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I have a question that is very important and i am so very curious. first id like to say, this online forum is spectacular and i geeked out for hours reading everything. with so much knowledge here. If everyone had to take a hard answer guess. what would you say 99% of movies HZ frequency range will be within? is it OPTION #1 20-100 HZ (or) is it OPTION #2 20-200hz? if you had to pick one of those ranges for the best most consistent HZ frequency range, what would you pick and why?

All links updated, let me know if there are any missing graphs. JSS

I've been very interested in building some skrams for a while now, but unfortunately havent had the pleasure of hearing any in the wild. Does anyone know of any UK based soundsystems using these that I could listen to?

Only links in first post yet to be updated are 3-3.5 star movies. Will hopefully finish updating everything soon. Hope to measure Dune 2 next month. Let me know if anyone has any requests. JSS

Yes they are painted black, they gained 3db’s and no strong lighting around 3db is a joke

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

Are they painted black and some strong lights were pointed at them?

Question for anyone running four plus skrams, last weekend we were running 4 cabs standing strapped together with 2*215 , and a pair of F1 res3 sh , anyway after the gig the two cabs in the middle were pretty hot, the cabinets plywood like very warm , cabs are loaded with B&C Sw 152 8ohm running all four off a K20

The Gjallarhorn 2 was never built that I recall. It was designed around a very expensive and hard to find driver with parameters that were rare back then. It would've marginally improved the original GH performance and improved the cabinet bracing and solidity. I liked the horn fold I used on that one. It would've still had the response issues inherent to TH designs tuned so low. Ragged FR in the top of it's range and potential ringing. Also the performance would greatly vary based on the driver. It is a very large, heavy cabinet. However...Over a 1.5 to 2 octave range it is very potent and smooth. I'm not sure what current driver options would work well for it.

Hello Josh, If i recall correctly the weighing was done with the driver installed. So afterall really not bad. I live in the Netherlands. Bike systems are more and more popular here, some people just prefer openair dancing i guess. Also its easy to move when authoritys disagree. Ill probably make the ckram into a bike cart and will upload pics of it. Unrelated question, do you know if anyone ever posted measurements of the gjallard horn #2 its very intreguing. Im considering building it aswell the ckram has gotten me appreciative of that low end information. Can you tell me how it would compare to the ckram?

Let us know what you think of the LF in Dune (2021). JSS

I had a similar problem with a 2.1 setup, I had to purchase an old BD player that would decode DTS-HDMA and Dolby TrueHD as LPCM to get the LFE channel content. JSS

Dune (2021) - Dolby ATMOS (measured 7.1 bed) Level - 5 Stars (112.99dB composite) Extension - 4 Stars (12Hz) Dynamics - 4 Stars (25.64dB) Execution - TBD, vote in the poll. Comments - NO clipping on this track, it appears to be very well executed. Not the best track I have ever heard, but very good. JSS

I watched the movie two days ago and was very confused and disappointed about the bass I was getting, even tho it seemed to go deep by the graphs and didn't even need BEQ. Turns out MadVR doesn't downmix the LFE channel into stereo! I'll have to see how I can fix this, since my mains go to like 16Hz. (this was the first movie I watched on the stereo setup) Edit: I solved this problem with the LAV Audio Decoder. It baffles me that the default MPC-BE option (ffmpeg?) only downmixes center+surrounds into stereo and leaves out the LFE. There is no slider for LFE mix, which you luckily get with LAV. But in LAV, the mix sliders don't give you values in dB, but in numbers and the default is 0.707. What the hell!

Agreed. We essentially just got a flash and low boom/rumble. Not the ST warp-boom blastwave I was expecting. One of the best movies I have seen. JSS

I voted 3 stars. This was primarily a slow burning dialog driven movie as expected. I wanted LFE effects to end all LFE effects when the bomb was finally detonated. It didn't quite deliver that to say the least. Good movie though.

Hello Lex, I'm glad that you like the design and that the front plate appears to be solid enough. The modeling for it only ever indicated a modest amount of gain in the kick and upper bass region. Does look cool and provide driver protection as a bonus. Unfortunately a 21" cabinet can only be so small / light. Physics grrrrrrr. Did you happen to weigh the finished product with the driver installed? It looks like you measured the weight as about 52 kg without the driver. 70kg with the driver? This should be about right. A little big and heavy for a one man lift. You could add wheels or a dolly system. The 18" design you are thinking of is probably what I tested the BMS 18N862 in. It is much smaller and lighter but that cab is tuned a little lower and was intended for a heavy duty bass guitar rig using AE TD18H+ Apollo's. Traditional BR designs aren't that difficult. You could probably design your own. What country are you in? The bike systems seem interesting and fun. This would be a lot of sub on a bike!

I may have to check this one out. BTW - I got most of the links fixed from the first post. Still need to fix the 3-3.75 star films' links, will hopefully get to it soon. If anyone notices a missing graph on a post, let me know. We lost all of bosso's scenecaps at some point, unfortunately. If anyone has any film requests for measurement, let me know. JSS

Picked up this Bluray for cheap and really enjoyed this film! Same writer as The Quake and The Wave. You aren't kidding, massive bass in this one. Definitely worth a buy on disc, especially while it's so cheap.

Hello Josh, 8 ohm 21sw152 is the driver that i used, driven by a Powersoft Digam amplifier. The front plate looks cool and as far as i can see raises the plot a little between 40 and 50 Hz. The plip around 150Hz is no problem for me as i am testing the sub currently underneath Art Welters Syntripp's. These are crossed at 80 Hz to minimize sense of direction in the sub (not sure this is the right word but at this moment its difficult to locate the sub by ears alone). The Syntrips Themselves have a way of dissapearing (diffucult to locate blind) audibly if that makes sense. I am very pleased with the result i have tortured it quite little with some sub tests and there is no noises from the cabinet other then a poorly sealed speakon socket (very minimal). Building it, i made sure the front plate is not touching the cabinet on the sides. I still have to play loud music over it but sofar to my ears CKRAM has a very clean and accurate sound, revealing a lot of information in the lowest frequencys. Deepeer modern house tracks are truly a joy, but also recent music for instance billy eilish and for instance beonce. Even at higher levels (sofar) it doesnt sound boosted like with some commercial BR designs i find. The only minus is personal. I hoped it would be more portable. You cant have everything and to have impressive volume down to 30Hz obviously comes at a cost. For this setup to be a solo operation is not as easy as i hoped. its just a little to much weight x size, to comfortably load alone. That being said it matches the Syntrips very well i think. As in some occasions i am looking to transport the sub by bicycle, i am considering building another smaller sub cabinet. I saw a design allegedly by you😀, wich would match my project. single 18" BR with a square port in one of the corners of the front plate. I cant find it at the moment (Diy audio forum rabbit hole syndrome). Does this sound familliar at all? Thx again for the great drawings and calculations wich i am sure have costed a lot of attention. If there is anything that you or anybody else want me to measure or test please let me know. Currently i am using a focusrite Dac and Umic measuring mic. combined with REW. Lex,

I'm much in the same boat MM. Behind on movies. I've been watching mostly docu series and sports lately. I did watch Godzilla Kong and Minus One, both in the theater. There was plenty of bass for sure but whether either truly dug deep or not I can't tell at the local Plex.

Excellent job Lex. The cab looks solid and well built. Nice pictures of the process too. What driver are you using? The 4 ohm or 8 ohm 21sw152? Give me a day or two and I'll go through the measurements and formulate a reply. Apologies for the extra extra late reply. I've been on hiatus from audio for quite a spell. Overall the measurements look about as expected with the vent pipe resonance causing the blip at about 150Hz. Looks like the tuning may have come in a smidge lower than the target, but that isn't unexpected given the size of the vents and the cramped space inside of the cab. Any thoughts on the sound and structural solidity of the cab? The driver cap plate? Are there issues with vibration or noise from it during loud playback? That's been a concern since day one of the design. Secondarily I'm not sure if the acoustic effects of it are worthwhile. At least it's a glorified driver grille if nothing else.

I should have Dune pt1 measured next week. JSS

Hey Ricci! I have not really been watching films as often as I used to the last few years, partly in fact because I have yet to rebuild the HT since I moved. I have a decently capable temporary HT outfitted with crowson transducers so I can monitor the Infrasonics, and the plan is to be reviewing a few films every month. If anyone has any suggestions for movies of the last few years that you would like evaluated, post the requests in this thread, I'll try to get everything updated so the thread works as it used to. Also now that Mandalorian is out on BluRay, I may get around to measuring it, as some of the episodes sounded like they may have had some great sound design. JSS

I'll have to give this a watch John. Haven't seen it yet.