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· Premium Member
19,397 Posts
Discussion Starter · #1 ·
I had been thinking of building a small sub for the A/V system in our work out room at home. Space is limited so it had to be a small sub. The sub will be used for 50/50 HT and music, so a ported sub is what I wanted. CSS had just introduced a line of small subs with Passive Radiators, and after looking over the various kits, I choose the QUARTET10 subwoofer kit.
The kit comes with the SDX10 subwoofer, 2 APR 10 Passive Radiators, a 300 watt Bash amp, 4 cabinet spikes, and all mounting hardware. The kit is priced at $379, a quick check shows the individual parts total $475, the kit is definitely an excellent value. I ordered the kit and 4 days later it arrived. The kit arrived in two boxes.

Box Carton Package delivery Packaging and labeling Material property

The first box contained the amp, the chart of boost tables for changing the high pass filter, the cabinet spikes and the mounting hardware.

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The second box contained the SDX10 subwoofer and the two 10 inch Passive Radiators.

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The PR's were well packaged, with recessed firm foam top and bottom protectors to prevent the PR from moving around in the box.


Each PR comes with 20 45 gram tuning washers, a lock washer and a wing nut to hold them in place.

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The SDX10 was equally well packaged, with the same firm foam top and bottom protectors.

Box Audio equipment

Here's a couple pics of the sub. It's well built and the quality shows.

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This is everything the kit comes with.
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Metal Auto part Screw Titanium

· Premium Member
19,397 Posts
Discussion Starter · #2 ·
Here is some modeling of the sub. The recommended cabinet size is a cube with an external measurement of 18 inches, so the net volume will be 66 liters or 2.3 cu.ft. Adding 270 grams of mass to each PR will tune the cabinet to 22 hz.
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Here is the SDX10 cone excursion with 300 watts input, a high pass filter at 20.4 hz, and 1 db of boost form 31 to 35 hz.
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Here is the Passive Radiator excursion.
Text Line Font Screenshot Wave

· Senior Shackster , Platinum Supporter
828 Posts
I have the same sub in my truck, tuned to 28hz with 300 watts and it rocks, by far the best sounding sub that I have heard, really nice subs, I'm thinking about doing a 15" for my living room:bigsmile:.

Cant wait to see the results!!

Good luck!:T

· Premium Member
19,397 Posts
Discussion Starter · #8 ·
Finally got some work done on the sub. Dimensions worked out to a 18 inch cube. Here's a couple pics of the box. All cut outs done and Hurricane nuts installed.

Box Wood Plywood Cardboard Hardwood

Box Wood Plywood Hardwood

I mounted all the components so I could figure out the bracing.
Audio equipment Technology Electronic device Subwoofer Room

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I used hot glue around he perimeter of the Hurricane nuts to ensure they don't come loose. Although I've never used it, Gorilla glue works well also from what I've read.
Audio equipment Technology Room Loudspeaker Auto part

Some general pics of the sub.
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Subwoofer Loudspeaker Sound box Audio equipment Electronics

Subwoofer Loudspeaker Sound box Audio equipment Computer speaker

· Premium Member
3,368 Posts
Looks great.....:T

· Premium Member
19,397 Posts
Discussion Starter · #12 ·
Bracing made easy. Use the width of the wide end of a framing square to draw a "I" on a 16.5" x 16.5" square.
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Paper Paper product Cardboard Wood Pattern

The cut out brace.
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The brace installed on the driver and amp side.
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Add 4 pieces from the center of the "I" brace to the top and bottom of both PR sides.
Wood Furniture Plywood Box Table

Wood Plywood Box Beige

· Premium Member
19,397 Posts
Discussion Starter · #13 ·
Cabinet lined with egg crate foam. This is my own personal choice, the foam is not included with the kit. The purpose (supposedly) is to damp the back wave of the sub so it doesn't have a "hollow" sound to it. Some people say it has no effect on the sub, some say it does. More testing is needed to verify the benefits or lack of. I have always lined my subs with foam, this one is no exception.
Wood Box Beige Rectangle Wooden block

Foam has to be cut away from the Hurricane nuts. If not, the bolt will snag the foam and the foam will wrap around the bolt and cause binding.
Wood Tile Beige Metal Room

· Premium Member
19,397 Posts
Discussion Starter · #16 ·
wouldn't it be advantageous to support the PR's with a brace between the two to cancel out each others' vibrations?
Since the PR's are mounted opposed to each other I don't think vibration will be an issue.

I have the cabinet completed and all components mounted for a test run.
Loudspeaker Subwoofer Sound box Audio equipment Studio monitor

It's time to tune the Passive Radiators. The sub design calls for 270 grams to be added to each PR. The PR's come with twenty 45 gram washers, so 6 washers need to be added to each PR. With the CSS PR's tuning couldn't be simpler. First unscrew the cap on the PR's center tube.
Audio equipment Loudspeaker Subwoofer Auto part Technology

Add the required washers.
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Tighten down the supplied lock washer and wing nut.
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Replace the center cap. It's that simple!
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With 270 grams added to each PR the box tuning will be 22 hz. Since changing the weights on the PR's is external, I be experimenting with different tuning just because it'll be so easy! :T Listening test will be next.

· Premium Member
19,397 Posts
Discussion Starter · #18 ·
I did a quick listening test on the sub. Testing was done is a 15' by 30' room that is open to other areas. I must say I'm impressed! Music was a Celine Dionne CD that has some demanding bass tracks. The sub had no problem producing loud levels in such a large room. Test tones from 15 hz to 80 hz show what this sub can do. This little guy digs deep! The sub was not corner loaded, it was in the center of the 15' wall and about 2 feet away from the wall. Very impressive performance for a 10 inch sub. I will post a frequency response vs. SPL graph as soon as I get a chance.

· Premium Member
19,397 Posts
Discussion Starter · #20 ·
I did some SPL tesing today to see what the sub is capable of. The sub was placed in a corner of the room with the SPL meter one meter away on a tripod stand. I used the R.S. 33-2055 Digital Meter and applied the correction file to the readings.

10 hz - 104 db
12 hz - 106 db
16 hz - 101 db
18 hz - 103 db
20 hz - 104 db
22 hz - 100 db
25 hz - 102 db
30 hz - 103 db
35 hz - 108 db
40 hz - 113 db
45 hz - 110 db
50 hz - 103 db
55 hz - 101 db
60 hz - 98 db
65 hz - 96 db
70 hz - 95 db
75 hz - 96 db
80 hz - 95 db

The SPL meter was set to fast response and "C" weighting. The effects of room gain are obvious in the 10 -12 hz range, as well as a room interaction issue in the 35 - 45 hz range. I'll get REW setup on my laptop and post a graph, hopefully next week when I get home from work. All in all, I'm impressed with the performance of this 10 inch sub.
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