ckeeler11 Posted July 26, 2019 Report Share Posted July 26, 2019 Just my opinion but if you are going sealed and want something musical I would look at the Dayton HO or the Image Dynamics IDQ. DC makes solid stuff but I think the other two would be a better fit in this case. The only way you will be able to port your box and keep the volume anywhere near what it needs to be they will have to be external ports. A 6" port 20" long takes up .3 cu. ft. and 20" is probably not going to be long enough for low tuning. Link to comment Share on other sites More sharing options...
Casparado Posted July 27, 2019 Author Report Share Posted July 27, 2019 Triticum, that makes so much sense.... I didn't even think about surface area of the vents. So, just to get a little deeper (pun definitely intended) with my questions... If I were to do a rectangular port with my limited dimensions, would having a very thin rectangular port influence the waves as they exit? In other words, would a 2"x14" port vs a 4"x7" sound the same? Or would the more narrow port constrict the waves? I'm very interested in harmonics and how wave amplitude vs reflected area affects perceived sound. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted July 27, 2019 Report Share Posted July 27, 2019 12 hours ago, Casparado said: Triticum, that makes so much sense.... I didn't even think about surface area of the vents. So, just to get a little deeper (pun definitely intended) with my questions... If I were to do a rectangular port with my limited dimensions, would having a very thin rectangular port influence the waves as they exit? In other words, would a 2"x14" port vs a 4"x7" sound the same? Or would the more narrow port constrict the waves? I'm very interested in harmonics and how wave amplitude vs reflected area affects perceived sound. So the way sound energy moves through a port is different than how it moves through a horn or wave guide. With a ported system the mass of air in a port moves together like a piston. You want that mass of air to be able to move with the least amount of restriction as possible. Another thing to consider is port aspect ratio. Its the ratio of your ports width to its height. Taking your 2" x 14" example, its aspect ratio would be 7:1, the 4" x 7" port would have a 1.75:1 aspect ratio. The lower your aspect ratio the less internal surface area you are going to have and the better your port will perform. I try to keep aspect ratios below 5:1 as much as possible and never go above 8:1. In the case of your two different example ports, they aren't going to sound any different, at least at lower volumes. At higher volumes the 2" x 14" is more likely to start having port noise and port compression, both of which are things you do not want. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
Casparado Posted July 27, 2019 Author Report Share Posted July 27, 2019 Man, you have a great way of explaining things. The analogy of air moving through the port like a piston is very cool. I assume that means you want to have as little friction as possible, and the lower the aspect ratio, the stronger the piston. Very cool, man! Thank you. I just pulled the trigger on the B2 sub! I'm so excited! I'm literally giddy like a kid on christmas day! I am going to run it for a while in this prefab sealed box, but the walls are thin and, frankly, the bug has bit me (thanks to your help) so..... I think it's time to go get some baltic birch! Thanks again for all your help. This community is seriously rad! Once I get around to building this thing (I am the foreman of a small construction company, so my time is super limited) I will document it well and post pics on this thread, if that's ok. One last quick question..... I tend to over build things. My girl asked me to build her a chicken coop... so I built a 4'x8' coop that was about 4' high. I used 3/4 MDF, 2x4 framing, 16" centers, joist hangers, hurricane ties on the rafters, etc etc etc. Anyway when I was done, this simple 4x8 chicken 'house' was so heavy that 4 of us (one guy on each corner) could barely lift it an inch off the ground! I was worried about predators getting in, but I think it could survive a nuclear blast! ..... anyway to get back to the point, how thick realistically should the walls of the box be? I was thinking 1" sheets and double the baffle wall... buuuut that might be a little overkill. for a 2ft^3(ish) box (not including speaker and port displacement), what thickness material should I use? Link to comment Share on other sites More sharing options...
bassman_soundking Posted July 28, 2019 Report Share Posted July 28, 2019 That might be a little Overkill, but nothing wrong with a solid box. If you can speed the extra cost over 3/4" and the extra exterior box dimension slight increase i say do it. Have you seen how many layers thick competition audio walls are? In Bass We Trust Link to comment Share on other sites More sharing options...
Casparado Posted July 28, 2019 Author Report Share Posted July 28, 2019 Hey Triticam, one more question.... How close to another object can I have the mouth of a port before it affects airflow? I know there are a lot of factors... as in is it hitting a wall or just the edge of another object. Reason I ask is because the box I am starting to design will have the port(s) facing upwards, but I also plan on mounting the amp on the wall just above the port. I am not even sure if the surface of the amp will be directly over the port opening or if it will be recessed enough... but I am curious as to what point it might cause a problem. Any help is as always greatly appreciated. 🙂 Oh, and thanks for the reply bassman! Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted July 28, 2019 Report Share Posted July 28, 2019 So when it comes to building enclosures, you want an enclosure that is air-tight, stiff, & rigid. Using thicker material is one way to get a stiff and rigid enclosure, but its not the only way and its rarely the best way IMHO. I built one enclosure out of 1" material and have no desire to do it that way every again. 1" material is just needlessly heavy. If you want a solid enclosure the best thing to do is using something stiffer than MDF. A good quality 3/4" plywood with at least 7 plies will be much stiffer and lighter. There is nothing wrong with MDF, its just that quality plywood is better for the job. The second thing you want to do is add bracing. A 24" wide panel made from 3/4" material with a brace in the middle will be stiffer than a 24" wide panel made from 1.5" thick material and no bracing. Bracing uses very little material, adds little weight, but makes a huge difference in strength. Here is a thread I made on how to do bracing: For your ports, ideally you want there to be at least one port width of space in front of the port to allow it to breath properly. You can get away with a 1/2 of a port width, but it will probably lower the tuning frequency a bit. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
Casparado Posted July 29, 2019 Author Report Share Posted July 29, 2019 Oops sorry after re-reading the thread I just realized I meant to say CDX plywood on the chicken coop. I don't know why I had MDF on the mind... I just read that other thread. Great info! What type of glue do you prefer? At work I use Titebond III... is that sufficient? Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted July 29, 2019 Report Share Posted July 29, 2019 1 hour ago, Casparado said: Oops sorry after re-reading the thread I just realized I meant to say CDX plywood on the chicken coop. I don't know why I had MDF on the mind... I just read that other thread. Great info! What type of glue do you prefer? At work I use Titebond III... is that sufficient? Titebond II or III is what I use 99% of the time. Occasionally I'll use PL Premium when I have a big gap to fill or I'm bonding dissimilar materials. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
Casparado Posted August 2, 2019 Author Report Share Posted August 2, 2019 Holy sheep sh!t that B2 rocks!! 🤯 This thing gets it! So... How in HELL do you hold back and break a brand new sub in for a week without playing full tilt?! I had to give it a quick test at maybe 50% power and jeeeesus I think I am in love! .... Sweet Like Danish! 😁 Link to comment Share on other sites More sharing options...
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