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Discussion Starter · #1 · (Edited)
I changed the place of where my sub is currently sitting, and it opened up some options for a larger box :yay:
I talked a few things over with Mike P. (he's a huge) help.) about port dimmensions for a 16 cu.ft. box, and he came up with this for me. I wanted to be able to change the tuning by blocking/plugging up some ports. That way I can have the best for music, and for movies.
He came up with eight 4x5 inch ports at 45 inches long for a 23hz tuning, plug up five of those ports, and it lowers the tuning down to 14hz. Port velocity for the movie tuning is 23m/s at 13.60hz, so that will be fine. That's with a 14hz HPF. The port resonance is 150.42hz, so that is kinda close to the optimum 190hz resonance. Keep in mind that I can block more ports to lower the tuning even more, but high port velocity starts to kick in. :neener:

Here's a WinISD graph showing the improvements over my current box.



I should expect a 4dB gain from 17hz down. At 14hz, I should be up by about 6.5dB with the new box. With a few ports clogged up, at 10hz, I will be up ~8dB up from the old box, although I don't really care about 10hz output.

I'm working on drawing something up on Paint to hopefully let you guys see my design. I would use Sketchup, but I don't have it installed at the moment. And Paint is easier for me because I haven't experimented with Sketchup much yet.

I also have the thought for two-four 18" passives from Kevin in my mind. So, I might end up going down the PR route instead lol. It just looks much easier to build, and I can keep the box slightly smaller due to not having extra port volume.

Hopefully I can get this second build started sometime soon, but I'm currently busy with my racing, and school. So its kinda on the back burner for a while. But, I will get this new box built sometime soon! lol.
 

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Discussion Starter · #4 ·
One quick question. I recently saw a box that was ported for movies, but had multiple smaller ports in the box also. They were just sealed up when the movie porting was wanted. What I'm getting at is, will the ports that are blocked off still function somewhat unless they are completely clogged up? Like not just sealed off at the tip of the port so no air could get by, but would that affect performance any if you didn't have the whole port sealed off so air couldn't go half way up the port?
 

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Discussion Starter · #6 ·
Now that I've gone back through a few designs, I will be able to fit a 22 cu.ft box into the wanted space. It will be tuned to 14.32hz. <Outer> Dimmensions for the box will be 20.75 inches deep (countersinking driver; add .75" for second panel), 48 inches tall, and 56 inches wide.

I wish I could get this built right away! But, patience is a virtue...
 

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Dylan,

That size for a sub would yield 32 cu ft before port, bracing and wood etc.... This leaves about 25 cu ft. A single maelstrom could still take 1500 watts before max excursion and you would need a 10" port to keep port velocity down. 1st port resonance is 189hz and tuned to 14hz would give you some crazy bad bass mate. No hpf on my pic but you probably woudn't need one. I have not found the need for one yet.

Here's what I come up with. Defo a 2 man job to build it though.

cheers

Graham
 

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I'm for you using those discounted PR's they have and then using the additional space for an even bigger internal size.
 

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I don't want to sound negative, but I want to play devil's advocate here before you possibly do something you regret.

Changing tunes by plugging ports is not a sound concept in my opinion. When you lower the tune, you need more cross sectional area, not less. Also, using 8 ports not only makes the build harder, but it increases the turbulent flow in each port as compared to using a single larger port.

What are you hoping to achieve with music with a 23hz tune that you can't achieve with a 14hz tune? If there isn't much below 30hz in the majority of all music to begin with, getting extra extension doesn't help or hurt anything, as it isn't being used. Since the enclosure volume stays the same, excursion above 30hz will stay almost exactly the same above 30hz as well, so the bass won't be noticably cleaner. There may be a minimal headroom advantage above 30hz, but I doubt you'd be able to get everything out a Maelstrom 18" in that range to begin with, even sealed.

All you would really be accomplishing is degrading your transient response with the higher tune, as can be seen from measurements of SVS subs with this concept.
 

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I did a LOT of modeling to try the same thing with 12"s, basically just extra complexity with a lot more work. Unless you tune much closer to 30hz (and likely use a 25hz hpf) you're not getting much more spl. If you want that much spl increase for music and can handle the box displacement- look to the tuned horn concepts, like those used for concerts (and use ear protection). Otherwise, build the Mal-X LLT style and enjoy the movie ride. If you want more, you might consider what I'm doing- getting more drivers for music, in my case two more 12"s:bigsmile:
 

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Discussion Starter · #12 ·
I don't want to sound negative, but I want to play devil's advocate here before you possibly do something you regret.

Changing tunes by plugging ports is not a sound concept in my opinion. When you lower the tune, you need more cross sectional area, not less. Also, using 8 ports not only makes the build harder, but it increases the turbulent flow in each port as compared to using a single larger port.

What are you hoping to achieve with music with a 23hz tune that you can't achieve with a 14hz tune? If there isn't much below 30hz in the majority of all music to begin with, getting extra extension doesn't help or hurt anything, as it isn't being used. Since the enclosure volume stays the same, excursion above 30hz will stay almost exactly the same above 30hz as well, so the bass won't be noticably cleaner. There may be a minimal headroom advantage above 30hz, but I doubt you'd be able to get everything out a Maelstrom 18" in that range to begin with, even sealed.

All you would really be accomplishing is degrading your transient response with the higher tune, as can be seen from measurements of SVS subs with this concept.

With the 26hz tuning, I would be gaining 3.5dB at 40hz, 2dB at 50hz, and at 30hz and 25hz, I would be gaining 8dB more. I might not be much more, but It might cure me for my bass wants on music. For movies, it seems pretty much fine. I could always use more output, as I can't go past 65dB on my receiver and still maintain a decent amount of bass (the max is 80dB), or I get into amp clipping.
And for music, either I can clip the amp depending on the content, or bottom out the driver on stuff around 30hz (which I don't understand why.)

Maybe I will just build the box to 23 cu.ft, with a single 10 inch port 40 inches long. That would yield a 13.92hz tuning, but the port resonance will be 169hz. Would that still be an ideal port resonance?

Oh, and I really like the idea of PR's...but I don't think my dad will let me spend another ~ $260 on four 18" PR's. Especially after I got the AntiMode :spend:
 

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I have SVS subs with the ability to change the tuning, but once I've got them set up for the lowest extension with the flatest response I don't touch the port tuning. It sounds like we have similar listening preferences and I use a BFD eq to achieve what your talking about. The 1124p has several pre-sets for different curves. I set up around 6 different pre-sets, one flat for movies and several house curves for music. I just toggle to the pre-set that suits what I'm listening to; I would use just 2 pre-sets, flat and my favorite house curve, for 90% of my listening. But sometimes I come across something that sounds better with a different curve.

Since I'm using two subs I have lots of headroom which gives me the flexibility to use house curves freely. It sounds like your amp might not have the headroom to use house curves, but you could always sink your money into a new amp and BFD instead of a new sub. Just a thought.
 

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With the 26hz tuning, I would be gaining 3.5dB at 40hz, 2dB at 50hz, and at 30hz and 25hz, I would be gaining 8dB more.:
You'd likely end up with a very boomy 25-35hz boosted area. Most of the action in music is above there so it may not be as big of a difference as it looks like on paper. If you feel like giving it a shot, go for it, what's the worst that can happen?
 

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Discussion Starter · #16 ·
You'd likely end up with a very boomy 25-35hz boosted area. Most of the action in music is above there so it may not be as big of a difference as it looks like on paper. If you feel like giving it a shot, go for it, what's the worst that can happen?

I would only use the 26hz tuning for music strictly, and adjust it back down to 14hz for movie stuff. Would the 26hz tuning make it sound bad for music though?
 

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Discussion Starter · #18 ·
Thanks for the advice Mike :T

One thing that I noticed since I've installed the AntiMode, is that a 60hz LPF sounds more like a 80-90hz LPF with it turned off. And when I turn it up to 80hz LPF, it sounds like a 120hz LPF. A 80hz LPF sounds good with the AntiMode in bypass mode, but then everything else suffers lol. It has boosted 70hz-120hz a considerable amount, in case that isn't normal. It makes most songs sound better, but on some, it cna really make them sound bad. Such songs as AC/DC don't sound good unless I have the LPF around 50hz. With it set to 80hz, there is just way too much of the bass guitar, and not enough of the drums' bass hitting.
 

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Discussion Starter · #19 · (Edited)
Quick question; do you guys think that it would be a bad idea to put ~4,000w to a single Mal-X in a 23 cube box ported to 25hz, and just listening to music? I know that I would be doubling the rated power recommendations, but I'm just curious. And, it wouldn't be a solid 4,000w to it for a long time, because I'm sure that I would have too much bass then lol. I could just use more power for songs that hit really hard, as I can clip the EP2500 pretty easily on stuff like that.
 

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Quick question; do you guys think that it would be a bad idea to put ~4,000w to a single Mal-X in a 23 cube box ported to 25hz, and just listening to music? I know that I would be doubling the rated power recommendations, but I'm just curious. And, it wouldn't be a solid 4,000w to it for a long time, because I'm sure that I would have too much bass then lol. I could just use more power for songs that hit really hard, as I can clip the EP2500 pretty easily on stuff like that.
Easy. Model, look at the excursion.
 
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