
Are cheap Chinese TDA3116D2 amps junkie tinker toys? No. It's a Texas Instruments chip with a flat frequency response. https://www.ti.com/product/TPA3116D2
Amplification used to be expensive, bulky, and really heavy. Technology progressed, now excellent quality power amplification is inexpensive, small, and light weight.
Same thing happened with power supplies. They used to be godawful. Now you can buy very high quality efficient power supplies with more power than your system will ever use for $30 or less.
Best of all, it's simple. Run a wall plug into your power supply. Run 12VDC or 24VDC -- your choice -- from the inexpensive power supply to your inexpensive Chinese amps. If you're in Europe you toggle the little switch on the side of the power supply to make it compatible with your AC. So easy it's comical.
DIYing speakers today is easy and inexpensive if you don't use old technology. As a new DIYer you aren't blocked by the old ways. It's as if you're sitting in front of a laptop working in an Excel spreadsheet and someone comes along and says you should buy a calculation kit that includes a pencil and a slide rule.
Are cheap Chinese TDA3116D2 amps junkie tinker toys? No. It's a Texas Instruments chip with a flat frequency response. https://www.ti.com/product/TPA3116D2
Amplification used to be expensive, bulky, and really heavy. Technology progressed, now excellent quality power amplification is inexpensive, small, and light weight.
Same thing happened with power supplies. They used to be godawful. Now you can buy very high quality efficient power supplies with more power than your system will ever use for $30 or less.
Best of all, it's simple. Run a wall plug into your power supply. Run 12VDC or 24VDC -- your choice -- from the inexpensive power supply to your inexpensive Chinese amps. If you're in Europe you toggle the little switch on the side of the power supply to make it compatible with your AC. So easy it's comical.
DIYing speakers today is easy and inexpensive if you don't use old technology. As a new DIYer you aren't blocked by the old ways. It's as if you're sitting in front of a laptop working in an Excel spreadsheet and someone comes along and says you should buy a calculation kit that includes a pencil and a slide rule.
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This is terrible idea for any newcomers, in fact for anyone new or not, unless they want to spend hours and hours futzing around with a table top full of lose parts and a rat's nest of wires going all over the place.
Not to mention, of course, the need the have a microphone and REW. Plus the learning curve to be able to properly use REW, which is quite extensive and not trivial at all.
And after all of that still only have an amplifier and DAC capable of mediocre performance at best.
So no thank you. This may be fine for you and a few others, but it's a terrible suggestion for a newbie like the original poster if he wants to enjoy listening to his music with quality sound anytime soon.
A kit from a well know designer is the far better way to go.
Not to mention, of course, the need the have a microphone and REW. Plus the learning curve to be able to properly use REW, which is quite extensive and not trivial at all.
And after all of that still only have an amplifier and DAC capable of mediocre performance at best.
So no thank you. This may be fine for you and a few others, but it's a terrible suggestion for a newbie like the original poster if he wants to enjoy listening to his music with quality sound anytime soon.
A kit from a well know designer is the far better way to go.
Hi all
And thank you all for all your input. Been great reading pro's and con's (Y)
So will I be buying a kit?
No - that would take away all the fun and pain in this stupid project 😀
Building a speaker, I have done before. Probably not the hifi result I'm looking for now, but I am older and wiser now - and the internet brings info I did not have in 99 - right out of high school.
But I do get it - a kit would give me learnings I might need for my project - as it's a bit over my head.
Building 2 speakers + audio receiver board, Amp board, DSP board, and getting it all to work together - well.. good thing is that I might not have to learn how to build crossovers just yet.
I know speaker design is a daunting task in it own, so right now I'm just trying to figure out what to do with the amp.
Guessing I'll be powering up some 1 channel amps and have a go with the DSP. Professionally I'm a computer geek, so that's a bit more up my alley.
But to be honest - I'm unsure what the right path it.
And thank you all for all your input. Been great reading pro's and con's (Y)
So will I be buying a kit?
No - that would take away all the fun and pain in this stupid project 😀
Building a speaker, I have done before. Probably not the hifi result I'm looking for now, but I am older and wiser now - and the internet brings info I did not have in 99 - right out of high school.
But I do get it - a kit would give me learnings I might need for my project - as it's a bit over my head.
Building 2 speakers + audio receiver board, Amp board, DSP board, and getting it all to work together - well.. good thing is that I might not have to learn how to build crossovers just yet.
I know speaker design is a daunting task in it own, so right now I'm just trying to figure out what to do with the amp.
Guessing I'll be powering up some 1 channel amps and have a go with the DSP. Professionally I'm a computer geek, so that's a bit more up my alley.
But to be honest - I'm unsure what the right path it.
In any case a true 50 watt amp is enough for most normal speakers playing normal music at normal levels in a normal room, to answer the original question.
It really depend on what is your goal. The destination or the journey.
To have high quality sound fairly quickly with minimal learning curve and delay so you can enjoy your music
-or-
enter into a long tinker toy type project with a somewhat uncertain outcome in terms of sound quality just so that you can do it all yourself.
I assume that for most people who post here it is the former, but there certainly is the possibility of the later.
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Well, if you must create something of your own design...
1) Pick up a copy of Loudspeaker Design Cookbook, a driver measuring jig, and a calibrated microphone, or;
2) Get a DSP (standalone might be easiest), a calibrated microphone, and enough channels of amplification to match what you'd need for active speakers. With a pair of 2-ways, you'll need 4 channels total.
With 1), you'll need to be confident in all your measurements and simulation that you don't make an error in the crossover design. If you change your mind about the crossover design you'll need to order new parts. The main benefit is that you only need one amp channel per speaker.
With 2), you need the extra channels of amplification, and sometimes controlling the volume (gain) of multiple channels simultaneously can be pretty tricky depending on what you have. But on the other hand, if you don't like the crossover you put together, you can change it just by moving some sliders in the software.
If your goal is to make a speaker that sounds good, and want to try DSP, just buy the amps and DIY the rest as required.
1) Pick up a copy of Loudspeaker Design Cookbook, a driver measuring jig, and a calibrated microphone, or;
2) Get a DSP (standalone might be easiest), a calibrated microphone, and enough channels of amplification to match what you'd need for active speakers. With a pair of 2-ways, you'll need 4 channels total.
With 1), you'll need to be confident in all your measurements and simulation that you don't make an error in the crossover design. If you change your mind about the crossover design you'll need to order new parts. The main benefit is that you only need one amp channel per speaker.
With 2), you need the extra channels of amplification, and sometimes controlling the volume (gain) of multiple channels simultaneously can be pretty tricky depending on what you have. But on the other hand, if you don't like the crossover you put together, you can change it just by moving some sliders in the software.
If your goal is to make a speaker that sounds good, and want to try DSP, just buy the amps and DIY the rest as required.
Lots of conflicting advice here, but in a way, it is all good advice.
Classicalfan is making a good point. A novice needs to be realistic about their capabilities. If a person knows very little about acousitcs, very little about electronics and signal processing, and has little woodworking skills and very few tools, I would strongly advise them to start with a kit. There are just too many new skills and knowledge that must be mastered.
On the other hand, an telecomunications engineer who also does a lot of woodworking as a hobby, well we might advise a different path for them... or a recording engineer who wants to design his first speaker... way different situation.
So CasperH, If you want to begin down the active DSP path, we are here to help... It won't be a fast journey, but it will be a fun one...
Classicalfan is making a good point. A novice needs to be realistic about their capabilities. If a person knows very little about acousitcs, very little about electronics and signal processing, and has little woodworking skills and very few tools, I would strongly advise them to start with a kit. There are just too many new skills and knowledge that must be mastered.
On the other hand, an telecomunications engineer who also does a lot of woodworking as a hobby, well we might advise a different path for them... or a recording engineer who wants to design his first speaker... way different situation.
So CasperH, If you want to begin down the active DSP path, we are here to help... It won't be a fast journey, but it will be a fun one...
Ok Casper, now my advice is to buy a kit and first concentrate on making it active!
- first make it ready and listen to it as passive
- learn how to take measurements of it, woofer and tweeter separately and with crossover, also off-axis. Evaluate your results and compare to data available in the web
- buy a minidsp multiway dsp-crossover unit and software and learn how to use it Software is crucial and later on you can try to find or make somthing better!
- buy amps (either normal stereo amp or chipboards, decide if it will be line level or balanced
- bypass the crossover in speakers and find appropriate software dsp settings (freq response eq, crossover type and freq, gain settings and delay for the tweeter by measuring!
This is not vey difficult, but you must learn basics of general loudspeaker design also, and that takes some time because it is so wide world of compromises and different opinions.
I learned a lot from John Reekie here miniDSP tutorials and most of it applies no matter which dsp and measurement software you use
Learning to master simulation programs like VituixCAD is not necessary, but it has many useul modules that help to figure out basics and evident problems
I managed with my 4-way project quite well, it took only about 6 months from start of tinkering, but then I made several updates... And I had made my first kit speaker 40 years before that, and followed hifi and speaker building magazine articles and web forums all the time.
Later on you can make other speakers from driver choice and baffle/box design up. You can also recycle your current components, if you get serious and take all this as a hobby.
Wellcome to the herd!
ps. my amp modules are Danish design IcePower 125 and 50 watt. I could break my speaker with those, very easy with dsp when you test the tweeter and forget to highpass it before measurement!
- first make it ready and listen to it as passive
- learn how to take measurements of it, woofer and tweeter separately and with crossover, also off-axis. Evaluate your results and compare to data available in the web
- buy a minidsp multiway dsp-crossover unit and software and learn how to use it Software is crucial and later on you can try to find or make somthing better!
- buy amps (either normal stereo amp or chipboards, decide if it will be line level or balanced
- bypass the crossover in speakers and find appropriate software dsp settings (freq response eq, crossover type and freq, gain settings and delay for the tweeter by measuring!
This is not vey difficult, but you must learn basics of general loudspeaker design also, and that takes some time because it is so wide world of compromises and different opinions.
I learned a lot from John Reekie here miniDSP tutorials and most of it applies no matter which dsp and measurement software you use
Learning to master simulation programs like VituixCAD is not necessary, but it has many useul modules that help to figure out basics and evident problems
I managed with my 4-way project quite well, it took only about 6 months from start of tinkering, but then I made several updates... And I had made my first kit speaker 40 years before that, and followed hifi and speaker building magazine articles and web forums all the time.
Later on you can make other speakers from driver choice and baffle/box design up. You can also recycle your current components, if you get serious and take all this as a hobby.
Wellcome to the herd!
ps. my amp modules are Danish design IcePower 125 and 50 watt. I could break my speaker with those, very easy with dsp when you test the tweeter and forget to highpass it before measurement!
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Everything I've read about driver power ratings is that they are approximate, and likely not the biggest thing to worry about for speaker design. Sensitivity of each driver is probably more important, this will tell you, among other things, how much of a pad (value of series resistor) to use in the tweeter part of a passive crossover.
Regarding the rest of the thread, do you just want to make a pair of good sounding speakers? If so, get a complete kit from Parts Express, Madisound or similar supplier. All the design is done for you by a knowledgeable and experienced designer, you only have to follow the directions.
Or do you want to go down the rabbithole of designing as well as making your own speakers? If so, there's a lot to learn, but you still may want to start with a 2-way passive crossover design. Get the Loudspeaker Cookbook as already mentioned, read previous threads like this one, and bewarned that your first pair, even your first several pairs of speakers may not sound as good as a kit. Here's yet more reading:
BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1
These guys are out of stock in the USA but they sell in Europe so you might get stock there. A Dayton DSP has 8 channels for $150.
Dayton Audio DSP-408 4x8 DSP Digital Signal Processor for Home and Car Audio
Why 8 channels? You'll use four channels for your two tweeters and two woofers. You'll use the other three/four for low frequency speakers, subwoofers. Todd Welti/Earl Geddes multi-sub low frequency strategies use multiple sub woofers to address modal behavior in small rooms. Or, you can just use one subwoofer to start and have extra channels available to use later for the more complex strategies if you want.
Everyone interested in audio should have a microphone ($16 to $75 and up) and REW software (free.) The reason a mic is important is it helps you equalize high frequencies and identify low frequency room behavior as you move subwoofers and seating locations around the room. The microphone helps you from wasting time running down rabbit holes as your ears and brain deceive you.
Dayton Audio UMM-6 USB Measurement Microphone
In addition, REW software plus a microphone will automatically equalize DSP settings (filters) to approach an ideal home audio listening curve. I've attached a graph by Harman to show you what that looks like.
After you use the automated DSP filters you can add manual tweaks to suit your preferences. Or not. The automated system works really well. But the mic + software reduces a great deal of the confusion people go through trying to equalize their speakers. A $16, $75 or $120 or more expensive mic is worth every penny in time and confusion saved.
Do you need some of the other audio tools? Probably not. Once you've moved to DSP + individual amplification you don't need the stuff that helps you build passive crossovers.
Box/cabinet building is another area that will be easier for you as a new DIYer using DSP. Cabinets get complex as people try to combine high and low frequency transducers into a single box so they can be driven by a single amplifier. Sometimes, people build complex cabinets to extend low frequency performance. But it's all for naught because the room screws up the low frequency response they designed into their cabinets. As a new DIYer you won't suffer through that because you'll design one set of cabinets for mid/high and a separate set for lows. Not only will your boxes be more simple they'll be more effective. Your speaker cabinets may very well look like a couple of simple small bookshelf speakers in addition to one or several simple subwoofer boxes. Of course, it will all be individually amped DSP.
The book I'd recommend reading is Floyd Toole's Sound Reproduction, 3rd edition. You won't be suffering through the problems introduced by passive crossovers so you'll benefit from learning how sound works in small rooms in addition to how humans hear and interpret music. You'll also learn not to judge your speaker system by the poor performance of a poorly recorded music soundtrack. People who do that wind up endlessly changing things and it never works. Toole's book will save you from spinning your wheels.
Amazon.com: Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Audio Engineering Society Presents) eBook: Toole, Floyd E.: Kindle Store
Before buying his book you can check out some of his YouTube videos.
Floyd Toole - Sound reproduction – art and science/opinions and facts - YouTube
If you go with the TPA3116D2 Texas Instruments amps you'll probably want to run them at 24VDC. If you go with another style of chip use their recommended voltage settings. The switching power supplies allow you to choose between different voltage settings using a potentiometer dial so you aren't going to run into trouble there. I personally like Mean Well brand power supplies but there are many good brands to choose from.
Another issue you might run into is signal source. Your computers are MUCH better than any expensive DAC, compact disc player, or turntable. So are your standard audio streaming services you play through your computer. Your human ears are not oscilloscopes. Today's computers and audio streaming compression algorithms are more than sufficient to accurately reproduce music. You do not need -- nor would you benefit from -- any upgrades in this regard. If you enjoy playing vinyl records on turntables that's great but they'll never be better at accurately reproducing recorded music than a standard streaming service. Do it because you enjoy the nostalgia but don't do it if someone tells you analog is more accurate.
Adult humans lose hearing capability. You probably (maybe) can't hear above 16,000 Hz. Children can hear up to 20,000 Hz. In addition, you can not hear below 20 Hz. Due to the limits of human hearing you will not benefit from buying some transducers you see out there. You're better off focusing your efforts on the areas of human hearing and sound interpretation that matter, which you can learn in Floyd Toole's book.
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Yeah, I have a lot of problems also with bradleypnw's last post. Not only his comments about DACs, which seem completely wrong and backwards, but the whole essence of all those recommendations to a beginner. It's way over the top for someone just getting started and it's completely unnecessary.
As several of us have previously posted, the OP would be best served by buying a kit designed by someone with experience. Then over time he could add a DSP, learn how to program it, learn how to use REW, and use it initially for room correction.
And then move onto the next step of replacing the passive crossover with an active one in the DSP. That's a progression that makes a lot more sense than biting off the whole big chunk and trying to learn all those new things at once.
As several of us have previously posted, the OP would be best served by buying a kit designed by someone with experience. Then over time he could add a DSP, learn how to program it, learn how to use REW, and use it initially for room correction.
And then move onto the next step of replacing the passive crossover with an active one in the DSP. That's a progression that makes a lot more sense than biting off the whole big chunk and trying to learn all those new things at once.
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You'll find all the help you need here. From here you might want to learn what your drivers give you, where to trim each of them, how to blend them together, what your cabinet is doing, and what you want to end up with.
Whichever way you filter, that much is the same.
Motherboards obsoleted external DACs years ago.
Here's the more complete quote from Geddes.
As always, context matters. For example, I pointed toward Geddes' solutions to modal behavior of low frequencies in small rooms. Geddes individually amplifies multiple subs to deal with small room modal behavior. What does he think about the added complexity of multi-subs?
Geddes added DSP to his high frequency speakers but it was difficult because he had to customize his receiver. He converted a commercial off-the-shelf home theater system into a custom system. Yeah, sounds like an enormous headache to me too.
I do disagree with Geddes when he says there aren't inexpensive solutions to the home theater problem. If he streams, he probably streams from a streaming device like an Amazon Fire then sends the audio to his home theater receiver. But if you stream video through a personal computer the DSP+individual amp solution is inexpensive. IMO, home theater receiver setups are a solution for the days of Blockbuster not Netflix.
Personally, I lean toward using PC for the primary home entertainment area because today's entertainment includes things like YouTube videos. It's hard to navigate through YouTube and Google with a streaming box. I guess that same evolution kind of makes dedicated home theaters obsolete too.
Which brings up another interesting subject related to Earl Geddes. Geddes prefers speakers that supply a narrow soundfield in his home theater in the geometric acoustic region to contend with room reflections and please seated listeners. He's liked it for 20 years. In contrast, Toole discusses good speaker design in his book and says experimental results suggest consumers prefer wide directivity speakers. Toole shows wide directivity spinoramas as examples of good speaker performance. So, two different approaches in the high frequency spectrum lead to good results. You just need to be aware of what you're doing and why you're doing it. If a new DIYer just buys a speaker kit they really don't know why the speaker was designed the way it was designed or how it fits into an overall plan. Does a new DIYer have a hard wood floor? If so, they might want to know speakers exist that can turn hard floors into a benefit rather than carpeting their room in the pursuit of good sound. For that matter, legacy DIYers should update their information as well -- there is still a lot of resistance in the legacy audio world to low frequency modal behavior in small rooms despite the science.
The reason Toole's book is so good for DIYers is that it emphasizes small room audio. Most DIYers are designing for their homes not movie theaters or large venues. In addition, most DIYers are using their systems to listen to recorded music rather than live performance. Understanding the differences saves DIYers from chasing their tails. Once a new DIYer understands the small room audio environment the speaker building part is really easy (if they use DSP + individual amplification.)
Here's the more complete quote from Geddes.
As always, context matters. For example, I pointed toward Geddes' solutions to modal behavior of low frequencies in small rooms. Geddes individually amplifies multiple subs to deal with small room modal behavior. What does he think about the added complexity of multi-subs?
Geddes added DSP to his high frequency speakers but it was difficult because he had to customize his receiver. He converted a commercial off-the-shelf home theater system into a custom system. Yeah, sounds like an enormous headache to me too.
I do disagree with Geddes when he says there aren't inexpensive solutions to the home theater problem. If he streams, he probably streams from a streaming device like an Amazon Fire then sends the audio to his home theater receiver. But if you stream video through a personal computer the DSP+individual amp solution is inexpensive. IMO, home theater receiver setups are a solution for the days of Blockbuster not Netflix.
Personally, I lean toward using PC for the primary home entertainment area because today's entertainment includes things like YouTube videos. It's hard to navigate through YouTube and Google with a streaming box. I guess that same evolution kind of makes dedicated home theaters obsolete too.
Which brings up another interesting subject related to Earl Geddes. Geddes prefers speakers that supply a narrow soundfield in his home theater in the geometric acoustic region to contend with room reflections and please seated listeners. He's liked it for 20 years. In contrast, Toole discusses good speaker design in his book and says experimental results suggest consumers prefer wide directivity speakers. Toole shows wide directivity spinoramas as examples of good speaker performance. So, two different approaches in the high frequency spectrum lead to good results. You just need to be aware of what you're doing and why you're doing it. If a new DIYer just buys a speaker kit they really don't know why the speaker was designed the way it was designed or how it fits into an overall plan. Does a new DIYer have a hard wood floor? If so, they might want to know speakers exist that can turn hard floors into a benefit rather than carpeting their room in the pursuit of good sound. For that matter, legacy DIYers should update their information as well -- there is still a lot of resistance in the legacy audio world to low frequency modal behavior in small rooms despite the science.
The reason Toole's book is so good for DIYers is that it emphasizes small room audio. Most DIYers are designing for their homes not movie theaters or large venues. In addition, most DIYers are using their systems to listen to recorded music rather than live performance. Understanding the differences saves DIYers from chasing their tails. Once a new DIYer understands the small room audio environment the speaker building part is really easy (if they use DSP + individual amplification.)
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Originally Posted by Gedlee
“there are all the separate amps and yada yada, yada ... Many might like this kind of complexity, but I don't. If I ever do anything more to my system, it will be to go back to passive.”
Originally Posted by gedlee
“Yea, quite true. But some complexity is worthwhile - others not so much. I would never give up my multiples subs, but I would give up my active crossovers.”
It appears that Geddes is very clear on the subject. And if he doesn’t think all this complexity is worth it, then why in the world would a new DIY person want to do it?
What you are recommending doesn’t make any sense. There are no significant sonic benefits and potentially many detrimental performance issues using cheap Chinese amplifiers modules and DACs. Not to mention the visual rat’s nest of components and wires spread out all over a table top along with many possibilities of ground loops and RF noise susceptibility.
It’s a tinker toy approach and Geddes essential said so. Maybe it’s fine for you, but not really for most others. And particularly not for newcomers.
“there are all the separate amps and yada yada, yada ... Many might like this kind of complexity, but I don't. If I ever do anything more to my system, it will be to go back to passive.”
Originally Posted by gedlee
“Yea, quite true. But some complexity is worthwhile - others not so much. I would never give up my multiples subs, but I would give up my active crossovers.”
It appears that Geddes is very clear on the subject. And if he doesn’t think all this complexity is worth it, then why in the world would a new DIY person want to do it?
What you are recommending doesn’t make any sense. There are no significant sonic benefits and potentially many detrimental performance issues using cheap Chinese amplifiers modules and DACs. Not to mention the visual rat’s nest of components and wires spread out all over a table top along with many possibilities of ground loops and RF noise susceptibility.
It’s a tinker toy approach and Geddes essential said so. Maybe it’s fine for you, but not really for most others. And particularly not for newcomers.
Geddes says DSP + independent amplification is not only worth it in the low frequency spectrum but critical (multiple subwoofers.) It's his claim to fame. In contrast, He said it wasn't worth it in the high frequency spectrum for home theater with multiple surround channels generated by off-the-shelf audio receivers. I agree with Geddes in that regard, I wouldn't want to hack an off-the-shelf surround unit either. But that's not what we're talking about doing here.
DSP + individual amplification supplies superior performance compared to passive crossovers. Floyd Toole explained why it is superior. Today, DSP+individual amplification also happens to be a lot easier than passive crossovers. In fact, it's even automated with REW software and a measurement microphone. DSP is really really easy.
DSP + individual amplification supplies superior performance compared to passive crossovers. Floyd Toole explained why it is superior. Today, DSP+individual amplification also happens to be a lot easier than passive crossovers. In fact, it's even automated with REW software and a measurement microphone. DSP is really really easy.
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Side note: I've seen several complaints about DSP = lots of wires. Have they not seen the interconnects between receivers, equalizers, pre-amps, and amplifiers? Plus all the power cords powering each unit.
Also, if anyone thinks my suggestion of Chinese Texas Instruments amps is bad they are free to offer alternatives. Stop complaining and start posting better alternatives.
Also, if anyone thinks my suggestion of Chinese Texas Instruments amps is bad they are free to offer alternatives. Stop complaining and start posting better alternatives.
You make these statements as though they are absolute truths, but they are not.
"DSP + individual amplification supplies superior performance compared to passive crossovers."
There are many people who would strongly disagree with you about this. In particular the quality of DAC that is required on the output of DSP is of major concern. For vinyl fans the whole idea of putting the signal into the digital domain and back out again is blasphemy. And for good reason.
"Floyd Toole explained why it is superior."
I don't recall ever reading this in his book, but perhaps you can point to a page number. I have the Third Edition.
"Today, DSP+individual amplification also happens to be a lot easier than passive crossovers. In fact, it's even automated with REW software and a measurement microphone. DSP is really really easy."
That's just plain not true at all if someone just simply builds a kit from one of the well established designers instead of trying to design their own crossovers. Nothing else could be easier.
Nope. Multiple subs is an acoustic concern. I've done it passive according to the original method.