Lets face it speaker DIY had its top in late 197ties when it was cheaper and better than most industrial products which had lousy sonic quality at very high prices. But industry caught up fast. This is an attempt to revive the 197ties DIY spirit. Given are some thick boards of some precious wood with excellent acoustical qualities such as damping. Next you make an enclosure design that fits your office or living room pretty well. Now the maximum volume is given for bass section there is no more wood. You could try to find a woofer with parameters for a Butterworth alignment of a vented box. But doing so is strictly against said spirit. Rather you have an excellent broadband speaker for ex. Jordan and an also excellent woofer. But this requires a 55 liter volume for Butterworth alignment and you have just 28 liters. This is the case where "active" makes sense. The patent by R.Stahl demonstrates how to alter the 4th order hi pass filter characteristics of speaker in vented box thus that it results in a perfect 4th order Butterworth hi pass. Add a frequency-dependend limiter thus that when cutoff is set to 20/sec xmax is never exceeded.
This is the old spirit is it not?
This is the old spirit is it not?
Late 70's? Active? Yes...
Solid wood? Vented box? Industry caught up fast? No!
SB1980-3way
and
Whatever_happened
Solid wood? Vented box? Industry caught up fast? No!
SB1980-3way
and
Whatever_happened
Well the old way was to build a test box and play around with box and crossover till you liked it. You could tediously map out the specs (with the tools we had then) to make your calculations. But we had to build and test. Now with graphical computers in nearly every home, we can simulate to the point where we are pretty confident that we will be within 'tweaking distance', so we often build our final outside box and adjust stuffing, ports,interior baffles,etc. And of course tweak the crossover. We can account for box,room, placement, to a much greater degree than before.
My suggestion for you is this-get a microphone, build your 28l box, tune your 28l to the frequency recommended for that 'ideal' box, and adjust from there. If you have not lined your box with thin ply or mdf to lessen the issues of splitting, I would recommend saturating the inside if not the outside of the wood with the sort of epoxy that boatbuilders use. It penetrates nicely, and can prevent splitting. I have used epoxy on the inside and oil on the outside. The tuning I have suggested will give a gentler rolloff than that 'ideal' box. Earlier, but gentler, more like a closed box. If you look at Troels' designs, he has ended up at half the 'ideal' volume often, it's not absolute. When you shrink the volume, you'll get a hump. You lower the tuning to get rid of the hump. There you are. So find a simulation program you like, and have at it. What you propose will work, just not in textbook form.
My suggestion for you is this-get a microphone, build your 28l box, tune your 28l to the frequency recommended for that 'ideal' box, and adjust from there. If you have not lined your box with thin ply or mdf to lessen the issues of splitting, I would recommend saturating the inside if not the outside of the wood with the sort of epoxy that boatbuilders use. It penetrates nicely, and can prevent splitting. I have used epoxy on the inside and oil on the outside. The tuning I have suggested will give a gentler rolloff than that 'ideal' box. Earlier, but gentler, more like a closed box. If you look at Troels' designs, he has ended up at half the 'ideal' volume often, it's not absolute. When you shrink the volume, you'll get a hump. You lower the tuning to get rid of the hump. There you are. So find a simulation program you like, and have at it. What you propose will work, just not in textbook form.
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