I’m trying to put something together for Iowa. I might bring a 3D printed Mechano23 with me just for grins but I would prefer to have something that was wholly my own design and I’m totally running out of time.
Long story short, I need a midrange - preferably in the 6-8" size - that is reasonably shallow and digs down to 200 Hz or so with low distortion. A neo motor could be helpful. Size is kind of important for the style I’m going for, but if there is something close I guess I could make a ring around it to make it look bigger.
There are several pro audio mids that might work but they all run so hot compared to the woofer I (tentatively) selected they’d need significant padding. Ideally I’d find a mid that was a bit inefficient, something around 87 dB. Something at a reasonable-ish cost (~$100 or less) would be nice, but I’m open to expanding that a bit if needed.
On the shortlist so far (I’m ALL OVER the place on this):
Satori MR16 (~88dB) - A little on the pricier side but it’s close.
Peerless FSL-0512 (~91dB) - A little small but I own some already, unsure it could cross as low as I’d like.
BMS 8N519 (94! dB) - I REALLY want to use this driver for something but I don’t think this is it. Sensitivity is high and would about match my (tentatively) selected tweeter though. Also it’s like twice as expensive as the Satori.
MAC-06 (~86 dB)- I have a pair of these too, they’d dig a bit deeper than the FSL and match sensitivity pretty well but I suspect the FSL is a bit cleaner.
Please send help!
Edit:
I do have the FaitalPRO 5FE125 as well. A little small but it could work.
Budget is…well I’m seriously considering the Textreme version of the Satori MR16, which I can get around $400 a pair. Let’s say that is the ceiling for now…but obviously we can go lower than that. Or free even, if I decide to go with what I have.
Crossover point is expected to be between 1500-2000 Hz, so it needs to play nicely up to meet the tweeter. Ideally without steep slopes.
Volume for the mid will be a constraint for sure. Needs to be minimal. Like 4L or less.
Other drivers will probably be a single ~6-8" woofer the mid hands off to which will have its own volume to play with.
Well, I made a few decisions and sort of ran with them…still work to be done on the cab but I have enough modeled that I can print the baffle and mid/tweeter compartment. Baffle should be done today but I’ll be out of town a bit so will hold off on the compartment. I also need to do some printer maintenance as these will use nearly all of the X/Y/Z printing capacity I’ve got.
Generally not great to have a PR facing up or down position. The extra mass pushes on the suspension, and sags over time. Even if not adding mass, usually PRs have a starting mass built-in to get them near the tuning ballpark.
Yeah, I considered this. My first choice was woofer on the bottom/PR on the back. Unfortunately there was just no way I could fit it on the back while leaving enough room for the woofer magnet - without making these even deeper than they already are or making the taper barely, you know, taper. And putting a single PR on one side would just look off to me. Choosing aesthetics over function this time, I guess.
Based on the model in VituixCAD it should not need any additional mass at least. This is the RSS210-PR, only 110 grams when bare. Assuming the calculation is similar to that for subwoofers (just with xmech in place of xmax, maybe?), we’re looking at about 3-4% sag.
Sagging “over time” might also not be a thing depending on how these end up sounding!
‘Generally’ depends upon the veracity of the total suspensions of the PR. Not scientific, but if the PR is employed within its Xmax, while a downward positioning would have the starting ‘center’ down a bit (probably immeasurable, but theoretically) due to weighting, final ‘tuning’ will balance out the downward vs upward movement to ‘match-up’ with the woofer employed. ‘Right’ or ‘wrong’ I’ve had PRs in vertical and downward positions without fail ( ‘course I don’t keep a build around for too many seasons…) and when tuned with the woofer its been of zero issue. Lots of subwoofers with downward firing drivers and with advantages of coupling. Just pick a solidly built PR for your project.
I agree with you in that ‘best practices’ is not to have it facing downward- it’s just that I’ve not had an issue (maybe I just don’t crank it up to 11).
I have an old Velodyne sub that has a down firing 15" PR that has a permanent sag. I bought it in the 90s but just didn’t end up using it all that much. It did take a quite a few years of idle time for that to happen and it may have a lot of added mass.
Thanks didn’t realize it’s a 3 way. Maybe the pr can go on the side, but can cause walking in small light boxes, if you can go with smaller, two opposed would put a cone on all four sides!
I tried quite a few PRs on this one, unfortunately there aren’t many that have the right size, tuning, and excursion and I spent hours trying to get them to work. Even more hours trying to get a slot port or two to fit - I actually had a really cool idea for that so I hope I can try it for a future build, but it just created too many problems in this box.
After all that time, I tried the RSS210PR and it was like magic! One modeled so perfectly it was unbelievable. I really do wish I could cram it on the back somehow but that just doesn’t work, unfortunately. Using two doesn’t really work quite as well either. I think it’ll be okay for the October at least.
No worries, it’s good as is, we were just throwing out ideas! Down firing can cause sag, but it takes many years to happen and smaller prs are lightweight anyways, so may not be an issue.
The RS line is pretty stout with a robust suspension. There will be some sag no matter what, but may not ever be an issue if there is little to no added mass.
No problem at all! Any thoughts on integrating the rear woofer with the mid? Thought process was to cross it low enough it was essentially omnidirectional.
Yep probably not much issue if crossed low. The driver phase would be 180deg from normal, but that is easily changed by reverse wiring if it somehow is an issue.
Actually, placing the driver on the rear, physically rotated to face the opposite direction, does not reverse the acoustic phase angle if polarity has not changed. Bipolar operation is in phase. Dipolar operation is out of phase.
Another thing that could be fun is mounting the rear driver inverted and reversing the phase to compensate and cancel nonlinearities.
