Rebuilding a pair of srx

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I bought a pair of old SRX boxes for the drivers. So what to do with the cabinets? They are about 200 liters so they should be suitable as bass cabinets for single 2226 drivers. I did some simulations and decided to build a pair of party bass boxes for my nephiew Anton.

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I wanted the port at the bottom of the cabinet. Since the cabinets are trapezoid, the port will be conical. Placing the port at the bottom allowed me to simulate the box using hornresp.

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Input parameters.

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Driver arrangement.

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Schematic.

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Port response.

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Combined response.

The half wave interference at 150 hz is controlled by placing the driver in the middle of the box, at the speed maximum of the standing wave. The full wavelength standing wave at 300 Hz is amplified by the placement of the driver, at the pressure maximum of the standing wave.

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Gluing three 12 mm (½ inch) plywood for the baffle. I am using visco elastic glue in order to reduce standing waves in the baffle.

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Port mounted.

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Port details.

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Bracing added. These should have been placed just below 1/4 and 3/4 from the top. Placing dampening wool on these would allow dampening the standing wave at 300 Hz.

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Dampening wool added

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Baffle mounted

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Trying to dampen standing wave at 300 Hz.

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My friend Hans glueing

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Done!

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Detail.

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Raw response measured outdoors at 1 pi (floor and wall support). Quite close to the simulated response. This measurement was done before adding dampening material in the bracing.

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Gated response. Pulse response looks nice.

My friend Blomman helped me fine tune the system. I am using E-120 and Pioneer PD/PH-50 in the tops. It is actively filtered. The basses started to sound boxish above 170 Hz. The standing wave at 300, or possibly a half wavelength standing wave between front and back could be the problem.

The boxes are designed for 400 Watt input. At 400 Watt xmax is reached.

I am very pleased with the result. I believe these sound as good as BR can sound. They are usable as party speakers in a 100 m2 room. In fact they are pretty good HiFi speakers too.

[GoldcountryJim]

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Nice work! The carpet looks good as a finish on these and makes sense for party boxes. Its also nice to see the hornresp simulation parameters. Is the damping material fiberglass or something else? I'll use fiberglass in my boxes, but get itchy just thinking about it! The baffle looks really solid. Impressive glue-up on that.

Have you measured the low end response?

Great project!

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Thanks GoldcountryJim

I am using wool. This Swedish thread compares different materials: http://www.faktiskt.se/modules.php?name=Forums&file=viewtopic&t=40658. Run through google translate (http://translate.google.com/translate?sl=sv&tl=en&js=n&prev=_t&hl=sv&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.faktiskt.se%2Fmodules.php%3Fnam e%3DForums%26file%3Dviewtopic%26t%3D40658&act=url).

Check my fourth post, it contains the measured response.