Nest Music Theater Party Twenty Eight ~ Building The Tri-Ports For Surround Sound 13Jan24-05Feb24

Though I decommissioned the NOnkens, I didn't give up on 5.1; I need some new smaller speakers and can reuse the wild Tang Band W4-2356 full range drivers that I didn't use in the salad bowls. I also need to derive acceptable surround signaling from 2 channel PCM, as well as get DD 5.1 discrete. Here's a shot with the finished full range Tiny Tang Band Tri-Ports as suspended surrounds in the NestMT.

Building Tri-Ports... I really overshot sizing my last two speaker projects for the NestMT and need a scheme for much smaller, hanging surrounds. I chose to build a new small full range speaker. It's a bass reflex I call the Tri-Port. I built a pair from the disassembled NOnken materials and some other scrap 15mm Baltic birch. I made all my own table saw cuts for these small simple cabinets. Here are the starting parts and design "process." Tang Band is not known for their Theil/Small parameter accuracy but I found an article online from a lab guy who received a couple of units and did testing ~ I used his empirical data to guide modeling and decisions.

So these drivers can be used in a sealed cabinet of ~8.5 liters (EBP=92), but would perform better as full range in a larger bass reflex box. For grins I intend to build out in a way I can measure both. Further, to stick to my "small" target size, I will not build the optimal 12.5 liter bass box but will instead stuff a smaller box (to raise it's apparent size by ~20%); this should allow me to get the bass tuning down to ~50Hz... but maybe I won't need that. I won't profile the entire build process ~ I've done so plenty before. Here are the partially finished tiny Tri-Ports; I haven't hole-sawed port holes yet, done any interior stuffing, or done the staining/finishing. They're cool, they're tiny, they sport odd drivers, and will suspend fine as surrounds. I measured and listened to them sealed and sans stuffing for a bit... the cabinet is almost perfectly sized for a sealed box for this driver and they sounded good. They measure decent though I don't yet understand the iceberg 6KHz-12KHz and then reemergence to 20KHz.

I opened up the sealed cabinets and dropped in a center-line of 1" wool fiber for any standing waves and stuffed the rest with acoustic fiber. I also tightened down the cabinet and drivers. I measured again and saw smoothing and improvement at the high end ~ the iceberg is almost gone. All these measurements are taken at the listening position ~3m away. I know the bass could be aided significantly by the intended triple porting but these sound pretty darn good sealed up. They are just surrounds after all and will be supplemented with a subwoofer anyway. After I drill and install the ports, that's it ~ no going back; hmmm... I'll get the rest right first.

Hanging Tri-Ports... I suspended the sealed Tang Band Tri-Ports as is on the keen wall mounts I'd prior added in the Nest Music Theater room. I also re-swept sound pressure levels at their final location, assuredly from the listening position. The graph with one sweep is the 90° one of both speakers at listening position and the double sweep are directly measured at left & right speakers discretely - more as my ears will be oriented at the speakers. Still excellent; still weak bass.

Porting The Tri-Ports [03Feb23]... Today I gutted up and cut the 3 bass ports on the Tri-Ports. The bass is improved without any other loss of fidelity. Of course I measured them too. The 50Hz area improvement is noticeable but subtle in measuring and listening. Here are the unfinished, but ported and stuffed, Tri-Ports... they finally look their name; uhhh Tiny Tang-Bang Tri-Ports.

Finishing The Tri-Ports [05Feb24]... Sanded, stained, polycoated, and rehung the Tri-Ports... I also installed a wall-colored conduit to get the speaker wire back to the surrounds from the electronics in the front of the room. I do have need to finish off installs like this ~ and that's attended by a fear of sight of cabling.