Greetings! I recently ordered 2 x BMS 15n820's, and im wondering if anyone could help me design a cabinet for them. I would like to use them as "midbass bins", tuned to around 50hz. I would prefer to have a slot port at the front, if possible. Can this be done ?
Something like this should work for you.
~3.2cuft net internal built from 1/2" material (add 1/2" to overall dimensions for 3/4"). 2" high slot port across the front with a single brace running down the middle, the port length should be about 6.5" which should put tuning right around 50hz. Port velocity and cone excursion will be kept within safe limits up to 500W input power with a highpass filter at 45-50hz.
If you want both in one cabinet just double the width of that one using three braces in the port and don't forget to brace either cabinet as well.
I think you probably could have gotten the TD18h cheaper than the 15n820 if you paid retail for the BMS. But I am going to guess that you live overseas so that might not be the case.
My dual sealed LMS 5400 Ultra build
My dual sealed LMS 5400 Ultra build
While I can not speak for the OP, I have spent a good bit of time listening to the Palladiums in my local dealers showroom. To me, they have good clarity, detail and an overall nice top end. The mid-bass is pretty nice as well. I have spent a lot of time comparing the B&W 805D2 to the Klipsch Palladium bookshelf monitors, and while I can't say which one I like best, (they both have their own strong points), the Palladium bookshelf monitors have a ton more punch, output, and overall better mid-bass than the 805D2!
Have you tried EQ'ing your subs to have a little boost around the 60hz to 120hz area?
Interesting ... have you considered the room acoustics? It's entirely possible you already possess sufficient SPL capability, however there's SBIR issues lessening the energy in all the wrong freqs. Do you have measurement capability?
Seeing all the nice gear, you may or may not already know all this. No offense if you do.
Subjective punch and impact reside entirely within the heart of the SBIR (speaker boundary interference response) range. Quarter wave interactions can easily suck the impactful energy out of a presentation. To know for sure, one must measure. However, simply moving around while a powerful track or movie effect is playing will allow you to determine if some locations adjacent to your LP have more impact than others.
With adequate bass trapping, you lessen the blurring time related bass "overhang", this allows greater transient delineation to be experienced. It's typically not the initial transient, it's the problematic excess of energy that doesn't dissipate quickly enough ... this is often what many perceive as lacking punch, etc. Trapping also smoothes the FR, always a positive step.
Also, the rear wall bounce, and our seating location in general can have even a greater impact than the time related effects I mention above. Never sit in the center of the room, front to back, .. this is a null zone. Often 38% off the front wall, or rear wall is a solid starting location for seating.
Another consideration is time alignment. Improper time alignment between the subs and mains will null the critical range you're interested in. So yeah it's a minefield, that's why without measurements, you're flying blind. Quarter-wave nulls, SBIR, proper time/phase integration between subs and mains, excessive bass decay in the room, room modal issues, everything's got to fall into place.
As I said, you may or may not be aware of these items. All said, there's few things as punchy as the aptly powered pro-audio LF driver, in a well executed environment/system.
Flat, Deep, Clean, Linear, and Loud
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB