I’m had to look this up because I was thinking along the lines of what Drew was saying. Interesting reading about how that works!
That said, I’m curious what you mean about cancelling nonlinearities with the driver facing ‘in’ to the chamber. I couldn’t find much on that unless we were talking about an isobaric arrangement, which technically is in the cards I suppose.
Push-Pull, check out their White Papers
Under 150hz, lower the better, but gets more difficult to measure and there will be a huge acoustic center gap, so larger timing gap.
The lower and longer wavelengths will make the acoustic shift less noticeable.
Oh okay, I thought we were talking about just reversing a single woofer, not adding another one! While I have enough woofers to do this I’m not sure the benefit would be terribly audible in the range these would operate in. However! This gives me an idea for a future project.
I was just talking about flipping a woofer.
Would the reduction in non linearities be then limited only to the fequency overlap between the mid and the woofer?
For clarity, I decided I would annotate the potential drivers that are being used here.
Tweeter: Peerless DA25TX (90% sure this is finalized, but sidestepping to the DA32TX is a possibility).
Midrange: I’ll be testing several (if I have the time and filament) in the following order:
Each are selected based on a number of factors excluding price. I expect that some, if not all, could be made to work well, but I think the key will be how low they can cross to the woofer and how much output I can get out of them.
Woofer: Anarchy 708 with the RSS210PR tuned with no weights to around 43 Hz in the ~10L range. F3=42 Hz, F10=34 Hz as modeled in VituixCAD.
I tried the Epique subs but just couldn’t make them work in the volume I had. I didn’t even think about the Misco Bold North XBL2 woofers I have until today, so I probably won’t bother modeling them to save time given all the work stuff I have going on. Other than those I didn’t really have any sort of “designed for bass” drivers lying about.
Did you consider the bigger brother to those Faitals, the 6FE100?
I did consider the 6FE, however some changes occurred since my original post in this thread. The biggest change is the tweeter. I have a pair of small frame beryllium tweeters from SB Acoustics I had been considering but opted for the Peerless DA25TX instead. The difference in flange size is rather large and generally keeps me from using anything larger than a 5-5.5” mid.
Modest beginnings - a color test for the dark gray and neon green I’ll be using throughout the project; these are the feet (upside down). I’m a fan of the color, less of a fan of the TPU. This is really hard for TPU, which can be rather rubbery in softer formats. Problem is I couldn’t find a softer version in the color I wanted. We’ll see how that turns out.
Since the feet looked goodl I transitioned to printing the larger pieces; this is the mid/tweeter chamber and associated gasket and I’m pretty happy with them, but there is a line all the way around where it transitions from the 18mm thick ‘rear’ to just printing the side walls (this is the bottom horizontal line in the photos below, I believe the top line occurred due to a changeover in filament and is probably not avoidable without using ‘fuzzy skin’ or some other time-consuming process). I’m thinking I might intentionally put a ‘V’ groove or something there to help hide this transition if time allows (and if I have enough PETG - these are ~1.2kg of filament apiece). Both the mid and woofer chamber walls are constructed of 15% infill and 6 wall loops, based on previous testing this should be adequate.
I had printed a test baffle out of PLA and discovered a few things that needed corrected, so now I’m printing a ‘real’ one out of PETG for the 5FE125. Baffles are designed with 25% infill and 6 wall loops and are about 0.6 kg each.
Finally, this is the rear of the mid chamber - a ton of holes were necessary. The eight largest are through holes - 5" long bolts will start through part of the woofer module, run through the mid chamber (and seals) and screw into the rear of the baffle to hold everything together. It’s not an ideal solution but given the relatively shallow depth of the mid chamber and a desire to avoid bolts on the front of these baffles this was my best effort. Four of the other holes are for pass-through binding posts which the crossover (and mid/tweeter) will connect to, and the remaining holes are for mounting the primary crossover board.
Baffle complete! The faceplate of the Peerless basically looks identical to the deep gray of the baffle when observed in-person. The woofer brings up a question I had forgotten about, namely, what countersink to use? I currently have it set as the frame depth, but that is actually shallower than the thick foam surrounding the cone by a good 2mm or so (as seen in the second pic). Should I inset it further so the foam is level with the baffle, or just go with the lip of the frame as the countersink?
No doubt those look great !!!
You can make them pretty strong even of they arent solid. Like cardboard the strength to weight ratio is high. 6 layers is probably close ton1/8 inch thick brace that and then add another 1/8 thick wall and it gets pretty strong quickly.
Yeah, in my limited testing I didn’t see any resonances in the Mechano23 that gave me pause. Pretty normal stuff really.
Looks great! I like the color selection.
I say countersink to the foam. It’ll give it a more polished look.
Or remove the foam and 3D print a prettier trim ring.
I plan on testing this since I already pulled the foam from another driver.
Totally rad!!
Thank you all for the comments by the way, it’s motivating me to continue the push on these…even as I contemplate whether Iowa is in the cards for me this year. My wife can’t come this time which is a real downer, and we are just starting some home renovations that will probably be peaking around that time - assuming the selected contractor sticks to their schedule.
