I did not put any lining, just a bit of stuffing. I have to lookup the data if you want exact measuremnets but from memory it should by close to 9 cu.ft. The port is 4 in high and 24 in wide, a about 66 in long! Tuned frequency around 19 Hz.
I just tried it with the intro to Blade Runner 2049...geeeezzzz! 😱
Yup! it is big... actually make that huge! I estimate it's close to 200 lbs with the driver installed.
I actually hurt my back bringing it downstairs with my friend... 😡
I think that's the largest port I've ever seen, equivalent to 3 x 6inch round ports, or a single 11 inch round port - extremely impressive! Think you'll have definitely got the velocity down to acceptable with that port! Given your port length of 1.6 meters, you're going to get a port resonance around 100Hz, which will probably show in your measurements. I had one around 130Hz with my 1.3meter port length - Although above the passband of my sub (LPF at 60Hz), I apply mild attenuation using dsp to knock out the hump.
Originally, I did not plan to make it that wide in order to keep the length down a bit, but for fabrication consideration, it was much easyier to make it the full width of the box so i designed the port like this... we'll see the measurement soon enough!
Caused a 10dB spike at my listening position, on a measurement with no LPF / PEQ, but I dont notice issues when listening with the LPF configured, even without the PEQ attunation.
If you're interested, details on my thread - Project – 2 x Peerless XLS 10” 20Hz tuned slot port subwoofer
Looking forward to seeing your measurements. Wish I had your skills to make ports like yours!
It's really not that difficult, I happen to have a fab lab not too far away with a CNC machine, I basically just did the drawings and put it in the CNC and all the parts came out! LIKE MAGIC! LOL. I can send some 2D drawings and machine cut path it it can help. The original 3D drawing have been done with Sketchup, but there is better tools out there, this one happens to be free!
Nice ! Extension into the low teens !
You using a UMIK ? Although they're calibrated down to 10Hz, mine seems to go out from 12Hz downwards, not sure if this inaccurancy of the mic, or low frequency transmission through mic stand / mic itself as opposed to actual acoustic sound pressure measurement.
I'm using the ECM8000 from Berhinger, REW and the Calibration file with a flat system curve calibrated in loopback. I usually place the mic ona small tripod in the headrest of the couch. I'm assuming it is well isolated from the floor but it is possible that there is some resonance with the headrest. I could roun some tests with different materials for isolation. I think my biggest problem is my room, I should turn everything 90 deg. but the door would be behind the seats and they barely fit the width so no space to pass en the sides... 😡
Hi Tintin1977, just found your post about the Crown K2 restoration. I am just restoring one K2 which I found recently with a case very badly used/worn, and fully redoing the powder coating job and I have also been facing the impossible way to remove the two faceplate overlay stickers. Tried several ways: impossible to remove without destroying the vinyl sticker.
I am just curious if you would still have saved the graphic illustrated layouts or if they would be a way to maybe get and buy some replicas from you.
I have done graphic editing with adobe Illustrator at home for silk screen printing layouts for my R2R's but actually not getting time to do it again right now.
*I must say the replicas you made are just top notch craftsmanship, congratulations!
Thank you for your reply.