# Appreciate verification sonotube

#### blue*thunder

##### CarAudio.com Newbie
I'm attempting my first ported box~sonotube as it were.
I made a sealed sonotube and it exceeded expectations but never being satisfied, it's time to see what more better, looks or sounds, like.
I'm using an 8" sub, 400w rms, the recommended (ported) box volume is .65-.70 cuft with a tuning frequency of 53hz.
The tube volume I understand and factoring in available space, I can get .675 cuft per sub/tube.
What I'm not totally convinced of. Is the round port required. Based on online calculators, I should use a port with 2" inside diameter, 3" long.
Does that look right?
I spoke with the sub tech and they didn't validate my findings, instead, suggest I use 12.75 sq in port.
I then tried find calculator that would convert port physical dimensions to sq in internal area, and haven't had any luck or just not educated enough to know what I'm trying find.
Figured I better find a car audio forum and see if I could get some help.
Thanks

#### 1aespinoza

##### Junior Member
10+ year member
I spoke with the sub tech and they didn't validate my findings, instead, suggest I use 12.75 sq in port.
Sq. in. is the measurement of an area. They forgot to tell you the length of the port.
For your round port the formula is >
Volume = radius squared × 3.14 × length
Radius of 2 is 1. So 1×1=1 then 1 × 3.14 = 3.14
Length is 3. So 3.14 × 3 = 9.42
So the round port is 9.42 cubic inches
Their slot port is already bigger just by area alone. IMO, the 9.52 cu.in. sounds about right for an 8" 400 watts subwoofer. I found this somewhere a long time ago >

#### SlugButter

##### CarAudio.com VIP
53 HZ is a very high tuning frequency for a music setup. 12.75 sq. Inches of port area would be fine for a slot port, but with a round port it will get too long to fit into the box without bending the port or letting it stick out of the box.. Round ports do not require the same amount of port area as a slot port. There is less surface area in the inside of a round port than a slot port for the air to interact with.

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#### blue*thunder

##### CarAudio.com Newbie
Sq. in. is the measurement of an area. They forgot to tell you the length of the port.
For your round port the formula is >
Volume = radius squared × 3.14 × length
Radius of 2 is 1. So 1×1=1 then 1 × 3.14 = 3.14
Length is 3. So 3.14 × 3 = 9.42
So the round port is 9.42 cubic inches
Their slot port is already bigger just by area alone. IMO, the 9.52 cu.in. sounds about right for an 8" 400 watts subwoofer. I found this somewhere a long time ago >
View attachment 46770
So with that in mind, 16 x box volume (.675 cuft)= 10.8. So the 2" x 3" port being 9.42 would be close.

Ok appreciate everyone's response.

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#### blue*thunder

##### CarAudio.com Newbie
Slugbutter

53hz does seem high. I wasn't sure why they recommend that as the tuning frequency, when the same sub in their own box, is reported to be tuned for much lower, the companies words.

##### CarAudio.com Recruit
What is make and model # of the sub?

53hz sounds about right for a small low powered 8 but still on the high side.

Is there a reason why you are trying to build using sonotube rather than a full wood enclosure?

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#### blue*thunder

##### CarAudio.com Newbie
Skar svr 8 d2
Skar 1200.1 amp, 2 subs 2 ohm load. On paper 400w rms to each sub.
As to, why a tube enclosure.
Things kinda snowballed. Have a regular cab, mid life crisis truck.
Was just looking to add lows, cheap, didn't really expect much. Never tried 8" subwoofer.
Bunch online reviews seem suggest skar svr 8" may be the winner.
I thought I was going be able put one sub in a wood box, behind center console, what I didn't anticipate, was just how big the magnet would be.
So then I did a lil more research and found myself buying round concrete forms, aka sonotube.
Put it together, and found myself fascinated at what that lil sub was doing. So then I found myself ordering another one. I'm in a phase we're I want listen to bass boosted techno type music. I just want big bass, relatively speaking, no concern for sound staging, clarity etc.. I've had that, this truck will probably evolve into that but right now, I just want find out what a ported sonotube will do.
Mainly for fun.

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##### CarAudio.com Recruit
Can you fit a 10 inch tube in your truck?

Since your enclosure is 95% cardboard. I would highly suggest coating it with some type of a hardening agent such as Minwax wood hardener, fiberglass resin or epoxy resin.

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#### blue*thunder

##### CarAudio.com Newbie
The sonotubes I'm using are closer to 7.75" OD than 8", and I'd say 8" is the limit. I was gonna try find a true 8" if I do a ported version. Even though they say 8", they actually vary the sizes so they can put multiple tubes in one tube. For shipping purposes.
I almost coated these tubes but instead I put polyfill in them, fill weighed per cu ft recommendation and it really gave the tubes mass. Get rid of any chance resonance.

I could fit a 10, maybe even a 12 in a regular box. A JL W0 would work or a rockford p3s 12, something with a depth and magnet shape that lends itself to tight space.
I still have the p3s in a box, never tried it in this truck though, should fit.

This is more about taking a 8" and seeing how crazy it'll get.

I'm just trying perfect the port size before I start cutting.

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#### blue*thunder

##### CarAudio.com Newbie
Out of curiosity, installed the P3S 12" rockford fosgate in place of the 8s.
Amp is rated 500w at 4 ohm and sub was wired 4 ohm load. In a RF box designed for that sub.
It was significantly louder, lived up to the punch name. The outright power, put smile on your face.
But while I listen to everything from folk to metal, the RF didn't sound right playing the techno bass songs.
The 8s generate alot more low bass sound.
Definitely not as loud at the same volume but at same time, able provide way more deep bass.
I think an svr 12 would get me the best of both worlds but no room for it. For now I'll choose the 8s and get to work on those ported tubes

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#### blue*thunder

##### CarAudio.com Newbie
Out of more curiosity and having the extra wood.
Figured I'd hear what these subs are really capable of, vs making a tube and wondering. I found plans for a slot ported, 53hz box, specifically for the svr 8.
Couple hours later, built and installed, in my car, using rockford fosgate amp rated 300w rms at 4 ohm.
Dvc sub wired for 4 ohm load.
It's definitely peaky.
My only experience with ported boxes, were loaded kicker 10" boxes, designed for behind seat reg cab truck. 30 yrs ago. They were not peaky that I recall.
This svr 8 under normal music. Fills the lows as it should, nothing dramatic, or noticable. But play bass specific music or something like post malone. Wow or congratulations, it became a different animal. Incredible bass.
Audibly, the single ported 8. 300w, seemed equally as loud or louder, than 2 of the same two 8s in sealed box, getting 800w.
Not sure how the ohm load played a role. Single sub was 300w at 4 ohm.
Where the 2 were getting 800w at 2 ohm. But the subs were wired for the appropriate load and the amps rated for that specific load. Both amps being well known and tested as having legit watt rating. Not inflated garbage.
Appreciate the responses given.

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#### blue*thunder

##### CarAudio.com Newbie
In the event someone's finds themselves reading this thread. I'll throw out the end results.
For the 1 svr 8, in a reg cab truck. I ended up with an 8" diameter sonotube. Shy of 38", Long arse thing, with internal volume of 1 cuft. I tried a 2" diameter round port, 3" long.
Bass was surprisingly tight and punchy. I wanted loosen that up, so I
Followed that up with a 4" diameter round port 9" long. If I had a 3" pvc handy I would have used that but I used what I had handy. Bass became more boomy but still has a kick, actually nice sound overall. It'll sound clean when it should and get nasty too. Both port dimensions based on a formula, i didnt guess. Where I'm stopping with that endeavour.

The other svr 8 went in my cars trunk. Skar sells a box for this sub, thats affordable, makes more sense to just buy that.
But I have the material and ability, so I built the box in the link below.
It met all expectations. I've spent some time dialing the lows back. But the box delivers tight punchy Bass when needed or will get raw and vibrate your brain within your skull. Would recommend that design.
My two cents, others mileage may vary.

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#### 1aespinoza

##### Junior Member
10+ year member
My two cents, others mileage may vary.
Thank you. I love reading firsthand results.

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#### blue*thunder

##### CarAudio.com Newbie
Thank you. I love reading firsthand results.

I'm sure my opinion will change, as the new wears off and I start picking up on characteristics that annoy me.

Did take look at that rockford sub/box and wonder. What would that sound like ported.
But in order to keep the top and bottom depth, and achieve the 1.25 recommended cuft, the box would have to be 56" wide.
Maybe one day.
Lol

#### 1aespinoza

##### Junior Member
10+ year member
I'm sure my opinion will change, as the new wears off and I start picking up on characteristics that annoy me.

Did take look at that rockford sub/box and wonder. What would that sound like ported.
But in order to keep the top and bottom depth, and achieve the 1.25 recommended cuft, the box would have to be 56" wide.
Maybe one day.
Lol
In that case, welcome to the rabbit hole.

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### blue*thunder

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