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Low Earth Orbit
DIY Audio
subwoofer advise
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<blockquote data-quote="Moritz Bachmann" data-source="post: 215701" data-attributes="member: 13680"><p>I will post measurements as soon as i have time to make some. The ones I did to test tuning frequency were really dirty (no fix mesaurement distances and even bader, a back panel that was hold together with clamps, as I had to be able to remove the pipes through it to make them shorter). </p><p>Actually, I always made a ~2m ground plane measurement and another one at the outlet of the port. With the second one it was pretty easy to determine a tuning frequency, although I have no idea how close this one comes to an impedance measurement.</p><p>Honestly, I don´t even know why it´s important to know the exact tuning, or how I can find the optimum, but the measurements showed some dB more around 40Hz with the shorter port, still there was enough low end in the listening test.</p><p>The great thing is that the ports are so big, that it should be ok to close one of them for small gigs or a home theatre show at home, tuning drops down to ~25Hz with one port closed.</p><p></p><p>I only watched a short video about the impedance measurement in REW, and already lost the link, so if someone has an advice for me, how to do this properly, I will try it during the next testing.</p><p></p><p></p><p>Carl you don´t need to worry, the vent back flare was planned to be removable too, it was just the last part that was cnc machined and not ready when I made the pics <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p></p><p></p><p>Some facts about the cab:</p><p>The "main" front is 30mm, plus 15mm added under the driver cutout to have enough depth for the 40mm Flare, and another 15mm at the backside of the front, as reinforcement for the driver (30mm-20mm would have left just 10mm for screws) and as pipe-holder. (this one was meant to be 12mm, I just didn´t think about it and used 15mm instead). </p><p>So at the thickest part, the finished front is 60mm or 2,36" thick, yet it wasn´t that heavy, obiusely because the front is mainly just three holes rather than remained material.</p><p>All the other parts were made of 15mm MPX, but as you can see, i didn´t skimp on brazings, so the cab should still be pretty stiff....</p><p>I hadn´t time to put it on a scale yet, and this one isn´t a lightweight for sure, but at least, a single person is able to lift it up and put it on a wheel board.</p><p>Outer dimensions are 43x58x65,5cm so ~164L.</p><p></p><p>[ATTACH=full]209495[/ATTACH][ATTACH=full]209496[/ATTACH]</p></blockquote><p></p>
[QUOTE="Moritz Bachmann, post: 215701, member: 13680"] I will post measurements as soon as i have time to make some. The ones I did to test tuning frequency were really dirty (no fix mesaurement distances and even bader, a back panel that was hold together with clamps, as I had to be able to remove the pipes through it to make them shorter). Actually, I always made a ~2m ground plane measurement and another one at the outlet of the port. With the second one it was pretty easy to determine a tuning frequency, although I have no idea how close this one comes to an impedance measurement. Honestly, I don´t even know why it´s important to know the exact tuning, or how I can find the optimum, but the measurements showed some dB more around 40Hz with the shorter port, still there was enough low end in the listening test. The great thing is that the ports are so big, that it should be ok to close one of them for small gigs or a home theatre show at home, tuning drops down to ~25Hz with one port closed. I only watched a short video about the impedance measurement in REW, and already lost the link, so if someone has an advice for me, how to do this properly, I will try it during the next testing. Carl you don´t need to worry, the vent back flare was planned to be removable too, it was just the last part that was cnc machined and not ready when I made the pics :) Some facts about the cab: The "main" front is 30mm, plus 15mm added under the driver cutout to have enough depth for the 40mm Flare, and another 15mm at the backside of the front, as reinforcement for the driver (30mm-20mm would have left just 10mm for screws) and as pipe-holder. (this one was meant to be 12mm, I just didn´t think about it and used 15mm instead). So at the thickest part, the finished front is 60mm or 2,36" thick, yet it wasn´t that heavy, obiusely because the front is mainly just three holes rather than remained material. All the other parts were made of 15mm MPX, but as you can see, i didn´t skimp on brazings, so the cab should still be pretty stiff.... I hadn´t time to put it on a scale yet, and this one isn´t a lightweight for sure, but at least, a single person is able to lift it up and put it on a wheel board. Outer dimensions are 43x58x65,5cm so ~164L. [ATTACH type="full" width="345px"]209495[/ATTACH][ATTACH type="full" width="356px"]209496[/ATTACH] [/QUOTE]
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