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Custom Enclosures 12" Round Hole, Long Rear Slot Ported Enclosure

121RP, 121KPRO

Discontinued
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This item has been discontinued

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Ground Shaker SQPXL 1 12

OUR PRICE: $69.95

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Custom Enclosures 12" Round Hole, Long Rear Slot Ported Enclosure

121RP, 121KPRO

$79.99

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Scosche WGB12

12" Protective Waffle Style Subwoofer Grille

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High-Performance Streetwires Speaker Wire

25 ft. of 12 Gauge speaker cable with twisted pair construction for improved power flow and fine-stranded copper windings.

$37.85

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  • 12" Round Hole, Rear Ported Subwoofer Enclosure
  • Mounting depth: 10-3/4"
  • Cutout diameter: 11-1/8"
  • Box volume: 2.70 cubic feet
  • Total port volume: 0.32 cubic feet
  • Dimensions: 15"D x 30-1/4"W x 15"H
  • 30 Day return policy

Product History:

Ground Shaker SQPXL 1 12 thumbnail
(newest, current model)
Custom Enclosures 121KPRO thumbnail
(previous model, replaced by Ground Shaker SQPXL 1 12)

Speaker Box / Enclosure Specifications

Subwoofer Size
Refers to the diameter of the subwoofer, measured in inches.
12"
Subwoofer Cutout Shape
This is the shape of the enclosures cutout hole and defines the style of subwoofer that can be installed.
Round / Circle
Box Type
Represents the style of the enclosure. Be sure to purchase the appropriate enclosure type and internal volume that will be compatible with your subwoofer's recommendation.

Sealed - Sealed boxes are those that have no holes or vents in it. The only hole in a sealed box is where the subwoofer is installed. Smaller sealed boxes require more power than a larger sealed box. They provide a tight, accurate bass, while the larger sealed enclosures provide a "boomier" and louder bass.

Ported / Vented - Ported/Vented Enclosures provide an even boomier, louder bass, but less accurate then a small, sealed box. Ported enclosures typically require more airspace per sub and also less power output from an amplifier to perform correctly.

Bandpass - Bandpass enclosures make subwoofers perform efficiently, but loose. The bass is not as "boomy" as a ported enclosure nor as punchy as a sealed enclosure. Bandpass enclosures work well with lower to mid-level subwoofers.
Vented / Ported
Number of Subs/Speakers
This value represents the number of speakers or subwoofers that the enclosure accommodates.
1
Box Style/Shape
The box style or shape refers to the actual shape of the box. Square and rectangular boxes are straight-edged boxes on all sides, whereas hatchback and truck style enclosures feature an angled front or back design that allows for installation in places short on depth such as single cab pickup trucks. You can also use such enclosures in hatchback cars or other vehicles where space is a premium. Tube and cylinder shaped boxes were made popular by Bazooka and are a great option for those looking for a nice amount of bass without sacrificing lots of space. They may even fit in locations that slim truck boxes cannot fit in. If the enclosure is vehicle specific, we encourage you to read the product description to find out which vehicles the enclosure is made for.
Square/Rectangle
Cutout Diameter or Length
The actual diameter of the hole in the subwoofer box. Length is the measured length per side of a square subwoofer or speaker opening.
11-1/8"
Maximum Speaker Depth
Your subwoofer or speaker must not exceed this dimension in order to properly mount in this enclosure.
10-1/2"
Total Box Volume
The internal volume measurement in cubic feet before subwoofer magnet displacement.
2.7 cubic feet
Box Volume (Each Chamber)
This is the total air space inside each chamber of the empty subwoofer enclosure. By matching this value with the recommended air space of the subwoofer, you will be able to know if the subwoofer will match this box.
Height
The height of the item, measured from top to bottom, in inches.
15"
Width
The width of the item from left to right (side-to-side) measured in inches.
30-1/4"
Depth
The front-to-rear depth of the item, in inches. If the item is angled or slanted, this value is the bottom measurement.
15"
Wood Thickness
The thickness of the wood the enclosure is made of, measured in inches.
3/4"
Number of Terminals
The number of terminals the enclosure has. Each terminal represents 1 positive and 1 negative.
1
Terminal Type
Spring clip terminals work best with bare wire connections with small-gauge speaker wire, or pin-type connectors.

Binding post terminals are a sturdier, more versatile type of speaker terminal. Because binding post terminals are are threaded, you can tighten them down against the wire or connector for a tight, clean connection. The most popular style of binding post terminals is known as a "5-way binding post". This type can accept bare wire, or any of the common speaker wire connectors. Binding posts with the option to be used with banana clips are even more versatile

Spring posts are a hybrid of the two. Instead of using a thread and "screwing" them tight, they use a spring to allow the wire to fit and tighten against the terminal.

Binding posts (banana clip ready)
Box Exterior Color
The color of the enclosure's exterior/outer finish.
Black
Box Finish
The material used on the outside of the box. Most boxes are carpeted to prevent exterior scratches; however vinyl is popular as it can often be color-matched to a near exact look of your leather factory interior.
Carpet
Tuning Frequency
Compatible Vehicle Make and Model
The model of vehicle that this vehicle specific product is designed for. Please keep in mind that engine variations can affect the compatibility of the products.

Port Details

Number of Ports
The number of ports the enclosure has.
1
Tuning Frequency
Port Diameter
The outside diameter of the port. Check the product's owner's manual for the recommended port diameter for your sub.
13-1/4"
Port Length
The length of the included port tubes. Many tubes are cardboard and may be cut to the length recommended by the sub's manufacturer. Check your product's owner's manual for the recommended port length for your sub.
17"

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Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
Manufacturer

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
79%
4 Star
11%
3 Star
11%
2 Star
0%
1 Star
0%

Average Attribution Rating

Durability
4.5
Value
4.6
Features
4.5
Design
4.5
Usability
4.7
Greg

framingham, MA

Overall
Durability
Value
Features
Design
Usability
awesome box for the money

February 27, 2011

I have my Alpine Type R in this and it pounds! I had it in a .8cu ft box I got at bestbuy and it was too small and choked it out, the whole car vibrates now and hits lower notes better, gets those real low ones i love :) only thing I don't like is the port is on the side so its kind of against the trunk, but its far back enough to work so if you have a small car like a civic you just need to measure =]

4 of 5 found this helpful

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SPL

Charlotte

Overall
Durability
Value
Features
Design
Usability
Destroyed

September 27, 2010

I got this box for my 12" Fi BTL and it's a great box while it lasted. Now my box smacks wood and sounds horrible i had to put 5 screws to keep it from making that sound. this box is perfect unless you have something pushing to much power like my sub

4 of 5 found this helpful

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Ryan

Vancouver, WA

Overall
Durability
Value
Features
Design
Usability
Best Bass Pounding Box EVER!!

August 9, 2010

I have the Hifonics Brutus OLM1612 sub enclosed in this bad boy box and it pounds like no other. Its a very solid box and is true to the dimensions and box volume...I would HIGHLY suggest buying this box to my friends, family or strangers (plus Sonic has the best shipping, was super fast). If you want an all around great looking, great sounding and great performing box...then just click.."+ Add to Cart" button and let the pounding begin!!

4 of 5 found this helpful

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fern

vacaville, ca

Overall
Durability
Value
Features
Design
Usability
booom!

March 19, 2010

This box kicks hard! It makes my JL Audio 12w3v3 hit so harder than it did before in my old 1.3 cu ft ported box. I love it. I would definitely recommend this box and website to anybody. Thanks Sonic

4 of 5 found this helpful

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Fredy

Findlay, Ohio

Overall
Durability
Value
Features
Design
Usability
Good prefab box

March 3, 2010

Box does look clean and nicely built. Put my american bass 12" xfl in it and it pounds! Had to make cut out a lil bigger for my sub to fit but not a big deal recommended for anyone who can't build their own

4 of 5 found this helpful

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Nick

Fort Myers, FL

Overall
Durability
Value
Features
Design
Usability
Very Nice!

September 16, 2008

Solidly built, and Creates nice bass. Very good price also. Nice color, and nice to have built-in terminals.

4 of 5 found this helpful

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Cobbsy

Hampton, VA

Overall
Durability
Value
Features
Design
Usability
12'' Ported Box

January 4, 2012

I recenly purchased this box along with the power acoustiq mofo 122x. I tried the mofo in a box i had for two kicker comp 12's, and it didnt sound up to par. When i put it in this box, its like it got 10x louder. And it hits the lows perfect like i wanted. Cant really use my rearview or sideview mirrors.

The box is well built and sturdy. I drive a 99 blazer 2 door btw.

3 of 4 found this helpful

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Blake

Torrance, CA

Overall
Durability
Value
Features
Design
Usability
Nice Box

December 28, 2009

dropped my FiQ12 into it...well built and very solid looks really clean with the black carpet

3 of 4 found this helpful

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Elder

Orange County

Overall
Durability
Value
Features
Design
Usability
Great Buy! Custom Enclosures 12" Round Hole, Long Rear Slot Ported Enclosure

February 26, 2013

Bought a big enclosure in order for it to fit exactly in my trunk and wouldn't move and slam around because of my driving :p. I really love it, bass kicks great even of how big it is. It is ported so it helped out from the size. Great Buy! Great quality! Recommend!

2 of 3 found this helpful

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Colin

Annapolis, Md

Overall
Durability
Value
Features
Design
Usability
Great Box

January 16, 2013

This is a great enclosure! Very sturdy and sounds amazing. Helps my JBL fill my car with nicely, hits lows harder with nice accuracy. Worth the buy 100%.

2 of 3 found this helpful

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John

Los angeles, ca

Overall
Durability
Value
Features
Design
Usability
Pretty good box

September 16, 2012

I got this box for my power Acoustik Mofo 12 and combined it with the power Acoustik bamf 2000.1, and damn this thing slams. It's tuned probly between 35-40 hertz, but i can get it to play down to 29 or 30 hz pretty well. It moves a ton of air, nice clean sound, shakes all my mirrors, roof, and back hatch. People hear me coming from in their houses. great box for a single 12! IF it can handle that much airspace lol.

2 of 3 found this helpful

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Jacoby

Ballwin, MO

Overall
Durability
Value
Features
Design
Usability
Great!

July 14, 2012

Great box, and the reason why is because it makes big sounds! Makes a 12" feel like a 15".

2 of 3 found this helpful

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Brad

East Dubuque, IL

Overall
Durability
Value
Features
Design
Usability
Fantasic Box!

May 23, 2012

I recently bought this box for an MA Audio 12" Hard Kore subwoofer and it ...POUNDED! hahahahaha, this box is litterally great for anything! And since it was defective and had a weird rattling noise, i had to send it back. Felling "bass-less," i went and bought a $30 Dual 12" subwoofer from walmart. And it made the sub sound....FANTASTIC! Great box overall, i reccomend it for all kinds of subs! (That are 12" of course)

2 of 3 found this helpful

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Main Bull

Kilauea, Hawaii

Overall
Durability
Value
Features
Design
Usability
Good Deal

April 6, 2011

Used this box for a Fi Bl 12 and it slammed hard. The tuning frequency is around 41-42 hz so the lows arent very loud and the sound quality isnt always the best but its good for a prefab box. Good box if you dont mind that high of a tuning.

2 of 3 found this helpful

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Christopher

Fort Polk, LA

Overall
Durability
Value
Features
Design
Usability
Great box

March 27, 2011

It a good and quick fix for you subwoofer.

2 of 3 found this helpful

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Lowerghut

Virgin Islands, British

Overall
Durability
Value
Features
Design
Usability
Custom Enclosures 12" Round Hole, Long Rear Slot Ported Enclosure

January 20, 2011

Good make and construction, Good all around box.

2 of 3 found this helpful

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bluetc

el paso, tx

Overall
Durability
Value
Features
Design
Usability
Great Product

April 27, 2010

This is by far the best pre-fab box ever built. It is solid and sounds great. Continue the great service!

2 of 3 found this helpful

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3g shake

los angeles

Overall
Durability
Value
Features
Design
Usability
Big Box!!!!

April 10, 2010

This box is great i have a 12" fi btl put in it. I kinda had to make the hole bigger because of my magnet but other than that the box is great.

2 of 3 found this helpful

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Jason

League City, TX

Overall
Durability
Value
Features
Design
Usability
didnt work well for me

November 6, 2012

had the box for 6 months and it is coming apart. re audio sxx12 with a mb quart onyx 1500.d. hit hard while it was in good condition

1 of 2 found this helpful

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Accessory Tools and Products

Accessories added

NVX XKIT42 - 4 Gauge Amp Kit

Pure Virgin Copper, 4 Gauge Amplifier Installation Kit

Your Price $89.99

Belva BAK42 - 4 Gauge Amp Kit

CCA 4 Gauge Wiring Kit with RCA & Speaker Wire

Your Price $29.99

8 Gauge - Stinger Amp Kit

Single amplifier 4000 Series complete installation kit.

Your Price $39.99

Belva BAK02 - 1/0 Gauge Amp Kit

CCA Wiring Kit with 2-Channel RCA & Speaker Cable

Your Price $39.99

NVX XKIT02 - True Spec 1/0 Gauge Amp Kit

Pure Virgin Copper, Full 1/0 Gauge Amp Kit with RCA

Your Price $149.99

Scosche WGB12

12" Protective Waffle Style Subwoofer Grille

Your Price $6.99

GS Audio BG-12

Chrome Bar Style Grille for 12" Subwoofers

Your Price $11.21

High-Performance Streetwires Speaker Wire

25 ft. of 12 Gauge speaker cable with twisted pair construction for improved power flow and fine-stranded copper windings.

Your Price $37.85

NVX SDRLR1 Universal Roller Tool

Install your sound damping with the SDRLR1 tool

Your Price $7.99

20 ft. of Dynamat Xtreme Trunk Kit

Keep your trunk from rattling and improve bass quality by using a sound dampening trunk kit.

Your Price $87.63

NVX SDBP40 - 40 ft. (10% More Than Competition)

40 ft. Bulk Pack of Sound Dampening Material

Your Price $97.99

36 ft. of Dynamat Extreme Bulk Pack

Make your sound system sound perfect by reducing road noise with 9 sheets of sound dampening material.

Your Price $159.99

Banana Clip Terminals

These high grade banana clips allow you to plug into your banana clip ready terminal for a secure connection.

Your Price $1.99

12 oz. Can of Adhesive Spray

Spray adhesive used for adhering carpet to subwoofer boxes without bubbles or can be used for your polyfil.

Your Price $8.97

Car Stereo and Speaker / Subwoofer Installation Tool Kit

Includes Test Light, Crimp/Splice Tool, Multi-bit Screwdriver and more.

Your Price $18.99

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Product Summary

Manufacturer

Model Number

121KPRO

Weight

51.00lbs

Internal SKU

121kpro

Internal Product ID

14600

Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Custom Enclosures 12" Round Hole, Long Rear Slot Ported Enclosure