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Hey all, long time lurker, been using the Skram for about 2 years now and decided it's finally time to post some proper calibrated measurements. I’m an acoustical engineer at QSC, and run my own custom rig as a side hobby. I've only been in acoustics for 2 years, before that I was an amplifier engineer so I'm still learning some of this stuff. Been meaning to get this info for a while and finally had some outdoor measurements to make for work, so while I had things set up, I thought I would go ahead and get some comprehensive measurements for this build. I’m currently running them with the 21SW152-8, but we’ll be getting our hands on the new cost-effective Celestion TSQ2145 for evaluation soon, at which point I’ll get another indoor groundplane & impedance measurement. I haven’t added fiber fill/acoustic foam to mine yet, so that could be another interesting data point. Indoor ground plane measurements are done with our 1/4th space calibrated, scaled, & windowed measurement sequence that we use for all product qualification. Also got some measurements of THD and harmonics at 10v. The one downside is that the signal path has >100ms latency for phase response and there are minor reflections even with the windowing of the impulse response. Unfortunately I can’t post pictures of this setup due to product confidentiality. 1w1m looks to be about 94dB SPL. I am a bit surprised how different the "knee" at 30 hz looks compared to previous measurements in this thread, I'm not sure where that difference is coming from... Earthworks M30 measurement microphone used for all data. ARTA outdoor setup, 22C, 30%humidity: RME Fireface UCX QSC PL-380 Q-SYS Core250i Outline ET series turntable Indoor measurement data: Audio Precision AP2700 for impedance response Lynx Aurora(n) audio interface Grace m801mk2 mic preamp Measured with SoundCheck 15 Outdoor setup has hard walls ~16 meters on either side, so spatial IR responses are windowed to 90mS (2x 16m). Turntable setup to rotate about the physical center of enclosure. Outdoor SPL scaled to match calibrated indoor measurement. I took 2 polar data sets, one with the enclosure vertical, with ports at the bottom, and one on its side, and you can see the slightly asymmetric polar response. I’ve attached a .vacs file with all of the measurements, and I can provide all of the outdoor .pir files if someone was interested. This is an amazing subwoofer, many thanks to @Ricci for his work. Hopefully this information will be useful to you, let me know if there’s anything else you would like to see, or clarification, and I’ll do my best to provide. Skram Data.vacs

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

I should have Dune pt1 measured next week. JSS

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.

My first exposure to DataBass and I can honestly tell you this thread is a game changer! Thank you!

JAMI, you rock !! thanks for sharing your CNC work with us! For convenience I packed al your CNC files on a rar archive (for the couch potatoes like me ) SKRAMCNC_JAMIPACK.rar

So.. here are some measurements with front plate installed and up to 3 ports blocked with grain sacks (quite tightly) Measurements were done in an mostly open area, the speaker was sat on a few tonnes mill stone on some paper bags to make it very stabil. The cobble stones were too uneven. there is a highway nearby but during spl calibration the noise of the cars didnt surpasse 68 dB. the microphone was sat 360cm from te center of the cabinet. It was sat close to ten meters away from the building wich is round so we felt that maybe it would be less visible in the measurements. Please comment on the plots so i know what to look at. And thanks again to Josh Ricci for sharing these plans Regards Lex ckram Dec 30 molen meting volledig.mdat

Using economy style plywood and some scraps for the 12mm parts i started construction here are some pictures of the process. First off thank you Josh the drawings are flawless! Sadly upon reaching this point my work shift starts again so will continue with the circular bit once i get back home. sofar everything is up to the millimeter exactly as drawn. Upon completion i would like to submit measurements. I think i have everything (software, calib. mic., mic, stand etc) Could anyone point me in the right directions on a step by step measurement process? I know theres a big chance this thread is dead, no one will be reading this but im trying anyway and like to thank Josh again for the nice drawings. Greetings Lex Breijs.

OK. I'm Now decided to build the amazing SKRAM. Like always you're so helpful Ricci, Many thanks Mr. designer speaker genius. 😉