You are quite welcome.
I know what I write doesn't pose questions to you all. Instead, I've mostly laid out the facts and some science. It's up to you to use those to develop your own questions. This is how I proceeded back in the early 1970's, by reading all of the AES papers and many others on speaker design in old and current magazines, on acoustics, studied basic physics, calculus, and psychoacoustics. Later, I returned to university to master all the math, and to learn more about how materials behave when vibrations exist and when electromagnetic fields pass by/pass through.
Sometimes I would find an error in the logic or math of someone's research paper. Usually, I used a paper as a springboard, expanding upon the author's thoughts and test methods, to better look at 'something' in detail.
To choose that 'something' to examine, to fix, or even to ignore, I first had to understand the very basics of WHY and HOW that 'something' would be important to what we hear, and then learn WHY and HOW 'it' occurs. This included how and why cabinets vibrate, cones break up, critical damping is achieved, a tweeter can fail to move on very tiny sounds, the air itself distorts... countless questions.
The most important ones are addressed in the Audio Engineering Society's Audio Anthology 3-book set.
Also, one should get The Audio Cyclopedia, even a twenty-year old copy. It is full of important info on acoustics, speaker design and recording methods, found nowhere else. Make sure you get one that's not falling apart in its binding.
Another book, out of print, is Elements of Acoustics by Temkin. You need to know calculus to get the most from it, but it's readable without that.
Finally, the Theory of Sound by Rayleigh, from Dover Press, is exactly like reading Isaac Newton's original papers. Get both volumes one and two, first published in the 1880's.
If you are interested in design but will never build your own speakers, these books are full of the very best information found nowhere else, and are written well enough to make for good, casual reading.
In these books, you get to see how others approached issues and usually find out WHY they did, along with what had been tried before then and WHY.
Knowing WHY is the most important factor in making better speakers. I can tell you most current speaker designs say to me that their designers know no more than what was mastered by 1979. If you read over the topics presented in those AES books, you'd see this for yourself, darn it.
At this point, I see nowhere on the internet any guidelines on how to select the proper woofer, etc. While I cannot help you directly with that, I can point out the principle differences in the drivers you selected, and leave you to have a good weekend!
- The Classic Scanspeak woofer has ALL of the right numbers for a sealed box. I wish it were more efficient.
- The more expensive Scanspeak woofer will not go as low in its proper sealed box. And unless you are stroking the heck out of it (not likely), it has no less bass distortion than the less expensive Scanspeak. However, it would be very slightly clearer in the lower-voice, high bass range. But then it goes nuts above 1kHz, all from its harder cone. Its first resonance at 1kHz is from its heavier rubber surround bouncing back, like a ripple in a flag, and then vibrating the cone running around its rim, like a church bell's 'first mode' of ringing `round-the-mouth vibration. The big spike above 1khz is its harder cone ringing like crazy.
- The Accuton woofer is a lot of $$, has high bass distortion, and will not go as low as the Classic Scanspeak.
- The Accuton mid driver has many wrong numbers and is not quite efficient enough.
- The Scan mid has the right numbers, its cone breakup is under control, and it has a vented suspension like the Scan woofer. Cross it over at ~300Hz. Read my Continuum 3 and Calypso speaker design papers for more info on using a mid.
- The only ribbons worth using, for sonic quality and which will not break for our purposes, are from RAAL. Excellent products, the best by far. You will need to create a Zobel to offset its inductance. Cross it over at 3kHz. Use their smallest model, for the best highs.
- I advise you fade in the subwoofer(s) below 40Hz, leaving the main three-way to run 'full range'.
So now you face a zillion other questions. Get the AES books above and the Audio Cyclopedia at the minimum for both guidance and answers, compared to the Loudspeaker Design Cookbook.
The Acourate approach is not right. I advise anyone hopefully learn what 'the numbers mean' for any driver, then use the parts I like above to fine-tune your own passive crossovers, with woofer mid and tweeter in their own boxes so you can move each one back and forth.
- You only need to build one speaker, as I posted before.
- You need a $100 voltmeter, a $200 fairly-low-distortion sinewave generator, a decent measuring mic with preamp, to run into some kind of third-octave spectrum analyzer for looking at pink noise.
- And a pocket calculator (scientific), especially to calculate real "L-Pads" for mid and tweeter using the best wire-wound resistors.
That's about it for tools, IF you go through the AES books.
When 'designers' do not understand in depth the extensive research from the past, they rely upon digital test gear. And then get many wrong answers since they do not understand 'the basics'. They have purchased an expensive tool that does not help solve the real problems. But they don't know-- they just stick a mic up in the air and tweak their crossovers to 'get the right curve' for each driver, which is soooo wrong.
And then they hear something 'not quite right', to then tweak the circuits by ear, so their favored recordings sound 'right'. And of course then brag about how carefully their gifted designer listened, how much money they (Revel/Harman) spent on a robotic speaker-comparison room or anechoic chamber (Paradigm/Canadian government). Hey, this isn't the space program where people get killed. This is an unsupervised field of endeavor, with no university program for it, requiring money more so than any real technical education. They always claim, "Well, we all just hear differently." Pooh.
And do get rid of/prevent any cabinet reflections for your mid and tweeter (get the mid's box away from the woofer's and tweeter's boxes, vertically). Put wool felt near the tweeter's dome.
Hope this gives you food for thought!
Best,
Roy
