Another small PA sub

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Hi

I have build a pair of small PA- subwoofers. The driver I have used is a BMS 12N630. I have no measurements of the finished sub but I have some pictures of the build. Especially the vent is a little shall we say not normal.

Best regards
Uwe

Last picture is a comparison off size.
BMS 18N862, BMS 12N630 and a cheap Visaton BG20
 
Last edited:
Here are the pictures

Hi

Pictures too big the first time

uwe
 

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No measurements yet

Hi Chris

No I do not have any measurements yet. In fact I never tried to measure a loudspeaker before. Some years ago I bought a measurement microphone and installed Arta/Limp on my laptop but never tried it out. I have no idea how to measure and I could need some advise.

From the sound of it with sinus test tones it goes to 35 - 37 Hz, with quit a bump down there. It is louder at that frequency than at 40 or upwards. The plate amp I use has a +3dB at 40 Hz I think. Also I calculated the box to have an overshoot at the bottom end that I wanted to flatten out with a large capacitor. The capacitor will flatten the bump and shift the lower frequency down with a few hertz.

best regards

uwe
 
Size

Hi

Size of the sub is W x H x D: 45 x 49 x 50 cm. I have no filling in them, i tried with some polyester fibers but the sub sounded borring. So I took it out again. Despite the heavy bracing the sides of the cabinet(OSB plates 18 mm) do vibrate a lot at medium power levels. Front plate is 19 and 15 mm mdf glued together.

I had to improvise when it comes to the vent. It is not really long enough. So I put a little piece af mdf at the start and at the beginning to make it longer. With the extra panels the vent is appr. 50 cm long and has a area of 146 cm^2, all edges of it are rounded.

best regards

uwe
 
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