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Enclosure for Sundown Audio X-15 v.2


image91

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Good day all. Was presented with the opportunity to switch over to an X-15 from my current Obsidian Audio 18. Although I really like the way it sounds, from my understanding, the 15 will free up some trunk space & will hopefully out-perform the 18 in terms of low end & overall output. Can anyone share their thoughts on this? Basically I was told it would be like comparing an SA-18 to an X-15.

With that being said, Sundown recommends 4.25 net ft^3 tuned to 32 Hz with 68 in^2 of port. Considering tuning to 30 Hz & wanted to use aero ports for the first time if possible. Would two 6" aero ports work @ 28 in^2 per port? (56 in^2 total). The ports will end up being approximately 35.5" long per. One 8" aero will only be 50 in^2 & a single 10" aero will be 78 in^2. Didn't want to go too much higher or lower than the suggested. If the two 6" aeros also won't be enough I'll have to revert to a slot port which will add to the volume considerably. Also, would 1500 rms be okay to play this sub as it is rated at that? Or would I only get the performance it is truly capable of at 2500 wrms + ?

Any input/advice/opinions would be greatly appreciated, thanks!

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Here's some modeling results for you to consider,  the X15v2 (in red) in 4.25 net @32hz vs the obsidian 18 (in yellow) in 5.5 net @32hz on the same 800W power, you can see that the X15 matches the obsidian at tuning, if given 1500W to the X15 would be even louder on a relatively short frequency range, more so at 2500W:

image.jpg

 

The only thing going for the obsidian is a flatter and wider bandwidth which may be pleasing. 

 

On the two 6" ports you can see the vents airspeed on 1500W below so you can use those if you want but they will be pretty long, likely a slot port would be more practical.

 

image.jpg

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Thanks for the input Joe! Do you think it would be worth it upgrading to the x-15 though? The flat/wide bandwith is pleasing indeed. I have a preference of between 30 Hz & 38 Hz however, so if the X will out-perform in that range & at least match in the others then I'm all for it. Too bad the graph doesn't compare 1200w vs say 2500w. Would get a more accurate visual comparison.

After doing some calculations, the slot port was coming up to around 4.5" W x 15" H x 40.75" long O_o compared to the two 6" aero coming up to 35.5" long. Slot port alone is close to 1.85 ft^3, lol. The difference in box sizes is around 0.75 ft^3. If I'll get better performance from the slot then I'll go with that despite the increase in volume.

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2 hours ago, Triticum Agricolam said:

If it were me, I'd stick with the OA-18. 

Was hoping to hear from you on this matter = ) Appreciate the time, know you're busy O_o

The suspense in your statement though, lol. Do share? Have you had hands on with both & leaned towards the OA? What advantages do you think sticking with it would have?

To be honest, the OA has a lot going for it. Really want to get the new battery in & try a couple different things to get it closer to its' true potential. If I have to end up keeping it, not a problem by me = P

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On 8/8/2018 at 7:31 AM, image91 said:

Thanks for the input Joe! Do you think it would be worth it upgrading to the x-15 though? The flat/wide bandwith is pleasing indeed. I have a preference of between 30 Hz & 38 Hz however, so if the X will out-perform in that range & at least match in the others then I'm all for it. Too bad the graph doesn't compare 1200w vs say 2500w. Would get a more accurate visual comparison.

After doing some calculations, the slot port was coming up to around 4.5" W x 15" H x 40.75" long O_o compared to the two 6" aero coming up to 35.5" long. Slot port alone is close to 1.85 ft^3, lol. The difference in box sizes is around 0.75 ft^3. If I'll get better performance from the slot then I'll go with that despite the increase in volume.

 

From the plot above both subs at 800W if you drive the X15v2 to 2500W the red plot would move about 5 db up, seems to me that the 30-38Hz range would be louder (+5dB is a considerable output gain) so if that's the sort upgrade you want then yes I think it would be worth trying. Anyhow I wouldn't get rid of the obsidian, it's a nice sub and it may be pretty hard to get one new if you ever wanted it back.

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On 8/8/2018 at 9:59 AM, image91 said:

Was hoping to hear from you on this matter = ) Appreciate the time, know you're busy O_o

The suspense in your statement though, lol. Do share? Have you had hands on with both & leaned towards the OA? What advantages do you think sticking with it would have?

To be honest, the OA has a lot going for it. Really want to get the new battery in & try a couple different things to get it closer to its' true potential. If I have to end up keeping it, not a problem by me = P

The smoother frequency response of the OA-18 is what I find most appealing about it.  The extra efficiency it has is very nice too.  While you can get louder with the X-15 over a limited frequency range, its going to take a LOT more power to do it.  

In the end, you have to decide which will make YOU the happiest.  Neither choice is right or wrong, it just depends what is going to work best for you.  Smooth frequency response is important to me, but that doesn't mean it has to be important to you.  

"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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9 hours ago, Triticum Agricolam said:

The smoother frequency response of the OA-18 is what I find most appealing about it.  The extra efficiency it has is very nice too.  While you can get louder with the X-15 over a limited frequency range, its going to take a LOT more power to do it.  

In the end, you have to decide which will make YOU the happiest.  Neither choice is right or wrong, it just depends what is going to work best for you.  Smooth frequency response is important to me, but that doesn't mean it has to be important to you.  

Agreed on all points made. I intend on trying to see what else I can get out of the OA-18 before I make a decision. Considering re-doing an enclosure, tuning to 28 Hz & firing up instead. Apart from this, re-doing some wiring & upgrading my battery. After that, will see how it goes =)

If I do fire the port up, my port ratio might be horrible, is there anything I can do about that? How negatively will that affect the output?

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32 minutes ago, image91 said:

Agreed on all points made. I intend on trying to see what else I can get out of the OA-18 before I make a decision. Considering re-doing an enclosure, tuning to 28 Hz & firing up instead. Apart from this, re-doing some wiring & upgrading my battery. After that, will see how it goes ?

If I do fire the port up, my port ratio might be horrible, is there anything I can do about that? How negatively will that affect the output?

High aspect ratio ports increase port air resistance, but that's not as much of a problem if you can keep port velocities low.  It would be best to avoid the high aspect ratio port but as long as you make the port nice and large so airspeed is low, it shouldn't be a problem. 

"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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22 hours ago, Triticum Agricolam said:

High aspect ratio ports increase port air resistance, but that's not as much of a problem if you can keep port velocities low.  It would be best to avoid the high aspect ratio port but as long as you make the port nice and large so airspeed is low, it shouldn't be a problem. 

How large are we talking here? lol. Think in the current box I used around 63 in^2 of port. Approximately 12 in^2 per net ft^3. What area might I have to use to cater for it? We're talking 24" or so by maybe 2.75" O_o 

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