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Hey Father Francis. Heat happens for sure, on gruelling bass music shows I can feel the heat on the metal of the hatch handles, and if you put your hands in the vents you can feel the warmth coming off the drivers. I've rolled mine out to the trailer in cold Canadian winter nights and seen heat causing a bit of fog to come out the vents haha. There was some mention in previous pages regarding the potential for heat to be a problem for this cabinet. While you should be careful with your limiters, in real life I don't think its turned out to be as big of a concern as was warned against. I've been using a pair of thermocouplers to pull temperature data off the magnet, if I'm working them hard I can get temps up close to 70-80 degrees or so when I'm tickling my limiters during heavy bass music shows. Bennett Prescott from B&C stated that the 21sw152 should survive 100 degree magnet temps reliably, but I've made it a point not to run them that hot. I only really see that high of temps for dubstep or modern bass music shows, for most everything else temps never seem to build up when I push them to the verge of limiting. I've actually found this a bit interesting, as it was stated earlier in this thread that one should avoid pounding techno with this cabinet but that hasn't been my experience at all. I specifically use this guide to set my limiters and I haven't burnt one up yet, its written by XTA but can be applied to any amplifier. Start at page 5 and follow the instructions closely. https://www.xta.co.uk/wp-content/uploads/2018/05/XTA-Application-Note-DPA-Amps-Limiter-Settings.doc.pdf

Jami, Thanks for the cnc files and sharing them! I'm sure it will be a huge help to some other builders. I know it probably took some time to put those together.

Hello Andyman3k. Nice work and thanks for the measurements. QSC eh? I've used my share of QSC amps and speakers over the years. The impedance plot suggests that the tuning of the vents is near 30hz or so. That's right about where it should be. The corner drooping a little is probably due to the 8 ohm 21sw152 having a little lower motor force than some of the other drivers used. That's one effect is that the vents aren't loaded as aggressively which results in a little bit of a roll off before the tuning. Not the end of the world in the scheme of things. In general you'll get a sharper more aggressive low corner with drivers having more motor force ( BL^2/Re) / lower qts. My cabs are usually a bit undersized vs extension and thus require extra energetic drivers. That indoor measurement rig sounds intriguing. Too bad it's not for public consumption. Am I correct that the polar work was conducted outside but the FR and Imp were on the inside rig? Nice measurement rig. Again thanks for sharing your info. More data is always welcome.

I modeled a CNCable version of the SKRAM fit exactly to the detailed plans provided by Ricci in post #1. Feel free to use them as a base. These are meant to be used with Adam Hall 3402 and Neutrik NL4MPRXX, so you might want to adjust the respective pockets and cutouts. I did not yet include pockets/holes for wheels. SKRAM 3D.step Assembled enclosure SKRAM PARALEL CAM.f3d - Fusion 360 File including programmed toolpaths. 12mm Sheet 1.step 12mm Bracings as optimized flatpack 18mm Sheet 1.step18mm Sheet 2.step18mm Sheet 3.step 18mm Parts as optimized flatpacks. SKRAM Individual Parts.zipIndividual Parts