The first amp board was a 3channel tpa3255 board w/bt. Should have worked great, but the built in woofer crossover/independent volume control didn’t pan out for this application. Ordered two plain tpa3255 boards. 18v-50v, 2x300w@4ohm chinese watts.
Measured sub and one mid/tweet only. Not flat by any means. This was the final measurement after an earlier flatter attempt sounded thin in the workplace. The large dip around 5k-14k was surprising because it was not apparent with listening. IMO, with both mid drivers ~14’ish inches apart, and the apparent lobing it creates, both the on and off axis sound like they fill in this area.
Here’s where I sort of messed up by modeling only the woofer and one mid/tweet. With the mid/tweets being so close together, I ‘think’ their interaction had a large affect on the actual measured freq output.
Little bit of eq. Dropped the very bottom out of the equation for more power handling and pulled a hump down around 200hz. Left the top end alone as it sounds good in actual use at work.
The original box was built from 1/2” mdf and simply too big and heavy to be carrying around to the work. Had an idea of using some expanded 1” cardboard to cut weight. This stuff is light and way stronger than you would think but have to be very careful of tightening nuts n bolts down as it will easily collapse the thin wall without some kind of reinforcement. Glued 1/8” formicca wherever something had to be bolted/clamped to the cardboard. The overall weight of the box was greatly reduced, but the weight of the sub/good drivers/amp boards/two batteries all added up and it’s still just too big and heavy to carry to the work. For the most part, it stays in the shop.
Here’s the expanded cardboard used for all of the box except front. As far as resonances go, it’s dead. Going to use this in more builds.
I’ll get the “ measurements later, but the first box was ported with a ~3db hump around 60hz. This was intended as I felt it might be necessary with no boundary reinforcement and a noisy factory environment. Second box is about the same volume but sealed. Mids are in a ~4”x4”x5” internal enclosure with poly and denim stuffing.
Just a suggestion if you are still figuring out enclosures material, I like using 3/8” Baltic when trying to save weight. Rigid and light and then stain for a high end look. Just ideas.
Too late. Done deal. Been using it at work the past couple weeks. Although the enclosure was light weight, after adding all the drivers, crossover, amps, and stuff, it’s still way to big and heavy to take to the work.
The tpa3255 amps pack a punch and sound way better than the $40 prices says they should, but I’m wondering if swapping out some caps would open up their sound.
Yeah I’ve been using the Fosi (and Dayton) amps that use the TPA3255 and they have all sounded pretty darn good to my ears. Based on what has been said in that other amp thread I need to pick up the affordable '200’x2 watt ICEpower and see how it compares at some point.
I ‘think’ they have a bit of a clanky? sound, but yeah, at $40 for these tpa3255 boards, I wonder if they could be modded and compete with the icepower tpa3255ap boards and still be under the icepower $140 price tag? FWIW, these are battery powered so power supply noise is a none issue.
