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Can somebody check my calculations before gluing the baffle?


CorNut

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I measured the total volume minus all displacement (woofer/bracing/port), what's left is 1.035

 

The internal dimensions of the port are 2.1875 (height), 22.375 (length), 5 (top), 5.75 (bottom)

 

Using the 12volt box calculator (I can't figure building programs out) it says I need to extend my port 4" to get down to 33hz, I have 8" before the wall so there's room to do it. Ideally I'd like 32hz but stopping at 33hz gets me to .9984 cu ft, the bottom of Sundown's recommendation of 1-1.25 cu ft for the SA 10. When calculating the extra .75" for wood on the port wall, I lose ~.009 cu ft every inch I extend it.

 

It'll have a sort of double baffle where the woofer's going to be mounted. I know it's not optimum how I'll have to angle the sub's top and bottom screws for mounting the woofer but I'm trying to make the box as small as possible. It's going in a family member's daily Chevy Cruze hatchback so space is at a premium. I was limited on height because of the cover separating the cargo area. When I place the baffle, the parts above and below the sub will be glued with at most 1/2" to spare, being ported I hope it's ok but she'll have to go sealed if not.

 

Does my calculation of extending 4" to get 33hz look accurate? My goal was 32, unless my math is off it didn't work out. My amp (Kicker CXA800.1) claims 872 on the birth sheet and it has a non-adjustable 25hz filter so I was hoping to keep the tuning low. 

 

 

 

IMG_20191218_182331.jpg

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Sorry I can’t check it right now, but you are not going to hear a difference in 33 vs 32, so I would lean towards more air space then trying to tune it a little lower. Just my 2 cents....

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2 hours ago, Scotnemily said:

Sorry I can’t check it right now, but you are not going to hear a difference in 33 vs 32, so I would lean towards more air space then trying to tune it a little lower. Just my 2 cents....

I'm lowering it for the subwoofer's safety with the non-adjustable 25hz subsonic filter, not for sound. I've also already decided I'm changing it to 33 to keep box size at the recommended space but I'm concerned about my calculations. I'm hoping somebody can check my #'s before I do something permanent, that's all. 

 

This isn't going to be in my vehicle, she loves low bass and is deaf to distortion. 

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I show you to be at 35hz given your port area, length and box volume

 

My math says a 28" port gets you to .995 cubes and 32hz

18 Sierra 6.2 Z71 : 3 F8L's, DD M2a @.67, 1.95@33

05 TL build log SOLD

04 YukonXL : jvc kw-v51bt , RE 6.5c, 4 jbl gt5 12s, Memphis pr1000.1 5.5 cu.ft. sealed

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32 minutes ago, YukonXL04 said:

I show you to be at 35hz given your port area, length and box volume

 

My math says a 28" port gets you to .995 cubes and 32hz

wow really? That's taking into account the port displacement including the 3/4" port wall? I think I'll add 5" for it to fall closer to 32 than 33 if it'll keep it right at 1 cu ft. 

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1 hour ago, CorNut said:

wow really? That's taking into account the port displacement including the 3/4" port wall? I think I'll add 5" for it to fall closer to 32 than 33 if it'll keep it right at 1 cu ft. 

No, I forgot about the 3/4" on the port wall, just did the port airspace. Just do the 5" and call it good. 

 

1 cube on a ported 10 is definitely on the small side. I would be shooting more for 1.25-1.5 personally 

18 Sierra 6.2 Z71 : 3 F8L's, DD M2a @.67, 1.95@33

05 TL build log SOLD

04 YukonXL : jvc kw-v51bt , RE 6.5c, 4 jbl gt5 12s, Memphis pr1000.1 5.5 cu.ft. sealed

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2 minutes ago, YukonXL04 said:

No, I forgot about the 3/4" on the port wall, just did the port airspace. Just do the 5" and call it good. 

 

1 cube on a ported 10 is definitely on the small side. I would be shooting more for 1.25-1.5 personally 

This is for a small car. It'll be replacing a 1 cu ft sealed 12" Punch HX2 D4 (old). This box is 1" taller, a little wider but significantly less depth than what it's replacing. The amp's 1-ohm stable so the SA 10 D2 will pull more out of it. My hope is that it has a lot more output which I'm certain it will.

I appreciate your responses. I don't want the box too small but 1cu ft (.98) is at the small end of the manufacturers recommendation, plus I'm slightly overpowering it so it should be ok. It took forever to get the #'s, I appreciate you confirming my calculations. With the number of boxes I build I need to get better at calculating.

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21 hours ago, CorNut said:

This is for a small car. It'll be replacing a 1 cu ft sealed 12" Punch HX2 D4 (old). This box is 1" taller, a little wider but significantly less depth than what it's replacing. The amp's 1-ohm stable so the SA 10 D2 will pull more out of it. My hope is that it has a lot more output which I'm certain it will.

I appreciate your responses. I don't want the box too small but 1cu ft (.98) is at the small end of the manufacturers recommendation, plus I'm slightly overpowering it so it should be ok. It took forever to get the #'s, I appreciate you confirming my calculations. With the number of boxes I build I need to get better at calculating.

After box rise, you wont even be giving rated power to it... I would think for an SA you would want atleast 1k.

As for manufacturs box specs, they usually run on the small side, so going with the minimum on their specs, is probably a poor choice. But it might be better than the sealed 12.

18 Sierra 6.2 Z71 : 3 F8L's, DD M2a @.67, 1.95@33

05 TL build log SOLD

04 YukonXL : jvc kw-v51bt , RE 6.5c, 4 jbl gt5 12s, Memphis pr1000.1 5.5 cu.ft. sealed

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1 hour ago, YukonXL04 said:

After box rise, you wont even be giving rated power to it... I would think for an SA you would want atleast 1k.

As for manufacturs box specs, they usually run on the small side, so going with the minimum on their specs, is probably a poor choice. But it might be better than the sealed 12.

The box needs to be small for this vehicle and the SA has been sitting around for a while, I figured wth. Would you suggest pairing the box/amp with a different sub? I went to finish it today but it turns out I don't have the right size hole saw for the terminal cup so I ordered a different sized one. Being a single ported 10 I decided it's ok to use a terminal cup. It needs to sit flush against the seat and a terminal cup is the only way. I don't mind putting a different sub in there if I'll be doing the SA a disservice. Before port displacement it'll be ~1.08 cu ft and the port will be 28" long. 

 

Now it's time to go learn about box rise

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