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Sundown Xv2 15 - Port & Box Volume

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@DiBo i don't doubt anything you're saying bro. It's not to say that less port area will sound "bad" etc. As with most things in life, there's a trade-off. Checked out the build with the four X-12s. Looks sweet & the guy seems to be very knowledgeable, but who are we to say that if he used more port area that the system wouldn't have more output? Or sound "better"? It's all relative. Your system i'd bet anything is smashing the lows like crazy. Do we know for a fact that with more port area or with different specs, wouldn't do so even more? Different strokes for different folks i suppose. It's all about what works for the individual & their situation.

Edited by image91

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5 minutes ago, CstrokerV said:

I see a lot of misinformation in this thread.... go with what triticum told you your friend will be fine 

I'm assuming you're speaking about me... Please enlighten me with what misinformation you mean. I'm experienced with these subs. I actually design and build too. I know what I'm talking about. This isn't complicated at all. I'm not trying to argue I'm legitimately asking what misinformation you speak of? I smacked a [email protected] hz with a Sundown 15 with 1700 watts from the trunk. Wasn't sealed off or broken in so I'd say that's pretty decent. Box was 4ft³ with 62in² of port area. Not the best score but I could've gotten a 148+ if I really tried. instead of telling somebody to just go with what somebody else said why don't you offer up some experience or advice of your own? 

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Triticum assisted me with my multiple X-15v2 enclosures & i have no complaints about any of them. Whatever information i posted here was using his calculator. Taking that into consideration, the new port area/tuning sounds good. i don't know how much a single chamber/multi sub enclosure changes things, so maybe wait to hear from someone a bit more experienced on the matter. Looking forward to updates 😃

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21 minutes ago, image91 said:

@DiBo i don't doubt anything you're saying bro. It's not to say that less port area will sound "bad" etc. As with most things in life, there's a trade-off. Checked out the build with the four X-12s. Looks sweet & the guy seems to be very knowledgeable, but who are we to say that if he used more port area that the system wouldn't have more output? Or sound "better"? It's all relative. Your system i'd bet anything is smashing the lows like crazy. Do we know for a fact that with more port area or with different specs, wouldn't do so even more? Different strokes for different folks i suppose. It's all about what works for the individual & their situation.

There is trade-offs. I'm giving you my experience with these subs. Triticum is knowledgeable but it doesn't mean his way is law. I've tried it with bigger ports and I've tried it with slightly smaller than recommended... Me personally I found that slightly smaller than recommended works pretty well with good power. 

plus the bigger the port the longer you have to make it to get low tuning which makes the overall enclosure bigger. Trade offs

Edited by DiBo
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I didn't get a chance to read this thread until now.  

DiBo is absolutely correct, I am not infallible and most of the stuff I talk about is based on my own research and experience, other people have had different experiences than I have had and as such may have had different results.  With that being said, one thing do want to speak out on is this notion that smaller port area somehow reduces cone excursion.  That is absolutely false in almost all circumstances except one.  I'll cover the exception first and that is if you are playing WAY below the tuning frequency where the box isn't even operating like a ported box anymore, its just a leaky sealed box.  At that point having a smaller port WILL reduce cone excursion, but you should NEVER be playing so far below the tuning point with a ported enclosure for that to matter anyway.  

At any point near, at, or above the tuning frequency reducing port area is going to INCREASE cone excursion.  To know the reason why you need to understand that the point when air is rushing into the port is NOT when the cone is moving outwards, air rushes into the port at the same time as the cone is moving inwards.  One of the purposes of a ported box is to bring the movement of the air in the port and the movement of the cone into phase with each other so they don't cancel each other out.  When this happens it puts a great deal of force on the cone and this is what greatly reduces cone excursion around the tuning frequency.  This is also why ported boxes have a lot less cone excursion than a sealed box of the same size (until you get way below the tuning frequency like I spoke about above).  Anything that limits the port's ability to do its job (like port compression from not having enough port area) causes the box to begin to behave more like a sealed box and cone excursion goes up.  Port compression also pushes impedance up, which is not something you want.  If you want to see how reduced port area increases cone excursion you can test this easily for yourself.  Play a sine wave tone right at your tuning frequency, observe how much cone excursion there is, then obstruct the port with something and see how your cone excursion changes.  

Edited by Triticum Agricolam
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"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:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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On 3/11/2019 at 10:30 PM, shredder2 said:

Everything I design is modeled in Winisd, roughed in with Torres, then drawn with Sketchup. Then volumes are re-checked, all displacements subtracted and end-corrections factored in for the final volume/port length then it's re-modeled in Winisd for the final volume/tuning result. That info line is what the sub will "see"... or as close as an enthusiast like me can get it figured. 

I gave up on using just box calculators about 2 years ago... too much actual information you'll get with modeling is not available with just a box calculator.

Appreciate the lesson Trit... Wasn't trying to come off as an expert or be argumentative. I was trying to give him my experience with this particular high xmax woofers. Explanations like these clear stuff up even for me..I play under tuning with DJ rusticals and got 160's type music... The Low Lows haha. I should've said that instead of assuming he would too. Also, you've helped me personally and I always appreciate your input. 

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48 minutes ago, DiBo said:

Appreciate the lesson Trit... Wasn't trying to come off as an expert or be argumentative. I was trying to give him my experience with this particular high xmax woofers. Explanations like these clear stuff up even for me..I play under tuning with DJ rusticals and got 160's type music... The Low Lows haha. I should've said that instead of assuming he would too. Also, you've helped me personally and I always appreciate your input. 

No worries man.  I think its good you are thinking critically about stuff that I or anyone else says on here and are sharing from your own experiences.  Its better for the community as a whole if people don't assume something is correct just because of who the person was that said it.  Get them to explain why.   

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"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:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Thanks for all the help guys!

I went with 8.25 ft3 and 140 in2 port area at 30.5 hz

I started the mock up earlier today so I can get all my cuts made, but we jus now found 13 ply birch for the face and the port, so hoping to get it all finished up tomorrow. 

Still making some decisions on the bracing to keep the port clear, but I'm waiting until I get the speaker holes cut to see if an MDF window type brace or dowel rods will work better. I calculated the airspace using 2 vertical and 2 horizontal dowels bc it seems the air will flow around them better, but am thinking of sandwiching the back section of a window brace flush between where the birch and MDF will meet instead. I'm not 100% sure, but heres how its all laid out.

 

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